percy harris radiogram · percy harris radiogram gets j stations shillingsworth in radio january...

PERCY HARRIS RADIOGRAM GETS j STATIONS

SHILLINGSWORTH IN RADIO

JANUARY 1933

NEW fSESt'J + NE TUNING PRINCIPLEEXPLAINED (PAGE 737)

STERLINGSTUDIOS

Wireless Magazine, January, 1933

FREE1

for the tkOtAtCONS1

ix C

6 tiCt1t.t.%A141

CIR.CU

Desvredby experts,

thesecNrcu\ts Published

by

are foracrateur

corstructors

re-

t'(c`tare'aM

ccv:)aerse\ect\`ie

set

I4h\ccar easM

be cradeat home.

Ihe k-ev4cosCOCIWOCents

recorr

rrertdedfor

tse 0 the6rcu\ts

assurear urpara\\e\ea

degreeoi

reproduct\or

.

qk040f NCI

success0 both

receptor2,11a

\k 110t,obtikrab\e

frorryour

dea\er, tsit01014gp,oo

.tirteto-day

for your07<

copy

to ikadoPubW6ty,

SectorNk.

LEWCOS RADIO PRODUCTS FOR BETTER RECEPTIONTHE LONDON ELECTRIC WIRE COMPANY AND SMITHS LIMITED, CHURCH ROAD, LEYTON, LONDON, E.IO

Editor:

BERNARD E. JONES

Technical Editor:

J. H. REYNER,B.Sc. (Hons.). A.M.I.E.E.

Wireless MagazineThe Rest Shillingsworth in Radio

Vol. XVI ::

Assistant Editor:

D. SISSON RELPH

Research Consultant:

JANUARY, 1933 :: No. 96 w. JAMES

Published by BERNARD JONES PUBLICATIONS, LTD.. publishers of "Wireless Magazine" and "Amateur Wireless." Editorial and AdvertisementOffices : 58.6r Fetter Lane, London, E.C.4. Telephone: City 3733, 3744. Telegrams: "Beelapee, Fleet, London." Subscription: Great Britain and abroad,

15$. 6d. a year post free (Canada oniy, 135. 6d.). Next issue published on Wednesday, Friday, January ao

emarableAS I write-a fortnight before you read-I look

forward to attending the formal opening of theEmpire short-wave broadcasting station at

Daventry. When these new transmitters come intooperation they will put this country right at the head inshort-wave broadcasting, and every reader's interest inshort-wave affairs and possibilities will be immediatelyincreased.

The station will have been opened and the service longstarted before this issue of " W.M." is published, butyou will welcome Alan Hunter's article in which heexplains the scheme on which the new service is basedand gives details of wavelengths.

I am asking all my enthusiastic constructor readers tocomplete the form which I print on page 711. This isnot a prize competition-it is simply a scheme designedto test readers' wishes in certain directions.'''

I want my readers to tell me-freely and withoutreward-whether they prefer a super -het or the so-called " straight " set ; whether they like variable -muor the ordinary screen -grid valves ; whether they wantone tuning knob or many ; whether they prefer a singleoutput valve or the push-pull arrangement ; and, finally,I should like to have some indication of the amount ofmoney they individually are prepared to pay for theirsets.

I am particularly happy this month in my chief set-the Harris Ethergram, in the design and constructionof which Percy Harris has done extremely well. In hislaboratory he pick -d up no fewer than sixty stations-that is quite goo,' going for a" three "-and his log wassubsequently coyfirmed independently by a member ofthe " Wireless Magazine' staff. I am presentingthis set as a complete battery -operated table radiogram,and am quite sure that it is what thousands of peoplewant for the new year.

You will note the special style wiring diagram repro-duced at half scale and the very great care Percy Harris

Radio Ideashas taken to make the description of the set intelligibleto everybody, whether beginner or enthusiast. I ammaking an innovation with this set. With every full-size blueprint (obtainable at half price by readers usingthe coupon printed on page 792) I am sending, free, ascale, marked with the names of stations, for stickingto the condenser scale.

The ensuing year will unfold a number of remarkableideas in radio. I am in touch with two or three of themore outstanding at the moment. One of them is theiron -cored tuning coil-the Ferrocart-invented byHans Vogt and explained in this issue by AlfredSchneider, a technician in close touch with the inventor.Technical circles are taking a deep interest in this newcoil, and readers may rely upon our keeping them well intouch with the progress of the coil in this country.

You will remember that in October we publisheddetails of the Calibrator, a four -valve battery set whichhas become very popular as the months have passed.In this present issue we are able to present its companion,the A.G. model, which contains only three radio valves(the reduction is made possible by the greater efficiencyof mains valves), although there is, as a matter of fact,a fourth valve used only as a mains rectifier. Thisset, like its predecessor, has a dial calibrated directly inwavelengths.

Are you listening to America nowadays-or ought weto say nowanights ? An article in this issue will helpyou ; it is by I. Godchaux Abrahams and explains whatAmerican stations can be heard, their wavelengths, andthe best times to listen to them. You will bear in mindthat it is quite wrong to suppose that the American sta-tions can only be heard on the short waves.

For the rest of the bill of fare this month, just turnover the pages and see for yourselves. I think you willfind it to be a good issue.

A vent happy New Year to you all !B.E.J.

ro

FOR THE CONSTRUCTORPAGE

MAINS POWER FOR YOUR SET. By the" W.M." Technical Staff 708

THE HARRIS E l'HERGRAM. By Percy W.Harris, M.Inst.Rad.E. .. 713GETTING STATIONS WITH THE HARRIS

ETHERGRAM .. 723THE A.C. CALIBRATOR. By the " W.M."

Technical Staff .. 746THE 1933 ECONOMY S.G.3. Further Hints 760GANGING THE SEVENTY-SEVEN SUPER. By the

" W.M." Technical Staff 768

GENERAL ARTICLESGUIDE TO WORLD'S BROADCASTERS. By Jay

Coote 5911WAVELENGTHS OF THE WORLD'S BADAD-

694IN TUNE WITH THE TRADE. By. Fetter Lane 700EMPIRE BROADCASTING. By Alan Hunter .. 705ON THE CREST OF THE WAVES. By Jay Coote 712HULLO-ALMOST-EVERYBODY 1 Caricatures

by Slade.

.. 724WHAT WE WANT TO HEAR IN 1933. By

Whitaker-Wilson 728NOTES FROM HERE AND THERE .. 739SEVEN WISE MAXIMS 739

ContentsPAGE" CT1AA CALLING." Lisbon's Short-wave

Station .. .. .. .. .. 740DANCE MUSIC : GETTING IT ACROSS 1 ByKenneth Ullyett ........743STORIES OF THE OPERAS : La Traviata .. 745RADIO IN KENYA COLONY .. .. - 745RADIO MEDLEY. By BM/PRESS .. .. 751

VA WIRELESS PARODY. Verse .. .. .. 755SOUTH AFRICAN BROADCASTING ....759LISTEN TO THE NEW WORLD ! By J. God-

chaux Abrahams .... .. 762..PRINCIPAL NEW WORLD STATIONS .. 764

RADIO AS FURNITURE. By Walter H. Clark 766RADIO MUSIC FOR THE NEW YEAR. By T. F.Henn.. .. .. ..

:: (fi)NOTES AND JOTTINGS .. ..AUSTRALIAN SHORT-WAVE TRANSMISSIONS .. 792BLUEPRINT AND INFORMATION COUPONS .. 792INDEX TO ADVERTISERS .. . .. 792

GRAMO-RADIO SECTIONTHE NEEDLE. AND THE RECORD -4. By P.

Wilson, M.A. .. .. 773CHOOSING YOUR NEW RECORDS. By Whitaker -

Wilson and Chopstick .. .. 777

TECHNICAL FEATURES

. .. 7WHAT KIND OF SET Do You WANT1VALVES TO USE IN YOUR SET

SHOULD A TONE CONTROL BE A STANDARDFITTING? By J. H. Reyner, B.Sc.,A.M.I.E.E. 726

WE TEST BEFORE You BUY. By the "W.M."Set Selection Bureau : .

R.I. MADRIGAL THREE .. 732H.M.V. SUPER -HET RADIOGRAM MODEL

532 .. .. 733EKCO SUPER -HET CONSOLETTE MODEL

SH25 734MACNAMARA 'GOLDEN VOICE RECEIVER .. 735EDDYSTONE 7 -METRE CONVERTER 736FERRANTI CLOCK SUPER -HET .. 736

THE NEW IRON -CORED TUNING COILS. ByAlfred Schneider 737

RADIO IN REVIEW. By Morton Barr 742AMONG THE " DWARF WAVES. By Morton

BarrVARIABLE.. . " 754CONDENSER. By Percy W.THE

Harris, M.Inst.Rad.E .. 756SET REPORTS FROM OUR READERS .. .. 783TESTS OF NEW APPARATUS .. 784

731

?egistered at the General Post Office for transmission by Canada Magazine Post

681

Postage on this issue, 3d. (inland and abroad).

T

rWireless Magazine, Jatwarx 1933

/0111110MATCHED TUNING UNIT

MAK IPAIrld:st off Me yea4HEAR

OF THE

FORIv-rk)'THUR PREEN & Ce LTD.

TRIPLE GANG, MATCHED

TUNING UNITSpecified without alternative

FORMO TRIPLE GANG ASSEMBLYAS SPECIFIED

Complete Coil and CondenserAssembly; Matched H.F.and 1st and 2nd Band PassCoils, with ganged switching,mounted on aluminium basewith triple gang condenser.

DUAL SANG ASSEMBLYBand Pass, Cat. No. 72C.Aerial and H.F., Cat. No. 68C.

46t6CAT. No. 69C

3 316

WJITH this outstanding set, Mr. Percy HarrisW proves what an infinitely finer receiver you

can build with a FORMO Matched Coil andCondenser Assembly.

The heart of the "Ethergram" is a FORMOTriple Gang Tuning Unit. The results obtainedare sotnething new in radio performance and instraightforward set construction.

The complete Formo Assembly provides thefinest band-pass tuning obtainable. It enablesselectivity and volume to be instantly adjustedto meet any conditions. The unit is all ready forthe set, with coils perfectly matched and con-densers accurately ganged. Its accuracy ensuresperfect results. It simplifies construction. With ityou can build a truly "great" set.

Ask your dealer. Be sure you get a FORMOAssembly as specified. If you have anydifficulty in obtaining, please send us yournearest dealer's name and address.

FORMOLondon Showrooms :-23 GOLDEN SQUARE, PICCADILLY CIRCUS, W.I.Head Office CI Works : Crown Works, Regents Park, Southampton

682

It helps us if you mention " Wireless Magazine"

Wireless Magazine, ,,u: 1933

FORMO COMPONENTSareThe Makincfof a better Set

foremost for Best Results 1 Long Service , Reliable Performance

FORM()MAINS

CONDENSERS

Formo Mains Condensers are the out-come of much patient research whichhas produced a new standard ofefficiency in Mains Condensers. FormoCondensers are tested by the suddenapplication of the test voltage, insteadof through a non -inductive seriesresistance. In this way the Condensersreceive a surge test in addition to thesteady application of the test voltage.The special features of Formo MainsCondensers are :High Test Voltage. High WorkingVoltage. Insulation Resistance not lessthan 2,500 megohm per mfd. at work-ing voltage. Low A.C. Resistance.Low Power Factor. Long Life. LowPrice.

Cat. No. 39.C. 1 mfd. 2'640.C. 2 mfd. 3 341.C. 4 mfd. 5 642.C. 6 mfd 8 -43.C. 8 mfd 10 6

fREttBLUEPRINTSof 3 efficient

FORMOCIRCUITS

The FamousFORMO - DENSOR

Type "J"Specified for the"ETHERGRAM"The FORMO-DENSOR was unques-tionably the pioneer among smallCompression Type Condensers, and hasbeen for many years the foremostPre-set Condenser in the world.FORMO-DENSORS are used for alarge number of purposes and aredesigned to take the Ace of theordinary small Fixed Condenser wheresome flexibility in capacity is required.The knurled knob permits a VernierAdjustment which can be locked in anypre -arranged capacity by means of thelocking nut provided.Insist on a FORMO-DENSOR. Ever',dealer will supply on request, even if

at the moment out of stockType F. .0001-.000005 1/6

J. .0003-.000025 116,, G. .001-.0002 16

H. .002-.001

FORMO has designed three of the mostefficient receiver circuits of the year, whichenable the home constructor to build aparticularly fine set at a moderate cost.The FORMO Band Pass Screened Grid 3,

The Band -Pass 3,The Straight Three.

Write for Free Blueprints and completeconstruction Guides.

Post the CouponRemember the name FORMO has for over ten years stood for theforemost in radio components. If your usual dealer is out of stockof any FORM() lines, please write direct to us.

FORMOLondon Showrooms:

23 Golden Square, Piccadilly Circus, W.1Head Office and Works : Crown Works, Regents Park, Southampton

FORMO DUAL -

RANGE SWITCHEDCOILS

Formo Dual Range Coils are designed togive the finest possible selectivity with acomplete absence of break -through be-tween the long and medium wavebands.Careful selection of insulating materials, tominimise the losses, and careful combi-nation of inductance values and coupling,ensure a very high degree of selectivityunder all conditions.There are separate coupling coils for thelong and medium waves. Optional tap-pings are provided on all coils. Each coilis efficiently screened with screen cans indistinguishing colours. The switchingmechanism is definite and reliable withgold -silver contacts. A wiring diagram isfixed inside each coil.

El. P. Coils on atss-Matched Aerial and' Imintum base with Cat. No.ganged switching. 70 C.

Matched tat and 2ndBand Pass Cons and 23 /6H.F. Coil ON alst-stsiniane base with Cat. No.ganged .saliching. 71 C.I ME WM WM MIMI MB OM I= El IIIII NM II EN

I23 Golden Square, Piccadilly Circus, London, W.1

Aerial, H.F., 7 /and 1st and2nd BandPass Coils. each

II

I

Address1

FORMO

Please send me the Formo Catalogue and FREEBlueprints and construction Guides of the FORMOBand -Pass S.G.3, FORMO Band -Pass 3, and FORM()Straight Three.

(Cross out those not required.)

Name

W.M. Jan. 33.

683

Please me ntion "Wireless Magazine" when corresponding with advertisers

Wireless Magazine. January, 1933 i

pi IN /WV TA Wry' Lk y. 'Kan 111 0AL11113 iv WE III

Characteristics of All the Most Important British Types

Mace Typeti

iLfi

gz .211:4

s

1

mc°a

II

`',, El

el -11

TypeI II

1 ig 1

,...

1 -ta

M

0..,

make Type

4

-140-24.1

8

t ;a -4

42

2 -volt Three -electrode Valves 2 -volt Variable -mu Valves 6 -volt Three -electrode ValvesMazda ,,,,.! . . I-1210 59,000 47.8 .5 Lissen 40

1:8Lissen" .. 14210 50000 35 7 10 Mazda : : S2 RIM 3r),SSS 7-00 1:70 - Mazda .. -112% ZS :g5Cossor .. 21ORC 50,000 40 .8 .5 Mazda .. S2 I 5B 334,000 700 2.1 - Lissen .. 11610 60,000 40 .66 1.0Osram .. H210 50,000 35 0.7 1.0 Cossor 220VSG 110,000 - I.6 - Marconi .. 11610 60,000 40 .66 .35Six -Sixty . . 21ORC 45,400 50 1.1 1.0

..Osram VS2 - - 125 - Osram .. H610 60,060 40 .66 35

Lissen . . 1-12 45,000 50 1.1 2.0..

Marconi VS2 .- -- 1.25 - Six -Sixty .. 6075RC 58,000 42 .7 .5Mazda .. I-12 45,000 50 1.1 1.8

..Six -Sixty .. 2I5VSG - - -- - Cossor .. 6 IORC 50,000 40 .8 .75

Mallard . . PM I A 41,600 50 1.2 .75 Mallard .. PM5B 49,000 40 .85 .5Marconi . . 1-12 35,000 35 1.0 1.0 2 -volt Pentode Values Marconi .. HL6I 0 30,000 30 .0 1.0Osram 1-12 35,000 35 1.0 1.0 Osram .. HL6 10 30,000 30 .0 1.0Six -Sixty 210HF 25,000 19 .75 1.0 Lissen .. PT225 71, COO 100 1.4 7.0 Lissen .. HL D610 21,000 25 .2 2.5Osram HL2 10 23,000 20 .87 1.5

Six -Sixty .. 230PP 64,000 80 1.25 10.0 Cossor 6IOHF 20,000 20 .0 1.75Marconi HL2 10 23,000 20 .87 1.5 Marconi .. PT240 55.000 90 1.659.0 Mazda : HL6 I 0 20:000 22 .1 1.8Mallard PM I HF 22,500 18 8 1.0

Lissen .. PT240 28.000 64 2.3 12.5 Mallard : . PM5D 20,000 26 .3 1.0Cossor 2IOHL 22,000 24 .1 1.75 C.'"" " 220PT - - 2.5 - Six -Sixty . . 6071 -IF 15,200 7 .1 2.0Lissen .. H,_2 22,000 35 .8 3.0 Cossor .. 220HPT - - 2.5 - Mallard . PM5X 14,700 7.5 .2 1.6Mazda .. HL2 21,000 32 5 3.6 Marconi .. PT2 - - 2.5 5.0 Six -Sixty .. 610D 9,250 8.5 2.0 2.0Lissen .. HL210 20,000 20 0 2.2 Mazda .. 220APen. - - 2.5 - Mullard . PM6D 9.000 8 2.0 2.0Mullard .. PM I HL 20,000 28 4 1.2 Mazda .. Pen.2.20 - - 2.5 - Lissen . . L610 8,100 6 2.0 2.0Six -Sixty .. 2IOHL 20,000 26 .3 1.0 Mallard .. PM22A - - 2.5 4.0 Cossor .. 6IOLF 7500 5 2.0 3.4Mazda . . 1-1L210 18,500 26 .4 3.0 Mullard .. PM22 - - 1.3 12.0 Marconi .. L6 I 0 7:500 5 2.0 3.0Marconi . . HL2 18,000 27Osram.5 1.0 Osram .. PT2 - - 2.5 5.0 L6 I 0 7,500 5 2.0 3.0Osram HL2 18,000 27 5 1.0 Six -Sixty .. 220Pen. - - 1.5 - Mallard : : PM6 3,550 8 2.25 7.0Cossor .. 210FIF 15,800 24 5 2.2 Cossor 610P 3,500 8 2.28 8.0Cossor .. 210Dat 13,000 5 .15 2.5 Marconi .. P610 3,500 8 2.28 6.0Six -Sixty .. 210LF 12,500 0.6 .85 2.5 4 -volt Three -electrode Valves Osram .. P6 I 0 3,500 8 2.28 6.0Mullard . . PM I LF 12,000 I .9 2.6 Marconi 14410 60,000 40 .66 .5 Six -Sixty 610P 3,400 7.8 2.3 8.0Osram .. L210 12,000 I .92 2.0 Osram .. H410 60,000 40 .66 .35 Lissen .. P610 3,210 8 2.5 6.0Marconi .. L210 12,000 1 .92 2.0 Lissen .. H410 60,660 40 .66 1.0 Cossor .. 625P 2,500 7 2.8 13.0Mullard .. PM2DX 12,000 8 1.5 2.0 Six -Sixty .. 4075RC 58,000 37 .64 .55 Lissen .. P625 2,500 7.5 3.0 8.0Six -Sixty . . 21013 10,000 8 1.6 2.0 Mullard .. PM3A 55,000 38 .66 .3 Marconi .. P625 2,400 6 2.5 11.0Cossor .. 210LF 10.000 4 1.4 3.0 Cossor .. 410RC 50,000 40 .8 .6 Osram .. P625 2,400 6 2.5 11.0Liman .. L210 10,000 2 1.2 3.0 Lissen .. HLD4 I 0 21,000 25 .2 2.5 Cossor .. 610XP 2,000 5 2.5 15.0Linen L2 10,000 20 2.0 3.0 Marconi .. HL4 1 0 20,800 25 .2 1.25 Mullard .. PM256 ,850 6 3.25 8.0Mazda . . L2 10,000 9 1.9 3.0 Osram . HL4 I 0 20,800 25 .2 1.25 Six -Sixty .. 625SP ,780 5.8 3.25 8.0Marconi . . P215 5,000 7 1.4 6.0 Cossor .. 410HF 20,060 22 .1 1.0 Marconi P625A ,600 3.7 2.3 20.0Osram .. P215 5,000 7 1.4 6.0 Mullard .. PM3 13,000 14 .05 2.0 Osram . . P625A ,6C0 3.7 2.3 16.0Six -Sixty .. 220P 4,800 7.2 1.5 5.0 Six -Sixty .. 4075HF 12,500 13.5 .1 3.0 Linen . . P625A ,500 4.5 3.0 12.0Mullard .. PM2 4,400 73 1.7 5.0 Cossor .. 410LF 10,000 17 .7 2.5 Six -Sixty .. 625SPA 500 3.9 2.6 20.0Lissen

: : '28:SSNLissen1S7 1.75

MarconiL410 8,500 15 .8 3.5 Mullard : :PN6AISMazda Pg0

3.62.620.0ssor

Cossor ..22215P 4,000 9 2.25 5.0 Osram .. L410 8,500 15 .77 3.0

Cossor .. 220Pa 4,000 16 4.0 5.5 Mullard . . PM4DX 7,500 15 2.0 2.0 6 -volt Screen -grid ValvesMarconi .. LP2 3,900 15 3.85 6.0 Six -Sixty . . 41013 7,250 14.5 2.0 4.0 Six -Sixty .. SS6075SG 210,000 190 .9 -Osram .. LP2 3,900 15 3.85 6.0 Marconi P410. 5,000 7.5 1.5 6.0 Cossor .. 610SG 200,000 200 1.0 -Mazda .. P220 3,700 12.5 3.4 11.0 Osram P410 5,000 7.5 1.5 6.0 Mullard .. PM 1 6 200.000 200 1.0 -Six -Sixty .. 220PA 3,700 13 3.5 6.0 Six -Sixty .. 4101' 4,100 7.8 1.9 7,5 Osram .. S610 200,000 210 1.05 4.0

Mullard .. PM2A 3,600 123 33 6.5 Cossor 410P 4,000 8 2.0 8.0 Marconi .. S610 200,000 210 1.05 4.0

Limn ..Marconi ..

LP2P240

3,5002,500

12.04

331.6

9,02.0

Millard ..Linen . .

PM4P410

4,0004,000

88

2.02.0

7.57.0 6 -volt Pentode Valves

Marconi .. P2 2,150 7.5 35 2.0 Marconi . . P425 2,300 4.5 1.95.14.0 Marconi .. P T625 43,000 80 1.85 0.0

Osram .. P2 2,150 73 3.5 0.0 Mullard .. PM254 2,150 6.5 3.0 9.0 Charm .. PT625 43,C00 80 1.85 0.0

Six -Sixty .. 220SP 2,060 7 3.4 3.5 Six -Sixty .. 420SP 2,150 6.5 3.0 10.0 Six -Sixty .. SS617PP 28,500 54 1.9 5.0

Mullard .. PM202 2,000 7 3.5 4.0 Marconi .. P415 2,080 5.0 2.4 14.0 Lissen .. P C625 14,000 60 2.5 4.0

Mazda .. P240 1,900 7 3.7 8.0 Osram .. P415 2,080 5 2.4 14.0 Cossor .. 6I5P - - 2.0 7.0

Mullard PM252 1900 7 3.7 4.0 Cossor .. 425XP 2,000 7 3.5 13.0 Mallard .. PM26 - - 2.0 5.0..Six -Sixty .. 240SP 1,900 6.6 3.5 4.0 Mazda .. P425 1,950 3.5 1.8 26.0Mazda .. P220A 1,850 63 3.5 3.0 Lissen .. P425 1,500 4.5 3.0 28.0 a

1"

i 12Lissen .. P220A 1,700 6 3.5 2.0 Cossor . . 415X1' 1,500 4.5 3.0 15.0 s. "0 ig a 8

Q.Liman ..Cossor ..Lissen ..

PX240230XPP240A

15001,5001,000

4.54.55.0

3.03.05.0

2.05.0

20.0

Osram ..Cossor ..Marconi ..

PX254XPPX4

1,2651,200

830

934.85

7.54.06.0

-13.035.0

Make Type

A"aI4aal

0Iti .

g[I.8 Paor-1.1 a.E

2 -volt Double -grid Valves Osram .. PX4 830 5 6.0 35.0

Marconi .. DG2 3,750 4.5 1.2 - 4 -volt Screen -grid Valves A.C. Three -electrode ValvesOsram .. DG2 3.750 4.5 1.2 - Castor 4 G VI 000 800 1.0 - Six -Sixty .. 4DX.AC 36,000 7.5 2.1 3.0Cossor .. 210DG 3,400 2.7 .8 - Mullard : : PMI4 230,000: 200 - Mullard .. 904V 34,000 75 2.2 1.8Mullard..Six -Sixty ..21ODG

PM1DG -- -- .8.8

-- Six -Sixty ..Lissen ..

4075SGSG4I 0

220,000200,060

190180

.87

.87

.93.0- Cossor ..

Cossor ..41MRC4IMH

9.5008,000

5072

254.0

2.72.0

2 -voltLissen ..

ScreenSG2 15

-grid900,000

Valves1,000 1.1 - Marconi ..

Osram ..5410S410

200,000200,000

180200

.91.0

333.5

Cossor ..Six -Sixty ..Mallard ..

41MHt:4GP.AC

354V

5,4002,0602,000

413636

2.83.03.0

3.04.04.0

Mazda .. S215A 727,000 800 1.1 - Linen .. AC/HL 1,700 35 3.0 6.0Mazda .. 215SG 455,000 500 1.1 - 4 -volt Pentode Valves Mazda .. AC/HL 1,700 35 3.0 5.0Six -Sixty_ .. 218SG 357,000 500 1.4 - Marconi .. PT425 50,000 100 2.0 8.0 Cossor .. 4IMHL 1,500 52 4.5 4.0Mullard .. PMI2A 330,000 500 1.5 - Osram .. PT425 50.000 100 2.0 8.0 Mazda .. AC2HL 1,500 75 6.5 4.5Cossor . . 215SG 300,000 330 1.1 1.25 Marconi .. PT4 50,000 110 2.2 - Marconi .. MH4 1,100 40 3.6 4.75Osram .. S215 300,000 180 0.6 - Osram .. PT4 42,600 120 2.85 - Osram .. MH -1 1.100 40 3.6 4.75Cossor .. 220SG 200,000 320 1.6 1.5 Linen .. PT425 28,000 70 2.5 15.0 Micromesh .. HLA I 0,000 80 8.08 6.0Osram .. S22 200,000 350 1.75 3.0 Six -Sixty .. 415PP 27,000 60 2.2 15.0 Marconi . . .. MHL4 8,000 20 2.5 10.0Marconi .. S22 200,000 350 1.75 23 Osram .. PT25 25,000 100 4.0 - Osram .. MHL4 8,000 20 2.5 10.0Marconi .. S21 200,000 220 1.1 3.0 Cossor .. 41OPT - - 2.5 12.0 Cossor .. 4 I MLF 7,900 15 1.9 9.0Osram .. S21 200,000 220 1.1 3.0 Mazda .. 425Pen. - -- 2.4 14.0 Six -Sixty .. 4L.AC 7,500 15 2.0 8.0Six -Sixty .. 215SG 190,000 200 1.05 2.0 Mullard .. PM24 - - 1.75 16.0 Mullard .. I64V 4,850 16 33 8.5Mullard .. PMI2 180,000 200 1.1 - Six -Sixty .. 4Pen.M - - 3.0 - (Continued on page 686)

684

ACCURACY... meticulous .

microscopic

MACHINES whirr . . . . filaments finer than a hair

.... nimble fingers work .... grids are wound .

anodes pressed . a hundred operations .... another

Cossor Valve is made . . made wiih the precisionof a watch . . . . accurate . . . microscopic distances

exactly spaced .... meticulous accuracy .... accuracythat ensures that your Cossor Valve . . . . whereveryou buy it . . . . whatever its type . . is the exactcounterpart of the original laboratory -developed design.

To A. C. COSSOR LTD.. Melody Dept., Highbury Grove,London, N.S.

Please send me, free of charge, a copy of the 40 -page Cossot Valve andWireless Book B.17.

Name

Address

W.M. JAN.


OSSORVALVES

Send for a free copy of the 40 -page Cossor Valve andWireless Book which contains a wealth of interestingand useful information including Radio Definitions-Useful Circuits-List of Stations, etc., etc. Please usethe Coupon.

A. C. Cossor Ltd., Highbury Grove, London, N 5 Dep.ots at Birmlnoam, Bristol,Glasgow. Leeds, Liverpool. Manchester. Newcastle Sheffield, Belfast and Dublin,

Advertisers like to know you " saw it in the Wireless Magazine '

685

.

Wireless Magazine, Januarx 1933

VALVES TO USE IN YOUR SET -continued from p. 684

Make Type ri.5.

Make Type

211 41.; 4

Make Type

a

A.C. Three -electrode Valves -ContinuedSix -SixtyMallardOsramMarconiMullardLissenMazdaCossorMullard :

CossorMazdaSix -SixtyMarconiOsramMallardMullard ..Micromesh

SS4PAC 3,170104V 3,000ML4 2,860ML4 2,860

AC104 2,850AC/P 2,800AC/P 2,6504IMP 2,500AC064 2,00041MXP 500AC/PI 4501-1PX2V411 450

5 ,265PX25 ,26505V 50

AC0444 ,1250

PA I ,050

2222000

168.7

11.25.46.39.59.5

412.6

3.84.04.24.23.53.63.757.53.07.53.73.07.57.54.03.512.0

11.017.025.025.0

1.020.013.024.020.040.020.018.0

30.030.035.0

A.C. Double -grid ValvesCossor 4 1 MDG 40,000 I 10 I .251 -

A.C. Screen -grid ValvesSix -SixtyMallardMazdaMazdaMarconiOsramSix -SixtyMallardCossorMarconiOsramLissenSix -SixtyMullard

4SGACS4V

AC/SGACS2MS4MS4

4XSGACS4VA

41MSGMS4BMS4BAC/SG

SS4MMACS4VB

1,000,000909,000630,000600,000500,000500,000485,000

400,000350,000350,000340,000300,000257,000

1,0001,1,C01,7003,000

550550

.600000000120120100900750

1.0I 1

3.05.01.1

1.1

3.32.02.53.23.23.253.02.5

1.52.54.04.02.52.5

4.53.03.53.58.0

9.5MazdaMazda

Cossor MSG/ HA 209,000 780 2.0Cossor MSGLA 200,000 750 3.75Six -Sixty .. 4YSGAC - 900 3.5

A.C. Variable -mu ValvesLissenCossorMarconiMazdaMazdaMallardOsramMallard

MarconiOsramMarconiOsramCossorCossor

MazdaSix -SixtyMallardLissenCossorCossorMullardMallardMu' lardMullard

.

ACSGVMVSGVMS4

ACISG,VMAC/S1,VM

MM4VVMS4VM4V

300,000 -200,C00

A.C. Pentode ValvesPT4 42,000PT4 42,000

. MP T4 33,000MPT4 33,000

MS.Pen.AMP.Pen.AC/Pen.

SS4Pen.ACPen.4V

. AC/PTPT41

PT4I BPM24APM24B

. PM24PM24M

12010100100

2.52.43.014.0

2.4

2.852.853.03.04.04.02.53.03.02.63.02.252.02.13.03.0

2.15.2

7.8

6.05.8

10.0

8.2

32.032.032.032.09.0

30.030.0

28.030.030.020.030.030.030.0

D.C. Three -electrode ValvesFilament Current .1 Ampere

DC3HL 11,700 35 1 3.0DC2P 2,650 10 1 3.75

5.015.0

Filament Current .25 AmpereMarconi DH 10,800 40 3.7 6.0Osram DH 10,800 40 3.7 6.0Marconi DL 2,660 12 4.5 25.0Osram DL 2,660 12 4.5 25.0

Filament Current .5 AmpereMazda .. 1 DC/HL 1 13,000 1 35 12.7Mazda .. 1 D../P 2,220 1 10 `4.5

D.C. Screen -grid ValvesFilament Current .1 Ampere

Mazda .. I DC2SG 1 - 11,200 2.0 14.5

Filament Current .25 AmpereOsram .. DS 550,000 500 1.1 2.5Marconi .. DS 540,000 500 1.1 2.5Osram DSB 350,000 1,120 3.2 3.5Marconi .. DSB 350,000 1,120 3.2 3.5

Filament Current .5 AmpereMazdaMarconi

DSCG - 4.0VDS - - 2.4 -

Osram VDS - 2.4

D.C: Pentode ValvesFilament Current .2 Ampere

.. I DC/2Pen. - I - 12.5 13.0

Filament Current .25 Ampere

Mazda

MarconiOsram

3.015.0

DPT 1 32:241 90 13:2 i12:2

Filament Current .5 AmpereMazda .. 1 DC/Pen. 1- I- 13.5 1 3 0

BUILD FROM A BLUEPRINT !ONE -VALVE SETS

is. each, post freeShort-wave One-valver (6d.) AW327Easy -to -Build One .. AW304

AW344Portable Short-wave One .. AW354

TWO -VALVE SETSAll these Is. each. post free

Ever -tuned Regional Two (D, Trans) .. WM241Station -finder Two (D, Trans) WM243Music -lover's Two (D, Trans) WM260New Economy Two (D, Trans).. .. WM265Family Two (D, Trans) .. WM278Economy A.C. Two (D, Trans) WM286Screen -grid Two (SG, Trans) .. WM289Two for Seven Metres (D, Trans) .. WM295New Style Radiogram (D, Trans) WM299

THREE -VALVE SETSAll these Is. each, post free

New Plug -in -Coil Three (D, 2 Trans) WM270Transportable Three (SG, D, Trans) .. WM271Multi-Mag Three (D, 2 Trans) .. WM288Percy Harris A.C. Radiogram (D, RC,

Trans) .. WM294Prosperity Three for Batteries (SG, D,

Pen).. WM296Prosperity Three for A.C. Mains (SG,

D, Pen) .. WM297Prosperity Three for D.C. Mains (SG,

D, Pen) .. _ WM2981933 Economy S.G. Three (SG,D Trans) WM306*Harris Ethergram (SG, D, Trans) WM308*A.C. Calibrator (SG, D, Trans) ... WM309

Each blueprint shows the position ofall components and every wire, andmakes construction a simple matter.Index letters "A.W." refer to "Ama-teur Wireless" sets and "W.M." to

:'Wireless Magazine" sets.

Send, preferably a postal[order (stamps over sixpencein value unacceptable), to -

New Regional Three (D. RC, Trans) .. AW349World -ranger Short-wave Three (D,

RC, Trans) .. AW355Wizard (SG, D, Trans) _ AW360Harris Build -as -you -learn Three .. AW366£2 2s. Family Three (D, 2 Trans) .. AW368

FOUR -VALVE SETSAll these is. 6a. each, post free

Economy Radio Gramophone (SG, D,RC Trans) .. . WM276

A.C. Quadradyne (2 SG, D, Pen) .. WM279Ideal A.C. Home Super (Super -het) .. WM290Gold Coaster (AC Short-wave) .. WM292Triple -tune Four (2SG, D, Trans) .. WM293Calibrator (SG, D, RC, Trans) _ .. WM300Table Quad (SG, D, R.C. Trans) .. WM303

FIVE -VALVE SETSAll these is. 6d. each, post free

Regional D.C.5 (SG, D, LF, Push-pull) WM252Ideal Home Super (Super -het) . .. WM280Easytune 60 (Super -het) WM284Easytune 60 on a Frame Aerial (Super -

het) . - WM301"W.M."; Short-wave Super (Super -het) WM302Ilritain's Super (Super -bet) AW31 IA.C. Britain's Super (Super -het) AW322

Mains section (1/-) ..AW322AJames Sh'ort-wave Super -het .. . AW3.28Simple Super (Super -het) .. AW340

SIX -VALVE SETSAll these Is. 6d. each, post free

Super 60 (Super -het) WM229A.C. Super 60 (Super -het Radiogram).. WM239A.C. Super 60 (Super -het Table Model) WM245Super 60 (with Wearite Base) .. WM249Super 60 (with Lewcos Base) WM2511932 Super 60 (Super -het) W11226729

1932 A.C. Super 60 (Super -het)New Century Super (Super -het) with

copy of A.W. 4d. post free .. AW363A.C. Century Super (A.C. Super -het) AW365

SEVEN -VALVE SETSIs. 6d., post free

Super Senior (Super -het) . WM256Seventy-seven Super (A.C. Super het) WM305

PORTABLE SETSSuper 60 Portable (Super -het) . WM238 1/6Home and Garden Three (D, Rd,

Trans) .. WM246 1/ -Town and Country Four (SG, D,

RC, Trans) WM282 1/6Everybody's Portable (Super -het) WM291 1/6General-purpose Portable (SGD, RC,

Trans) .. AW351 1/6

AMPLIFIERSAll these is. each, post free

Quality Amplifier (D.C.) ls. 6d.A -P -A (Public Address) A -P -A Radio Unit (SG, D) .

Economy Gramophone AmplifierDual -speaker Amplifier (A.C.)

.

.

WM264WM275WM281WM277WM304

MISCELLANEOUS"W.M." Standard A.C. Unit .. WM214"W.M." Standard D.C. Unit .. WM215Super 60 A.C. Unit (for Battery

Super 60) .. WM248Simple Neon Oscillator .. WM251Plug-in Adaptor .. WM267Super -het Adaptor .. WM268A Simple Mains Unit .. WM283Short-wave Director (wavemeter) WM285Voltage Regulator . WM287*A.C. Mains Unit. .. WM310

11-1 /-

1/-1/-1/-1/-1/-6d.1/-1/-

A blueprint of any one set describedin this issue can be obtained for halfprice up to the date indicated on thecoupon (which is to be found on thelast page. These blueprints are marked

with an asterisk (*).

WIRELESS MAGAZINEBLUEPRINT DEPT.,

58/61 FETTER LANE,LONDON, E.C.4.

686

,\oc*. '\N<cr

2v. 80 AMP. HRS. 11/6D.

[ Wireless Magazine. January, 1933 1

mE-LESSACCoAft

'V4s1/0

LASTS

TWICE

AS LONG

ON EACH

CHARGETHIS is the power source of a new era-a neat, richly coloured cylinder in place of the admittedly crude,

present-day accumulator. It is the independent patent of Mr. Leonard Fuller, M.I.E.E. (whose father and

grandfather made world-famous accumulators from the days of Faraday on). Called the Block plate -less

Accumulator, it gives 8o

not run down when

NEGATIVE1

amp. hours at little more than the cost of a modern 40 amp. hour accumulator. It will

out of use (no waste of the charge). And how it lasts ! (It is almost unbreakable). The

diagram shows its secret-the inefficient " plates " of the modern accumulator are

avoided by a special process that enables the accumulator cylinder itself to be made

the negative electrode, the positive electrode being a central core. (Hence the

ideal of unimpeded active surface, and even radial action.) Consider the result-

twice the life per charge ; more compact ; simpler; immeasurably stronger.

More than a battery-de-luxe-a revolution ! Get a Block Accumulator from your

dealer to -day, and be rid of old-time battery inefficiency.

PO ITIV1CORK BLOCK BATTERIES LTD ABBEY ROAD BARKING

687

Wireless Magazine. January, 1933

SELECTIVITY SELECTIVITY SELECTIVITYNo set is really up-to-date and able to meetmodern conditions unless it incorporatesGanged Tuning. And no set can be of thehighest efficiency unless this tuning is carriedout with a Polar " Star " Ganged Condenser.Where a " UNIKNOB " is used, tuning isgreatly simplified and, what is more impor-tant, there is a marked increase in selectivity.

The "Uniknob " is matched to within of 1% plus or minus1 mmfd. and rigid die-cast construction maintains this

0 accuracy under all conditions of use. A trimmer of 35 mmfd.in parallel with the front section is operated by a small knobsituated concentrically with the tuning knob, allowing thefinest adjustments to be easily made.

Ask your dealer for-

MARangenco

POLAR

"UN I KNOB"2 a .0005

PRICE

INCLUDINGCOVER

19/6Polar Condensers --obtainable from alldealers. Write for catalogue "W.M."which describes the full Polar range.

WINGROVE & ROGERS LTD., 188-9, STRAND, LONDON, W.C.2.

Tests ProveIt

the most suitable

for the 193 3Economy S.G. 3

The designers of the Economy 3used and specified the Press -land Coil exclusively. Theirexhaustive tests proved itscarefully balanced design togive greater selectivity andmaximum magnification with-out instability. Without breakthrough from short to longwaves. A screening box issupplied with each coil andterminals are clearly markedfor connection. Suitable foraerial or anode tuning. Writefor Free leaflet.Price at all radiodealers or fromt h e manufac-turers, post free. 4'6

PRESSLAND

C IpRESSL AND (SAL, S) LTD., 84, Eden Street,

Kingston -on -Thames

POLAR W'KS, LIVERPOOL

WHY NOT ?

FIT A (MIDRELIANCE

PICK-UP AND CARRIERIn the RADIO -GRAMYOU ARE MAKING

Acknowledged to be"First-class" in value,Tone and Workman-

shipNo Needle Screw

Turnover HeadArm In-

corporatesa Rest

Ask yourDealer or 15%

write eachLIMIT RADIO LTD., .5/.:0 Windsor St.. N.1

M I C RO FU"ETHER RAM'The Pure Gold Film of theMicrolu " blows" underoverload before the wire Mseven time to get warm, andguarantees full protection. FUSE 6d.

Absolutely Reliable.Mc!, British Holder 6d. Complete 1/ -

For full technical details of the Microfu andprices for special ratings, write for Folder M.MICROFDSES, Ltd., 36 Clerkenwell Ri.,E.C.1

7 elephone: Clerk. 4048Dam. 0

:1'

rtADI SuPPLISend your list of Radio needs for our quotation, Kite,Parts, tete, etc. Everything in Radio stocked. Promptdelivery seven days' approval. Catalogue free.Taylex and Standard Wet H.T. replacements stocked.B. TAYLOR, 67 Studley Road. STOCKWELL, LONDON

...,C It

RVOlegtSC0t4ST ,9fiv4ei,

7 51017.75st

15l7C:104°14

A Present that will be appreciated Is aCLIX

CONSTRUCTOR'S KITIt contains 9 Panel Terminals, 2 Spate Terminals, 6 " Master "Plugs; all the co nponents necuissary to give perfect A., E., R.I.,G.B.,L.T., and L.S. contact to any two- or three -valve receiver.

C..1 " 400 KIT Obtainable fromComplete Kit includes 3 Specified 61.11: all DealersWander Plugs, 9 Clix, H.T. " Master"Plugs, 11 Clix Panel Terminals. A Interesting Pol.All engraved. Price

0:1 VA !I 0411,:i4.-111-1WilliKel VANSLECTRO L1NX Ltd., 264, Vauxhall Bridge Road, 8,W,1

When you send your order don't forget to say you saw it in the ' W.111: "

688

AV No.101 ChokeSpecified for the A.C.

"Calibrator"

Illustration shows the DAVENSET Core -TypeTransformer

The incorporation ofthe "DAVENSET" 101L.F. Choke in the A.C."Calibrator" is typicalof the high reputationDavenset Mai ns Trans-formers and Chokesenjoy amongst expertsin radio set design.The homeset construc-tor will find in themthoroughly reliableand sound equipmentof the highest qualityand most original de-sign which w.11 make amaterial contributionto thesuccessof his set.

WRITE FORa copy of Mains Trans-formers and Power Smooth-ing Chokes for Radio and

Industrial Purposes."

PARTRIDGE, WILSON & CO.Dept. 31, Davenset Works, Leicester.

Scottish Branch : 200 Vincent Street, Glasgow, C.2.

FOR YOUR SET THERE ISA CAMCOCABINET

THE CAMCO "POPULAR"An Inexpensive Cameo Cabinet thatmeets the requirements of mostlisteners. Specially suitable for con-verting sets into radio-grams. Finished in shadedwalnut. Price 75/ -See these Cabinets among others at ourshowroom, open 9.15 to 5.45 (Saturday12.30), and send coupon for free copyof New Camco Cabinet Catalogue.

Post in itd. envelopeCARRPOTON MANUFALTU ,INC CO.. Ltd.Phono: Holborn 0202. Works: S. Croydon

NAME

ADDRESS

S W.M.

THE CAMCO " GRESHAM "Here is an entirely new Cabinet thatincorporates utility with appearance.itczi for converting your sec into amodern radio -gram. Constructed onsound acoustical lines with room forbatteries or eliminators. Includesmotor board, baffleboard, shelf, andautomatic stay.Price, finished in selected

E6-0-9walnut veneer

Advertisers

The "POPULAR"

Wireless Magazine, January. 1933

"A definite advance

says Mr. HI. Barton Chapple WhS(h. 8S414n4

Therevolutionary"MANSFIELD"

Moving -CoilSpeakers

This well-known radio andtelevision authority pays strik-ing tribute to the new W.B."Mansfield" Speaker MagneticSystem.

The ultimate result is areally astonishing high flux densityfor the size of the magnet used . . .

fidelity of tone of outstandingmerit . . . sensitivity very note-worthy, comparable in manyrespects with externally energisedtypes without the necessity formains or batteries. The Speakerwill handle an input more thansufficient for quite a large room andyet can be worked satisfactorilyfrom a small two -valve set.

" My conclusions . . . this newP.M.4 speaker is a definite advancein the permanent magnet class."

Write for copy of Mr. Barton Chapple'sfull report. The "Mansfield " (patent)Magnetic System is a revolutionarydevelopment. It makes possible amagnet 3o% more efficient than a goodcobalt steel magnet of same weightand io% more efficient than a chromesteel magnet of three times theweight. It enables a steel chassis to .be used without magnetic loss. Iteliminates the bugbear of loss ofmagnetism. Ask your dealer for ademonstration; you will be AMAZED.

"Mansfield " Senior (Improved P.M.4)complete with 3 -ratiotransformer - - 42"Mansfield " Junior (P.M.3) completewith 3 -ratio transformer - 27/6"Mansfield" Cabinet in well -finished Oak(for P.M.4 or 5), 25/- extra (if desired)

Whiteley Electrical Radio Co., Ltd., Dept. W.M., Radio Works, Mans-field, Notts. Loudon Office: 109 Kingsway, London, W.C.2. Telephone :Holborn 6714. Irish Free State Distributors : Kelly & Shiel, Ltd., 47 Fleet

Street, Dublin.

like to know whence the business comes-please mention "W.M."

689

Wireless Magazine. Januapx 1933

GUIDE TOTHEWORLDS BROADCASTERSSpecially Compiled for Wireless Magazine'. by JAY COOTE

Metres : 7 BERLIN(Germany)

Distance from London: Approximately 580 miles.

Standard Time: Central European (Greenwich Mean Time PLUSI hour).

Kilocycles :42,870

Announcer: Man.

Call: "Hier der (Hera Kurzwellensender lariat" (phon: "Bair -leanauf Sieben meter zwo upd Vierzig tauzend acht hundert andsiebzig kilohertz.")

Transmissions in speech (s.) and television (t.) are made accordingto following time schedule: Sundays, G.M.T. 10.30-12.00 (s.).Weekdays, G.M.T. 9.00-10.00 (t.); Mondays and Thursdays, G.M.T.22.00-23.00 (s.); Tuesdays and Fridays, G.M.T. 10.30-12.00 (s.);Wednesdays and Saturdays, G.M.T. 19.00-20.00 (S.).

sf 23'25 STL ASSISE (F.W.)15 kw. (Paris, France)

Distance from London: Approximately 214 miles.

Standard Time: Greenwich Mean Time.

Announcers: Man and woman.

Kilo-cycles :12,903

Opening Signal: Morse F (. . - .) followed by three notes (A, F, D.)Works public service telephony with Rabat (Morocco), Buenos Aites(Argentine Republic), etc. Also acts as auxiliary channel for relaysof Paris programmes to Algiers or Rabat, and for these broadcaststo Paris PTT when required.

Metre.3s

: FRANKFURT -am -MAIN Kilo1cycles

Power : (Germany)17 kw.Distance from London: Approximately 395 miles.Standard Time: Central European (Greenwich Mean Time PLUS

1 hour).Announcer: Man.Interval Signal: Metronome (200 beats per minute); if relayingStuttgart (Muhlacker) three notes (C, D, G).Call: "Achtung ! Suedwestfunk" When relaying Stuttgart : "HierSuedfunk."Main Daily Programme: Similar to that of Leipzig.Good -night Greetings : "Gute Nacht, meinDamen and Herren,"followed by "Deutschlandslied" ("Deutschland ueber Allen").Relay: Cassel, 246 metres (1,220 kilocycles), .25 kilowatt ;Treves (under construction).

Metres : 431 .s

Power : 1.0 kw. PAREDE (CTIGL) Kilocycle:696

Lisbon (Portugal)Distance from London: Approximately 970 miles.

Standard Time: Greenwich Mean Time.

Announcer: Man.

Call: "Radio Parede" (phon. "Par -ay -day").No interval signal.

Language: Portuguese only.

Transmissions: G.M.T. 21.00-24.00 (not daily), gramophonerecords, news bulletins, etc. The station is operated by the RadioClub da Costa do Sol and occasionally a short studio concert isbroadcast.

16.878 W3XAL BOUNDBROOKMetres :

Power: 12 kw. (New Jersey, U.S.A.)cycles

Distance from London: Approximately 3,050 miles.

Standard Time: G.M.T. LESS 5 hours.

Announcer: Man.

Interval Signal: Three notes.

Call: "W3X AL, Boundbrook, New Jersey, a short-wave station ofthe National Broadcasting Company of America operating on17,780 kilocycles." The call is given regularly every fifteen minutes.

Standard Transmissions: G.M.T. 13.00-20.00 daily. Relaysprogrammes from WJZ, Boundbrook; WEAN, New York; WBZ,Boston, etc.

Also transmits on 49.18 metres from G.M.T. 22.00-06.00 daily.

Metres: 25.5 CHAPULTEPEC (XDA) Kilo -Power : cycles :

20 kw. (Mexico) 11,763


Standard Time: Greenwich Mean Time Lass 0 hours

Announcer: Man

Call: 'Estacion XDA" (phon. "Aix-Day-Ah Tchar-pool-tay-peck")Broadcasts a news bulletin in the English language between G.M.T.20.00-21.00, and again between G.M.T. 01.00-02.30.

Metres : 389.6Power : 120 kw. LEIPZIG

(Germany)Distance from London: Approximately 537 miles.Standard Time: Central European (Greenwich Mean Time PLUS1 hour).Announcer: Man.Language: German only.Call: "Achtung ! Mitteldeutschland."Interval Signal: Metronome (240 beats per minute); occasionallyfour notes (B flat, A, C, B).Main Programme: G.M.T. 05.15, physical exercises relayed fromBerlin; 05.35, relay of concert from Hamburg; then continuousbroadcast throughout day; 18.30, official communications; 19.35,main evening entertainment; 21.10, news, dance music (almostnightly).Closes down with usual German "Gute Nacht" greetings, followedby "Deutschland ueber Allen."Relay: Dresden, 318.8 metres (941 kilocycles), .3 kilowatt.

17,780

Kilocycles :769.9

Metres : 438 VAS, GLACE BAY(Nova Scotia)

Kilocycles:685


Standard Time: Greenwich Mean Time LESS 4, hours.

Announcer: Man.

Call: "This is VAS, the Marconi Station of the Atlantic BroadcastingCompany, Nova Scotia.

Transmissions: G.M.T. 23.00-03.00, 04.00-04.30, fish prices,information regarding weather, ports, etc.

690

45.

EVERYTHING g C.Vouquarahtler

A 'CO

NOTE:-CLOSE MESH SCREENAND PLATE ANODEFOR LOW CAPACITYAND HIGH EFFECTIVEAMPLIFICATION.

o

RIGIDConstruction forReliable Control.

ELECTRICAL

Wireless Magazine. January/933j

0 ANY

°SRAM 2,-VOLTVALVES WITIK TIRE

WEMBLEYVILAMENT

The filamentwith the highest electron emission

efficiencyof any Battery valve filament

in theworld.

HIGHEFFICIENCY

VALVES

OF

OSRAM S.22GRID

CECHOIA

SCREEN

For full technical informationWRITE for OSRAM Wireless GuidePost free on request.

111111111111limmiii ,,,

SET

The high slope Screen Grid valve for extremely sensitivereception and increased range in screened coil sets.

Slope 1.75 m.a./v.Impedance 200,000 ohms.

Price 16/6

OSRAM S.2IThe sensitive, non-microphonic Screen Grid valve forstable and efficient H.F. Amplification in any screen gridset, and for Detection.

SlopeImpedance 200,00 ohms.

Price 16/6

OSRAM VS.2

1.1 m.a.,v.

The new Variable mu Battery Screen Grid valve whichrequires only a 9 -volt grid bias battery for effective anddistortionless volume control.

Max. Slope

MADE INENGLANDSOLD BY ALLWIFELESSDEALERS

FOR EXTRA QUALITY

Price 16/61.25 m.a./v.

WITHOUT EXTRA COST

Advt. of The General Electric Co., Ltd., Magnet House, Kingsway, London, W .C.2.

There is news in the "Wireless Magazine" advertisements

691


DOWNAND BALANCE

IN EASYMONTHLYPAYMENTS

D.C.15/25. H.T. for8-4 Valve Sets fromD.C. Mains. 39/6 Cash.

A.K. 22. H.T. and L. T.for 2-3 Valve Sets fromA.G. Mains. 7716 Cash.

THE OLYMPIABALLOT WINNERS* * Why pay at least 50/- a yearfor quickly exhausted dry batteries?Get your H.T. from the mains withan " ATLAS " Unit for less than ashilling a year. There's a model forevery receiver, fitted in a few minuteswithout alterations to set or valves.Ask your dealer for a demonstrationto -day, and insist on " ATLAS," theExpert's choice and winners of the" Wireless World " Olympia Ballots.No others can give such a reserve ofhum -free power..Manufactured and Guaranteed for 12 months byH. CLARKE & CO. (MC/R), LTD.,PATRICROFT, MANCHESTER.London . Bush House, W.C.2. Glasgow : The

G.E.S. Co., Ltd., 38 Oswald Street.

MAINS UNITS

POSTNOW!

......... N..- .....Messrs. H. Clarke & Co. (M/cr), Ltd.,George St., Patricroft, Manchester.

Please send full details of the complete rangeof " ATLAS " Mains Units.

NAME.. ...

ADDRESS...... ..................... ..........................

3311/33.101113M. ...... =a1m...1

M U LT ITO N ETONE CONTROLL.F. TRANSFORMERIS SPECIFIED IN THESEVENTY-SEVEN SUPER

because it adapts the tone of the setI. To any speaker.2 To any particular station to which

you are listening.Multitone suppresses heterodyne whistle andincreases the bass or treble at will.Invaluable for radiogramophone reproduction andpentode output.

EASILY FITTED TO ANY SETOUR BOOKLET ("C") ON TONE CONTROLWILL BE SENT POST FREE ON RECEIPT. OF

A POSTCARD.

116

11111111TIMIlrTONE CONTROL L.F TRANSFORMER

MULTITONE ELECTRICCOMPANY LTD95-95, WHITE LION STREET, LONDON, N. NORTH 5063

111111.0111MMAIMMINIIMINElommaSpecified for the"Wireless Magazine"SEVENTY-SEVEN SUPER"

this handsome

OSBORNCABINET

Model No. 234

Write for Free Catalogue aLatest Models, Post Free.

CHAS. A. OSBORN (Dept )W mTHE REGENT WORKS. ARLINGTON STREETLONDON, N.1. Telephone Clerkenwell 5095. Showrooms21 Essex Road, Islington, N.1. (2 minutes infra EsserRoad Tube Station) Telephone Clerkenwell 5634.

MODEL No. 234. Beau-tiful Queen Annestyle Radio -Gramo-

phone Cabinet, 3 ft. 3 fn.high by 2 ft. 0 in. wide by1 ft. 61n. deep. Takes panel.191n. by 12 in., or smaller.Ample room fur any type ofgramophone motor andlargest H.T. and L.T. bat-teries made. Storage for 35Records each side of set. Ityou desire larger panel space,this Cabinet takes panel27 in. long by omittingRecords Storage.

PRICESMachined ready to assembk,Oak, SS 10s.; Mahogany.£3 lbs.; Walnut. £4 10s.

Assembled Ready to Polish,Oak, £4 10s.; Mahogany,£4 153.; Walnut, £5 103.

Assembled and Polished, Oak,Is 16s.; Mahogany, £6 5s.;

Walnut, £7 6s,Alt Models Carriage Paid.

OSBORN SUPERACOUSTIC BAFFLEBOARD. Prevents 90pa. cent. of speaker worry.Guaranteed no vibrationeven when attached topowerful Moving -cod. Anysize hole cut FREE.18 by 18, 3s.; 24 by 24,5s.; 30 by 30, 8s.; 36 by36, ]le. 3d. Carriagepaid U.K.Send for Free Sample I

Better service results from mentioning" Wireless Magazine when writing to advertiser;

692

Wireless Magazine, thnuary1933

PERMANENT MAGNET M.C. REPRODUCER DE -LUXEIs your loud -speaker a " frequency filcher" robbing youof the upper frequencies which include the violin, piccoloand the high notes of piano?Is it a " filcher " accepting, but not reproducing, the bassnotes of the organ, the roll of drums?The R. & A. " Victor " reproduces all the musicalfrequencies, from below 5o cycles right up the scale to12,000 cycles. Every instrument in the orchestra is heardin true perspective, from the sustained notes of the 'celloto the staccato transient of the cymbal.The " Wireless World " Test Report states :-

" The outstanding feature . . is the uniform dis-ibution of output energy over frequency range . . .

especially noticeable in the bass, where the majorityof P.M. units rely on a resonance to give a falseimpression of sensitivity . The importantrange . . . between 75 and 400 cycles is free fromobjectionab12 resonances . . . The 60 -cycle resonance Includingis helpful in correcting the loss of amplification below 6 -Ratio100 cycles which occurs even in some of the best Ferrantiamplifiers. In upper register there is no sharp Transformercut -oft . . . appreciable output at 12,000 cycles."Ask your dealer to demonstrate, and write us for LeafletREPRODUCERS & AMPLIFIERS LTD., WOLVERHAMPTON,

7 /-

"VICTOR"Holden

FAR AHEAD INDESIGN ANDPERFORMANCE

A glance at the accompanying illustration will proveto you how far ahead Philomel receivers are in cabinetdesign. They are equally far ahead in mechanicaldesign and in the quality of the reception.

The model shown is the M.T.C.3, a three -valvetransportable receiver, which gives astonishingly goodresults, due to the skill with which the circuit hasbeen designed and the high-class accessories whichare used.

If you want the latest and best in radio receivers, orif you are asked by a friend to recommend a reliableand simply operated set, you can specify Philomelwith absolute certainty.

Philomel radios are producedin the following colours:

Black and Chromium.Green and Chromium.Scarlet and Chromium.

Other colours to special order.

No doubt you would like to see these models illus-trated in full colour. Send a P.C. for our brochure.

PRICE 17 G NS. A.C. or D.C.

ULTRA -MODERN SUPER RADIO -

PHILC)MEL RADIO EQUIPMENT CO.Philomel Works, Dover Road, Slough Trading Estate, Slough

Telephone : Slough 0848

Better service results from mentioning " Wireless Magazine" when writing to advertiser;

693

Watkins.o.


WORLDSBRO CAS- AVELENGTHS

Wave-length Name of Station Dial

Readings Country Wave-length Name of Station

I

DialReadings Country

77.75

BerlinB.B.C. transmissions

GermanyGreat Britain

30.430.43

Lawrenceville (N.J.) WQNMadrid EAQ ..

United StatesSpain

9.8 Coltano JAG Italy 30.77 Rocky Point WEL.WNC United States9.96 Golfe Aranci Sardinia 30.9 Rugby GCA Great Britain

13.92 E. Pittsburgh, W8XK United States 30.93 Buenos Aires LQA Argentine13.97 Daventry (Empire) GSH . Great Britain 31.14 Pragins HBQ Switzerland14.12 Rocky Point (N.J.) WQJ . United States 31.25 Lisbon CTIAA Portugal14.18 Buenos Aires LSL . Argentine Philadelphia United States14.47 Buenos Aires LSY . Argentine 31.28 { Sydney VK2ME New South Wales14.60 Malabar PMB Java Melbourne VK3ME Victoria14.72 Rugby GAA Great Britain 31.297 Daventry (Empire) GSC Great Britain14.96 Naven, DGX Germany 31.31 Radio Nations HBL Switzerland15.14 Ocean Township (N.J.)

WKN United States 31.35 Springfield W1XAZPoznan SRI

United StatesPoland

15.20 Ruysselede ORA .. Belgium 31.38 Zeezen DJA Germy15.48 Prangins HBL Switzerland 31.48 Schenectady W2XAF I.Initergtates

Sydney VK2ME Australia 31.51 Skamlebaek OXY Denmark15.5 { Ste Assise FTM France 31.55 Melbourne VK3ME Victoria

Kootwijk PCP Holland 31.58 Rio de Janeiro PRIM .. Brazil15.576 Rio de Janeiro PPU Brazil 31.545 Daventry (Empire) GSB Great Britain15.61 Lawrenceville (N.J.) WKF United States 31.61 Rocky Point WEF.. United States15.625 Ruysselede (Bruges) ORG Belgium 31.68 Rocky Point (N.Y.) WEJ United States15.63 Cairo SU Y Egypt 31.86 Bandoeng PLV Java15.86 Rocky Point (N.J.) WQE... United States 32.26 Rabat .. Morocco15.93 Bandoeng PLE Java 33.25 Rugby GBS Great Britain16.1016.19

Rugby GBUColtano IAC

Great BritainItaly

33.5934.66

Rocky Point (N.J.)Drummondville VE9AP

United StatesCanada

16.26 Bogota HKD Columbia 34.68 Long Island W2X v .. United States16.3 Kootwijk PCK Holland 35.05 Deal Beach (N.Y.) WOO ... United States16.36 Lawrenceville (N.J.) WLA United States 35.55 Rio de Janeiro PRDA Argentine16.54 Rugby GBW Great Britain 36 Norddeich Germany16.56 Bandoeng PMC Java 36.88 Baghdad Iraq16.57 Chicago (Ill.) W9XAA United States 36.92 Bandoeng PLW Java16.66 Rocky Point WAJ _ United States 37.0 San Paolo PY2SP Brazil16.72 Rocky Point (N.J.) WQB United States 38.07 Tokio JIAA Japan16.81 Malabar PLF Java 38.476 Radio Nations IMP Switzerland16.85 Kootwijk PCV -. Holland 38.56 Rio de Janeiro PPB Brazil16.878 Boundbrook W3XAL United States 38.65 Kootwijk PDM Holland16.88 Daventry (Empire) GSB . Great Britain 39.74 Calgary (Alb.) CKS Canada17.51 Budapest HAT Hungary 39.98 Tscheng-Ju XGD China18.44 Lawrenceville WLO-WLK United States 40.3 Radio Nations HBQ Switzerland18.56 Rugby GBX Great Britain 40.4 Warsaw SP1AX Poland18.75 New Brunswick (N.J.) WKQ United States 40.54 New York WEN United States19.36 Kemikawa (Tokio) JIAA Japan 41.6

..Las Palmas EAR58 Canary Isles

19.56 Schenectady W2XAD United States 41.7 Singapore VSIAB Sts. Settlements19.67 New York W2XE United States 43.11 Rocky Point (N.J.) WEO... United States19.68 Pontoise FYA France 43.3 Rocky Point WEL.. .. United States19.72 Saxonburg W8XK .. United States 43.75 Paris (Vitus) F8LH France19.737 Zeezen DIB Germany 43.86 Stuhlweissenburg . Hungary19.815 Daventry (Empire) GSF Great Britain 44.51 Rocky Point (N.Y.) WEJ United States-19.84 Rome (Vatican) HVJ Italy 45 Constantine FM$KR Tunis19.9 Heredia T14NRH Costa Rica 45.11 Coltano IAC Italy19.95 Moscow - . U.S.S.R. 45.38 Moscow REN U.S.S.R.20.0 Drummondville CGA Canada 45.5 Bucharest .. Roumania20.23 Rocky Point (N.J.) WKU United States 46.6 Moscow .. U.S.S.R.20.49 Deal (N.J.) WND United States 46.67 London (Ont.) VE9BY Canada20.5 Chapultepec XDA Mexico 46.69 Boundbrook W3XL. United States20.56 Lawrenceville WMN United States 46.73 Minsk RW62 U.S.S.R.21.44 Rugby GBA Great Britain 48 Casablanca CN8MC Morocco21.53 Rocky Point (N.J.) WIK United States 48.2 Rome 2R0 Italy21.83 Drummondville CGA Canada 48.35 Bogota HKC Colombia21.92 Stuhlweissenbuzg HAT Hungary 48.8 Winnipeg VE9CL Canada22.26 Rocky Point (N.Y.) WAJ . United States 48.86 Saxonburg (Pa.) W8XK United States22.35 New York WHR United States 49.0 Bombay VUB Br. India22.42 Nauen DGI Germany 49.10 Calcutta VUC Br. India22.58 Drummondville CGA Canada 49.18 Boundbrook W3XAL United States23.28 Radio Maroc (Rabat) Morocco 49.2 Johannesburg ZTJ.. Sth Africa23.45 Coltano IAC Italy 49.22 Bowmanville VE9GW Canada .

23.7 Drummondville VE9AP Canada 49.34 Chicago W9XAA United States23.858 Rabat .. Morocco 49.4 Vienna UOR2 Austria24.9 Kootwijk PDV Holland 49.43 Vancouver VE9CS British Columbia25.20 Pontoise FYA France Nairobi VQ7LO Kenya Colony25.27 East Pittsburgh (Pa) W8XK United States 49.5 Philadelphia W3XAU United States25.284 Daventry (Empire) GSE Great Britain Havana CMCI Cuba25.34 Chicago (Ill.) W9XAA United States 49.586 Daventry (Empire) GSA ... Great Britain25.4 Bowmanville VE9GW .

Rome 2R0CanadaItaly

49.5949.67

Halifax VE9GXMiami Beach W4XB

Nova ScotiaUnited States

25.5 Chapultepec XDA Mexico 49.83 Chicago W9XF United States25.53 Chelmsford GSD

-Great Britain 49.96 Drummondville VE9DR Canada

25.532 Daventry (Empire) GSD .25.6 fI Pontoise FYA

Winnipeg VE9JR .*

Great BritainFranceCanada

50 {50.1

Bucharest ..Moscow RV59Eindhoven ..

RoumaniaU.S.S.R.Holland

25.7 Rio de Janerio PPQ/PSN Brazil 50.26 Rome (Vatican) HVJ Italy26.83 Funchal CT3AQ Madeira 51 St. Denis Reunion27.3 Wellington ZLW New Zealand 51.7 Tananarive FIUI Madagascar27.55 Rugby GBP Great Britain 54.52 New York W2XBH United States28.28 Rocky Point (N.J.) WEA United States 57.03 Rocky Point WQN United States28.5 Sydney VK2ME New South Wales 58 Prague OKI MPT.. Czechoslovakia28.98 Buenos Aires LSX Argentine Repub. 58.3 Bandoeng PMY Java29.16 Konigswusterhausen DIQ Germany 60.3 Rugby GBC G6RX Great Britain '29.84 Abul Zabal (Cairo) SUV Egypt 62.5 Long Island (N.J.) W2XV United States30 Belgrade .. Yugoslavia 62.56 London (Ont.) VE9BY Canada

694Continued on page 696)

Wireless Magazine, January 1933

"Wireless Magazine"A.C. CALIBRATOR

Eao'

c 61 0 1-id., vfl? ii3

On. 60 % mid- tY9' 6

On.

incorporating

14DubilierCondensers

" The proof of the pudding is in the eating."Many thousands of set builders and setowners have proved conclusively the wisdomof this old adage when applied to DubilierCondensers. Once fitted, they are forgotten.They live their long life to the full, givingsheer satisfaction from the time they arainstalled to the day when their owner decideshis set can be relegated to " history."The experts realise this, too. Witness thelatest Dubilier triumph:

14 Dubilier Condensers exclu-sively specified by the Designers

for the " A.G. Calibrator."All Dubilier claims of absolute reliabilityhave been unquestionablyproved, both in the labor-atory and under actualworking conditions. Make 0/4your choice from Dubi-lier's universal range andyou will make a lifelongfriend.

follow thedesigner's lead and

o.°°5 mid Eachtype

610 2/3

- type t3F255 2 6

DUBILIER CONDENSER CO. (1925) LIMITED, DUCON WORKS, VICTORIA ROAD, NORTH ACTON, W.3Distributing Agents for Irish Free State: KELLY es? SHIEL LTD.. 46 & 47 FLEET STREET, DUBLIN, C.4

Mention of the "Wireless Magazine" will ensure prompt attention

695

Wireless Magazine. January; /933

BROADCAST WAVELENGTHS Continued frompage 694

Wave-length Name of Station Dial

Readings

63.1267.1167:6570.1770.276.079.581.4588.392.31

206207207.3209.7211.3214.2214.3215217

6

218219.4224225.2227.4230.3230.6232.2233.4236237.9238.1239239240.6241.3243.1244.1

245.9

247.7249249.8253.425,4.4255256.7259.3261.6263.8265.4266.8267.9269.4271.3271.9273.6276.5279.3281282.2

283

285.1286

288.5

291293293.7296.1298.8301.5304.9306.8307.1309.9312.8315

318.8319.7321.9325328.2331.4334.8338.2342.1345.2348.8351352.1355.8360.5363.3365.5

Deal Beach (N.J.) WOO ...Bagdad YIDDoeberitz DFKRocky Point (N.J.) WIRKhabarovsk RV15..Paris 8PCR ..Salisbury ZEAUtrechtRugby G6RXDoeberitzAntwerpPlymouth (shortly)FranchimontMagyazovarNewcastle ..Warsaw (No. 2) ..Aberdeen ..Brussels (Conference)Konigsberg..SalzburgBeziersCorkFecampFlensburg ..Radio WalloniaMalmoKiel .LodzKristianasandNimesBordeaux-Sud-OuestNurnbergBindleStavanger ..Liege EitperimentalBelfast ..BasleRadio SchaerbeekLinzBerne ..Trieste ..Prague (No. 2) ..Juan-les-Pins ..GleiwitzBarcelona EAJ15Toulouse PTTHarbyFrankfurt ..London National ..Morayska Ostrava ..LilleValencia ..Bremen ..BariRennes ..Cointe-LiegeTurin ..HeilsbergBratislava ..

Efstn entei AA :

Berlin .. :

Magdeburg.. ..Stettin ..Radio Lyons ..Montpellier.. _BournemouthScottish National ..PlymouthSwanseaViipuriTampereKosice ..Limoges PTTHilversum ..Tallinn ..North NationalBordeaux PTTZagreb ..Falun ..Cardiff ..Genoa ..Cracow ..Marseilles

SofiaNaples

..

Dresden ..Goteborg ..BreslauPoste ParisienMilanPoznan ..Brussels (No. 2)BrnoStrasbourg ..Barcelona EAJ1LeningradGrazLondon RegionalMOhlackerAlgiers .

Bergen ..

Country Wave-length Name of Station ReDtia z,t Country

United States 365.7 FrederikstaadIraq 366.1 SevilleGermany Helsinki ..United States 368.1 Bolzano .

U.S.S.R. KharkovFrance 369.3 Radio LL, Paris .. .

South Africa 372 Hamburg ..Holland 376.4 Scottish Regional ..Great Britain 378 Moscow Regional ..Germany 380.7 LvovBelgium 385 Radio Toulouse ..Great Britain 385 Stalin° .Belgium 388.5 Archangel ..Hungary 389.6 LeipsigGreat Britain 394 BucharestPoland 398.9 Midland Regional ..Great Britain 403 Sottens ..Belgium 408 KatowicGermany 411 Madrid (EAJ5)AustriaFrance 413 { Athlone

Dublin .

Irish Free State 416 Radio Maroc ..France 419 Berlin .

Germany 423.4 Madrid (Esplana)Belgium 424.2 Madrid EAJ7Sweden 430.4 Belgrade ..Germany 435.4 Stockholm .

Poland 441.2 Rome ..NorwayFrance 447.1 { Paris PTT

Danzig ..France 450 Odessa ..GermanyBelgium 453.2 Klagenfurt .

PorsgrundNorway 456.6 San SebastianBelgium 459.4 BeromuensterIrelandSwitzerland 465.8 Tartu ..

Lyon; PTTBelgium 472.4 LangenbergAustria 476 Sebastopol ..Switzerland 480 North RegionalItaly 488.6 Prague ..Czechoslovakia 496.1 Trondheim..France 500.8 Florence ..Germany 502.4 Nini Novgorod

508.5 AstrahkanFrance 509 Brussels No. 1Sweden 518 Vienna ..Germany 525.4 RigaGreat Britain 527 PalermoCzechoslovakia 533 Munich ..France 542 Sundsvall ..Stain 550 Budapest ..GermanyItaly 559.7 { Kaiserslautern

AugsbergFrance 563 WilnoBelgium 566 Hanover ..ItalyGermany 571.2 {

FreiburgGrenoble ..

Czechoslovakia 574.7 LjubjanaDenmark 675 OuaPortugal 678.7 Lausanne ..Germany 720 Moscow PTTGermany 748 OstersundGermany 759.5 Geneva ..France 824.2 Sverdlovsk ..France 840 Budapest (2)Great Britain 882 SaratovGreat Britain 900 Leningrad ..Great Britain 937.5 KharkovGreat Britain 967.7 Alma Ata - .

Finland 7,000 Moscow (Old Kom)Finland 1,035 Kiev .CzechoslovakiaFrance 1,071.4 { Tiflis .

Scheveningen -HavenHolland 1,083 OsloEsthonia 1,107 MinskGreat Britain 1,116 Moscow (Popoff) ..France 1,153.8 KalundborgYugoslavia 1,171.5 TaschkentSweden 1.190 Luxemburg..Great BritainItaly 1,200 { Reykjavik ..

IstanbulPoland 1.229.5 BodenFrance 1,258 Vienna (tests)Italy 1,260 NovosibirskBulgaria 1,304 MoscowGermany 1,348 MotalaSweden 1,380 NovosibirshGermany 1,411.8 Warsaw ..France 1,445.7 Paris (Eiffel ToweriItaly 1,481 Moscow (RV1)Poland 1,538 AnkaraBelgium 1,554.4 Daventry National..Czechoslovakia 1,600 Irkutsk ..France 1,635 KinigswusterhausenSpain 1,725 Radio Paris.. ..USSR. 1,796 LahtiAustria 1,875 HuiaenGreat Britain 1,935 Kaunas ..Germany 2,625 F onigswusterhausenNorth Africa 2,650 Eiffel TowerNorway 2,900 honigsw usterhausen

NorwaySpainFinlandItalyU.S.S.R.FranceGermanyGreat BritainU.S.S.R.PolandFranceU.S.S.R.U.S.S.R.GermanyRoumaniaGreat BritainSwitzerlandPolandSpainIrish Free StateIrish Free StateNorth AfricaGermanySpainSpainYugoslaviaSwedenItalyFranceDanzigU.S.S.R.AustriaNorway Spain.SwitzerlandEstoniaFranceGermanyUSSRGreat BritainCzechoslovakiaNorwayItalyU.S.S.R.U.S.S.R.BelgiumAustriaLatviaItalyGermanySwedenHungaryGermanyGermanyPolandGermany

_ Germany_ _ France

Yugoslavia_ U.S.S.R.

Switzerl tadU.S.S.R.SwedenSwitzerlandUSSR.HungaryUSSRU.S.S.R.U.S.S.R.USSRU.S.S.R.U.S.S.RU.S.S.RHollandNorwayU.S.S.R.U S.S.R.DenmarkUSSRLuxemburgIcelandTurkeySwedenAustriaU.S.S.R.U.S.S.R.SwedenU.S.S.R.PolandFranceU.S.S.R.TurkeyGreat BritainUSSRGermanyFranceFinlandHollandLithuaniaGermanyFranceGermany

696

Wireless Magazine. Januarx193s

THE EVER READY CO. (GREAT BRITAIN) LTD., HERCULES PLACE, HOLLOWAY, LONDON, N.7.

Advertisers take more interest when you mention "Wireless Magazine"

697


THERE IS A "COLTONE" COMPONENT-FOR EVERY W.M. RECEIVER.

The Four Sets described in this number, for instance, all includeGOLTONE METAL SCREENED TUBING.

Obtainable fromall First -{lassRadio Stores.Refuse Substi-tutes. If anydifficulty write

direct.

FREETwo four page fold-ers, with numerousexcellent descrip-tions of the various"GIOLTONE"SCREENED DUALRANGE COILS withlarge illustratedRadio CatalogueFree on request.

CIO 0,0 ;0 ,,,s

.*. gc,

n2,1 full

r`ccoloSuoe, re°

e CO'

'9033Suitable for all Screen -Grid and Super-" COLTONE " SUPER H. F. CHOKE

R3 '46 - - 4/6Het circuits.

Supplied

in S Ts ye pe es.e"Price

Seach.

Qotronie.

thGe EfeadCig°iLchSor

ww

ca/ RadioJournals

in ntheirPublished

AdpoptUe461rn

Rod\

PENDLETON...Z71r,MANCflESTERLD

D TO WITHIN of 1%-1- HALF A MICRO-MICROFARADA rigid chassis that is all one piece-not merely aframework bolted together. A one-piece chassis sostrong that there can never be the slightest distortionin use . . . . this is the chassis of the J. B. NUGANG.

Trimmers to each stage inside the chassis are operatedby external starwheels. Vanes wide spaced and ofheavy gauge. Special rotor bearings ensure perm-anent accuracy and give remarkably free movement.Capacity .0005.

Supplied semi -screened as illustrated or fully screenedwith lid.Capacity without trimmers : Minimum 20 m.m.f. Maximum520 m.m.f. Capacity of trimmers : 70 m.m.f.

NUGANGSemi -Screened Fully Screened

2 -gang I4/- 2 -gang I6/-3 -gang 2I/- 3 -gang 23/64 -gang 28/- 4 -gang 31/.

PRECISION INSTRUMENTSAdvertisement of Jackson Bros. (London) Ltd., 72 St. Thomas' Street, London, S.E.I.

You will get prompt replies by mentioning " Wireless Magazine "

698

Telephone: I 92i.

GIVEyour set a lastinggift this

Christmas.Convert it to an A.C. mains

set and give it a rectifier that will providean unending

and steady high-tensionsupply;one that will enable your set to

give of its best throughoutits whole lifeGIVE IT A

METAL RECTIFIE


You will thenen\oy

betterreceprAon

andredroductAon

nov.

earsto come.

full detailsof \Nestinghouse

AAMetal

Rectifiers--the

onlyrectifiers

to removethe Neorry

1

of periodicalrenevol--are

containedin "

P,1_1_-1A5C

THE \N f.S"f1SGVA 0 USS BRAKE

& SA1111and for

manyy

CO.,

YorkFload,

KiogsCross,

London,SA

933."

001)01410'D AN-1-

PV4C4S1.11"G141.141SfriiPiAllii;41_-

Ilkte 1111:\ %tiecaCtiZZ;si31:..?...3.

Piease sec'doiiestinghouseposratmieeti.,1

exist\ ngset to MESA...................................

............

e coo eftmy......

..... .... ...

1Address ..

..........

699

I


In Tune with the TradeFETTER LANE'S Review of Catalogues

SEND TO US FOR THESECATALOGUES!

Here we review the newest bookletsand folders issued by two manu-facturers. If you want copies of eitheror both them just cut out this couponand send it to us. We will see that youget all the literature you desire.

Just indicate the numbers (seen atthe end of each paragraph) of the cata-logues you want below.

My name and address are :-

Send this coupon in an unsealed en-velope, bearing 1/2d. stamp, to "CatalogueService," WIRELESS MAGAZINE,58/6 1 Fetter Lane, E.C.4. Valid till Jan. 31

A PLATE -LESSACCUMULATOR

IF you haven't yet heard of thenew Block idea, then be prepared

for a surprise. It is, in brief, theintroduction of a plate -less accumu-lator, much lighter, capacity fo-:

capacity, than an ordinary battery.The plates are dispensed with in

rather a novel fashion. The cylinderof the battery itself (these Blockbatteries are not the usual rect-angular shape) is the negativeelectrode, and the positive electrodeis the central core. It is claimedthat this special Block constructiongives twice the life per charge.

The Block people have many othertechnical advantages claimed for thisnovel type of battery, and I thinkthat if you are in any way dissatisfiedwith your present " juice " supplyyou should write, through my freecatalogue service, for details of theBlock construction.

The price is very reasonable, the2 volt 80 -ampere hour size costingI ls. 6d. So there's no question ofbeing called to pay a " fancy " pricefor what is undoubtedly a soundaccumulator development. 2 9 7

Make a note that the February"Wireless Magazine" will be

published on Friday, January 20.

BURTON!BURTON, that delightfully

refreshing name, has a specialradio significance, as is proved by afolder that has just arrived on mydesk! The folder is one of thosecatalogues in miniature which givethe salient points of the main com-ponents and kits in the range, and inthe Burton range there are somethings of outstanding interest.

If you don't believe me, get a freecopy of this folder for yourself. Itis useful for hanging on the wall ofthe radio den for handy reference.You'll find in it everything fromswitches to complete kits for setbuilders-including some kits forfine three-valvers.

It is in the range of small partssuch as valveholders, switches andvariable condensers that the name ofBurton has won its radio fame, andI must say that I am very impressedwith the workmanship of these partsas shown by the illustrated folder.

298

7 FROM THE BOOK THATSET DESIGNERS CONSULT

INthe new Wearite Booklet M.11 the set designer finds a veritable

component " inquire within " for every possible need is met-transformers, chokes, resistances, volume controls, switches, etc.On the right is just one item from this book-the WEARITEHETERODYNE FILTER UNIT-a component which, easilyfitted to any set, cuts out those disturbing heterodyne whistles andthat " mush " which mar faithful reproduction. Made in two types,A and B, to cut off at 3,500 and 5,000 cycles respectively, it providesthe means to interference -free reception and with the minimum lossof high notes. Price 10s. 6d.Get your copy of this bojk-the M.11-before you start any set-write now.

WRIGHT & WEAIRE LTD, 740 High Road, Tottenham.

700

ono O ea UUUU YO111 THE WEARITE H.T.8 MAINSTRANSFORMER IS SPECI-FIED FOR THIS H.T. AND

L.T. U NITThe designer of this H.T. and L.T. Unitconsulted the Wearite Book and foundthe Wearite H.T.8 Mains Transformer-the ideal for his requirements. Followhis lead-use only the H.T.8. Price 22/6.

THE WEARITEHETERODYNE FILTER UNIT

A good set needs a good earth and the best isthe NO TOOL type as illustratec. PRICE 3/6

The WEARITE H.T.8MAINS TRANSFCRMER

PRICE 22/6'Phone: Tottenham 3847-8-9


THE McMICHAELCABINET DUPLEXFOUR PORTABLE

(Type C.)

This Set is contained in anexceptionally handsome Wal-nut Cabinet and mounted ona ball -bearing turntable.A high efficiency four -valvecircuit is employed, doublegang tuned to indicate on theDuplex Scale. An AutomaticGrid Bias dispenses with a

Grid Bias Battery. TheDuplex Scale is an uniqueMcMichael feature whichmakes for extreme simplicityand certainty of operation.The receiver is entirely self-contained, with internal frameaerial. Complete and readyfor working. ,..,

Price I / Gns.(Including valves and royalties)

McMICHAELRADIO

A reputation such as attaches to the name McMichaelis neither lightly gained nor lightly held. Only byadherence to the finest traditions of craftmanship,the meticulous attention to details, and an lin-flinching regard for the virtue of quality, couldMcMichael's have attained their present proudposition. Every McMichael Radio Instrument canbe depended upon worthily to uphold the nameit bears.

H.M. THE KING USESMc MICHAEL RECEIVERS

Ask at any high-class Radio Store for a demonstration of these out-standing receivers or any of our other models, and details of our special"Deferred Payments on Hire Purchase Terms" system, if desired, orcall at our London Showrooms, 179 Strand, W.C.2.

McMICHAEL RADIO LTD.

WEXHAM ROAD, SLOUGH, BUCKS.Telephone : Slough 441-442. Telegrams : Radiether, Slough.

LONDON SHOWROOMS :

179, STRAND, W.C.2 (Tel. Temple Bar 6988)

THE McMICHAELDUPLEX FOUR MAINSTRANSPORTABLE

(For Alternating Current Only)

Within a handsome WalnutCabinet of modern design,the set is entirely self-con-tained. The circuit employedis similar to that of theDuplex Four Battery Models,except for the " mainsadaptation. Indicating on theDuplex Scale, this circuit givesmaximum range and selec-tivity. Contained in thereceiver is a Moving -CoilLoud -speaker, the reproduc-tion from which is quiteexceptional-no less thansheer delight. Provision is

made for gramophone pick-up,and 'speakers.

Price l" Gns.(Including all royalties.)

ALL BRITISH -built at ou Works at Slough, and embodyingexperience of twelve years' successful Radio Manufacture.

THE

ON -OFFSWITCH

for the

SEVENTYSEVENSUPER

and the"W.M. A.C. MAINS UNIT"

GEO. BECKER, LTD., Ampere Works,Wembley, Middx. Telephone: Wembley 3737.

SPECIFIEDfor the "HARRIS

ETHERGRAM""Smithcraft " cabinets are

again specified in an import-ant receiver design-sure testi-mony to the high standard ofcraftsmanship which putSmithcraft in the forefront.

SMITHS CABINETS LTD18-20 HERTFORD ROAD. N. I.

Phone: Clissold 3725

The Resistances Specified for the

A.C. "CALIBRATOR"

MADE INENGLAND

ORM-LEAKS and

RESISTORS

Write for Leaflet

THE RADIO

Confidently RecommendedAs half the constructor's troubles are due tounstable grid leaks and resistances-letERIE carry the load. They are guaranteedin every respect. Safe, silent, stable, andimpervious to humidity fluctuations, theywill solve one of, your biggest problems asthey have solved the similar problems of theleading radio manufacturers.

ERIE Resistorscarry an unquali-fied Guaranteeagainst break-down.

All values, one,two, three, andfive watts. 50ohms to 4 ine-g oh ms. Tagidentified andColour Coded.

LOOK FOR

The sign of Erie Resistors

RESISTOR CO., I, Golden Square, London, W.I.Telephone : Gerrard 7291

PRICE

EN PER WATTin all values

There is news in "Wireless Magazine" advertisements

701


C.116O6.k.,

tkitgivesconfileace

to 14e giver and

e ijc1 recept;on lo

the receiver.

RADE mARic

!DRY BATTE RI SACCU MU LATORS

Britannia Batteries Ltd., 233Shaftesbury Ave, London, W.C.2.Telephone: Temple Bar 7971(5 lines). Works Redditch(Worts.) Branches at Glasgow,Manchester, Bristol, Dublin,

Leeds and Newcastle.

Advertisers take more interest when you mention "Wireless Magazine"

702

Wireless Magazine, ,ranuarx 1933

HERE IS THE" RADIOPAK "

specified for theCALIBRATOR""AC

THE British Radiophone Band-passRADIOPAK bids fair to enjoy thesame popularity with designers of

famous modern sets that British RadiophoneGanged Condensers have enjoyed for so long.The RADIOPAK has been specially producedto bring perfect band-pass tuning withinreach of all constructors.The unit consists of the necessary coils withprovision for reaction; the gang condenserwith illuminated slow-motion escutcheon anddisc drive calibrated in wave -lengths; a wave -

PRICESStandard Radiopak with ro,000-ohm vol.control 60/-

Radiopak, as specified for the A.C.Calibrator, type 535A/5o,o00, with extraknob for Reaction condenser .. 60/6Radio -gramophone switch with knob 5/ -

change switch; and a wire -wound volumecontrol complete with on -off Q.M.B. powerswitch. The switching arrangement is thebest yet devised for any radio component,and the combined volume control and switchis one of the famous Radiophone standardtypes needing no further recommendation.Owing to the high degree of accuracy in thematching of the coils and condensers, thisunit REVOLUTIONISES modern set -con-struction. Write for full descriptive particularsto Department W.M.io.

BRITISH RADIOPHONE 3 -GANG CONDENSERTYPE 344C, WITH DISC DRIVE IS ALSO SPECI-FIED FOR THE "SEVENTY-SEVEN SUPER."

BRITISH RADIOPHONE, LTD.,ALDWYCH HOUSE, ALDWYCH,

LONDON, W.C.zTelephone - - Holborn 6744

When replying to advertisements, please mention "Wireless Magazine"

703

Wireless Magazine, January- 1933 I

NEW "SQUARE PEAK'SUPERHETYou may use it in any roomwithout external aerial

SELECTIVITY . . .. day by day the need growsgreater. Secure it in a Varley Superhet.Knife-edge selectivity, fine quality and singleknob control. Station after station clearlyheard on the built-in moving -coil speakers.Radio in every room ! For the local stationjust connect the set to any lighting socketand plug in the handy little "portable" aerialsupplied.

Write for FREE art booklet and address ofnearest dealer. He will gladly demonstrateVarley.

For use with external aerial or with handyportable aerial supplied. Five valves and rectifier.VARIABLE -MU H.F. AND INTERMEDI-

ATE FREQUENCY STAGES. Six tuned circuits withSINGLE CONTROL TUNING (remaining knobs onfront are Volume and Mains Switch). BAND-PASSINTERMEDIATE FREQUENCY COUPLING,giving great selectivity. ILLUMINATED SCALESmarked with STATION NAMES as well as wave-lengths. SEPARATE SCALES for the two wavebands.Operation of wave -change switch automatically dis-closes the correct scale (long or medium). TONE -BALANCED L.F. Amplifier. Energised MOVING -COIL SPEAKER. Provision for using an externalspeaker in place of, or in addition to, the M.C.speaker. SOCKETS FOR GRAMOPHONE PICK-UP. Beautifully finished BURR WALNUT CABI-NETS. For A.C. supplies only, 200/250 volts,40/100 cycles (25 -cycle models,1 guinea extra). Availableon H.P. TER V IS.

CONSOLEChassis as Table Model,but with snoring -coilspeaker of even morepowerful type. No ex-ternal controls onfront or sides.

Undistorted Output 2,250milliwatts. Current Con-sumption 60 watts. Dimen-sions 35 in. high by 15 in. deepby 20 in. wide.Model AP44 . 3 5 G n S.

TABLE MODELEasily carried by concealedhandle which lies flush withtop when not in use.

Undistorted Output, 1,6J0milliwatts. Current Con-sumption, 60 watts. Dimen-sions, 16/ in. high by 12 in. deepby 13 in. wide.Model AP38. 26 Gns.

11101111 rcri.PROPS OLIVER PELL CONTROL LTD.

Advt. of Oliver Pell Control Ltd., Kingsway House, 103 Kingsway, W.C.2. Telephone: Holborn 5 303

Speedy replies result from mentioning " Wireless Magazine '

704

Wireless Magazine. January. 1933

All About the B.B.C.'s Short-wave ServiceBy ALAN HUNTER

AFTER years of discussion andexperiment, the B.B.C. has at

last inaugurated an Empire broad-casting service. Two short-wavetransmitters of the very latest typehave been erected at Daventry, inNorthamptonshire. These replacethe experimental station knownthroughout the Empire as G5SW,which has been relaying the DaventryNational programme on a wavelengthof 25.53 metres.

As a preliminary to the new ser-vice the B.B.C. has been sending outfrom G5SW three special Empirenews bulletins at 12.15 p.m. 6.15p.m., and midnight. Thesebroadcasts, with the relay of theNational programme, have beenthe sole link between the B.B.C.and the various parts of theEmpire.

Two LimitationsTwo obvious limitations have

prevented this service from' giv-ing anything like universal satis-faction. We shall need to knowabout these limitations if we areto understand the modus operandiof the new Daventry stations,which have been designed toovercome them.

The first point is that ourentertainment period, say from6 p.m. to 10 p.m., is not theentertainment period of thewhole Empire owing to the greatdifferences in time. To take anextreme case, while we arebreakfasting the Australians are

returning home to their evening meal.Even supposing, therefore, that

technical means would enable us tostage a gigantic simultaneous broad-cast to the whole Empire, more thanhalf of it would not be " at home "to our broadcast visit.

The second point is that the wave-length suitable for long-distancecommunication between, Londonand say, Sydney might be quiteuseless for contact with, say, WestAfrica. In other words, there is nosingle wavelength that will simul-

WORLD-WIDE BROADCASTSCecil Graves, director of the B.B.C.'s EmpireService Department, bidding good-bye at Croydonto Malcolm Frost, who is travelling round the world

investigating short-wave broadcast possibilities

705

taneously provide the Empire with areliable signal.

The new Daventry stations, withtheir arrays of aerials, are designedto overcome, as far as possible, thedifficulties of these time and wave-length factors.

Two Hours A DayAt first the aim of the programme

builders of the newly constitutedEmpire Service Department, underthe direction of Mr. Cecil Graves, isto give every part of the Empire

at least two hours' entertain-ment at an appropriate periodin the evening.

Moreover, the technical am-bition is to send out signals thatwill, during the different enter-tainment periods of the differentparts of the Empire, be receivedat good strength.

Let us look first at the pro-gramme side. As we are cateringfor an Empire " on which thesun never sets " the aim to pro-vide every part with a two-hourevening programme from theLondon headquarters means thata " rotational " broadcast prac-tically throughout the twenty-four hours has to be envisaged.

It is not difficult to see thatat times in the twenty-four hoursthere will be a certain amountof overlap between two parts ofthe Empire. While the pro-gramme for one zone is drawingto a close, that for another zonewill be due to start.

[-Wireless Magazine. January 1933

EMPIRE BROADCASTING Continued

AERIALS FOR EMPIRE BROADCASTINGThis photograph shows the aerial for a broadcasting service to the Australian zone

erected by the B.B.C. at Daventry

This accounts for the installationof two short-wave stations at Daven-try, to replace the single experimentalstation at Chelmsford.

Unsuitable WavelengthsIt might be asked why the one

station could not be made to servethe two parts of the Empire simul-taneously. The answer has alreadybeen given-the wavelength that issuitable for one part might be quiteunsuitable for another.

It is this problem of differingwavelength requirements that ac-counts for the erection of no less thanseventeen aerials at Daventry.

Get this clear right now : the twostations are necessary to cover twoparts of the Empire simultaneously,while the numerous aerials are neces-sary to give each part of the Empirethe best possible signal.

Most Comprehensive SystemThe B.B.C. can, without exaggera-

tion, claim to have erected the mostcomprehensive short-wave broad-caster in the world. This being so,all readers will surely like to have adescription, however sketchy, of thelayout of the plant at Daventry.

The most outstanding featurefrom a technical point of view,though not, perhaps, from an on-looker's, is the system of aerials.

Here it should be explained that tomake the distribution of programmesas simple as possible the Empire hasbeen divided up into five parts or

" zones," and a directional aerial isprovided for each zone.

As a matter of fact there is morethan one aerial for each zone. Somezones have as many as three aerials,so that the best wavelength for anyparticular time and condition can beutilised at a moment's notice.

Although there are many so-calleddirectional aerials at Daventry, itmust be remembered that, owing tothe wide area to be covered by thebeam, as from Daventry to Australiaor Canada, the construction differsfrom that adopted for simple point-to-point beam working.

The beam from the Daventrydirectionals is broad, which meansthat reception at the distant pointcan be enjoyed over a wide area.

Let us look at each zone in turn.Only the big countries are men-tioned in these zone areas though, ofcourse, most of the colonies andother parts of the Empire are in-cluded in one or other of the zones.

Zone 1.-Australia. A directionalaerial with a wavelength of 25.6metres. There is a very interestingpoint about this aerial. The radiatorand reflector systems are reversible,so that the signals can be sent which-ever way round the engineers thinkbest.

Zone 2.-India. Directionalaerials to transmit on wavelengths of17, 25, and 32 metres.

Zone 3.-South Africa. Direc-tional aerials to transmit on wave-letigths of 14 and 32 metres.

Zone 4.-West Africa. Direc-tional aerials to transmit on wave-lengths of 32 and 48 metres.

Zone 5.-Canada. Directionalaerials to transmit on wavelengths of19, 32, and 48 metres.

These directional, or array aerialsas they are sometimes called, consistof a reflecting " curtain " of verticalwires behind a radiating " curtain "of similar elements. Each elementconsists of a copper wire of abouthalf the wavelength being trans-mitted.

Call Signs of the EmpireBroadcasting Stations

Zone Metres Call

I Australasia 25.5 GSD

2 India 16.9 GSG25.3 GSE

3 South Africa 31.3 GSC49.6 GSA

4 West Africa 31.5 GSB49.6 GSA

5 Canada 31.5 GSB49.6 GSA

Long feeder wires run from theseaerial arrays through impedance -matching transformers to the trans-mitting buildings.

There will be " great occasions "when it is desired that the wholeEmpire shall make a point of listeningsimultaneously to an event happen-ing in London or any other cityconnected by landline or wirelesslink with the Daventry stations.

Six Special AerialsThen the directional aer:als would

obviously not do, as only two zonescould be covered as there are onlytwo transmitters. To make pro-vision for Empire S.B.'s on thegrand scale there are six omni-directional aerials at Daventry, tunedto such wavelengths as will ensurethe world-wide reception of anyevent in any part of the Empire atany time of the day or night.

It might reasonably be asked why,if these aerials are effective, weshould worry over the directionaltypes. The real point is that thedirectional aerials provide a strongersignal and, therefore, a signal cap-able of being heard more reliably than

706


THE B.B.C.'s SHORT-WAVE SERVICEdo the extra omni-directional aerials.

The rotational beaming of thesignals to the zones as each zone'sevening period comes round theclock is the B.B.C.'s impressive planto give each and every part of theEmpire a really good signal.

Standard Telephones ApparatusThere is no need for-nor is there

much listener interest to warrant-alengthy description of the actualstation buildings and equipment atDaventry. The whole of the installa-tion work on the array aerials and theshort-wave transmitters has beendone by Standard Telephones andCables, Ltd., the apparatus beingmade at that firm's works at Hendon,near London.

The building housing the twoEmpire stations is very similarlyplanned to a B.B.C. regional centre,in that there is a common transmitterswitchboard at one end of the hall,with the two groups of transmitterpanels fitted up facing one anotherdown the length of the hall.

The two stations have an aerialpower of 20 kilowatts each, which,although considered low for normalbroadcasting wavelengths, is quitehigh power for short-wave working,especially when you bear in mind theconservation of energy provided bythe beam aerials.

An important part of the stationequipment is the quartz -crystal ap-

paratus for maintaining the wave-lengths. Unless absolutely steadysignals are sent out, reliable recep-tion will obviously be impossible-hence the very great importanceattached to this part of the equip-ment by the station designers.

At the time of writing the Empirestations are " on the air " day andnight testing out before the inaugura-tion of the full service on Decem-ber 19. Reports are being solicitedfrom all parts of the world, and,judging from those already received,there is no doubt that Daventry willbe synonymous with " big noise."

At this early stage in the develop-ment of the new service it is obviouslyimpossible to lay down any hard-and-fast rules as to the most suitableapparatus for the reception of theEmpire programmes.

Two Methods of ReceptionThe most one can do is to remind

readers, both at home and abroad,that there are two alternative waysopen to the distant listener to pickup these Empire programmes. Thesimplest way is to use a short-wavereceiver, or an adaptor connected toan ordinary receiver, thus picking upthe Daventry signals direct. For thelonely outposts of Empire and for" individualists " in all zones, thismethod will commend itself.

There is another way, though, thatmay be eventually adopted by broad-

casting organisations in various partsof the Empire. This is the re-broadcasting on the normal mediumwavelengths of the short-wave signalspicked up by a central receivingstation.

Element of UncertaintyThere are great advantages in this

method. Although the B.B.C. ischoosing the best possible wave-lengths for any given zone at anygiven time, there is still an elementof uncertainty about short-wavereception which a central stationwould be more able to cope withthan could a home installation.

The beaming of the signals willmean more strength at the receivingend, but it will not overcome fadingeither of the fast or slow variety.Fading, though it cannot be curedat the transmitting end, being aproduct of the ether condition, canbe greatly ameliorated at the receiv-ing end by automatic volume -control circuits and by the use ofspaced aerials.

While these devices are outside thescope of the ordinary listener, theyshould be worth while for some of theDominion and Colonial broadcastingorganisations. Then listeners wouldderive the maximum benefit from theB B.C. new Empire service, whichseems likely to become the mostpowerful bond any Empire has everknown.

SWUM

WrOuttOIAND

.6[11111)046

Ct,rtST 41.146

Kp611.11,111,

ZONE 5

811 4{]11 UNION

J

ZONE 4

.wlittatmCussis t

11.1.4 ....BUN, 4 I

Y,

1104Ists

I CLY14"st11.11LiALs te.

4191,00/$.44

ZONES ZONE. 2

HMO MWI6.

W 4t11111.S.

T141.0011A

ZONE 1

ca

I

Includes aboutZONES "THE EMPIRES 8 .500 000 white people

1

About 35,000white people

White popula- Covers a whitetion 2,000,000 population of

1,500,000

This zone includes awhite population of

app rox. 7,500,000

707


THE enthusiasm of the home -constructor for actually making

his own apparatus with his ownhands is never better demonstratedthan with mains units. Now thatthere are so many units of goodquality on the market at reasonableprices it might be thought that nolistener would trouble to build uphis own battery eliminator.

A Steady DemandBut that is not what happens in

practice. There is a steady demandthroughout the year for blueprintsof " Wireless Magazine " mainsunits and letters are constantly beingreceived asking for constructionaldetails of A.C. mains gear.

In this article, therefore, wepresent details of a new A.C. powerunit knowing that it will meet theneeds of-and that it will be built by-hundreds of keen constructors.

The value of a mains unit where anelectric -light supply is available doesnot need any stressing.It is well known by nowthat the cost of gettingthe high-tension supplyfrom the mains is sosmall as to be negligible,even when a big setwith a large anode -cur-rent consumption isconcerned.

Anybody with electriclight who still uses bat-teries for the supply ofhigh tension is simplywasting money in mostcases.

The particular unit

11T+

HT

Mains Powerfor Your Set

described and illustrated in thesepages is intended to supply anodecurrent to almost any " battery " set.It utilises a Westinghouse metalrectifier of the HT7 type, which israted to give an output of 28 milli-amperes at 200 volts. In practice, ofcourse, this output is not quitereached, because of the voltage dropproduced inside the unit itself by thesmoothing choke.

Whenever a battery set is operatedfrom a mains unit care has to betaken to see that adequate decouplingis introduced at some convenient

point. Many battery receivers arenot provided with any decouplingand they are therefore inclined tomotor -boat when connected to amains unit.

In this case there will be notrouble, for ample decoupling forany ordinary set is incorporated inthe unit itself, as will be seen from aglance at the circuit diagram below.

Two terminals on the metal

An A.C. Unit forHigh and Low

Tension. De-

scribed by the" W.M." Techni-

cal Staff.

rectifier are connected to the high-tension secondary of the mainstransformer. The negative terminalon the rectifier is connected to thezero -voltage terminal on the trans-former, while the centre terminal ofthe rectifier is connected to the135 -volt tapping on the transformer.It is of the utmost importance tosee that a voltage of only 135 isapplied across the metal rectifier.

Mains VoltageIt is equally important that the

tappings on the primary of the trans-former should be adjusted for thevoltage of the mains on which theunit is to be used. Tappings areactually provided for 200-, 210-,220-, 230-, and 240 -volt mains ofbetween 40 and 100 cycles inperiodicity. If the periodicity ofyour mains does not fall within theselimits then it will be necessary toorder a special mains transformer..

The transformer actually used is,provided also with a

CIRCUIT OF A.C. MAINS UNITThe A.C. supply is rectified by a metal rectifier, arrangedon the voltage -doubler system. Four output terminals areprovided and the maximum output is approximately 28

milliamperes at 200 volts

low-tension secondary..This gives an output ofraw A.C. at 4 volts andis centre -tapped forconnection to theheaters of A.C. mainsvalves.

It will thus be seenthat this unit canform the basis for anall -electric receiver if sodes!red.

In order to obtain ahigh -voltage output, avoltage -doubler circuitis utilised and for this

708

COMPACT, BUT EASILY MADEAlthough particularly compact, this A.C. unit iseasily assembled. When using the blueprint to wireup, remember to make the connections in numerical

order

purpose two 4-microf arad fixedcondensers are con-nected across therectifier. It is im-portant that theseshould be of thetype made forworking voltages ofnot less than 400volts.

A large low -fre-quency choke withan inductance of 70henries is used forsmoothing. Thereis, therefore, littlechance of any humbeing experiencedexcept with thevery worst ofmains. It is necessary to choose forthis position a choke that retains itsinductance even when passing cur-rents of the order of 25 milli-amperes.

Output TerminalsFour output terminals are pro-

vided; these are marked H.T.+ 4,H.T.+3, H.T.+2 and H.T.± 1respectively. H.T.+ 4 gives themaximum voltage output-the fullvoltage of the rectifier, except for thesmall drop introduced by the smooth-ing choke. This tapping will besuitable for supplying the largertypes of power valve.

H.T .+ 3 (with the 3,000 -ohm de -coupling resistance shown) gives 160volts with a load of 15 milliamperes;

Wireless Magazine, January, 1933 1

it will therefore also be suit-able for running a powervalve of moderate con-sumption. Valves rated at150 volts maximum high-tension voltage should beconnected to this tapping.

H.T.+2 will be suitablefor running the detectorstages and the anodes of thehigh -frequency valve orvalves. With a load of 3milliamperes (and the25,000 -ohm decoupling re-sistance shown) it gives avoltage of 125. This, ofcourse, will fall somewhatas the load is increased.

H.T.+ 1 is for supplyingthe screens of high -fre-quency valves. It givesbetween 15 and 90 voltswith the values of resist-ances indicated in the cir-cuit diagram.

ANOTHER VIEW OF THE UNITThis unit gives supplies of high tension and of low tension

for running A.C. mains valves if desired

It will therefore be seen that almostany set can be supplied with hightension from this unit.

The construction is quite straight-forward and will be clear from aglance at the quarter -scale layout andwiring diagram reproduced on thispage.. If desired, a full-size blueprintcan be obtained for half price (thatis, 6d., post free) if the coupon onthe last page of the issue is usedby January 31.

Ask for No. WM310, and addressyour application to " WirelessMagazine " Blueprint Department,58-61 Fetter Lane, London, E.C.4.

It will be appreciated from thephotographs that the layout of theunit is compact and that there is nowaste of space. Should it be desired

for any reason to use alternative partsto those specified on page 710 careshould be taken to see that they areof such sizes that they will fit into thelayout without difficulty.

Accumulator ChargingThis unit as it stands supplies

only high tension and low tension forapplication to the heaters of A.C.valves. But many people withbattery sets will want still to runthe filaments from an accumu-lator and they will therefore wantsome means of charging the low-tension battery from the electricmains.

A complete accumulator chargercan be obtained for quite a reasonableprice from Heayberd's. This isillustrated by the photograph onthe next page.

It will obviously not be at alldifficult to connect this up to the setwith a switch so that when the

INI.LICPROO4,1310

LAYOUT AND WIRING DIAGRAMIf desired, a full-size blueprint can beobtained for half price (that is, 6d., postfree), if the coupon on the last page of theissue is used by January 31. Ask for

No. WM310

709

0

Wireless Magazine. Jan:lary, 1933

MAINS POWER FOR YOUR SET Cont.

SPECIAL PLAN VIEWA photographic plan view of the A.G. mains unit.It is particularly compact, but is not at all difficult tobuild. A full-size blue -print can be obtained for 6d.

receiver is done with the accumu-lator can be put on charge.

It should be remembered, how-ever, that the battery will need" topping up " occasionally. Thelevel of the electrolyte should bekept up to the mark on the case bythe addition of distilled water asoften as may be necessary. In thewinter the evaporation will be veryslow, but during the summer monthstopping -up will be required morefrequently.

Metal CaseThis mains unit is provided with a

metal protecting case. The mainsplug should never be inserted in themains socket until the unit has beenscrewed into the case. If for anyreason it is desired to remove theunit from the case, the mainssupply should be completely dis-connected. If this procedure isobserved there will be no dangerof shocks. In some cases readersmay desire to change the values ofthe decoupling resistances connectedin series with H.T.d- 3 andH.T.+2. It should be remem-bered that for every milliampere

flowing through a resis-tance of 1,000 ohmsthere will be a drop of 1 volt.In other words, if a currentof 10 milliamperes is takenfrom H.T.-F 3 there will bea drop in voltage of 3 x 10;in other words, the voltagewill be dropped by 30 volts.

Care should be takenwhen connecting the unit toa set for the first time tomake certain that the totalanode -current consump-tion of the valves to besupplied does not exceedthe maximum output thatcan be safely taken from themains unit.

The operator should lookup the valve curves (or thetables that appear in thefront of every issue of" Wireless Magazine ") andfind the anode current takenby each valve at the anodevoltage at which it is to berun.

The total anode -currentconsumption can then befound without difficulty. Ifthe current required is too

great for the metal rectifier theanode voltages should be reduceduntil the current consumption comesdown to a value that is within thecapabilities of the unit.

If the unit is to be used as the basisfor an all -electric set (that is, oneusing A.C. mains valves) the low-tension terminals should be con-nected to the heaters; which are, ofcourse, in turn connected in parallelas is the case with battery -valvefilaments. The centre -tap of thelow-tension winding is already con-

nected to high-tension negative, sothat this connection need not bemade in the set itself.

It should also be realised that ifthis unit is to be used as the basisfor designing an all -electric receiverno decoupling will be needed in theset itself. It has already been

ACCUMULATOR CHARGERThis Heayberd accumulator charger makesa good companion unit to go with thehigh-tension unit described in these pa;es.

Its output is .5 ampere

pointed out that ample decouplingfor all ordinary purposes is incor-porated in the mains unit.

In order to save money someconstructors may be tempted to usethe unit without the metal case.This course is most dangerous,however, and one that we urgeshould be avoided at all costs.

Although the voltages handled bythe unit are not large, there is quiteenough " juice " to give anybody anasty shock unless the apparatus isprotected-and an earthed metalcase is the best protection of all !

COMPONENTS NEEDED FOR MAINS POWER UNITCHOKE, LOW -FREQUENCY

1-Tunewell, type S70/50, £1.CONDENSERS, FIXED

2-Formo 1-inicrofarad, 5s.1-Formo 2-microfarad, 3s. 3d.3-Formo 4-microfarad, 18s. 6d.

FUSE1-Belling-Lee twin fuseholder and fuses,

Is. 6d. (or Bulgin).METAL RECTIFIER

1-Westinghouse, type HT7, 17s. 6d.RESISTANCES, FIXED

2-B.A.T. 3,000 -ohm, 1 -watt type, Is. 9d.(or Erie, Dubilier).

2-B.A.T. 25,000 -ohm, 1 -watt type, ls. 9d.(or Erie, Dubilier).

RESISTANCE, VARIABLE1-Colverstat 25,000 -ohm, type ST5c,

5s. 3d. (or Lissen, Lewcos).The prices mentioned are those for the parts u

as indicated in the brackets

SCREENED BOXt-Heayberd 7 in..by I1 y2 in. by Sys in.,

12s. 6d.SUNDRIES

Tinned -copper wire for connecting (Lewcos).Lengths of insulated sleeving (Lewcos).Length of rubber -covered flex (Lewcos).1-Wooden baseboard 61 in. by 113/4 in.

SWITCH1-Becker on -off, type 482, 2s. 3Y2d.

TERMINALS5-Belling-Lee, type B, marked :

H.T. +3, H.T. + 2, H.T. +1, H.T.-,2s. 6d. (or Clix, Eelex).

TRANSFORMER, MAINS1-Wearite, type HT8, £.1 2s. 6d.

ACCESSORIESACCUMULATOR CHARGER

1-Heayberd, type A02, £.1 15s., ed in the original set; the prices of alternativesmay be either higher or lower

710


What Kind of SetDo You Want?

Everybody knows what would be their ideal radio set ; " Wireless Magazine " wants to know whatis your ideal receiver. You are invited to complete this form and send it (in an unsealed envelopebearing a 2d. stamp) to : Ideal Set, " Wireless Magazine," 58-61 Fetter Lane, London, E.C.4.No prizes are offered, but readers will be helping themselves and " Wireless Magazine " by

supplying the information asked for below as soon as possible

How will the set be operated: from batteries (B),alternating -current (A.C.) or direct -current (D.C.)mains ? (Indicate B, A.C., or D.C.)

Do you want the set to incorporate reaction?(Indicate Yes or No.)

If from A.C. mains, do you prefer a metal rectifier(M) to a valve rectifier (V)? (Indicate M or V)

Do you like a milliammeter in the detector (D) oroutput circuit (0)? (Indicate D, 0, or No.)

.

What type of cabinet : table (T), pedestal (P), uprightportable (UP), or suitcase portable (SP)?(Indicate T, P, UP, or SP.)

Do you want an intermediate stage of low frequencyamplification between the detector and the powerstage ? (Indicate Yes or No.)

Is the set to have a self-contained loud-speakei ?(Indicate Yes or No.)

Is the low frequency amplifier to be transformer -coupled (T), resistance -coupled (R), or a combi-nation of both (C) ? (Indicate T, R, or C.)

In the case of a table battery set, are the batteriesto be contained in the cabinet? (Indicate Yesor No.)

Do you want to incorporate a tone control? (Indi-cote Yes or No.)

Is the set to be a straight radio receiver (SR), tohave provision for the use of a pick-up (PU), orto be a complete radio gramophone (RG)?(Indicate SR, PU, or RG.)

What type of output stage: three -electrode (T),pentode (P), or push-pull (PP)? (Indicate T, P.or PP.)

Is your object to get the greatest possible number ofstations (N) or really good quality from a fewstations (Q)? (Indicate N or Q.)

What is to be the maximum high-tension voltage ?

What will be the distance, in miles, of the set fromthe nearest broadcasting station ?

What is to be the maximum anode -current con -sumption ?

Do you want the set to get short-wave stations aswell as medium- and long -wave transmissions?(Indicate Yes or No.)

In the case of a battery set, will you get the high -tension from a mains unit ? (Indicate Yes or No.)

Do you prefer a super -het to a "straight" set?(Indicate Yes or No.)

What type of loud -speaker will you use : moving -iron or balanced armature (BA), moving coil(MC), or electrostatic (E)? (Indicate BA, MC,or E.) ......_

What is to be the total number of valves?In the case of a moving -coil loud -speaker, is it to be

of the permanent -magnet (PM), or energised (E)type ? (Indicate PM or E.)

If not a super -het, do you want one or two stagesof high frequency amplification or none ?

Do you want to incorporate dual compensatedloud -speakers? (Indicate Yes or No.)

If a super -het, how many intermediate frequencystages do you want ?

Do you want terminals for connecting an additionalloud -speaker ? (Indicate Yes or No.)

Do you want the super -het to have a preliminarystage of high frequency amplification ? (IndicateYes or No.)

Do you want to use an external open aerial (E), ex -ternal frame aerial (F), or self-contained frameaerial (S)? (Indicate E, F, or S.)

Do you want to use ordinary screen -grid (SG) orvariable -mu (VM) valves P (Indicate SG or VM.)

In the case of a set with self-contained aerial, doyou want provision for an external aerial andearth ? (Indicate Yes or No.)

What type of coupling : tuned grid (TG), tunedanode (TA), or high frequency transformer(HFT)? (Indicate TG, TA, or HFT.)

In the case of a mains set, is a mains aerial desired ?(Indicate Yes or No.)

_Do you want one -knob tuning control ? (Indicate

Yes or No.)How much (approximately) are you prepared to

spend on the complete assembly?

Is the tuning dial to be calibrated in degrees (D),wavelengths (W), or names of stations (S)?(Indicate D, W, or S.)

Reader's name and address (for reference only andnot for publication).

What type of detector do you prefer: three -electrodeleaky -grid (LG), anode -bend (AB), diode (D), orscreen -grid (SG)? (Indicate LG, AB, D, or SG.)

711


0,

Radio News from All the World .. By J. GODCHAUX ABRAHAMS

BELGIUMFOR some time past experiments

have been carried out by the short-wave station at Ruysselede (Bruges)with a view to establishing a publicwireless -telephony service with Leo-poldville (Congo). Tests in speechand music may be heard almost dailybetween 10 and 11 a.m. G.M.T. on19.3 metres; at 11 p.m. the nightwave of 42.1 metres is used.

FRANCEFollowing a protest lodged by

German listeners in regard to thenumber of military marches incor-porated in the studio programmes,a Paris wireless journal points outthat the same accusation may bemade against the French studios." Les Allobroges," an old patrioticsong, is regularly used by Grenobleand PTT, Toulouse. " Sambre etMeuse," a march widely used by regi-ments, is broadcast almost daily byPoste Parisien and Ecole Superieure(Paris) opens its transmissions witha fanfare of trumpets played by theRepublican Guard.

GERMANYAt Betzenhausen, about one and a

half miles to the north-west ofFreiburg-im-Breisgau, a new 5 -

kilowatt transmitter is being erectedto replace the small plant now usedfor the relay of the Stuttgartprogrammes. When completed,the station will work on a wavelengthof 259.3 metres (1,157 kilocycles),common to Frankfurt -am -Main,Cassel, and later, Treves. It will beready to operate in the early spring.

. .The new 60 -kilowatt station

erected at Erdinger Moos, which isdestined to take over the duties ofthe present Munich transmitter, isnow testing daily on 532.9 metres(563 kilocycles). Built to the orderof the Bavarian authorities, incommon with other German stationsit is so planned that, should occasionarise, its power can be doubled atshort notice.

GRAND DUCHY OFLUXEMBOURG

Contrary to reports published tothe effect that the Dutch A.V.R.O.broadcasting association would bewilling to lease Radio Luxembourgfor its Sunday transmissions, it isstated in Holland that as long asthe new transmitter is not permittedto work on the higher portion of themedium waveband there would beno advantage resulting from such ameasure. Moreover, difficulty wouldbe found in obtaining a suitablelandline to connect the Luxembourgstation with the Hilversum studio,and the cost of the hire of such astation would be too high for aprivate company to use it purely forentertainment purposes.

HOLLANDSteps are to be taken to increase

the power of the Huizen tram mitterto 20 kilowatts. The expenses forthe conversion of the plant will becovered by the broadcasting associa-tions using that station.

ITALYA complete net of pupinised cables

for the broadcasting stations is beinglaid down in Italy and within thenext few months all studios will belinked up into one system, thuspermitting a free interchange ofprogrammes from such distant pointsas, say, Bolzano and Palermo. Inaddition, three international cableslink up Turin, Modena and Faris;Milan and Vienna (and an extensionthrough the latter) connects up withthe German system.

The first transmitter to operate ona wavelength of 60 centimetres isbeing installed at the Vatican (Rome)for communication with the PapalPalace at Cassel Gandolfo. It canbe used for either telegraphy ortelephony.

JUGOSLAVIAIn October, 1932, Ljubljana cele-

brated the fourth anniversary of itsinstallation; its studio is under the

712

direct control of two priests. Al-though a large number of the trans-missions are locally organised, thestation on some nights relays enter-tainments from Belgrade and Zagreb.In view of the interference byFreiburg-im-Breisgau, Hamar andGrenoble, the wavelength has beentemporarily changed to 575 metres(522 kilocycles).

ROUM ANIAListeners in Bucharest have pro-

tested against the power of theLeipzig broadcasts which, in view ofthe wavelength used, interferes withthe reception of the local programmes.The Roumanian Broadcasting Com-pany is appealing to Geneva for theallotment of a channel with greaterseparation from the German trans-mission.

RUSSIAThe U.S.S.R. stations generally,

but Moscow in particular, in theirtalks in foreign languages haveadopted a more sober tone, and nowlimit these lectures to descriptions ofliving conditions in Russia and to anexplanation of the Five-year Plan.During the period December -March,these talks will be broadcast fromMoscow (Trades Unions) on 1,304and 50 metres in French andEnglish between 8 and 9 p.m.; theyare followed by similar lectures inSwedish, Magyar, and Spanish.The studio holds the record for itsmulti-lingual broadcasts as, in addi-tion to the above, transmissions arealso made in German, Dutch andCzech.

SWITZERLANDAnticipating tXe erection of the

Monte Ceneri broadcasting station,the Swiss authorities have alreadybuilt a studio at Lugano. It willtake part in the special internationalconcert to be broadcast on March3 through Beromuenster and Sottens.Other programmes will be providedby Berne, Basle, Zurich, Geneva,and Lausanne.

The, 11Eth

By

PERCY W.HARRIS

M.Inst.Rad.E.

EVERYBODY is interested in three -valve sets, whichare by far the most useful radio outfits for present-day

conditions when they incorporate a good stage of high -frequency amplification. But this set, which has beenspecially designed for "Wireless Magazine" by Percy W.Harris, is more than a plain three -valve receiver-it is acomplete radio gramophone housed in an attractive tablecabinet.

A real attempt has been made to overcome the usualganging troubles by utilising a set of coils that are actuallymatched up in the factory with the gang condenser withwhich they are to be finally used. So accurate is theganging that we have been able to prepare a special scalemarked with the names of stations so that the operator cantune directly to any particular programme he desires with-out having to look up wavelengths lists.

Apart from a very fine performance in the way of radioreception-sixty stations have been received in two differentlocalities in London-the Harris Ethergram gives all theadvantages of a good -quality gramophone amplifier. Hereis the ideal three-valver for 1933 !

-Wireless Magazine. January 1933

Percy W. Harris at work in his laboratory

Special Features of the SetA variable -mu screen -grid valve gives

great high -frequency amplification andan easy control of volume.

The pentode output valve is matchedto the moving -coil loud -speaker bymeans of a tapped choke so that correctmatching is obtained. This gives fullvolume and the best quality.

A tone control is provided so thatindividual preferences in the way oftone can be met at will.

A special scale calibrated with theactual names of stations will be givenwith each full-size blueprint of the set.By this means the operator can tune into stations directly by name, withoutthe need for looking up dial readings orlists of wavelengths.

The layout of the set is particularlyclean and there are no snags in theconstruction.

A half -scale layout and wiring diagramis included in these pages. All the con-necting leads are numbered in the bestand most convenient order of assembly.

Sixty stations were received by thedesigner in his laboratory; this log wassubsequently confirmed independentlyby a member of the "Wireless Magazine"staff-a fine performance for a "three."

713


Building the EthergramEven the beginner will have nodifficulty in understanding theseexplanatory notes by the de-signer of the Ethergram. Theset is quite straightforward tobuild and we recommend Itwithout reservation-a glanceat the special test report onpage 722 should convince even

the most sceptical !

THERE are strong reasons whythe three-valver remains one of

the greatest favourites with listeners.Using modern valves and modemcircuits, both range and selectivityof a high order are obtainable, whileas to current consumption, par-ticularly when a modem pentode isused, it comes well within the rangeof a medium-priced high-tensionbattery.

Use of the MainsOf course, where mains are avail-

able, high-tension consumption doesnot matter, but it must always beremembered (although the tradeseem to have forgotten it) that themajority of homes in this countryhave no such mains.

The Ethergram is, then, a batteryradio gramophone, designed aftermuch thought and experiment togive those qualities most desired atthe present time-high selectivity,big range, and first-class tonequality, coupled with economy ofoperation and maximum simplicityof control.

Selectivity has been my specialstudy for a number of years, and Iwould suggest that you will find itvery helpful, when consideringreceiver circuits, to remember thatthe selectivity of a set is governedlargely by the number of tunedcircuits through which the signalpasses.

Two Circuits NeededA detector with two low -frequency

stages, coupled to the aerial by asingle tight -coupled tuned circuit, isfar too flat for present conditions.By using a very loose aerial couplingand a fairly critical reaction, areasonably high degree of selectivitycan be obtained (save in swamp

areas), but for modem conditions aminimum of two tuned circuits isreally required.

Quite a number of three -valvesets have only two such circuits-one in the first grid circuit connectedto the screen -grid valve, and theother in the grid circuit of thedetector.

If the aerial is loosely coupled tothe first tuned circuit this arrange-ment gives very good selectivity,and the fact that a large number of" detector and two low -frequency "circuits have only one tuned circuit,while " screen -grid, detector andlow -frequency " sets always haveat least two, has led many people tosuppose that it is the screen -gridvalve which gives the selectivity.

You can disabuse your mind ofthis idea at once-the screen -gridvalve has no bearing on the subject.It is just a question of the numberof tuned circuits used. If you usetwo tuned circuits in front of thedetector in a " detector and two low -frequency " set you will get admir-able selectivity, as I showed in theA.C. radio gramophone, details ofwhich were published in " WirelessMagazine s" for August.

For a long time I have been turningover in my mind the construction ofa screen -grid set of particularly highselectivity, combined with goodquality, but did not put the designinto execution because I could notfind just the kind of parts I requiredfor my plan.

It is a comparatively simple matterto work out a selective receiver usinga multiplicity of tuned controls, butsuch a set is often unwieldy tomake and inoperative save in skilledhands.

If the circuits are ganged, thenmatching and ganging problemsenter into it.

As many designs with gangedcondensers lose heavily in efficiencydue to inadequate matching andganging, I made up my mind Iwould wait until I could find justwhat I needed.

My requirements were, so far asthe circuit was concerned, a properlydesigned and screened band-passarrangement preceding a screen -gridvalve (which should be of thevariable -mu variety) and a soundly

designed coil, completely screenedfrom the first two coils, in thedetector -grid circuit.

At the same time a good three -gang condenser was required withadequate trimmers and, if possible,arrangements should be made at thefactory to match up the coils andcondensers accurately. Furthermorethe price of such a device must bereasonable. Fortunately at the RadioShow two manufacturers producedthe right scheme.

Drastic TestsIn this set I have chosen the

Formo assembly, consisting of athree -gang condenser and three coilsmounted on a single baseplate withterminals arranged all ready to wireup. As this device proved verysuccessful on rather drastic tests forganging and matching, I decided itwould solve my main problem, soI set to work to build the designround it.

The circuit in its theoretical formyou will see on page 718; it consists,as I have indicated above, of a tunedcircuit coupled to the aerial througha compression condenser, this firsttuned circuit being in turn coupledto a second one by a .01-microfaradcondenser at the lower end.

The second tuned circuit is con-nected to the grid and 'filament ofthe variable -mu screen -grid valve,provision for varying the magnifica-tion being made by the potentiometerwhich is mounted as a volume controlin a suitable position on the panel.

In the anode circuit of the screen -grid valve is a carefully -screenedchoke. I do not suggest alternativesto this, by the way, as the particularchoke chosen works admirably inthis set. If you substitute for itanother make you must do so atyour own risk as a design of thiskind has been worked out as a whole.

" Interlocked Design "I am not suggesting that all other

makes of radio -frequency choke arenot good-it is just a question ofwhat may be termed an " inter-locked " design. The variations ofvoltage set up across this choke areapplied through a .0001-microfaradcoupling condenser to a tuned circuit

(Continued on page 71()

714

Wireless Magazine. thnuarx 1933

ROAM THE ETHER IN 1933 WITH THEHARRIS ETHERGRAM !

(Above).-A view ofthe Harris Ethergram which clearlyshows the neat arrangement of theparts, which are all quite accessible

(Right).-The set housed in theSmith table radio -gramophonecabinet. The batteries are arrangedon a shelf behind the moving -coilloud -speaker, while the set itself is

placed at the bottom of the case

(Below).-Trying out theHarris Ethergram, a sixty -station three -valve combina-tion with finely controllable

selectivity

A plan view of the set showingthe disposition of the parts. Thecoils and three -gang condenserare supplied as a complete

assembly on a metal baseplate

Do not overlook the half -scale wiring Diagram on pages 716 and 717

715

TH

E H

AR

RIS

ET

HE

RG

RA

M C

ontin

ued

conn

ecte

d to

the

dete

ctor

val

ve.

Not

ice

here

that

ther

e is

an

adju

stab

le ta

ppin

g fo

r co

uplin

g to

the

dete

ctor

cir

cuit.

In p

ract

ice

it w

ill b

e fo

und

that

whe

n th

e pl

ug is

join

ed to

tapp

ing

No.

2 th

e be

stov

eral

l res

ults

will

be

obta

ined

.In

the

anod

e ci

rcui

t of

the

dete

ctor

val

ve w

ill b

efo

und

the

diff

eren

tial r

eact

ion

cond

ense

r an

d a

radi

o -

freq

uenc

y ch

oke

conn

ecte

d to

the

prim

ary

of a

Var

ley

Rec

tato

netr

ansf

orm

er.

Thi

sis

one

ofse

vera

l exc

elle

nt tr

ansf

orm

ers

now

ava

ilabl

e en

ablin

gth

e to

ne q

ualit

y to

be

vari

ed a

t will

.

Dif

fere

ntia

l Rea

ctio

n C

onde

nser

As

it ha

ppen

s, th

e ch

arac

teri

stic

of

this

tran

sfor

mer

with

out m

odif

icat

ion

adm

irab

ly s

uits

the

rest

of

the

set,

so f

or r

adio

wor

k I

wou

ld s

ugge

st th

at th

e kn

obof

the

tone

-co

ntro

l res

ista

nce

conn

ecte

d to

the

Rec

ta -

tone

is k

ept a

t the

pos

ition

of

min

imum

cor

rect

ion.

The

act

ual v

aria

tion

of to

ne p

ossi

ble

by m

eans

of

this

res

ista

nce

will

gen

eral

ly b

e co

nfin

ed to

the

repr

oduc

tion

of g

ram

opho

ne r

ecor

ds.

The

out

put s

ide

of th

is tr

ansf

orm

er is

con

nect

edto

a p

ento

de v

alve

, whi

ch g

ives

hig

h m

agni

fica

tion

with

a v

ery

reas

onab

le h

igh-

tens

ion

cons

umpt

ion.

In o

rder

that

the

loud

-sp

eake

r an

d pe

ntod

e m

ay b

epr

oper

ly m

atch

ed a

s to

impe

danc

e, in

the

outp

utci

rcui

t of

this

val

ve th

ere

is in

clud

ed a

tapp

ed p

ento

dech

oke.

Ade

quat

e de

coup

ling

ispr

ovid

ed w

here

nece

ssar

y, a

s sh

own.

Thu

s yo

u w

ill s

ee th

at th

e th

eore

tical

cir

cuit

is to

a la

rge

exte

nt c

onve

ntio

nal.

I am

no

advo

cate

of

" tr

ick

"ci

rcui

ts in

whi

ch v

aria

tions

are

intr

oduc

edju

st a

s va

riat

ions

, with

out a

dequ

ate

reas

on.

I am

onl

y in

tere

sted

in d

esig

ns b

ased

on

soun

den

gine

erin

gpr

inci

ples

,an

dI

ampa

rtic

ular

lyin

tere

sted

in g

ivin

g yo

u go

od, w

ell -

trie

d, p

ract

ical

Hal

f -S

cale

Lay

out a

nd D

iagr

amO

n th

is p

age

appe

ars

the

pane

l lay

out;

the

base

boar

d la

yout

is r

epro

duce

d be

low

.

'-'80

4AR

WIW

MPI

NW

A.A

41-5

MA

TM

Vig

alW

at,

BLU

EP

RIN

T H

eW

M30

8

Cip

t..or

f'W

iTet

t.

appl

icat

ions

of

thes

e ci

rcui

ts, f

or it

is in

the

prac

tical

expr

essi

on a

nd th

e ac

tual

layo

ut th

at th

e vi

rtue

s of

apa

rtic

ular

des

ign

are

usua

lly f

ound

.It

is g

ener

ally

pos

sibl

e to

tell

from

the

look

of

are

ceiv

er w

heth

er it

has

bee

n m

ade

by a

rel

ativ

ely

unsk

illed

mec

hani

c fr

om a

theo

retic

al d

iagr

am o

rw

heth

er it

has

bee

n w

orke

d ou

t by

a pr

actic

al d

esig

ner

on th

e la

bora

tory

ben

ch.

Inte

rest

ing

Poin

ts in

Lay

out a

nd D

esig

nT

here

are

man

y in

tere

stin

g po

ints

in la

yout

and

desi

gn in

the

pres

ent r

ecei

ver,

and

few

hav

e gi

ven

me

such

ple

asur

e in

thei

r de

velo

pmen

t.L

et m

e in

trod

uce

to y

ou f

irst

of

all a

par

ticul

arly

sim

ple

met

hod

of o

btai

ning

sta

bilit

y an

d lin

king

up

a nu

mbe

r of

par

ts a

t a u

nifo

rm p

oten

tial.

Com

-m

erci

al m

anuf

actu

rers

who

hav

e ad

equa

te f

acili

ties

have

now

pra

ctic

ally

sta

ndar

dise

d m

etal

cha

ssis

, for

the

two

reas

ons

that

they

are

mec

hani

cally

str

ong

and,

bei

ngco

nduc

tive,

pro

vide

a p

lane

of

unif

orm

pote

ntia

lto

whi

chva

riou

s pa

rts

can

be c

onne

cted

,th

us m

akin

g fo

r st

abili

ty.

The

hom

e co

nstr

ucto

r fi

nds

itdi

ffic

ult

to w

ork

on a

met

alch

assi

s un

less

he

has

it al

read

ydr

illed

for

him

(w

hich

inci

-de

ntal

ly r

emov

es m

uch

of th

epl

easu

re o

f bu

ildin

g a

set)

, and

it ha

s be

en th

e cu

stom

in a

num

ber

of o

ur d

esig

ns to

cov

erth

e ba

sebo

ard

with

a s

heet

of

met

al f

oil.

Ano

ther

Met

hod

ofSc

reen

ing

The

re is

, how

ever

, a m

etho

dw

hich

I h

ave

been

usi

ng in

my

labo

rato

ry v

ery

succ

essf

ully

for

som

e tim

e an

d w

hich

I a

m n

owin

trod

ucin

gin

toth

isde

sign

.T

his

is to

cov

er th

e ba

sebo

ard

with

a s

heet

of

mat

eria

l kno

wn

as K

ondu

ctite

, whi

ch c

onsi

sts

of a

she

et o

f st

out p

aper

on

tow

hich

is g

lued

a v

ery

thin

she

etof

alu

min

ium

foi

l.

0 4a

0,

17,3

:1k

-0 -

As

co43

eN

45. .

.

,FR

TS:

S.

Alu

min

ium

isa

high

con

-au

ctin

g m

etal

, and

the

thin

foi

lis

qui

te g

ood

enou

gh f

or th

epu

rpos

e fo

r w

hich

we

requ

ire

it.T

his

mat

eria

l,th

efo

ilbe

ing

glue

d to

pap

er, c

an b

eve

ry e

asily

hand

led

and

cut

with

sci

ssor

s ju

st li

ke o

rdin

ary

pape

r.

Beg

inni

ng C

onst

ruct

ion

To

begi

nou

rac

tual

con

-st

ruct

ion

we

take

a b

aseb

oard

mea

suri

ng 1

4 in

.sq

uare

and

atta

ch a

shee

tof

Kon

duct

iteto

this

base

boar

dw

ithan

ysu

itabl

e ad

hesi

ve (

I us

e Se

cco-

tine)

.T

hepa

per

isth

enne

atly

trim

med

and

we

asse

mbl

e th

e pa

rts

as s

how

n.T

he F

orm

o co

nden

ser

-and

-co

il as

sem

bly

has

supp

lied

with

it a

drill

ing

tem

plat

e fo

rth

epa

nel

soas

toen

able

the

beve

lled

win

dow

to b

e fi

tted,

but

the

asse

mbl

yits

elf

issc

rew

ed to

the

base

boar

d an

dth

e pa

nel h

as n

otto

sup

port

anyt

hing

mec

hani

cally

.

Stic

k to

the

Lay

out

Not

ice

part

icul

arly

how

the

vari

ous

part

s ar

e ar

rang

ed a

ndad

here

str

ictly

to th

is a

rran

ge-

men

t.D

o no

t suc

cum

b to

the

A f

ull-

size

blu

epri

nt c

an b

eob

tain

ed f

or h

alf

pric

e, th

atis

6d.

, pos

t fre

e, if

the

coup

onon

the

last

pag

e is

use

d by

Janu

ary

31.

Ask

for

No.

WM

308

and

addr

ess

your

appl

icat

ion

to"W

irel

ess

Mag

azin

e" B

luep

rint

Dep

t.,58

/61

Fette

r L

ane,

Lon

don,

E.C

.4. N

ote

that

all

the

lead

sar

e nu

mbe

red

in th

ebe

stor

der

of a

ssem

bly.

With

each

blu

epri

nt w

ill b

e su

p-pl

ied

a fr

ee s

tatio

n sc

ale

(see

repr

oduc

tion

on p

age

721)

for

fixi

ng to

the

vari

able

con

-de

nser


THE HARRIS ETHERGRAM Continuedtemptation to modify the layout inorder to suit a particular panel, base-board or cabinet. In this directionsuccess does not lie !

Very many hours were spent indetermining the exact shape, lengthand disposition of the leads in thehigh -frequency end of this set, soadhere very strictly to the design atthis part too !

Question of StabilityAs the condenser and coils are

shielded it might be imagined thatthis alone would give sufficientstability, but it must be rememberedthat we are dealing in this set withvery high -gain valves and we haveto.be careful.

When the first bench assemblywas finished and the set switched onit worked admirably over most of thescale, but was unstable from about15 degrees down to zero on eachwaveband. Careful tests showedthat the instability was purely in thescreen -grid portion of the set.

Ultimately it was traced down tocoupling on tothe grid lead ofthe screen -gridvalve and wascompletely curedby taking thislead from the coilto the grid ter-minal of the valveholder throughan insulated tubecovered on theoutside withmetal braid,this braid beingearthed.

The set thenbecame com-pletely stable andthe only effectof the braid was to add a little to thecapacity between grid and filamentof the screen -grid valve.

Extra " Trimming "As we have already a large capacity

in the tuning circuit it was onlynecessary to alter the trimmer on thesecond condenser in order to com-pensate for this as the additionalcapacity is simply in parallel. Onlya short length of this braided tubingis required and as it is a standardproduct for screening radio -gramo-phone pick-up leads it is quiteeasily obtainable.

Do not attempt to put similarscreening on the anode lead of thescreen -grid valve. There are anumber of technical reasons whyyou should not do this and in anycase it is entirely unnecessary.

The set can be operated at anypart of the tuning scale, even as lowas one or two degrees on either wave-band, with the volume control turnedfull on without the slightest in-stability and, in addition to this, thegreatly enhanced magnification givenby reaction in the detector circuitcan be used up to the limit withoutany backlash or overlap.

It is this careful layout of the high -frequency end, enabling the highmagnification of the screen -gridvalve to be used in conjunction withthe greatly enhanced sensitivity ofthe detector circuit, which makes thisset so amazingly sensitive andselective.

The panel, as you will notice, is astandard 14 in. by 7 in. size and thewhole assembly is so made that thosewho do not wish to build a radio

Actually on the blueprint (a copyof which can be obtained for halfprice, by the way, if application ismade by January 31) the set is shownwithout the wiring for a pick-up.If you just want a straight radioreceiver, then wire up exactly asshown.

Pick-up ConnectionsShould you want to build the com-

plete radio -gramophone assembly,as many of you will no doubt, omitthe lead numbered 33 and take thepoints x and 'Y to the gramo-radioswitch as indicated in the diagramon page 720.

Only four terminals are used-those for aerial and earth and loud-speaker - as the batteries areincluded within the cabinet andflexible, leads go from the variouspoints without the intervention ofterminals.

So much, Then, for the construc-tional work, which I think you willfind is particularly simple. Now forthe adjustment and the tuning up "

of the set afteryou have corn -

50000 11

20.0005

so.000n '-oar Mn w

0 0-P 60

214.0

60-1 65-2 65-3 60+

0117+2

OPIT4.1

2 MM. 0'4T -

L.60

g1-651

OLT-

T.

A STRAIGHTFORWARD CIRCUIT WITHOUT ANY " TRICKS"Much of the success of the Harris Erhergram is due to the fact that the circuit is quitestraightforward. It comprises a screen -grid variable -mu stage, a detector and a

pentode output valve

gramophone can use the set in aconventional cabinet. When usedin a radio -gramophone cabinet it isslid into the base as shown, with theloud -speaker placed just above itand the batteries on a shelf behindthe loud -speaker.

A pair of leads then goes from thegrid circuit of the detector valve upto a radio -gramophone switch, whichis placed on the board supportingthe turntable, and another pair ofleads goes up from the Rectatonetransformer to the tone -controlresistance (or potentiometer) whichis also placed on that board.

pleted the con-structional work.

The operatingcontrols of thisset are, of course,the tuning knob,which controlsall three circuits;the reaction knob(on the right)which in accord-ance with normalpractice is madeto increase reac-tion as it isturned in a clock-wise direction;the wave -change

switch, which changes from themedium to the long wave and backagain through a quarter of a turnonly; and the volume control, whichshould only be used when thestrength without reaction is toogreat and when the set gives signs ofoverloading on strong signals.

Using the Volume ControlIt operates by reducing the mag-

nification given by the screen -gridvalve and is normally kept at the" full on " position, which is as faras it will go in a clockwise direction.

(Continued on page 720.)

718

a


EXCELLENT QUALITY WHEN USED AS ARADIO GRAMOPHONE !

(Left).-The trimmersshould be adjusted witha wooden stick shapedat one end like a screw-driver. Ganging willnotgive any trouble even

to the beginner

(Right).-Putting the HarrisEthergram through its pacesas an electrical gramophone.

A tone control is provided

(Left).-Top of motor -board, showing theposition of the pick-up.The connections areindicated on page 720(Right).-A view of theHarris Ethergram com-pletely assembled andwith the valves in

position

A free station -calibrated scale will be given with every blueprint

719

Wireless Magazine, January1933

THE HARRIS ETHERGRAM ContinuedBROWKTO GB- -= = = = =BLACK

TO EARTH

TO L.F.COUPLIIIUNIT ON

SET

4-

7 4/8

BRAKE

-t-. .)---... ,,..50,000 OHM

VARIABIA RESISTANCE.

MOTORSPINDLE

//

ToDETECT OR

VALVE GRID

SPEED REGULATOR

TO GAIT)COKDEASECE^Ik.,

T. "

14,2

Iva =11111

11

111

H

BRAIDED

GRAMO-RADIO q=SWITCH ---r\+-

AT.LAYOUT OF THE MOTORBOARD FOR THE HARRIS ETHERGRAM

This diagram shows the position of the pick-up, gramo-radio switch and tone -controlresistance. The method of connecting these parts to the set is explained in the article

There is, of course, also the usualon -and -off switch at the bottomright-hand side of the panel.

The compression condenser whichis attached to the baseboard near theaerial terminal serves to controlaerial coupling, while the wanderplug on the first coil (the green one)also has the same effect.

If at any time the tuning is notsharp enough one can slightlyunscrew the compression condenseror alternatively plug in a lower holeon the green coil. Normally itwill be found thoroughly satisfactoryto keep the compression condenserscrewed right down and the wander -plug in hole No. 2 of the green coil.

Anode TappingIf you examine the theoretical

circuit you will see that the anodeof the screen -grid valve goes througha .0001-microfarad fixed 'condenserto a suitable tapping point on thedetector -grid coil. Four tappingpoints are provided, numberedrespectively 1, 2,3,4 on the blue coil.

Here again selectivity can be

adjusted by altering the coupling,but I would suggest that you alwaysuse the plug in socket No. 2.

Start off, then, with the com-pression condenser screwed rightdown, the wander plugs in socket 2of the green coil and in socket 2 ofthe blue coil, the volume controlturned full over to the right orfully clockwise, and the reactioncondenser fully anti -clockwise.

In the first socket you will have avariable -mu screen -grid valve of thebattery type, an HL type of valvein the detector socket, and in theoutput a low -consumption pentode.I recommend a 120 -volt high-tensionbattery with the H.T.d- 1 plug inabout 80 (or whatever other valueis recommended for the screeninggrid by the makers of the particularvalve) and, of course, H.T.-F 2 in 120.

The set works perfectly satisfac-torily with any good mains unit, andif you are using it with such a devicedo not exceed 150 volts for H.T.+ 2.

Grid bias is so arranged that thepositive wander plug goes to theswitch (and thence to L.T.- when

the switch is closed), while thewander plug connected to thepotentiometer goes into maximumor 9 volts. The wander plug con-nected to the grid bias of theRectatone goes into a socket corres-ponding with the grid bias recom-mended for your maximum anodevoltage by the makers of the pentode.

With everything switched on,first of all try the reaction condenserto see that it makes the set oscillate.You need have no fear of causinginterference as the oscillation ispurely in the detector circuit anddoes not get into the aerial.

Trimming the SetIf this is satisfactory turn all three

dial wheels connected to the trim-ming condensers in a clockwisedirection as far as they will gowithout forcing and then unscreweach of them by an equal amount-about one turn. Next turn thetuning condenser until you hear anystation (not necessarily your local).

If the first station you hear isvery loud turn the volume -controlknob in an anti -clockwise directionuntil you have reduced the strengthreasonably. It is essential, how-ever, that you should set the tuningcondenser at a maximum tuningposition and reduce the volume onlyon the volume control.

Then, with the set dead in tune,slowly turn the trimmer wheel onthe second condenser (the middleone) one way or the other till youget the maximum strength on thatparticular station.

Next re -tune slightly (if necessary)on the tuning knob and then makea similar adjustment of the thirdcondenser (that at the rear) untilyou get maximum signals.

Final AdjustmentsA further slight re -tuning if

necessary, and perhaps a touch againone way or the other on the secondcondenser, and your set should beganged for this station.

Do not touch the first trimmerat the moment. What you have beendoing is to adjust the second andthird circuits to the first and there isno point whatever in touching thefirst condenser just now.

Now with or without the aid ofreaction you should be able to pickup a large number of stations oneither waveband, and when you have" got the hang " of the set test out

720


AN IDEAL "THREE" FOR 1933 !the ganging at top and bottom endof the tuning scale and in the middle.

You will find that the set gangsnicely anywhere and if it is properlyganged at the lower end it will besatisfactorily ganged at the top, andthere will be no need to make anyfurther adjustments in this regard.

Sixty StationsIn the first two evenings of my

test with this set, using the " Wire-less Magazine " Station Finder givenin October, I easily located sixtystations. The method I adoptedwas to put down what I thought wasthe station, judging from the identi-fications given in the " WirelessMagazine " Station Finder, andhaving done this, to start positivelyto identify them.

Several stations were at onceidentified by their own announce-ments and those less easily identifiedin this way were soon tracked downby a combination of language,programme items, and identity ofprogramme with the correspondinglong -wave stations.

An Easy TaskI purposely ignored stations which

were weak or badly heterodyning,and concentrated only on thosewhich gave a really good signal.Towards the end of the preliminarytest, finding stations became veryeasy for, as the dial readings weredotted down in pencil all over theguide, it was quite easy to estimatewhere a particular station shouldcome on the one tuning dial.

COMPONENTS NEEDED FOR THE HARRIS ETHERGRAMCHOKES, HIGH -FREQUENCY

1-Kinva screened, standard type, 2s. 9d.1-Lewcos, type MC, 2s. 6d. (or Peto-Scott,

Ready Radio).CHOKE, LOW -FREQUENCY

1-Varley Pentode Nichoke, type DP24,12s. 6d.

COMBINED CONDENSER AND COILASSEMBLY

1-Formo, triple -gang, type 69c, £2 6s. 6d.CONDENSERS, FIXED

1-T.C.C. .0001-microfarad , type 34, ls. 6cL(or Telsen, Lissen).

1-T.C.C..0003-rnicrofarad, SP type, 2s. 4d.1-T.C.C. .01-microfarad, type M, 2s. 3d.

(or Telsen, Lissen).2-T.C.C. .25-microfarad, type 50, 2s. 3d.

(or Dubilier).1-T.C.C. .5-microfarad, type 50, 2s. 7d.

(or Dubilier).2-T.C.C. 2-microfarad, type 50, 7s. 8d. (or

Telsen, Lissen).CONDENSERS, VARIABLE

1 -Magnum .0003-microfarad differentialreaction, 2s. 6d. (or Lotus, Bulgin).

1-Formo preset .0003-microfarad max.,ls. 3d. (or Goltone, Sovereign).

EBONITE1-Becol 14 in. by 7 in. panel, 4s. 5d. (or

Permcol, Parfait).FUSE

1-Microfuse 100 -milliampere type, withholder, Is.

HOLDERS, VALVE1-W.B. five -pin, rigid type, 8d. (or Ben-

jamin, Igranic).2-W.B. four -pin, rigid type, ls. (or Ben-

jamin, Igranic).PLUGS AND TERMINALS

7-Eelex wander plugs, marked : H.T.+2,H.T. +1, H.T.-, G.B. G.B.-1,G.B.-2, G.B.-3,i101/2d. (or Belling Lee,Clix).

2-Eelex spade terminals, marked L.T.-t-,L.T.-, 4d. (or Belling Lee, Clix).

4-Eelex terminals, marked : Aerial, Earth,L.S. (2), ls. 6d. (or Belling Lee, Clix).

RESISTANCES, FIXED1 -B.A.T. 5,000 -ohm, 1 -watt type, 101/d.

(or Erie, Dubilier).1 -B.A.T. 20,000 -ohm, 1 -watt type, 10Y2d.

(or Erie, Dubilier).1 -B.A.T. 50,000 -ohm, 1 -watt type, 101/2d.

(or Erie, Dubilier).The prices mentioned are those for the parts u


1-Lissen 2-megohm grid leak, 6d. (orDubilier, Telsen).

RESISTANCES, VARIABLE1-Varley 50,000 -ohm tone -control poten-

tiometer, type CP159, 6s.1-Lissen 50,000 -ohm volume -control poten-

tiometer, type LN538, 4s. 6d.SUNDRIES

Tinned -copper wire for connecting (Lewcos).Lengths of insulated sleeving (Lewcos).Length of Goltone shielded cable, 9d.Length of rubber -covered flex (Lewcos).2 -Sovereign terminal blocks, is. (or Belling

Lee, Junit).1 -Sheet of C.A.C. Konductite, 2s.1 -Belling -Lee anode connector, 4d.1-Bulgin duplex needle cup, type NCI.,

2s. 6d.SWITCHES

1-Bulgin radiogram, type S86, ls. 9d. (orTunewell).

1-Bulgin junior three-point, type S39,ls. (or Tunewell, W.B,).

TRANSFORMER, LOW -FREQUENCY1-Varley Rectatone, 15s.

ACCESSORIESBATTERIES

1 -Smith's Anodex 120 -volt high-tension,lls. (or Pertrix, Siemens).

1 -Smith's Anodex 9 -volt grid -bias, ls.(or Pertrix, Siemens).

1-C.A.V. 2 -volt accumulator, type 2NAG912s. 6d. (or Oldham, Exide).

CABINET1 -Smith table radiogram in oak, £2 15s.

(or Pickett table model, £1. 7s. 6d.).GRAMOPHONE MOTOR

1 -Garrard No. 30 clockwork with 12 -in.turntable, £1 10s.

LOUD -SPEAKER1-W.B. permanent -magnet, type PM4,

with output transformer, £2 2s.MAINS UNIT (in place of batteries)

1-Regentone, type 5WA, unit with tricklecharger for A.C., £4 12s. 6d.

PICK-UP1-B.T.H. minor, with volume control, £15s.

VALVES1-Cossor 220VSG metallised, 16s. 6d.1-Cossor 21OHL, 7s. (or Marconi HL210,

Osram HL210).1-Cossor 230HPT, 17s. 6d. (or Marconi

PT2, Osram PT2).sed in the original set; the prices of alternativesmay be either higher or lower

Actually a friend of mine sat byme with the guide in his hand andsaid, " So -and -So ought to be atNumber So -and -So," whereuponI would turn to this figure and, sure

r

811, e7

4011 us 01,e

GoAck,--.000101 414050

10

O

./9P

rod

+."

sus

FREE STATION -CALIBRATED DIAL WITH EVERY BLUEPRINTAbove is a reproduction of the station -calibrated scale for fixing to the variable condenserso that stations can be tuned in directly by name. A free scale will be given with every

blueprint of the Harris Ethergram

enough, there was the station !Of sixty stations located in this

way fifty-seven were positively iden-tified by their announcement, pro-grammes andlanguage ; the remainingthree powerful stations I have notmuch doubt about.

A Final TipJust a final tip. If you want your

tuning chart to read at the samefigures as mine you can do this inmost cases by adjusting the firsttrimming condenser. For example,if on your set a given station comesin at, say, 53 degrees, whereas on mychart it comes in at 51 degrees,adjusting the first trimmer will bringthe reading back to 51 for you. Ofcourse, you must re -gang to thisfigure, but otherwise everything willbe the same.

I know you will like this set,whether or not you desire to use itas a table radio gramophone oras a straight set in a still smallercabinet.

721


Getting Stations with theHarris Ethergram

Sixty stations were received 1on the Ethergram by PercyW. Harris in his Wimbledonlaboratory. His log was con-firmed independently by a mem-ber of the "Wireless Magazine"staff at Brockley. With the aidof the instructions given inthese pages no constructor ofthe Harris Ethergram shouldhave any difficulty in repeatingthese excellent results-or of

improving on them !

THIS is the best battery three-valver I have designed. I am

going to build an equivalent A.C.model for my own use at home."This is what Percy Harris said whenhe handed over his new set for test.I have never seen him so enthusiasticover a set before.

" W.M." Station FinderHe produced a copy of the

" Wireless Magazine " StationFinder (given free with the October,1932, issue of " Wireless Magazine ")on which he had logged sixty stations.Fifty-seven stations had beenpositively identified.

Such a bold claim for a batterythree-valver does, I admit, seemstartling, but my tests have provedthat this set is the goods." Theselectivity is startling; the set doesbring in dozens of stations; thebackground is silent, and tuning issimplicity itself.

Independent TestThe set was tested twenty miles

from Brookman's Park, using an out-door aerial, with the specified valvesand loud -speaker. The tests weremade on the set chassis only.Although the Varley Rectatone trans-former is a tone -control gadget, Imade no use of its tonal capabilities.

As a straightforward low -frequencytransformer, the quality was reallysplendid. Plenty of volume and noundue emphasis of any particularband of frequencies made listeningvery enjoyable.

The long waveband was tried first

on a Sunday evening; conditionswere quite good. Huizen at the topend of the dial was easily discoveredat splendid strength and entirelyfree from interference from RadioParis. Radio Paris, a shade fartherdown, was heard at fine strength.

Next came Zeesen (Konigswuster-hausen as it is sometimes called).Here there was just a faint back -

hour broadcasting area weatherreports.

Such results for the long waves aregood, and as most of these stationscan be heard at any time of the day,the Harris Ethergram certainly pro-vides a high entertainment value onthe long waveband.

Next I turned to the mediumwaveband. I " ran over " the dial

twice, once when the Lon-don transmitters were work-ing and again when theywere silent. It was herethat my best impressions ofthe set's capabilities wereformed.

CONTROLS OF THE HARRIS ETHERGRAMThe two knobs in the top left-hand and right-handcorners are for controlling volume and reactionrespectively. Along the bottom of the panel are thewave -change switch, the main tuning knob, andthe on -off switch. The gramo-radio switch and thetone control are mounted on the motorboard, thegramophone volume control forming part of the

pick-up

ground of interference from DaventryNational, but nothing to speak of.The strength of Zeesen was hardlyfull. Daventry, of course, was areliable and very strong signal.

All the other long -wave stations onPercy Harris's log were heard atreasonable strength and practicallyfree from morse or other inter-ference. In addition, Croydon andHeston were logged. The latterstation can be heard throughoutthe day at thirty minutes past the

With the Locals WorkingWhen the local stations

were working I easilymanaged to pick up abouttwenty stations in additionto the locals at full loud-speaker strength andsufficiently free fromheterodyne whistles andother noises to give realentertainment.

Rome, Stockholm, Lan-genberg, Leipsig, PosteParisien, Breslau and Hil-versum are examples of thetype of stations which gavereproduction almost asgood as the two localstations.

The lower -powerstations-Grenoble, Berlin,Lodz, Poznan and Genoaare examples-were easilylogged, but I cannot saythat they were heard at fullstrength and free of inter-ference.

Even so, they are stations that canbe heard and they do provide thatfascination for the amateur who takesdelight in spending hours searchinground the dial and logging everystation he can.

A Good German StationWhen London Regional and

National were not working, stationsaround their wavelength were pickedup very easily. Take Miihlacker, asan example. This big German

722

came through every bit as loud asLondon Regional and at fine quality.

Selectivity on the medium wave-band was found to be decidedly abovethe average for a screen -grid three-valver. This degree of selectivity canbest be described as being nearlysuper -het type, except round thatplace on the dial where the localstations came in.

Local -station SpreadThe local stations only spread two

or three degrees either side of theirmaximum readings and adjacenthigh -power stations-Breslau andPoste Parisien, for example-couldeasily be separated.

On the intervalve and aerial band-pass coils there are tappings num-bered from 1 to 4 to vary the degree ofselectivity. No. 1, the most sensi-tive and least selective, gave anadequate degree of selectivity for mypurposes.

You will notice from the list ofstations that Fecamp was heard at areading of 10 degrees on the dial.From this we can safely assume thatlisteners in the Newcastle and Aber-deen areas will have no difficulty intuning down to their local stations.

It should benoted, by theway, that I ad-justed the firsttrimmer on theset so that mydial readingscorrespondedwith those ob-tained byPercy Harrisduring histest. That ac-counts for thefact that onlyone set of dialreadings isgiven in thelog that ap-pears belowfor both theWimbledon and the Brockley tests.

If you make a similar adjustmentwhen you first " trim up " theHarris Ethergram you should haveno difficulty in picking up thestations included in the log. Ofcourse, during the course of a weekor so you will be able to extend thelog considerably.

I understand that with every blue-print of the set will be given a free


PLAIN TABLE CABINETA special Pickett cabinet for the Harris Ethergram. This will appealto those who do not wish to make a complete radio gramophone

station -calibrated scale for stickingto the variable condenser. With thisyou will be able to tune in to stationsdirectly by name.

Percy Harris, I think, has reasonto be proud and enthusiastic abouthis new set. I agree with him that itis one of the best battery three-valvers I have had the pleasure to putthrough its paces. You will beamazed at the results.-T. F. Henn.

Log of Sixty Stations Receivedon the Harris Ethergram

LONG WAVEBAND Station Degrees Station Degrees

Station DegreesTriesteGleiwitz

15.517.5

Scottish RegionalToulouse

4648

Lenin grad 15.5 Frankfurt -am -Main 18 Leipzig 49.5Oslo 21 London National 19 Bucharest 50

Kalundborg 27 Bari 20.5 Midland Regional 52

Motala 43 Turin 21.5 Softens 53

Warsaw 47 Heilsberg 22 Katowice 55

Eiffel Tower 50 Bratislava 22.5 Dublin 56

Daventry National 59 Scottish National 24.5 Berlin 57

Konigswusterhausen 66 Hilversum 26 Madrid 58.5

Radio Paris 75 North National 27 Stockholm 62

Hui zen 88 Bordeaux -Lafayette 28 Rome 64

Kaunas 93 Genoa 29 Paris 65.5Goteborg 31.5 Beromuenster 69Breslau 32.5 Langenb erg 73

MEDIUM WAVEBAND Poste ParisienMilan

33.534

North RegionalPrague

7578

Station Degrees PoznanBrussels No. 2

3738

FlorenceBrussels No. 1

81.583.5

Fecamp 10 Barcelona 38.5 Vienna 86Lodz 11.5 London Regional 40 Riga 88Nurnberg 13 Miihlacker 41 Budapest 95.5Belfast 14.5 Hamburg 44.5 German Relay 97

All the above stations were heard at good loud -speaker strength by Percy W. Harris in his Wimbledon laboratoryand the log was confirmed by a member of the "Wireless Marrtzine" staff at Brockley

723


ROYHENDERSON

WALTER.WIDDOP

STEPHENKING -HALL

ARTHURCATTERAL

ROBERTTREDINNICK

VERNON

BARTLETT

TOMCLARE

°AUBE HuLBERT

cRANKLYN KELSEY

CHARLESLEGGETT

MAGGIE TEYTE

LESLIEBRIDGEWATER

COLEcat

LAFfiTTE

It*'-y

GEORGE

BAKER

SIR. HENRY.WOOD

LEONA

JOSEPHFARRINGTON

JOSEPH

MU SCANT

SIR.wALTORDDAM

MP

JOSEPHLEWIS

SIR.DANIEL

HALL

WEE GEORGIEWOOD

HAROLDSAMUEL

FLORENCE MARKS

ANNETNLIRSFIELD

GILBERTBAILEY

HAROLDFAIRHURST

HELEN

HENSOFI

MOsCH ET TO

JELLYDARANYI

ISSUEWOODGATE

WOMENAL LEN

RUSSELL

GREEN

ERICCO

,W1JACK

PAYNE

KENDALLTAYLOR

JOHNBRIDGE

ALFRED

KIRB1

ERMANDAREWSKI

DAVIDWISE

B-WALTON 0.DONN EU..

MAVISBENNETT

Is This TheIdeal Programme?

724

r\-Vireless Magazine. January 1933

GUY MACTRATH

CLAIREGRO IS

NORRISSTANLEY

NORMANALL IN

JACHARKRIS

LAURA M ORAND

SARAHALLGOOD

!AO(H YLTON

s.KNE

IOMKINN

SUMNERAUSTI N

KEY

HAROLD

KIM9ERLEY

DEGROOT

DEREK

M4 CULL011

GLADYsPARR

SOPH I EROWLANDS

NORAHGRUHH

Es1COO

DOROTHY

BE/0E7

w. HADORE

DALE la-SMITH

ADRIANSO U LT

SUGG IA

HULLO

Almost EVERYBODY!The caricatures published on these pages are taken from the topicalfeature "Personalities in the Programmes" by SLADE which appearsweekly in "Amateur Wireless." Many of the sketches have also beenreproduced in Continental radio journals. Since the early days ofbroadcasting SLADE has specialised in caricaturing microphonepersonalities exclusively for "Wireless Magazine" and "Amateur

Wireless "

HENRYHALL

CYRILNASH

RONALDGOLIAlAy

ELSIECARLISLE

GERALDBARRY

EDWARDHENRY

MICHEAL

I-10CAN

VICTOROLOF

SYDEY

KYTE

HERBERTDAYnno

CECIL

XON

H.SQ UIRE

JANVAN DER (M1011

ELSIESuDDABY

CEDRICSHARPE

MONS

E.M.STEPPIAN

GERSHONRARKJNGTOI

OTTOS IE PM AN

SIR. LANDONRONALD

CHRISTOPHERSTONE

725

Wireless Magazine, ./anuarx1933

MORD ATONE CONTROL

ASIANRIT FITTING?By J. H. REYNER. E.

During the past few monthsquite a lot has been heardabout tone control. Many lis-teners must be wonderingwhether it is really worthwhile. In this article J. H.REYNER discusses the effectsof tone control and explainsthe advantages of includingsuch a control in a modern

receiver

MANY of the sets in thisseason's show incorporated

a tone control, and there is no doubtthat the system is gaining in popu-larity.

There are two methods of con-trolling tone. One of these is tooperate on the loud -speaker byproviding an excess of the upperand lower frequencies and thencutting out either or both accord-ing to the preference of theuser.

This method has come tothe fore lately owing to theimprovements made in loud-speaker design, and most ofthe tone controls fitted oncommercial sets are of thistype.

The second method is tovary the amplification of thereceiver itself. This is par-ticularly useful in making upfor deficiencies in the tuningor amplifying circuits.

us assume first that we have anamplifier that gives us faithfulreproduction from 50 to 5,000cycles.

Theoretically the frequencyregister should extend above thisfigure, but in practice there are fewpeople able to appreciate thedifference between reproductionextending to 5,000 cycles and super -reproduction which includes fre-quencies of 8,000 to 10,000 cycles.

For one thing many people cannothear a note of 8,000 cycles frequency.For another the vibrations at theextreme top of the frequency scaleare principally harmonics ofrelatively short duration, and areonly used in transient effects.

No.modern loud -speaker will givea satisfactory reproduction of tran-sients, so that until we have solvedthis problem it is of little useworrying much about these extremeupper frequencies.

well-known curve, which manyreaders will have seen before, repro-duced in Fig. 1.

This shows the smallest air pres-sure required to produce audiblesound at different frequencies, andit will be observed that at 64 cyclesper second the ear is only 1/1,000thas sensitive as at 2,000 cycles.

Bass and VolumeMany readers will have noticed

that an amplifier and loud -speakermay give quite good reproductionwith ample bass as long as thevolume is loud, but if the strengthis cut down, the bass seems todisappear.

This is because the intensity ofthe bass frequencies has fallen belowthe critical value shown in Fig. 1,and the ear does not hear them.

Consequently if the balance oftone is to be maintained, it isnecessary to apply more energy to

the loud -speaker in the bass

000

100

10

i

sraluWgw

l-a_1

ri FREQUENCY (cycles/sec.) .

% t. gg g t t t t t t 1 t t I 1

Fig. 1.-Sound pressures necessary to produce samevolume to normal ear

apparent

The Multitone transformer wasthe first device of this type marketedfor use by the general public, andthere have been several other com-ponents of a somewhat similarcharacter introduced within the lastfew months.

The two methods must be con-sidered separately although theyinter -link with one another. Let

Given an amplifier, therefore,having these characteristics, wenow require a loud -speaker capableof reproducing the results satis-factorily.

At first sight it seems that thiswould require a uniform radiationof sound at all frequencies, but thisis not so because the ear is notuniformly sensitive. There is a

register, this being increas-ingly necessary as we reducethe frequency.

A rather similar effectoccurs in the treble, so thatincreased radiation is neces-sary here as well. In fact,what we really require is aloud -speaker having greaterradiation of sound at thetwo ends of the scale thanit has in the middle.

We can do this by suitabledesign of the loud -speaker, in

other words by providing resonancesat both these points.

Fig. 2 illustrates a typicalresponse curve taken recently inmy laboratories of a loud -speakerwhich is provided with the tworesonances in question.

It will be clear, however, thatthis is not sufficient to compensatefor the deficiencies of the ear, added

726

to which is the fact that differentpeople's hearing is not the same.In order to make the reproductionreally pleasant the individual usershould be able to control the responseof his loud -speaker, and this canbe done quite simply by means ofa tone control.

Reference to the curve of Fig. 1will show that the ordinary ear ismore deficient in the bass than inthe treble. Therefore the tonecontrol principally required is onewhich will accentuate the bass.

Cutting Off TrebleThe simplest way of doing this

is to cut off the treble, alwaysassuming that we have sufficientpower at our disposal. Cutting offthe top (or any part of the repro-duction) will result in a drop in theapparent strength.

If, however, we cut down the topto a certain extent and then supplysnore power to the loud -speaker sothat we bring the strength back toits original level, we are now wherewe were before, but the bass isdistinctly more prominent.

F- 20.000OHMS

ECCli.

Fig. 3.-Simple tone -control circuit

The simplest form of tone control,therefore, is an arrangement such asthat shown in Fig. 3, consisting ofa condenser in series with a variableresistance connected across the loud-speaker. If the variable resistanceis at its maximum, very little currentwill flow through the condenser, andthe loud -speaker behaves normally.

At the other extreme, if we cutthe resistance all out we have thecondenser shunted straight acrossthe loud -speaker, and all theupper frequencies will gothrough the condenser inpreference to the loud-speaker windings. 5

At low frequencies theimpedance of the condenserwill be high compared withthe loud -speaker, so that noappreciable shunting takes -5place and therefore we get agradual cut-off of upper notes.

By adjusting the valueof the resistance we canarrange that this cut-off is

10

0

-Wireless Magazine, Jemmy 1933

just as severe as we require, andthe quality can be adjusted to suitthe individual listener.

It must be emphasised, however,that for this to be successful theloud -speaker itself must have aresponse reasonablysimilar to that shown 10

in Fig. 2. The bassresponse must bethere, although itneed not be somarked as in the ex-ample shown. Other-wise the applicationof the tone controlwill be ineffective.

Consider, for ex-ample, the responsecurve shown inFig. 4. This loud -

.5

0

-5

pensate for the sideband cut-off inthe tuning circuits, so that the neteffect is that of the levelcharacteristic which we assumed atthe outset.

We can, of course, carry this

FREQUENCY (cycles/iec

g t ws 8g d 1 81

Fig. 2.-Typical response curve of good loud -speaker

speaker has neither top nor bottom.The tone control, therefore, will haveno effect until it is nearly at themaximum cut-off position.

Here it will start to cut off themiddle frequencies, and will onlyresult in the quality sounding thinand lifeless. There will be noaccentuation in the bass becausethere was no bass there in the firstplace.

Tone controls are sometimes madeto accentuate the upper frequencies,but these have little practical appli-cation if the amplifier is a good one,because the average ear is quitesensitive to frequencies as high as5,000 to 6,000 cycles. In manycases, however, the amplifier itselftends to cut off the upper frequencies.

This may be in the low -frequencystage or it may be in the tuningcircuits, particularly with the modernmulti -tuned set or super -het receiver.

The more satisfactory solutionhere, however, is to use one of thecompensating transformers men-tioned earlier in the article. Thesetransformers give an increasedamplification in the treble to corn -

procedure a little further and com-pensate for a poor loud -speaker,such as that shown in Fig. 4, butthe better plan is to start with aloud -speaker capable of reproducingall the required frequencies equallywell.

It is then possible to apply atone control to bring up the bass,which is what the average user needs.

Incidentally, the increasing use ofpentode output valves falls into linewith this scheme, because a pentodetends to accentuate the upper fre-quencies, and it is customary toprovide a compensating circuit ofa type shown in Fig. 3 as a matterof course.

Variable ControlIt is only necessary to continue

this one step further in order toobtain a variable tone control.

When the question of loud -speakerreproduction is viewed in this light,the use of some form of responsecurve becomes desirable in makinga choice of a suitable loud -speaker.While the taking of reliable responsecurves is a matter of difficulty,

it is fairly easy to indicatethe approximate frequencyrange of a particular loud-speaker and to decide whetherit is of the type of Fig. 2or of Fig. 4..

In addition, it does givean indication of the relativesensitivity, and experimentshave been in progress forsome time with a view todetermining whether suchresponse curves would be ofuse to " Wireless Magazine "readers.

rA

FREQUENCY (cycle

gtYS Si g gig 1Fig. 4.-Response curve of poor loud -speaker

1 1 1

727


What We Want to HCciF

PI, 1933diy Whitaker Wilson.

THIS time last year we were inwhat are now referred to as the

" old days at Savoy Hill." Theyear 1932 will, therefore, go down tohistory as one in which great changeswere wrought at the B.B.C.; butchange of residence, of course, meansno more than that. It is change ofeffect that counts.

Very few listeners will deny thatbroadcasting has improved in everyshape and form since the B.B.C.

IMPERSONATOR ANDFlorence Desmond is a well-knownimpersonator and mimic who frequently

broadcasts

went to live in Portland Place. Per-sonally, I think there is no comparisonbetween broadcasting now andbroadcasting in the old days ofSavoy Hill.

Changes have been made andexperiments tried in almost everydepartment of broadcasting. Someof us would like to see further changesstill, but there is not much to be saidfor suggestions that are not prac-ticable.

Most of us begin our evening's

listening by asking " What's on thewireless to -night ? " Nobody everknows what is on-at least, theynever do in my house.

Often when I have turned forinformation I have noticed cases ofbad alternating. I suppose most ofus have accused the B.B.C. of badalternating when we have found twothings going on at the same time andhappened to wish to hear both.

Even so, there is something to besaid against alternating an all-starvaudeville with, for example, a relayor a production of a musical comedy.People who like one of these generallylike the other.

The only saving grace of a situa-tion like this is that very often themusical comedy is broadcast laterin the week in the opposite pro-gramme. I have argued with morethan one listener that these " twice -weekly " shows are good.

It may be irritating to find your-self confronted with a show you havealready heard ; on the other hand, ifyou have missed the first performanceyou are glad enough of the second.Sometimes you may listen a secondtime because you enjoyed it the first.So that is as long as it is broad.

I hope the B.B.C. will continue torepeat performances in this way.The idea was a happy one. On theother hand, I urge that alternatingshould be very definite where pos-sible. To oppose a play with a lec-ture or a talk is no better than to givelisteners the choice between a sym-phony concert and a broadcast ofchamber music.

Since broadcasting has beeneffected from Portland Place, radiodrama has undoubtedly come intoits own. The more I listen to wire-less plays, the more I feel sure theyshould be written specially for themicrophone and not adapted fromtheatre versions.

I have made a close study of writ-ing for the microphone during thepast few months and have come to theconclusion that the two techniqueshave very little in common. The factthat what you write in your theatreplay is for people who can be seen,and the fact that what you write inyour microphone play is for peoplewho cannot be seen-well, need Isay any more ? That is the dif-ference !

A POPULAR BROADCASTEROne of the most popular of regular broad-

casters is Paul England

Moreover, by designedly separat-ing theatre plays from microphoneplays, the B.B.C. will help thetheatres and at the same time makeit clear to listeners that they mustnot expect to have West End pro-ductions brought into their owndrawing -rooms. Personally, I lookforward to a great developmentin radio drama during 1933.

Programme -making is a psy-chological activity at the best oftimes. I have thought-and often

728

said in critical notes-that the B.B.C.loses a great opportunity of a personaltouch with listeners late in the even-ing, in the summer especially.

A Good Singer ?I am not one of those enthusiasts

who listens to dance music until BigBen tells me I ought to have been inbed an hour ago. I fancy I am notalone in that.

I should, however, appreciatesomething more to my taste at10.15 p.m. I feel that-even if it wereonly twice a week-some goodsinger should come to the micro-phone and sing something worthhearing. Not necessarily difficult tounderstand where the average man isconcerned, but good music.

Summer programmes are a prob-lem, in any event. It is probablytrue to say that the listening ishalved during the long evenings. Ifsomething with a good personal touchabout it were broadcast at the hour Ihave suggested, and made a featurethroughout the summer, I thinkpeople would respond and listen.

Suggestion for 1933I remember hearing a delightful

short recital of Chopin one evening,seated in a deck chair in the garden.The personal touch, though, will benecessary; an ordinary broadcast ofsomebody's quintet is not the samething. I offer the suggestion for thesummer of 1933.

The summer, how-ever, is not here yet.There will be somecold and foggy nightsbefore any of us listento Chopin under thestars. Undoubtedlythe winter evenings arethe evenings for thelistener.

Turning to thelighter side first, whatof the vaudevilles ?Echo answers, " Whatof them ?" I am afraid,in some instances.Everybody is saying" Aren't the vaude-villes awful ? "-atleast, that is what theyare saying to me.

I doubt whether anyof the press criticshave said ruder thingsabout the vaudevillesthan I have. I sin-cerely hope not, any-how ! All the same,

Wireless Magazine. January/933

I should not be honest if I did not saythat I do think every attempt hasbeen made to pull them into shape.There has been a fairly recent changein their management and I must sayfrankly I feel the change has broughtabout an improvement in many ways.

My quarrel is not with the manage-ment so much as with the artiststhemselves. Whether the B.B.C. hasintimated that the average intelli-gence of the listening public islamentably negligible, or whetherthe artists have formed an idea thatanything is good enough, I am notprepared to say.

There it is, whichever way youlook at it; the type of humour broad-cast in many of the vaudevilles isalmost beneath contempt.

As I am not here criticising anyparticular performance, I can hardlymention names; it would not be fair.For all that, and even though I canonly speak very generally, I must sayI have been amazed that so manywell-known comedians have beencontent to broadcast poor material.

I can call to mind three or fourreally well-known artists who haveeither relied on repetitions of somesuccessful turns of their earlier days,or who have seemingly relied on theirpopularity and risked sending " anyold thing " through. It is a poorpolicy.

To elaborate the point. If AdrianBoult makes a bad mistake in con -

THE FAMOUS COCKNEY COMEDIENNEMabel Constanduros is storied in the street by a newspaper seller, who

wants to give her a hot tip for the 2.31 race!

YOU HAVE HEARD THIS PAIRBill and Elsie Newell frequently take part

in vaudeville broadcasts

ducting (say, a Beethoven sym-phony), nine out of every ten lis-teners will miss the fact. That isobvious; we are not all musicians.If he gets wigged for it by the critics-well, I daresay he knows how totake it.

That is the position in the higherforms of art. A great singer can singout of tune and get away with it,"so far as the general public is con-cerned simply because not every oneof us has an acute ear.

When it comes tovaudeville and a come-dian broadcasts a poorturn, everybody noticesit and letters by thedozen reach Broad-casting House in pro-test.

Therefore, it seemsonly the commonest ofcommon sense to sug-gest that comedians-however well knownand popular-shall betold plainly that theymust not let the B.B.C.down-for that iswhat it comes to.

I should like thevaudeville departmentto be ruthless in deal-ing with all matter tobe broadcast.

The present methodof making up a vaude-ville programme wouldseem to be this : two orthree good people areselected and asked to

729


WHAT WE WANT TO HEAR Cont.appear. As they cannot be expectedto fill up an hour between them,others far less capable are also askedto give a turn. Consequently, everyvaudeville is patchy.

You know as well as I do thatpeople have been grumbling becausethey have to sit through so much

IN VAUDEVILLEAnother popular pair of vaudeville artists

-Payne and Hilliard

" tripe " in order to enjoy one or twogood turns.

The only conclusion I can arrive atis that there are not enough goodcomedians to go round. Yet surelythere must be some good ones wenever hear broadcast. What aboutthe music -halls in the great provin-cial cities of England ? There mustbe some in the first grade !

The non-stop variety programmes,at the time of writ-ing, are anythingbut a success. Ihave heard threeand have beendisappointed . Anair of forced gai-ety seems to havepervaded all ofthem.

The only pointabout them thathas commendeditself to me hasbeen that theyhave been timed.This, at least,gives us a chanceof switching offuntil 8.20 or 8.45p.m. when, for afew minutes, some

reliable 'broadcaster has come on.The older method of putting down

a few names in the programmes-andbroadcasting them in any but theadvertised order-has been anothersource of complaint. One has tolisten all the time in order not to missthe few items worth hearing.

I feel that while the vaudevilles areso patchy, it would be better to givethe precise moment at which thevarious artists appear; then we canplease ourselves what we do about theother kind.

Piano -accordions, banjos, xylo-phones, and other inventions of thedevil do not interest everybody. Asthings are, we get landed with themwhether we like it or not.

I have devoted the main part ofthis article to vaudeville because Ifeel it to be so important in thegeneral public sense. Personally, Ido not mind if I never hear another.

Were I not a radio critic, I shouldrarely listen to anything exceptserious music and good plays. Thatis not the point, however. TheB.B.C. can never get away from thefact that the vaudevilles earn thedaily bread in terms of licences.

I am certain that the licenceswould soon reach the ten -millionfigure if broadcast drama and broad-cast humour were really attractive.The drama has improved so muchrecently that I, for my part, look for-ward with every confidence thatradio plays will be a great attractionbefore 1933 is very far advanced. Ionly wish I could think the sameabout broadcast humour.

SOMETHING TO LOOK FORWARD TO!Whitaker -Wilson suggests that something with a personal touch should be broadcastat about 10.15 p.m. during the summer evenings. Here are two listeners enjoying

the programme with a Marconiphone portable

Surely the trouble lies in the factthat the intelligence of the listeningpublic is underated by vaudevilleartists ? The public in these dayslaughs at anything worth laughing at.It does not laugh at anything merelysilly.

Val Gielgud and I were discussingradio productions the other day, andhe told me he was definitely ofopinion that broad humour-theknock -about comedian humour, hemeant-is no good to wireless,whether in vaudeville or otherwise.

Radio AudiencesHis view is one I have held for a

long time. The wireless audiencecannot accurately be described as thelargest in the world. It is a mistaketo suggest that if you broadcast youplay to a mighty audience. You donothing of the kind. You often playto one solitary being sitting in hisown drawing -room.

In the aggregate it is true, but it is afact that your real audience may becounted in ones and twos. Thesort of humour that makes youlaugh at, a theatre with a thousandother people to laugh with you is notthe sort of humour that convulses youwhen you are alone. You need adelicate humour to do that.

Improvement NeededIt is obvious that broadcast

humour needs raising several degrees.If the vaudeville department willinsist on clever humour only, we shallprobably improve our vaudevilleprogrammes in 1933.

The higherforms of broad-casting are reach-ing a perfectionwhich is as sur-prising as it is satis-fying. It is thepopular form thathas not come upto standard. If ahigh standard inthe popular formsof broadcasting bereached by the endof this yearthe B.B.C. needhave no recrimi-nations nextChristmas. In themeantime - aHappy New Yearto it !

730

WE TEST BEFORE YOU BUY Wireless Magazine. January. 1933

11[ TfIT 13[FOR[ YOU BUYFree Gift

LAST month " Wireless Maga-zine " published a special set -

buyer's supplement, which made animmediate appeal to thousands ofnew readers.

The supplement itself helped thenewcomers to choose a satisfactorytype of set, but we went a step furtherand offered-free and post free-toevery purchaser of a new set men-tioned in the supplement a copy ofthat well-known 2s. 6d. book, " TheHow and Why of Radio," whichgives in concise and easily understoodform a complete explanation of theworking of a modern receiver.

Offer Still OpenThis offer still stands, but in order

to qualify for a free copy of " TheHow and Why of Radio " readersmust complete the form to be foundon page 560 o f the December issue.

MODERN APPEARANCEThis is the Murphy Transportable four-valver for battery operation, which hasrecently been reduced in price. Note theunusual layout of the controls on the top

of the cabinet

The following conditions should benoted :-

(1) Only one copy of " The Howand Why of Radio " will be presentedto any reader.

(2) The form on page 560 of theDecember issue must be completedand sent to : Set Selection Bureau," Wireless Magazine," 58/61 FetterLane, London, E.C.4.

(3) The offer holds good only

if the set bought was mentioned onpages 4, 6, 8, 10, 12, 14, and 16 ofthe set -buyer's supplement. Thiscondition will be strictly observed.

(4) The new set must have beenbought after the publication of theDecember issue of " Wireless Maga-zine," that is on or after November23, 1932.

(5) In each case the dealer's nameand address and the exact date ofpurchase must be supplied to us sothat we can verify if we wish to do so.

(6) In each case the Editor's

A FINE H.M.V. RADIOGRAMThis handsome receiver is the H.M.V.super -het radio gramophone in a specialwalnut cabinet. An automatic record -changer is incorporated in this receiver

decision must be accepted as finaland legally binding.

A limited number of copies of theDecember issue is obtainable fromthe Publisher, " Wireless Magazine,"58/61 Fetter Lane, London, E.C.4,at ls. 3d. each, post free.

Buying a new set ? If you livenear a regional centre and you wanta lot of foreign stations you willneed a selective set, such as asuper -het costing around £25. Ifyou are prepared to sacrifice someof the foreigners a simpler set willdo quite well, such as a three-valver

FREE ADVICE TOPROSPECTIVE SET

BUYERSTo take advantage of this ser-

vice it is necessary only to mention(I) the maximum price and whe-ther this is for a complete installa-tion or the bare set ; (z) where theset will be used ; (3) what particu-lar stations are desired ; (4) whe-ther a self-contained set with orwithout aerial, or an ordinary setwith external accessories, is pre-ferred ; and (5), in the case ofmains -driven sets, whether themains are A.C. or D.C.

A stamped -addressed envelopefor reply is the only expense.Address your inquiry to Set Selec-tion Bureau, " Wireless Maga-zine," 58-61 Fetter Lane, E.C.4.There is no need to send any cou-pon, but it is essential to give theinformation detailed aboVe on oneside of the paper only. Tell yourfriends about this useful service.

costing around £16. These are,of course, for mains operation.

Living far from a regional centrewill imply that you are outside theservice area of a regional station.For this reason a moderately selectiveset might fill the bill, but as youwill need a reserve of power owingto your remoteness, you come backto the same type of set as above,that is a super -het or at least apowerful straight set with at leasttwo stages of high -frequency amplifi-cation.

The most easily -served set buyersare those about twenty miles froma regional. These listeners, whoform a large proportion of ourcorrespondents, will obtain very goodall-round results with a three-valver.If ease of control is specially desireda larger set, such as a four-valveror a super -het, is an advantage forthose in this category.

Record ReproductionMost of the sets on the market

are fitted with certain arrangementsthat escape the non -technical listener.For example, gramophone pick-upterminals are fitted almost as astandard, enabling the low -frequencyportion of the set to be used as agramophone amplifier by the externalconnection of a pick-up.

731

Wireless Magazine. Januarx 1933 WE TEST BEFORE YOU BUY

R.I. Madrigal Three

VERY ARTISTIC APPEARANCEThe cabinet design of the R.I. Madrigal is to becommended. Note the combined on -off, wave -change, and gramo-radio switch beneath the main

tuning control

THE CHASSIS LAYOUTThis interior view shows how the components arearranged on the metal chassis. The mains trans-former is on the extreme right. The loud -speaker

is a Rola permanent -magnet type

EVER since the firm of R.I. has been making radiosets, and that is now a good many years, we have

expected good quality of reproduction to be placedbefore all other considerations.

The Madrigal three-valver we have been testingdelightfully lives up to this R.I. standard, not only inthe reproduction, but in the workmanship throughoutthe carefully -assembled metal chassis. ,.

One of the Best ExamplesWe have in this new three -valve set one of the best

examples of the table model. The cabinet is just largeenough to do justice to the ample bass -note output ofthe self-contained moving -coil loud -speaker and yet iscompact enough to be carried from one room to anothershould any such transportation be desired.

This is not an entirely self-contained set because toget the best from it you need an external aerial and anearth. There is, for flat dwellers and others whocannot or will not put up an outside aerial, a simple yeteffective internal aerial.

If you make use of this the local stations come in atfull blast, even without an earth wire. Thanks to thevery complete nature of the smoothing in the powersupply there is no appreciable mains hum even whenthe earth is left off.

In fact we should like to make a pointof this set's completely smoothedsupply. Seldom have we tested a setso silent in its background. Evenwhen the set is not tuned to a stationyou have to put your ear close to theloud -speaker to hear that the poweris indeed coming from the mains.

This entire absence of mains humis in itself very satisfactory, but youmust not overlook the fact that theresulting " clean " background also

helps to give real-istic reproduction.

There is nothingstartling about thecircuit, which is astraight three -valvesequence withscreen -grid, detec-tor and pentodevalves, a mainsrectifier feeding allthree valves withanode current fromthe A.C. supply.

There are twotuned circuits, con-trolled by a two -gang condenser,which has a trim-mer super -imposedon the main knob.

Other controlshave been carefullyconsidered with aview to giving the

operator sufficient flexibility to cope with modern con-ditions and at the same time keeping the general " feel"of the control knobs essentially simple.

There is a separate input volume control, which, whenused correctly with the reaction control, gives a gooddegree of selective tuning for the foreigners.

There is a well -designed combination knob for thewave -change switching, mains on -off, and gramophonepick-up. This four -position switch is one of the bestwe have come across, and does its many jobs silentlyand without fuss.

The large, open tuning scale, marked in mediumwavelengths from 220 to 560 in steps of 20 metres, andin long wavelengths from 900 to 2,000 metres in steps of100 metres, is brilliantly lighted when the set is in action.

Delightful Tone from Internal Loud -speakerThe mains -voltage panel is fully protected by a neat

metal plate. No provision is made for an externalloud -speaker. The internal loud -speaker is a permanentmagnet model and has a delightful tone. Reproductionhas as much top as ether conditions will permit, and isa little more brilliant than with most sets of this type.

Selectivity is up to standard for two tuned circuits,but depends to a large extent on the setting of the volume

control. There is no sensation of

BRIEF SPECIFICATIONMAKERS: Radio Instruments, Ltd.PRICE: £17 17s.VALVE COMBINATION : Screen -grid

(Mazda AC/SG), detector (MazdaAC/HL), pentode output (MazdaAC/Pen), and valve rectifier (MazdaUU60/250).

POWER SUPPLY: A.C. mains.TYPE : Table -cabinet set with self-

contained loud -speaker and optionalinternal aerial.

REMARKS : Gives fine quality of repro-duction.

local -station spread when the vol-ume control is half -way down. Atthis setting twenty foreigners camein on a 60 -ft. aerial.

With this type of set it is impor-tant to make proper use of the inputvolume control, as we were againreminded when trying out the Mad-rigal. Granted a certain adeptnessin using the volume and reaction con-trols, every listener should be able toobtain satisfactory results on this set.

732

WE TEST BEFORE YOU BUY Wireless Magazine. January:1933

H. M. V. Super -het Radiogram Model 5 3 2HOW are we to report on this working the control switch, a knob

gigantic instrument ? Obvi- for the tone control and a knob work-ously it is outside the normal ing a local -distance switch. Theserun of radio gramophones and will, are the radio controls.from the purchasing point of view, The volume control, working ofinterest 'a relatively' small section of (PX4). course, on radio and records, isour readers. sensibly mounted on the front of the

If we say the quality is very good cabinet so that variations can behow does this definition square up obtained without lifting the lid.to a similar appraisal of, say, a On the gramophone reproducingthree -valve table model? If we say side, this instrument is luxuriouslythe range is very great, how much equipped. There is the well -greater, you may ask, is the range of known automatic record -changingthis instrument than of, say, a table five -valve super- mechanism, with many detailed improvements.het ? , A very good point is that the entire mechanism

Difficult questions to answer ! can, if desired, be switched out of circuit, so that recordsHere we have de luxe radio carried to the uttermost can be played in the usual way on special occasions.

conclusion. Range is literally limited only by condi-tions. Certainly there is not a station in Europe that, Playing Eight Records Automaticallyat some time or another, would not come through on There is a switch that enables a record to be repeatedthis super -het instrument. indefinitely and this switch can also be set so that the

Quality ? Certainly above the average even for a pede- automatic mechanism comes into action for eight 10 -inchstal model. The very large walnut cabinet imparts or eight 12 -inch records. The third position gives theto the reproduction a sonority that simply cannot be independent action just mentioned.obtained on sets whose small cabinets limit the baffle With an aerial consisting of a yard of flex, we loggedarea. over thirty stations at full strength on the loud -speaker.

Turn up the volume when listening to radio or records With a short indoor aerial, all stations came in at suchand with this H.M.V. " ten " you get a majestic output volume that we had to revert to the " local " position ofthat has to be heard to be believed. the local -distance switch for several stations more than

Enough Volume fora Small Hall 500 miles away IThe super -het circuit works without any trace of

instability or second -channel interference. No doubtthe variable -mu valves account for some of this per-formance and for the fine control of the sensitivity.

This instrument is thoroughly recommended to listenerswho can install it in a room large enough to do it justice.

PRICE £84

NUTSHELL SPECIFICATIONMAKERS : The Gramophone Co., Ltd.

: .

VALVE COMBINATION: Six -valvesuper -het circuit with separate three -valve power amplifier and mains -valverectifier. Push-pull output valves

POWER SUPPLY: A.C. mains, from100 to 260 volts.

TYPE : De -luxe radio gramophone withautomatic record -changing mechan-ism. Needs short external aerial andearth.

REMARKS: An exceptionally powerfulset for the connoisseur.

The two PX4 power valves between them give anundistorted output of nearly 5 watts. This representsvery much more volume than would normally be wantedin the home. It is enough for a small hall, in fact.

An important feature is the tone control, which workson radio and gramophone.It cuts down the top notes.This means that needlescratch can be eliminatedfrom records, while hetero-dyne and other forms ofether vexations are cut downon the radio side.

The controls are mountedon the motorboard, under-neath the weighted lid ofthe cabinet. Tuning is byone knob. This controlworks a dual -calibratedscale. The wave -changeswitching is so arranged thatwhen on the medium wavesonly the part of the scalemarked in medium wave-lengths is lit up.

On switching over to thegramophone side, the diallight comes on under theword " Gram " on the scaleand the wavelength calibra-tions are in darkness. All the controls of the H.M.V. radiogram are

Apart from the tuning on the motorboard, except for the volume con-trol, which is seen just above the loud -speaker

knob, there is the knob fret. The appearance is really dignified

AN EXCELLENT INSTRUMENT THE INTERNAL ARRANGEMENTThe radio receiver is seen on the left of thecabinet (mounted vertically) and the poweramplifier is fixed to the bottom. The design

has been well thought out

733

Wireless Magazine, Januarx 1933 WE TEST BEFORE YOU BUY

Ekco .Super -het Consolette Model SI-125HERE we have a super -het that

gets over all the usual snagsof its type. This new Ekco set has one -knob tuning and it is simpler toget stations on this than with most

straight " sets.Just turn the knob for tuning and,

as the pointer traverses the gianttuning scale, marked in stations, pro-grammes come rolling in at fullstrength on the loud -speaker.

If they are too strong, a touch onthe volume control brings them

SPECIFICATION IN BRIEFMAKERS : E. K. Cole, Ltd.PRICE : £25 4s.VALVE COMBINATION: Super -het

sequence: first detector (CossorMSG/LA), oscillator valve (Mullard354V), intermediate frequency ampli-fier valve (Mullard VM4V or CossorMVSG), second detector (MazdaAC/HL or Mullard 354V), and pentodeoutput (Mullard PM24M, Cossor PT41,or Marconi PT4).

POWER SUPPLY: A.C. or D.C. mains(A.C. model tested).

TYPE: Table -cabinet set in bakelitecase, with self-contained moving -coilloud -speaker and optional internalaerial.

REMARKS: Gives satisfactory qualitywith very selective tuning.

down. If the locals are being receivedyou flick a switch and the overall amplification is cutdown so that full-strength reproduction can be obtainedwithout reducing the volume control to its minimum.

Switch to Reduce InterferenceShould the station you are listening to be troubled

with excessive background or a heterodyne whistle, youjust flick another little switch and the top -note responseis reduced-and so is the interference.

Baldly stated, that is what you can do on this newsuper -het. The more you operate it, the more youappreciate its excellent points. We are impressed withthe fact that, though the overall amplification is so great

VERY EASY TO TUNEThe station dial fitted to the Ekco super -het makestuning an easy matter for the beginner. Everywell-known station is marked. The cabinet is

make of bakelite

A WELL -DESIGNED CHASSISOn the left is seen the mains -voltage adjustmentpanel and the metal rectifier. The loud -speakeris of the energised moving -coil type. Note the

ample screening provided

that even weak foreigners are brought in at overloadingstrength, the background is not objectionable.

This is, in our opinion, a great achievement, andrather surprising in view of the fact that there is nohigh -frequency valve in front of the first detector. Theresults will appeal to the non -technical man on ordinarylistener standards, but the set has an added appeal to theseasoned amateur who appreciates the difficulties thedesigners of this set have overcome.

The five -valve chassis takes up the lower part of thebakelite case, and in the top is the moving -coil repro-

ducer. A feature is the metal recti-fier for the mains supply.

Around the periphery of the loud-speaker opening is the famous Ekcostation indicator. We admit that atfirst we doubted the wisdom of this,seeing that stations are apt to moveso inconsequentially about the wave-band. A _first-hand experience ofthe system justifies the makers infitting this dial, provided, of course,that a new one is available shoulddrastic wavelength alterations bemade.

Moreover, they have had the good sense to markwavelengths at suitable positions, so that though Leipsigand Frankfurt have already " done a swop," you canfind them by reference to their wavelengths.

There are about fifty stations marked on the medium -wave section of the station indicator. We got them all inless than an hour. Every one was at full strength. And-this is the marvel-all were clear of interference.

The London stations were cut out completely for thereception of the foreigners adjacent to them in wave-length. Such tricky neighbours as Poste Parisien,Milan, and Breslau came through without a trace ofinterference-a really good performance, this.

On the longwaves, the selec-tivity is not quiteso good, but thereis no difficulty ingetting all stationsworth hearing.Konigswuster-hausen had a" twitter " fromDaventry, but wasotherwise clear.

The quality isabove the averagefor a super -het and,if use is made ofthe tone control,there will be nocomplaints. Alarge volume out-put can be ob-tained without dis-tortion. This makesthe set especiallysuitable for repro-

duction of gramophone records, for which provision ismade, as with all modern receivers.

Easy for the Novice to OperateThe set is very easy to operate and the absolute novice

would easily be able to get all the stations marked on thestation indicator.

In our opinion, this is one of the most successful ofthe season's super -het sets. We warmly recommendit to station hunters, as well as to those who like goodquality and easy control.

734

WE TEST BEFORE YOU BUY

MacnamaraIT was a happy idea to

call this a golden -voice " set because, as ourextensive tests have clearlyproved, the reproductionfrom the Macnamara three-valver is pleasing above theaverage.

The designers haveachieved that rare blendingof tone colours that goes tomake music mellow withoutbeing woolly, and speechclear without being strident.

In other words, we thinkthis set is deserving of itsname. For a table model,With the obvious limitationsin baffle area, the bass -noteoutput is exceptionally wellmarked.

Probably, as the makerssay, the results have beenobtained by a careful choiceof cabinet to go with themoving -coil loud -speaker.By the way, speaking of the cabinet reminds us thatthis set is marketed with a choice of a de -luxe walnutmodel, which we actually tried, or a plain unpolishedcabinet at three guineas less.

The idea is good. Many listeners like the look of achassis and would buy it to put in an existing cabinetwere it not for the fact that usually the much -desiredchassis is available only in a cabinet that would be toocostly to throw away.

Then, again, there must be many listeners who,having limited means, want to be sure of good radioresults, and are prepared to sacrifice appearance tothat end.

Well, this Macnamara set is a good straight three -valve combination for A.C. mains; the fourth valve isthe rectifier. All four valves are mounted on what mustbe the best -finished chassis on the market. It ischromium -plated throughout !

Remarkable Response with Plenty of PunchThe chassis takes up the lower part of the cabinet and

the top part takes the moving -coil loud -speaker, whichis of the mains -energised type, and gives, as tests show,a remarkable response with plenty of punch.

The back of the chassis is notablefor the inclusion of every possiblegadget you can think of, includingextra loud -speaker sockets, pick-upsockets, mains aerial, fuses for themains, a hum -adjuster for noisymains, and a very simple plug -and -socket system for the mains -voltageadjustment.

An unusual point is the fixing ofthe mains on -off switch at the backof the set.

The front of the cabinet is veryattractive, with the loud -speaker fret


Golden Voice Receiver

A HANDSOME CABINETThe walnut cabinet of the Golden Voice set is oftasteful modern design. The tuning scale iscalibrated in metres. An unpolished cabinet is

also available

INSIDE THE CABINETAn interior photograph. All the componentsare underneath the metal chassis, except thecoils and valves. The on -off switch is at the

top -right corner of the metal chassis

at the top and the controls neatly arranged below.There is a very efficient tuning system, consisting of atwo -gang condenser with a trimmer knob on top of themain knob to vary the fixed plates of the aerial -tuningsection, thus keeping the condenser in gang all roundthe dial.

Subsidiary Controls of Real ValueThe subsidiary controls are just what are needed to

get the most from the circuit. There is a separatereaction control and another knob for volume. Actuallythe volume is controlled by a series aerial condenser,and at the maximum setting the condenser is shorted,thus giving a direct aerial coupling.

By a correct adjustment of the reaction and volumecontrols, this set gave remarkable selective tuning, inspite of the fact that there are only two tuned circuits.

The London stations spread only a little on each sideof their wavelength settings. Eighteen kilocycles awayfrom them foreigners could be picked up at loud-speaker strength.

We were impressed with the strength of foreigners onthe mains aerial. There is very little mains hum withthis set, even without the earth.

We should say that this is an idealset for the novice, since without any

BRIEF DETAILS OF THE SETMAKERS: Telsen Electric Co., Ltd.PRICE : £15 15s. in walnut cabinet, or

£12 12s. in plain unpolished cabinet.VALVE COMBINATION: Screen -grid

(Mazda ACS2), detector (MazdaAC2HL), pentode output (MazdaAC/Pen), and mains rectifier (MazdaU U120/350).

POWER SUPPLY: A.C. mains.TYPE : Table -cabinet set with

contained loud -speaker.

REMARKS: Gives very sweet tone andgets many stations easily.

self -

trouble at least twenty stations couldalways be brought in. With moreexpert control, meaning a nicebalancing of the reaction and volumecontrols, the set will give still betterresults.

The reception of foreign stationson the mains aerial was remarkablyfree from background noises. Nodoubt this is partly due to the goodsmoothing of the power supply fromthe A.C. Mains.

735

ULL details and a test report ofI' the Ferranti standard super -hetconsolette were published in theSeptember issue of " Wireless Maga-zine." Recently a new modelincorporating a synchronous electricclock and station dial has been put onthe market; this deserves specialmention.

The synchronous electric clock isfitted in the centre of the loud-speaker grille. It maintains accuratetime and is so arranged that it runscontinuously irrespective of whether

BRIEF DETAILS OF THE SETMAKER : Ferranti, Ltd.PRICE: £26 5s.VALVE COMBINATION: High -fre-

quency (Osram VMS4), oscillator(Ferranti D4), first detector (OsramVMS4), intermediate high frequencyamplifier (Osram VMS4), seconddetector (Ferranti D4), power output(Ferranti P4), and valve rectifier(Ferranti R5).

POWER SUPPLY: A.C. mains only,200 to 250 volts, and special models forother voltages.

POWER CONSUMPTION : 55 watts.TYPE: Self-contained table set needing

only an external aerial and earth tocomplete installation.

REMARKS : Best value in A.C. super-hets on the market. A synchronouselectric clock is incorporated on thefront of the cabinet.

Wireless Magazine, January- 1933

Eddystone

THE KIT ASSEMBLEDA photograph showing the Eddystoneconverter ready for use. On the rightcan be seen the special aerial -couplingcondenser, and on the left the unit forcontrolling the intermediate frequency

WE have recently built up andtried out, so far as conditions

would permit, the Eddystone unitdesigned for the reception of ultra -short -wave signals around 7 metres.

This unit works on the super -hetsystem. It can therefore be used onlywith sets having one or more stagesof high -frequency amplification.

WE TEST BEFORE YOU BUY

-metre Converter Kit SetThough designed for such very

short wavelengths this unit has quitea conventional circuit arrangement.The specially developed feature of theunit is the coupling device betweenthe unit and the aerial terminal of theset.

A screened tuned circuit isemployed in the anode circuit of theunit's valve. This is made variableby means of a small condenser knobon the top of the coupling unit's case.The wavelength range covered bythe unit is 240 to 500 metres, towhich waveband the set must betuned to give the intermediatefrequency in the super -het working.

The tuning and reaction circuitsof the one-valver follow generalpractice, but the tuning and reactioncondensers used are simply delightfulin operation.

Long extension handles are fittedto both these controls and the tuningis done with one of the finest slow-motion dials we have ever handled.

The assembly of the unit is quitesimple. The 7 -metre tuning coil withreaction winding is mounted directly

on the terminals of the tuningcondenser.

In action the unit behaves just aswell as if normal wavelengths werebeing tuned in. We were able to geton to an amateur at Baldock, thetest position being Letchworth,Herts.

BRIEF SPECIFICATIONMAKERS : Stratton & Co., Ltd.PRICE: £2 Ils. for the complete kit of

parts.VALVE COMBINATION : Oscillator -

detector, worked with the valves in thebroadcast set.

POWER SUPPLY: Batteries of theexisting set or, if a mains set, a 60 -volthigh-tension battery and a 2 -voltaccumulator are needed.

TYPE: Short-wave converter unit.suitable for connection to sets with oneor more high frequency stages.

REMARKS: A very interesting unit ofspecial interest to short-wave enthu-siasts.

Any good low -impedance valveseems to work well in this unit.

We found the best position for theintermediate -unit wavelength adjust-ment was around 240 metres.

One important point is that theaerial length must not exceed 20 ft.or the unit valve will not oscillate.

Ferranti Clock Super -hetNo change has been made in the

design of the set chassis and on testwe found that the results weresimilar to those we obtained withthe standard model. At night welogged almost every station worthhearing. Selectivity was so goodthat on the medium wavebandMtihlacker was absolutely clear ofLondon Regional and on the longwaveband K8nigswusterhausen wasjust clear of Daventry National.

Circuit for Modern ConditionsThe circuit has been designed to

meet the most rigid modern condi-tions. An initial stage of high -frequency amplification preventsinterference with other receivers,variable -mu valves provide goodvolume control and band-pass coup-ling gives selectivity without loss ofquality.

Just under the clock there is a littleknob which controls the tone. Thisis a very useful gadget when listeningto foreign stations which have a little" mush " or heterodyne whistle,spoiling reception. When the tonecontrol was in circuit backgroundnoises were almost negligible.

the set is switched on or not, that is,providing the mains attachment isplugged into the wall socket. Ontest, we found that the readings on

A FINE JOBA front view of the Ferranti clock modelsuper -het. The cabinet is made of solidwalnut. There will be no excuse formissing favourite programmes with aclock fitted in the loud -speaker fret

the station dial were extremelyaccurate.

The dial is illuminated by a beamof light from behind; this falls on thestation name, which the listenerchooses by rotating the tuning knob.

736

Wireless Magazine. January; 1933

THE NEW IRON CORED

TUNING COILSThe New Ferrocart Coils Explained by ALFRED SCHNEIDER

IN the October issue of " WirelessI Magazine " W. James gave aninteresting survey on modern tuning -coil practice. We learned from hisarticle that the goodness of a coildepends upon its size, small coilshaving greater losses and less selec-tivity than large ones, and came tothe conclusion that, from a practicalpoint of view, in spite of their higherlosses, small coils are to be preferred,being easier to shield and moreconveniently fitted.

New Type of CoilThis is perfectly correct in regard

to the air coils hitherto exclusivelyused. However, in this connectionit will be interesting to give a descrip-tion of a new type of coil which,though being small and possessingall the advantages of small coils,does not show the usual drawbacksas it has the same or even a greater" goodness " and smaller losses thanthe best large air coils hitherto used.

Lower losses mean increased selec-tivity, which is the most importantproperty of a modern receiver.

Use of Magnetic CoreThe great efficiency and the small

size of these new coils is due to theuse of a magnetic core. All radio -frequency coils so far used havebeen air -core coils, without anymagnetic core. It is obvious that amagnetic core (as used in low -frequency transformers) wouldgreatly increase the efficiency, buthitherto there was no material inexistence which was suitable for usein high -frequency coils.

This is because high -frequencycurrents induce very considerableeddy currents in any conductivematerial; so naturally they do also inthe magnetic core if it consists ofconductive material.

All known magnetic materials,such as iron and iron alloys, are good

electric conductors simultaneously;therefore enormous eddy -currentlosses would occur in such an ironcore, increasing the losses of the coilinstead of reducing them.

The problem, therefore, was tocreate a material with good magneticproperties but of a non-conductivenature.

Such a material has been inventedby the well-known talking -pictureinventor associated with the Tri-

Fig. 1 -Cylind ical air -cored coil (on theleft) and coil w th Ferrocart core, both ofthe same inductance. Both are shownscreened and unscreened. The losses areillustrated by the diagram below each

coil

09083 70.6

0.50.40.3

0.201

0-10 -13 -6 -4 -a

5te8

9KC

9.8

nC

3

FRLQUtliCY (c0 +2 +4 +6 +6 +JO

Fig. la.-Resonance curves of the coilsshown in Fig. 1. Curve 1 for an unscreenedair coil; curve 2 is a screened air coil; andcurve 3 for a Ferrocart coil, screened or

unscreened

Ergon sound -film group, Hans Vogt.He takes very small particles of amaterial of high-grade magneticproperties which are insulated fromeach other by a special insulatingprocess.

Insulated ParticlesThese insulated particles are dis-

tributed in a thin layer on a paperstrip and a number of paper strips soprepared are pressed together so asto obtain either a plate or a roll.Thus a material is obtained which issomething intermediate betweencardboard and iron (ferrum); it istherefore called " Ferrocart."

This " Ferrocart " is electricallynon-conductive, so that eddy currentscannot occur, and due to the ironparticles contained in it it can be usedas a magnetic core for high -frequencycoils.

Applying a Ferrocart core to a

tuning coil, you note two things :Firstly, the inductance of the coil isincreased considerably or, in otherwords, you require less wire forproducing a certain inductance, thusreducing the copper losses.

Close ScreeningSecondly, ycu can screen this coil

with a very small distance betweencoil and cover without any detri-mental effect on the inductance orthe losses of the coil. This is dueto the fact that the magnetic flux isconcentrated by the magnetic core,so that no leakage flux exists to causelosses in the screening box.

Fig. 1 shows a comparison betweena good air -core coil and a Ferrocartcoil. Both are shown screened andunscreened. The difference in sizeis considerable, although the induc-tance is the same and the losses ofthe Ferrocart coil are lower, as canbe seen from the comparativediagrams shown in the same figure.

Fig. 2 gives a further comparison

737 .


NEW IRON -CORED COILS Cont.

Fig. 2.-Various types of air coils compared with Ferrocartcoils (Nos. 5 and 7). The inductance of all the coils is the same.The losses are quite different, though, as shown by the

diagrams below the coils

.07

06

.05

04

.05

02

.01

---.......

i -

\\\\.. 2.... ...., -._ -_. _- -- -

3/ 5ILa

'aG

it1..1

PiC3 WAV El -MOH

7(METRES)

00 300 400 500 60big. ea.-Curves of the damping decrements of the coils

illustrated in Fig. 2

between air coils of all shapes andFerrocart coils. Coil 5 and 7 areFerrocart coils. The losses at 400metres wavelength are again shownin the diagram. Note that the Ferro -cart coils 5 and 7 have the samelosses whether screened or notscreened, while the losses of theothers are seriously affected byscreening.

For TransmittersFig. 3 shows two giant coils for a

transmitting station of 1.5 milli -henries inductance, the left one withFerrocart core and the right one withair core. It must be added that theFerrocart coil can easily be screened,while the air coil cannot convenientlybe screened because of the great size.

Hitherto the standard Ferrocartcoils have been of toroidal shape,but the newest ones have a form

similar to a shroudedtransformer. A coilof the latter form isshown in Fig. 4alongside an aircoil of the same in-ductance and losses.

The Ferrocartmaterial can beapplied not only totuning coils, butalso to chokes, coup-ling coils, reactioncoils, band-pass fil-ters, etc. A highquality selection cir-cuit with air core isshown in Fig. 5,compared with arejector and selec-tion circuit, with aFerrocart core, ofsimilar characteris-tics. The Ferrocartcoil is much smaller

than the other oneand the price alsois much lower.

Fig. 6 shows anumber of Ferro -cart radio compo-nents and Ferrocartplates, rolls andstampings. It maybe added that Ferro -cart can be easilyworked, that is, cut,sawn and stamped.Single parts can bepressed together bymeans of heat.

The manufactureof such Ferrocartcoils in this countryhas been startedalready, so that theywill be available onthe English market

for home -constructors and set makersere long.

As a matter of course, a definitejudgment on the new coils cannot begiven before practice has provedtheir usefulness in every respect. Itcan be anticipated, however, fromthe experiences so far gained thatcoils with Ferrocart cores will meana revolution in the practical designof radio receivers.

Efficiency and CompactnessWe may expect that quite new

constructional shapes of componentswill result so that there is a chancefor home constructors and set makersto rearrange the structure of theirreceivers fundamentally, and toincrease further the efficiency andcompactness of sets.

[EDITOR'S NOTE. - Readers willbe interested to know thatColvern, Ltd., of Romford, Essex,have secured the exclusive rights to

Fig. 3.-Coi s for a transmitter; on the right is an air coil,while on the left is a Ferrocart coil with the same electrical

chara teristics. The latter can easily be screened

Fig. 4.-A comparison in size between an air -core coil and ashrouded Ferrocart coil with the same inductance and losses

738


THE FERROCART PRINCIPLE

Fig. 5.-On the left is a good selector coil with an air core; onthe right is a similar coil but with a Ferrocart core

manufacture Ferrocart coils in thiscountry. They are now engaged onintensive research work in thisdirection, because certain alterationsare needed to make the coils suitablefor the British market.

For instance, it is necessary to

Fig. 6.-Radio components making use of Ferrocart cores andsome of the Ferrocart raw material. Colvern, Ltd., who havethe exclusive rights to manufacture in this country, are at

present engaged in development work

develop dual -range tuners with inte-gral switches, whereas all the coilsillustrated in this article are of thesingle -range type without anyswitching.

The announcement of the newcoils has intrigued radio technicians,

and the production models will betested with more than usual interestas soon as they appear on the market.Readers of " Wireless Magazine " willbe kept informed of the progress ofFerrocart coils in this country as soonas definite information is available.]

Notes fromHere and

ThereANEW permanent -magnet mov-

ing -coil loud -speaker, knownas type 95, is now being marketed bythe Marconiphone Co., Ltd.; the coilhas an impedance of 10 ohms at 800cycles and the D.C. resistance is7.5 ohms.

We learn that the City Accumu-lator Co., of 7 Angel Court, London,W.C.2, have taken additional show-room accommodation on the groundand first floors at 4 Surrey Street,Strand, W.C.2.

The price of the Loewe Varitoneloud -speaker, of which a report waspublished on page 548 of theNovember " Wireless Magazine," is£1 19s. 6d. and not £2 2s. as statedin the report.

Electric ClocksAttractive clock cases to match up

with different receivers are beingmade by the Junit ManufacturingCo., Ltd., of Steele Road, ActonLane, W.4, for their synchronouselectric clocks. For instance, amodel to match up with the cabinetof the Pye K receiver costs £2 2s.;models are also available for suchsets as Lotus, Ultra, etc.

From the Radio Resistor Co., of1 Golden Square, Piccadilly, W.1,we have received a copy of a four -page folder giving details of Eriegrid leaks and resistors. This foldergives details of colour coding forresistances, although all Erie resistorsare identified also by a label bearingthe value marked out in figures.

Every mains enthusiast andamateur electrician should have acopy of the attractive 92 -page cata-logue issued by M.K. Electric, Ltd.,of Wakefield Street, Edmonton, N.18.One of the most interesting of thegadgets described is a fuse plug.Even though the radio set is providedwith a fuse, one of these special plugsis an advantage.

Ferranti's super -het receiver wasvoted by a large majority to be " thebest value -for -money set " at theManchester Radio Exhibition in aspecial ballot organised by theManchester Evening Chronicle. MissAnn Penn, the well-known imper-sonator, afterwards presented Mr. V.Z. de Ferranti, managing director ofthe company, with a silver trophy onbehalf of the Manchester EveningChronicle.

A new valve -testing appliance,known as the AvoDapter, is describedin a folder received from the Auto-matic Coil Winder and ElectricalEquipment Co., Ltd., of WinderHouse, Douglas Street, S.W.1,makers of the well-known Avometer.

SevenWise

Maxims1. Install your loud -speaker in the

largest room of the house; it isperhaps all to the good if the apart-ment contains heavy carpets, curtainsand hangings.

2. Try placing the loud -speakerin different corners of the room ;one of these will be found the bestfor all-round production.

3. See that the room is not toobrilliantly lighted; a soft dim lightwill do much to increase your enjoy-ment of radio plays.

4. Don't attempt to read a book ifthe rest of the family wishes to listento a concert; you can neither read orlisten to music in these circum-stances.

No Twiddling !5. Adjust the dials of the receiver

correctly to the wavelength of thetransmission at the outset, then makea rule that nobody shall twiddle thecondensers during the broadcast.

6. If you are asked to tune -in toother broadcasts do so cheerily andwillingly, but when you have foundone listen to a complete item, if it ismusic.

7. Don't chop and change aboutevery few minutes; nothing willannoy your audience more than bitsand pieces. Jay Coote.

739

{-Wireless Magazine. January, 1933

LISTEN FOR THIS STATION ON THE SHORT WAVES !A general view of the main transmitting gear at the privately -owned station CTIAA at

Lisbon, Portugal. This station is well heard in the British Isles

DURING the last few years Portugal has enjoyedprogrammes from several low -power private

transmitters spread over the country, the most importantof which is CT1AA. This station, which works on awavelength of 31.25 metres, began its regular trans-missions early in 1924. It is well received in thiscountry.

This station has one uniquefeature. It is entirely supported byits owner, Senhor Abilio Nunes Dos.Santos, who has spent some £10,000in the transmitting gear, and whoalways keeps his station abreast ofthe latest developments.

No AdvertisingOne of Senhor Santos' rules is that

no advertising matter shall be broad-cast. Although the owner manages achain of shops in Portugal, noadvertisement for them has ever

(T IAAA special description and illus-trations of the privately -ownedshort-wave station at Lisbon,Portugal, which works under

been broadcast from the station.Cabinet ministers and high Portu-

guese officials have spoken throughCT1AA's microphone and in recog-nition of his services to Portuguesebroadcasting Senhor Santos hasbeen decorated with the MeritoIndustrial by the Portuguese govern-ment.

The transmitter and studios aresituated in the most exclusive residential quarters ofLisbon. The studios and transmitters are about half amile apart and great difficulty was experienced inconnecting them. Finally, after a considerable amountof experimenting, an aerial cable (shielded to earth) wasinstalled.

STUDIO FOR TALKS AND GRAMOPHONE RECITALSStudio No. I at station CT1AA, used for talks and gramophone -record recitals. It has been visited by many high Portugueseofficials. The gramophone equipment was specially made by

Western Electric

CRYSTAL -CONTROLLED TELEGRAPHY TRANSMITTERThis telegraphy transmitter, which forms part of the stationCTIAA at Lisbon, works on a wavelength of 21.28 metres.The power in the aerial is 18 watts. Note the many reception

cards fixed to the wall

Two studios are employed by CT1AA, Studio No.for talks, gramophone recitals, and instrumental solos,and No. 2, which will accommodate an orchestra oftwenty-five musicians, for orchestral and concerts of asimilar nature. The gramophone reproducing appara-tus installed in No. 1 studio was specially designed byWestern Electric and is enclosed in glass cases toprevent unwanted vibrations being picked up.

The original wavelength of the station was 42.9metres, but this has since been changed, after a period

740

MING,the call sign CT 1 AA. It trans-mits musical programmes andalso has two telegraphy trans-mitters working on 21.28 metres

of testing on lower wavelengths, to31.25 metres, where the station nowappears to have finally settled down.

The call sign is " CT1AA, RadioColonial, Lisbon, Portugal." Short-wave listeners should have no troublein picking up this station on Thurs-days and Fridays from 10 p.m. on-wards, as announcements are madein English, Spanish, French, and,of course, Portuguese.

The station has received some 4,500 letters from distantparts of the world, including California and South America,reporting excellent reception.

Push-pull Type of Transmitting CircuitThe transmitting circuit of CT1AA is a modern tuned -

plate tuned -grid push-pull type which has proved easy totune and operate. This system also permits the anodes ofthe transmitting valves to be fed at full voltage withoutdeveloping undue heat or giving rise to abrupt changes incurrent consumption.

A bank of Philips TA4/1,500 transmitting valves is used,the modulation being effected by three 1.5 -kilowatt valvesin parallel. A huge 18 -volt accumulator with a capacity of

THE SECOND TELEGRAPHY TRANSMITTER AT CTIAAA view of the second set of telegraphy gear used at CT1AA. This works on 21.28 metres

with a power of 500 watts in the aerial


THE MAIN STUDIO AT CT1AA, LISBONMain studio at the station CTIAA at Lisbon. This station is owned by Senhor Abilio

Nunes Dos Santos, who runs it entirely at his own expense

A VIEW OF THE CONTROL ROOMThe control room at CTIAA. Note theline amplifier on the left. The studiosare about half a mile distant from the

transmitter

800 ampere -hours is used for filament heating.

The mains supply voltage (110volts A.C.), which feeds the trans-mitter, is raised to 11,000 voltsthrough a transformer, oil insulated,and after being rectified, filtered andsmoothed, is applied to the anodes ata pressure of 5,500 volts steady D.C.CT1AA also operates two low -powertransmitters, both on 21.28 metres,one rated at 500 watts and the otherat 18 watts. L. L. Rego.

741


O

The Christmas Tribute . .

The Modern Super -het

AT this period of the year onehas to face the onset of Christ-

mas and the New Year, and theperennial problem of selecting suit-able presents for those who havein one way or other established avested interest on one's purse and/oraffections, as the case may be.

It is not an easy matter to choosegifts which are both welcome anduseful, but there is a wider varietyof the right sort to be found in anydecent wireless shop than in anyother quarter I know.

Pleasures of WirelessTimes are rather difficult for all

of us just now, but the Christmasspirit demands an extra generousgesture. What could give morepleasure than a wireless set, particu-larly if it brings the amenities ofbroadcasting to a household for thefirst time ? Or a mains -driven setto those who have not yet success-fully solved the battery problem ?

We cannot all afford to go so far,but on a smaller scale a new high-tension battery or a spare valve isalways a welcome gift, whilst for thehome constructor there is an endlessvariety of new components andgadgets which can be dependedupon to freshen up the performanceof an existing set, and give it a newlease of life.

Sound Conceit !Finally, there's nothing like a good

milliammeter to give the buddingenthusiast a sound conceit of himself.In return he will probably comealong one day to " vet " your ownset and point out a thing or two youmay-or may not-be interested toknow about it.

.The use of high -frequency coils

filled with a powdered -iron corepromises to set a new fashion in setconstruction.

In the first place they are muchmore compact than the standardtype, and require no screening,thus saving valuable space. In thesecond place they have a " selec-tivity " characteristic which compares

0

New High -frequency Coils: : A New Valve

By MORTON BARR

favourably with a high-grade low -resistance coil wound with Litzwire, that is to say, with the besttype of high -frequency coil nowavailable.

The core used is not, of course,solid-or even laminated-metal,otherwise the coils would not handlehigh -frequency currents withoutloss. Actually it is made of veryfinely -powdered iron, which canonly be prepared by a specialchemical process involving the reduc-tion of iron oxide by a stream ofhydrogen gas.

The deposited metal is so fine ingrain that it would ignite spon-taneously if openly exposed to theair. Accordingly it is first mixedwith heavy oil to form a paste, whichis then laid on a thick paper backing.The coated paper is finally rolled upto form the core.

In the paste each particle of ironis insulated from its neighbour by athin layer of oil, so that eddy -currents cannot flow and any ohmicloss due to this cause is prevented.At the same time the presence of theiron creates a heavier magnetic fluxthan an open air core, so that a giveninductance can be produced withfewer turns of wire.

In other words the proportion ofresistance to inductance is lower -thanusual, and the selectivity corres-pondingly higher.

This type of high -frequency coilhas already proved successful inAmerica. In fact, an ingeniousscheme of " permeability tuning "based upon its use was describedin this section of " Wireless Maga-zine " last March.

A feature of the new Ferrocartcoils is that they are wound toroidally,the coils being lapped around a ring -shaped, instead of a cylindrical, core.This confines the magnetic field toa closed circuit, and prevents it fromspreading outwards through the air.

. .One advantage of the up-to-date

super -het, as compared with the

earlier editions, is the small numberof valves in circuit. Nowadays fouror five is the standard number, andthey give far better results than thenine or ten stages formerly used.

The explanation lies, of course,in the superior characteristics of themodern valve, particularly as regardsamplification factor.

The use of a screen -grid inputvalve not only solves the old problemof re-radiation-because it effectively" divorces " the aerial from thelocally -generated oscillations-it alsogives greater amplification than twoof the old-timers.

S.G. and Pentode " Mixers "Some designers are now using

screen -grid or pentode valves for thelocal oscillator or " mixer," so thatthis valve also takes an active partin amplifying the signals. Theresult is that only one intermediate -frequency stage is necessary, insteadof the two or three that used to bestandard practice.

The present method of using aheated filament to produce theelectron stream inside a valve hascertain disadvantages, and variousalternatives have been suggested fromtime to time, including the use ofphoto -sensitive cathodes which willliberate electrons by the action oflight.

" Filamentless " ValveAlthough the ideal of a " cold "

emitter is still in the far -distantfuture, it is interesting to note a newtype of " filamentless " valve whichis now being developed in Germany.

The idea is to utilise the high-tension supply to provide the electronstream as well as the plate voltage,thereby avoiding the necessity for aseparate low-tension supply.

The high-tension voltage is appliedacross a pair of electrodes-separatedby a narrow gap-so as to producea sustained glow discharge, whichthen acts in the same way as a heatedfilament. The method is at presentonly applicable to valves whichcontain a proportion of free gas.

742

Wireless Magazine. January 1933

DANCEGetting It Actor(

IN an all too tiny office on the fifth floor of Broad-casting House, overlooking Langham Place,

Henry Hall directs the B.B.C. Dance Orchestra.Down in the Outside Broadcasts Department is theO.B. director, who controls the technical end of thepopular dance -music broadcasts from the Savoy,the Carlton, Dorchester House, the Monseigneurand even the Tower Ballroom, Blackpool.

London, you see, is the key point of all dance -music broadcasts.

Famous Seven Years AgoHenry Hall, as you may remember, made himself

famous in 1926 with the Gleneagles Hotel DanceBand broadcasts; and later from the Adelphi atLiverpool and the Midland Hotel at Manchester.

Last week I had a long chat with him about broad-casting. He was as cheerful as ever. It seemed likeold times, for I was the firstLondoner to interview himwhen he came down fromManchester to BroadcastingHouse-when he had nohome in London, no properoffice at the B.B.C., noB.B.C. Dance Orchestra,

HENRY HALL IN STUDIO 3AStudio 3a is a double-decker. This photograph of Henry Halland the B.B.C. Dance Orchestra was taken from the window of

the small listening room

There are things to learn,too. The present library ofthe B.B.C. Dance Orches-tra is 450 tunes. Some ofthese take the best part of aday to rehearse. Eachnumber is specially scoredfor the B.B.C. Dance

Come behind the scenes of broadcast dancemusic with KENNETH ULLYETT and learn howthe leading dance orchestras get their music

across the ether!

and only 700 applications for thenew jobs !

He is only thirty-three (or is itthirty-four by now ?), and has had anamazing career. He went to TrinityCollege, Cambridge, and afterwardsto the Guildhall School of Music.The one thing he used to hate wassyncopated music and when in his'teens he longed to conduct classicalconcerts; and did so.

Little Scope After the WarThe war started and he gave up his

musical career when only eighteenyears old. Little wonder is it, there-fore, that when he came back againto post-war England, he found thatthere was little scope for an en-thusiastic but inexperienced con-ductor of classical concerts.

After a little while we find him as adance -band pianist and then as theleader of one of the L.M.S. hotelbands. Another year or so and hehas risen rapidly up the ladder offame and is the musical director of allthe L.M.S. hotels.

It is in 1926 that he first comes" on the air." He is a leadingpersonality of the L.M.S. hotelchain. He is an artistic director forthe hotels and rumour links his namein a romantic fashion with big namesand with success with a capital " S."

He comes down one spring after-noon to the B.B.C. to discuss hisbroadcasting arrangements in con-nection with the Midland Hotel,Manchester, and finds himselfoffered a contract of quite a differentkind-to be the director of the newB.B.C. Dance Orchestra.

The rest of the story you know.Now Henry Hall and the B.B.C.

Dance Orchestra are working regu-larly every day from 10 o'clock in themorning till late in the evening.Often they do not leave BroadcastingHouse until the early hours of themorning, when Henry Hall is givinga late night broadcast.

The average is eleven hours a day,which cuts out any notion of sax -blowing being a cushy job, evenif a lucrative one.

Orchestra and the professionalarrangements issued as standardfor all popular tunes are alteredfor the B.B.C. combination by theleading music arrangers in thecountry.

The B.B.C. Dance Orchestra styleis distinctive. Henry specialises in" sweet " music. All the new tunesare scored to suit his ideas. Eachspecial orchestration of a tune costsabout ten guineas, so that there isapproximately £5,000 tied up in theorchestration alone of the DanceOrchestra's present library.

A Rumour DeniedThere is a rumour going the

rounds that now that DickieMatthews, the young oboe player, hasleft the B.B.C. Dance Orchestra andthat A. Williams, a new trumpetplayer, has been introduced, specialarrangements are not necessary forthe B.B.C. Band. Henry Hall deniesthis vehemently.

People seem to think that specialarrangements were only necessary

743

Wireless Magazine. January.- 1933

DANCE MUSIC Continuedbecause of previous unusual ideas,such as the introduction of a solooboe player. This is quite wrong,for all standard orchestrations include-as well as parts for the violins,horns, clarionets, second violins,saxophones and so on-a part for theoboe.

Songs from AmateursSpecial orchestration is expensive,

no matter whether the tune is a pro-fessional one or one sent into theB.B.C. by an amateur. Every dayHenry Hall and his manager, Mr.Hodges, are inundated with newsongs from amateurs. It is estimatedthat only about one in five hundredof these is good enough for con-sideration.

Good tunes picked in this way aresent out to one of .the arrangers, whore -writes it and orchestrates it for theB.B.C. band. Henry Hall risksbetween £10 and £20 on each tune inthis way, including overhead expensesand the orchestration fees, so that allthe amateur song writer receives isthe pleasure of hearing his numberbroadcast.

But, of course-andthis is the vital point-all the leading songpublishers will be will-ing to handle the num-ber if it is a good oneand if Henry hasthought fit to broad-cast it.

Big money is to befound in song writing.Irving Berlin's " AllAlone " brought himabout £19,000. Ama-teurs are misled bythese huge figures andsome of the " easy -money" attemptswhich reach HenryHall are pitiful for thelack of knowledgewhich they show of theconventional machin-ery of the music pub-lishing trade.

As the average dance -music en-thusiast is interested more inlistening to the B.B.C. broadcaststhan to adding to Henry Hall'srepertoire, let me take you behind thescenes of the B.B.C. Dance Orchestrabroadcasts.

Henry Hall uses studio 3a, whichwas originally intended for the

Children's Hour broadcasts andwhich is yet incomplete. This is thestudio which was among the firstto be utilised when BroadcastingHouse was built and in which theengineers tried the experiment ofhaving a glass wall.

Strangely enough it is a room verysimilar in shape to the old studio 7 atSavoy Hill, from which Jack Payneused to broadcast.

It is a double decker and is about20 ft. high. It is 35 ft. long and 15 ft.wide, so you see there is not over-much room for the members of thedance orchestra.

Studio 3a has its own silencecabinet and a listening room upstairsso that Henry can retire to thissoundproof cabinet and, lookingdown through a large glass panel, cansee the orchestra rehearsing while helistens in on one of the baffle loud-speakers in the listening room.

The dance -band studio is onthe same floor as the so-called" religious " studio and is at theside of the talks studio, from whichfamous speakers broadcast toAmerica via the Transatlantic

THE SAX -BLOWERS" HARD AT WORK !

Four of Henry Hall's saxophone players have a little rehearsal. Theyoften work eleven hours a day all told-not such an easy time!

phone. Studio 3a will probably beHenry Hall's home for anothermonth or so. Television transmis-sions are still being made from thebasement studio which he previouslyused.

The B.B.C. Dance Orchestrastarted off with a condenser micro-phone on a baffle. Then the old

Edison Bell microphone, beloved ofJack Payne, was tried. This is non -directional and was stood in aboutthe centre of the dance orchestra.The vocalist could address it in anydirection. Now Henry has againfavoured a directional microphone.This time it is the new R.C.A.condenser " mike."

All the rehearsing is done in 3a.The gramophone recording (whichtakes up two or three mornings aweek) is done in the big studio blockin St. John's Wood, and all theadministrative work is done inHenry's own fifth -floor office. Hesays that he now gives 48 percent. British tunes, 6 to 7 percent. Continental tunes, and therest American.

Another RumourRoger Eckersley, the programme

director, takes a keen interest in theDance Orchestra and rumour has itthat Eckersley, under a nome-de-plume, is the composer of tuneswhich Henry often broadcasts.

And now, as a change, look at theleading -broadcasts bands.

We are at the momentin the middle of bigchanges. Roy Fox,after a protractedperiod of illness, hasformed a new combi-nation at the CaféAnglais, and LewStone is carrying onfrom the Monseigneur.

The Monseigneur isa difficult place, archi-tecturally, from whichto broadcast. Roy Foxhad two special plat-forms built to keep thedancers away from themicrophone.

When Lew Stonetook over he had a newplatform built. MauriceWinnick, who broad-casts from the Carlton,experienced the sametrouble. Catcalls and

cheers were heard above the musicuntil a special platform was put up.

Will Jack Hylton ever settle downto regular B.B.C. broadcasting, andwill Jack Payne make a regular" come -back " ? These are questionswhich all dance -music enthusiasts areasking.

It is an open secret that Jack

744

Hylton finds it much more profitableto tour this country and Europe,making flying visits to all kinds ofContinental places, than to settledown to a regular concert.

Jay Whidden, who was previouslyvery well known in this country,used to broadcast from the Carlton,where he was paid £100 a week asmusical director. This may seem agreat deal of money but it is easilyput to shame by the giant feessecured by the ever -popular Hylton.

£400 a WeekFees of the order of £400 a week

can be secured by top -class artistswho tour the vaudeville theatres inthis country alone. Jack Payne stillfinds it more profitable to tour thevaudeville circuits than to link upagain with broadcasting-even Con-tinental broadcasting.

His recent visit to BroadcastingHouse was all too brief. Listenerswant more than just one half hourbroadcast in three months.

While the N.B.C. and Columbialiaison men from America are inthis country looking out for " stars "there is a big reason why dance -band leaders should not tie them-selves down to B.B.C. broadcasting.

It is well-known that both JackHylton and Jack Payne were paidabout £1,000 for their Americanbroadcasts (sent via Rugby to theU.S., and not heard in this country)and it is hardly possible for thesesums to be secured while a dance -bandleader is under a B.B.C. contract.

Broadcast dance -band money hasgone up by leaps and bounds sincethe 1924 days when Sydney Firmanand the London Radio Dance Bandprovided the official B.B.C. dancemusic. It took a cash offer of£8,000 and a promise of immenseroyalties to get Jack Payne away fromthe B.B.C.

Big Money for the BestAs with most broadcast items, the

B.B.C. has to spend big money toget the best.

When Jack Hylton and Ambrosehave given studio broadcasts theyhave for amicable reasons agreed toaccept fees to cover only the bareexpenses. Four -figure fees wouldhave to be paid for regular studiobroadcasts and that is why, forinstance, the Ambrose combinationis only heard once a week from anoutside hotel.


Stories of the Operas

La Traviata(The Frail One)

(VERDI)

CHARACTERSALFREDO, Violetta's Lover TenorGIORGIO, his Father BaritoneGASTONE DR LETORIERES TenorBARON DAUPHOL, Alfredo's Rival.... Bass

BassTenor

Soprano

MARQUIS D OBIGNYGIUSEPPE, Violetta's servantViourra, a CourtesanFLORA, her friend Mezzo -SopranoANNINA, Violetta's confidante.... SopranoDR. GRENVIL BassTime : Louis XIV. Place : Paris.

ACT IA salon in Violetta's house.

Violetta is conversing with Dr. Grenviland friends. Others, including theBaron, arrive. Flora enters on thearm of the Marquis. This is a house -party, a revel. Gaston and Alfredoarrive. Gaston tells Violetta thatAlfredo loves her. Although touchedby his devotion, she treats the matterlightly. She is a consumptive. Evi-dences of the frailty of her health aremanifest from the beginning.

Music is heard from an adjoiningroom and the guests move off.Violetta is seized with a fit ofcoughing and sinks on a divan torecover. Alfredo remains with her.A love scene concludes the act.

ACT IIA salon in a country house near

Paris. Violetta has left her societylife in Paris for Alfredo, with whomshe is living. Alfredo learns fromAnnina that the expenses of thishouse are greater than Violettathought. She has been selling herjewels. He leaves for Paris to raisemoney to reimburse her. After he

has gone Violetta gets a note fromher friend Flora, inviting her to staywith her. She smiles at the ideaof returning to her old life. Giorgio,Alfredo's father, is announced. Hebegs her to leave Alfredo, saying hiscareer is threatened by their conduct.She makes the sacrifice, even thoughshe knows it will injure her health.Giorgio retires.

Violetta writes a note to Floraaccepting her invitation. She thenwrites to Alfredo saying she intends toreturn to her former life and she willlook to his rival, Baron Dauphol, tomaintain her. Alfredo enters andshe conceals the letter. He tells herhis father may be coming to beg herto leave him. She goes, pretendingit is because she does not wish to bepresent at the interview. Alfredo isalone.

Violetta's letter is handed to him.As he reads it his father comes in.Giorgio tries to console him. Alfredoreads Flora's invitation. The scenechanges to a brilliant salon in Flora'spalace. Alfredo is winning at cards.The Baron and Violetta enter. TheBaron stakes against Alfredo, whowins. Later Violetta begs Alfredoto leave. Alfredo, in front of themall, curses Violetta, who faints.

ACT IIIVioletta's bedroom. Violetta is

dying. She learns that Alfredoknows of her sacrifice. He arriveslater-too late. La Traviata is dead.

WHITAKER-WILSON.

Radio in Kenya ColonyKENYA COLONY possesses a

white population of roughly15,000 souls and for its entertain-ment broadcast transmissions arecarried out daily, simultaneously on350 metres and 49.5 metres. Todefray the expense of this servicelisteners pay £2 10s. per annum.

The transmitter is actually situatedat Kabete, some eleven miles fromNairobi, and is housed in the samebuilding as the telegraphy plant usedfor commercial purposes. It isconnected by cable to a small studioin the capital.

The transmissions are carried outbetween 4.30 and 7.30 p.m. G.M.T.(Nairobi local time is three hoursin advance of Greenwich MeanTime).

They consist of a children's houron Mondays, Wednesdays, andFridays; news bulletins and gramo-phone records. For specialconcerts local talent is occasionallyavailable. On Saturdays dancemusic is broadcast.

Whenever possible the time signaland chimes of Big Ben are relayedand, if occasion offers, running com-mentaries on sporting events arebroadcast.

With the new Imperial Scheme ,bywhich Colonial and other stationswill be able to broadcast recordsspecially made in Great Britain fortheir benefit, such studios as Nairobiwill be shortly capable of offeringto their listeners a better and morevaried programme J. G. A.

745


T N the October number of "Wire-lessI Magazine " we published

details of a home -constructor setthat attracted immediate interest-interest, moreover, that is still beingmaintained.

The set was called the Calibrator;its chief features were that it had awavelength -calibrated dial and fourvalves, including a variable -muscreen -grid stage for high -frequencyamplification.

Complete Tuning UnitThe wavelength -calibrated dial

was possible because the threetuning coils and the three -gangcondenser for tuning them aresupplied as a complete unit, alreadyganged up before leaving the factory.With this assembly there is notrouble about the trimming of theset because the makers actuallymatch the coils up carefully withthe condenser with which they areused.

As soon as details of the Calibratorappeared in these pages we wereinundated with requests from readersfor an equivalent model for A.C.

CALIBRATORHere the "Wireless Magazine "Technical Staff describes the con-struction and operation of a com-panion set to the Calibrator forbattery operation, of which detailswere published in October. Thenew set is for A.C. mains operation.

mains operat:on. Thissented in these pages.

It will be seen fromdiagram on this pagethree valves are used;valve is a mains rectifiertherefore be consideredceiving " valve.

Owing to the greater sensitivityof mains valves as compared withequivalent battery types, three A.C.valves give results as good as arenormally obtained from four batteryvalves.

The A.C. Calibrator is, therefore,presented as a three-valver; it isevery bit as good in its way as thefour -valve battery model alreadyreferred to, and will meet the needsof hundreds of readers who want totake advantage of their electric -lightsupplies.

The sequence is actually a variable -mu screen -grid type followed by adetector and a power pentode, whichgives an undistorted output of theorder of 2 watts-enough for allordinary purposes.

The foundation of the set is, ofcourse, the Radiopak, which corn-

set is pre -

the circuitthat only

the fourthand cannotas a " re-

prises three tuning coils (a band-passaerial combination and a high -frequency coil), a three -gang con-denser, a mains on -off switch and apotentiometer for controlling volume.

The use of this combination unit,besides simplifying ganging asalready explained, also greatlyfacilitates the construction of the set.

As is usual with most "WirelessMagazine" sets nowadays, the A.C.Calibrator is presented as a completemains -operated radio gramophone.When radio reception palls, youhave only to turn a switch to enjoyall the advantages of the electricalreproduction of gramophone records.

No " Tricks " in the SetIt will be seen from the circuit

diagram that there are no "tricks"about the set, which is straight-forward in every respect. Longexperience had shown that perfectly"straight" circuits are nearly alwaysthe most successful in practice,and constructors can be assuredthat there is nothing in the A.C.Calibrator to give rise to anytrouble in operation.

.11

40.000.11 t5000Il

0

ultD7i-N

MINTMMFD.

RFG

060

1400n,

11FR:

P.0

MFDJ

MIFD

.sa 240

"1130

0

O.1

CIRCUIT OF THEA.C. CALIBRATORThree valves are usedfor reception-a vari-able -mu screen -gridstage, detector, andpentode power valve.The fourth valve isused for rectifying theA.C. supply so that itis suitable for applica-tion to the valveanodes. Only onetuning knob is used,and the dial is cali-brated directly in

wavelengths

746


Apart from the Radiopak, theonly part that is in any sense outof the ordinary is the low -frequencytransformer, which is of the latestparallel -feed type, with the necessarycoupling components included inthe case with the winding.

Ample decoupling is provided atthe necessary points, and it will befound that the set is quite stable inoperation and, what is perhaps evenmore important in the case of amains receiver, it is quite free frommains hum.

Sensitivity and SelectivityAs for its sensitivity and selectivity,

these qualities can be gauged fromthe special test report that appears onthis page.

All the power needed for runningthe three valves is obtained fromthe electric mains, which must, ofcourse, be of the A.C. variety. (Be-ginners should note that the set isnot suitable for operation from D.C.mains). Unless specially orderedfor any other frequency, the mainstransformer will be wound for 50 -cycle mains. 10

All the necessary grid bias-thatis, for the grid of the variable -muvalve, for the " detector " when usedas a gramophone amplifier, and forthe pentode-is supplied automatic-ally through resistances connectedin the cathode leads.

There are no batteries of any kind,and the cost of running the set fromthe mains is so small that it willmake no appreciable difference tothe electric -light bill.

That is one of the great advan-tages of using a mains set-therunning costs are so low that any-body can afford to have a reallybig output valve, which has theadvantage not only of giving finevolume, but also excellent qualityof reproduction, for the set is neverbeing " pushed."

No Unnecessary FrillsThere is no need for us here to

go into minute details about thecircuit. Nothing that is not essentialfor good reception has been in-cluded; on the other hand, nothingthat is necessary for the best qualityof reproduction has been omitted.

For those who want an easilyoperated A.C. set-remember thedial is calibrated directly in wave-lengths-the A.C. Calibrator can berecommended without reservation.

Actually, for the benefit of thosewho desire to use a loud -speaker

The Set on TestTWO of the outstanding

points noted during my testof the A.C. Calibrator were theexcellent quality-brilliant with-out being hard-and the fact thatmains hum was so small as to bebarely noticeable.

The set was first tried out inthe late evening when most ofthe foreign stations had shutdown. London's Regional andNational andNorth Region-al were heardat goodstrength.Madrid andand Cardiffwere heard atreasonablestrength inthis pre-liminary ex-cursion roundthe dial.Fecamp wasa very strongsignal.

The set wasnext put ontest between 8and 9 a.m. inthe morning.Hilversumwas a fine signal on the mediumwaveband. Leipsig, Langenberg,and two or three other signalswere also heard, although thesignal strength was not so great.On the long waveband RadioParis, Huizen, and Zeesen camein at splendid strength. There wasslight interference between RadioParis and Zeesen. '

So much for " out -of -hours "tests. The main test was made on

an outdoor aerial 70 ft. long inSouth London during a wholeevening. I decided to run roundthe medium waveband and pickout stations which could be list-ened to with minimum interfer-ence and good strength-in otherwords, fit for entertainmentpurposes.

These stations will be found atthe end of this report. In addition

COMPACT, BUT QUITE STRAIGHTFORWARDFor its type, the A.C. Calibrator is a particularly neat fob,and its construction will present no difficulties even to the

beginner if a full-size blueprint is used

to these stations many otherswere heard, of course; these willmeet the wants of the " knob-twiddler." Many of them were atsplendid strength but,because theywere spoilt by heterodyne whistles,I cannot put them in the " musiclover's " class.

On the long waveband theperformance was very satisfactory.I heard a dozen stations altogether.

T. F. Henn

SOME OF THE STATIONS RECEIVEDLong Waveband Station Metres

Station Metres Breslau .. 325Warsaw 1,412 Poste Parisien 328Daventry . 1,554 London Regional 355.8Zeesen 1,635 Scottish Regional 376.4Radio Paris . 1,725 Leipsig 389.6Huizen 1,875 Midland Regional 398

Sottens 403Medium Waveband Stockholm - 435

Station Metres Rome 440Fecamp 225 Beromuenster 459London National 261 Langenberg 472Scottish National 288.5 North Regional 480Hilversum .. 296 Prague .. 488North National 301 Florence . 500Goteborg .. 322 Brussels No. 1 509Although over forty stations were heard on the A.C. Calibrator, the above can

be relied upon to give real interference -free entertainment.....

747


THE A.C. CALIBRATOR-Cont.

QUARTER -SCALE LAYOUT AND WIRING DIAGRAMA full-size blueprint can be obtained for half price (that is, 6d. post free) if the coupon

on the last page is used by January 31. Ask for No. WM309

that is not provided with an outputtransformer, the set is providedwith the usual choke -output circuit.If the loud -speaker to be used withthe set has an output transformer ofthe correct ratio, this choke -outputdevice can be omitted.

It is not really necessary, though,with the loud -speaker specified, butit is included as a safeguard in casethe reader wants to use some otherreproducer.

High Anode CurrentCare should be taken to see that

the transformer provided with anyloud -speaker is capable of handlingthe rather high anode current passedby the pentode output valve. Infact, when the loud -speaker isbeing ordered (if it is to be a newone) the reader should mentionthat it is for use with a MazdaAC/Pen valve; then there will beno possibility of going wrong.

So much for theoretical considera-tions; let us now turn our attentionto the practical points of construction.

The photographs included in thesepages will make clear the layout ofthe set, and how most of the partsare arranged. Those who desirestill more detailed' guidance will

find it in the quarter -scale layoutdiagram reproduced on this page,while full-size blueprints are avail-able for those who desire them.

Until January 31, those whowant them can obtain full-sizeblueprints for half price, that is 6d.each, post free, by using the specialcoupon that appears on the lastpage of this issue. Applicationsshould be made to " WirelessMagazine " Blueprint Department,58-61 Fetter Lane, London, E.C.4,and the reference No. WM309should be mentioned.

Value of a BlueprintThere is no need to buy a blue-

print if it is not specially desired;all the essential details for theconstruction of the set are includedin these pages. Most constructorswill prefer to have a blueprint,however, for this shows all thecomponents full size, and the posi-tions of the fixing holes.

It will be noted that on the layoutdiagram reproduced in these pages(and also, of course, on the full-size

(Continued on page 750)

COMPONENTS NEEDED FOR THE A.C. CALIBRATORCHOKE, HIGH -FREQUENCY

1--Slektun, standard type, 4s. (or ReadyRadio, Peto-Scott).

CHOKES, LOW -FREQUENCY1-Igranic constant -inductance, type CH2,

9s. 6d. (or Wearite, Tunewell).1-Davenset, type 101, 18s. 6d. (or Wearite,

Tunewell).CONDENSERS, FIXED

1-Dubilier .0001-microfarad, type 870, ls.(or T.C.C., Lissen).

1-Dubilier .001-microfarad, type 870,ls. 3d. (or T.C.C., Lissen).

1=Dubilier .005-microfarad, type 610,2s. 3d. (or T.C.C., Lissen).

1-Dubilier .1-.1 microfarad, type BE256,3s. (or T.C.C., Peak).

6-Dubilier 1-microfarad, type 9200, 16s. 6d.(or T.C.C., Peak).

1-Dubilier 2-microfarad, type 9200, 3s. 9d.(or T.C.C., Peak).

1-Dubilier 2-microfarad, type LSA, 400 -volt D.C. working, 4s. 6d. (or T.C.C.).

2-Dubilier 4-microfarad, type LSA, 400 -volt D.C. working, 16s. (or T.C.C.).

CONDENSERS, VARIABLE1-Polar Compax .0003-microfarad, 2s. 6d.

(or Lotus, Lissen).1-British Radiophone knob for above, 6d.

FUSE1-Bulgin twin, type F9, with fuses, 2s. 3d.

(or Belling -Lee).HOLDER, GRID -LEAK

1-Readi-Rad, 6d. (or Bulgin, Telsen).HOLDERS, VALVE

3-Telsen five -pin, 3s. (or W.B., Benjamin).1-Telsen four -pin, 9d. (or W.B., Benjamin).

RESISTANCES, FIXED1-Erie 200 -ohm, 1 -watt type, ls. (or B.A.T.,

Dubilier).2-Erie 400 -ohm, 1 -watt type, 2s. (or B.A.T.,

Dubilier).1-Erie 5,000 -ohm, 1 -watt type, ls. (or

B.A.T., Dubilier).1-Erie 7,500 -ohm, 1 -watt type, is. (or

B.A.T., Dubilier).The prices mentioned are those for the parts us


1 --Erie 20,000 -ohm, 1 -watt type, ls. (orB.A.T., Dubilier).

1-Erie 40,000 -ohm, 1 -watt type, ls. (orB.A.T., Dubilier).

1-Lissen 1-megohm grid leak, 6d. (orTelsen, Dubilier).

SUNDRIESTinned -copper wire for connecting (Lewcos).Lengths of insulated sleeving (Lewcos).Length of rubber -covered flex (Lewcos).Length of Goltone shielded cable for pick-up

leads, 9d.1 -4 -volt flashlamp bulb for dial.1-Sheet of aluminium foil, 16 in. by 12 in.

(Peto-Scott).1-Bracket for mounting reaction condenser

(Wearite or Peto-Scott).1-M. K. fuse plug, type 640, 2s. (or Ferranti).

TERMINALS3-Lissen terminal blocks, marked: Aerial

and Earth, L.S. (2), Pick-up (2), 3s.TUNING UNIT

1-Si itish Radiophone Radiopak with gramo-radio switch, £3 5s.

TRANSFORMER, LOW -FREQUENCY1-Bulgin Transcoupler, type LF10, lls. 6d.

TRANSFORMER, MAINS1-R.I. type EY30, £1 10s.

ACCESSORIESCABINET

1-Stenibac, model 19, radio -gramophonein mahogany, £4 15s.

GRAMOPHONE MOTOR1-B.T.H. Truespeed, 9s. 6d.

LOUD -SPEAKER1-Ormond permanent -magnet moving -coil,

type R464, £3 5s. (or W.B., Blue Spot).PICK-UP

1-Harlie model 36 with volume control,£1 7s. 6d. (or B.T.H. Minor).

VALVES1-Mazda AC/SGVM, metallised, 19s.1-Mazda AC/HL, ruetallised, 13s. 6d.1-Mazda AC/PEN, £1.1-Mazda U2 rectifier, 12s. 6d.

ed in the original set; the prices of alternativesmay be either higher or lower

748

Wireless Magazine. anuary, 1933

An A.C. Three-valver with A High Degree of Selectivityand Giving Fine Quality of Reproduction

( GRIDLEAKAND

CONDENSER

BY- PASSCONDENSERS

H. F.CHOKE

FUSES

L. F.TRANSFORMER

A photographic plan view, showing the dispositionof the parts in the A.C. Calibrator; note the

compact layout

RESERVOIRCONDENSER

SMOOTHINGCONDENSER

L. F.CHOKES The set in its Stenibac cabinet, with an

Ormond moving -coil loud-speaker-a com-bination that gives fine quality

L F. CHOK E,

MAINSRECTIFIER ilmieftw.,,

MAINSTRANSFORMER

TUNINGUNIT

DETECTOR

PENTODE

VARIABLE -MUS.G. VALVE

REACTIONCONDENSER

Above: Another view of the A.C. Calibrator, withvalves in position ready for use. Left : View ofthe motor -board with Harlie pick-up in position ;

this incorporates a volume control

749

1


THE A.C. CALIBRATOR Cont.- may be needed, and

therefore the valuesof the cathode re-sistances for obtain-ing automatic biaswill need revision.

If other valvesare used the makersshould be con-sulted as to thecorrect values ofbias resistances forinclusion in thecircuit.

As soon as theconstruction of theset has been com-pleted the readerwill want to try itout as quickly aspossible. But donot forget to makethe connection tothe anode terminalon the top of the

blueprint) that each connecting screen -grid valve before switchingon !

There are only four control knobs.On the extreme left is the volumecontrol, which alters the bias appliedto the variable -mu valve. Volumewill be at its maximum when thisknob is turned as far as possible in

TURN TABLE

15'

PICK-UP

MOTOR(DRILL MOU/ITING HOLESTO MAKERS TEMPLATE)

eV,i;

r1F-010

PICK-UPRUST

LAYOUT OF MOTORBOARDThis diagram shows clearly the positions of the electricmotor and pick-up with volume control. There is room

at the right for needle cups and a station log

wire bears a number. These num-bers indicate the best and mostconvenient order of making theconnections.

Start off with connection No. 1and, when this has been completed,cross through the correspondingnumber on the blueprint.

If the set is wired throughoutin this way there can be no possibilityof making a mistake or of omittingany connection-in other words,the constructor can be quite certainthat the set will work as soon asthe valves have been inserted intheir holders and the mains trans-former connected to the electric -light mains.

Position of ReactiOn CondenserOne point should be specially

noted, however, and that is theposition of the reaction condenser.This is actually mounted at thefront of the set under the baseboardso that when the set is placed inits cabinet the reaction knob appearsunder the main tuning knob.

As long as this point is borne inmind (it will be quite clear fromthe photograph that appears on page749) there will be no confusion.

It will be noticed from the listof parts that no alternative valves arerecommended. This does not meanthat the set is especially sensitive asregards valves, but if other valvesare used different grid -bias voltages

control is turned up, the set isautomatically switched on.

In the centre of the set is the maintuning knob, with the reaction knobimmediately underneath. The knobon the right of the set is for changingthe wave range and switching in thepick-up. It has two positions, forthe medium and the long waves.

It should be further noted that asthe set itself does not incorporate alow -frequency volume control, thepick-up should be of a type that hasits own volume control. If this pointis observed the set is complete inevery detail necessary for the greatestutility.

Trimming the SetWhen the set is first put into use

it should be tuned to the localstation and the trimmers should beadjusted to about the half -waypositions. Then adjust the backtrimmer (that is the one remotefrom the dial) so that the trans-mission is tuned in at the correctreading on the dial. If you are inany doubt about the actual wave-length of your local station, look upthe list of wavelengths that appearsunder the title "World's Broad-cast Wavelengths," at the beginning

of this issue.When the first

trimmer has beenadjusted so that thedial reading is cor-rect for a particularstation, adjust theother two trimmersfor the best volume.If the initial trim-ming is done onthe local transmis-sions it should bechecked up after-wards on a moredistant station.

It will be foundthat there is nodifficulty about ad-justing the setfor good volume.Remember that

the coils have actually been matchedup to a high degree of accuracy withthe gang condenser during the courseof manufacture.

The trimming carried out by theoperator when the set is in use issimply to compensate for the addi-tional circuit capacities that areunavoidable.

A THREE-VALVER THAT GETS THE STATIONS !With the A.C. Calibrator you are certain of real entertainmentfrom a score or more of Continental stations. If you are notso particular about quality your log will run to fifty or more

transmissions !

a clockwise direction, that is to theright; when the knob is turned tothe left the volume will be reduced.

Combined with the volume con-trol is the on -off switch. This is

automatically brought into action asthe volume control is put in theposition of minimum ' volume; inother words, as soon as the volume

750


.,dr:Auct4imr-Rimwaw 'Wooerttofte-d_PrAimilesimaiinicamighltIllitallimimal ilikassswansnwwiriww."'

41111:7"igiffMI

A Radio Fan's Causerie: Conducted by BM/PRESSRoyal Interest in Radio

HAVE you noticed how theRoyal Family has figured in

the radio news of the past fewweeks ? During November PrinceGeorge visited the Kolster Brandesworks at Sidcup and also the Pyeworks at Cambridge. Prince Georgeis reported to be most interested inradio.

Now we have the news that theKing himself is to give a broadcasttalk on the afternoon of ChristmasDay. Even Royalty must indulge inChristmas festivities and everybodywill appreciate what it must mean toHis Majesty to give up this afternoon-of all afternoons-to talk to thenation by radio.

Many people were disappointedby the cancellation of the Prince ofWales' broadcast from Belfast on theoccasion of the opening of the newparliament buildings. I understandthat the King's public-address micro-phone was taken specially to Belfastfor the use of the Prince.

And, to crown all that, the Dukeof York is reported to be a keen radioconstructor !

The Prince's CarAnother matter of interest is that

the Prince of Wales' latest car, ofwhich he took delivery only a weekor two ago, is equipped for radioreception whilst in motion. The

aerial is concealed in the roof and theonly indications of the installation arethe control, which is within easyreach of the Prince's seat, and the setitself, which is contained in a boxthat looks like part of the footrest forthe back seats.

By means of the " transitone "system of volume control, weaksignals are automatically amplifiedand strong signals are toned down,so that the overall response is moreor less level. In this way the volumeremains constant although the carmay be passing in and out of badreception areas.

It is typical of the Prince that heordered a second loud -speaker forthe driver's compartment so that hischauffeur can relieve the monotonyof long waits by listening in.

Three New BooksI have been interested to see three

new little books on radio that havejust been published. The first twoare published at ls. each by W.Foulsham & Co., Ltd.; the titles are" Wireless Really Explained," byP. J. Risdon, F.R.S.A., and " Short-wave Radio Reception," by W.Oliver.

Mr. Oliver's name will be knownto many readers through his con-tributions to " Wireless Magazine."He is a keen listener and his short-wave hints will be of value to many

constructors-and to many pros-pective overseas listeners on accountof the new B.B.C. Empire trans-missions.

" Wireless Really Explained " hasappeared before; the present editionhas been thoroughly revised by Mr.Oliver and will meet the needs ofmany who are taking an interest inradio for the first time.

The third item is a little 26 -pagepamphlet entitled " Wireless Wrongsand How to Right Them," publishedby J. W. Arrowsmith, Ltd., at 6d. Ifyou ever have any trouble with a setthat will not work then this littleguide will show you how to trace thetrouble systematically.

It is very well arranged and shouldprove a boon to the beginner whodoes not know very much about hisset.

.On the Short Waves

You remember the Gold Coaster,the four -valve short-wave set ofwhich details were published in theAugust issue of " Wireless Maga-zine " ? The original set was sentout to Accra, in the Gold Coast, fora special test.

The other day I ran into Mr.George Hutton, who actually madethe tests and who is in England onsix months' leave. He told me thathe had just had a letter from a friendto whom he has lent the set in his

751

Wireless Magazine. Januarx /933

RADIO MEDLEY-Continued

GENERATOR FOR THE B.B.C. WEST REGIONAL STATIONThis large generator was specially made for the B.B.C. regional station at Washford

Cross by the English Electric Co., Ltd. The station should be well heard !

absence; this listener had reportedthat 5SW had come in so well on theloud -speaker that he was able towalk outside the bungalow and hearit 50 yards or so in all directions.

A Battery NeededWhen will somebody develop a

primary cell that can be sold at areasonable price and that will besuitable for running several valve

A BIRD'S-EYE VIEW OF PYEThis fine aerial photograph shows the huge Pye works at Cambridge, recently

visited by Prince George. It has been extended greatly in recent years

That is something like reception!Even if you are not very keen on

Empire broadcasting now you wouldbe if you were to talk to anybody likeMr. Hutton; it is his only direct linkwith the mother country, and is verygreatly appreciated. Indeed, thereis a tremendous market for ourmanufacturers to tap if they willonly get down to it. Expenseis almost no object to these temporary" exiles " who want a link with home.

filaments over a long period ?This seems to me to be oneof the greatest difficulties inthe way of the rapid develop-ment of Empire broadcasting.

There are so many placesoverseas where there is noelectric -light supply, and un-less you have a mains supplyof some kind you cannot evencharge accumulators. Youtherefore have to fall back

on a primary cell which will produceits own current.

If such a cell were available itwould give a tremendous impetus toshort-wave broadcasting in out-of-the-way places where at present manyprospective listeners are unable totake advantage of the services thatare offered because of the impossi-bility of running a set at all owing tothe lack of a suitable power supply.

.A Record Riddle

When is a record not a record ?That question arises with peculiarforce in view of a recent developmentmade by the technical department ofthe Gramophone Company. Theyhave taken an old acoustic recordingof Caruso's, filtered it so that thequality is as good as a present-dayelectrical record, cut out the originalaccompaniment, and grafted a neworchestral accompaniment on toCaruso's voice !

Is that really a record of Caruso oris it simply a synthetic voice thatsounds like Caruso ? In any casethere is no question that the newrecord will meet with great success.

How It Was DoneAs many readers will be interested

to know just how this new recordwas made I cannot do better thanquote from the official H.M.V.explanation, so here goes

" The Gramophone Company

PRINCE GEORGE AT K.B.During November, Prince George also made a visitto the Kolster Brandes works at Sidcup. He is

seen here leaving the main offices

752

I Wireless Magazine. Januarx 1933

A RADIO FAN'S CAUSERIEhave perfected a secret process bymeans of which they have taken aCaruso record originally made in theearly days of horn recording and,after transforming the waves in thewax into minute electric currents,have passed them through filterswhich correct the deficiencies in theoriginal recording; thus a new waxmaster was made of the originalperformance.

" A new orchestral accompani-ment was provided after the con-ductor had played Caruso's originaldisc over many times and thus be-come thoroughly acquainted withevery inflection of the singer's voiceto ensure absolute synchronisation.

" The record was then playedthrough for re-recording, the con-ductor listening by means of head-phones and simultaneously directinghis orchestra. Thus the voice of thedead singer, which originally sung in1903, was wedded with the accom-paniment from an orchestra playingin 1932."

A Grid -leak PuzzleI was surprised the other day to

learn from a resistance manufacturerthat many constructors think thatthere is some difference between a2-megohm anode resistance and a2-megohm grid leak.

That is why you will see on someleaflets dealing with fixed resistancesthe words " anode resistances andgrid leaks," although in fact there isnot the slightest difference betweenthem except for the resistancevalues.

Funny how some impressions getabout, isn't it ?

Battery SetsI wonder if you were as surprised

as I was to see how many battery setsthere were in the Set -buyer's Supple-ment in the Christmas number of" Wireless Magazine." In all, closeon ninety sets were listed under theheading " Classified Guide to BatterySets."

But there is still a dearth of reallygood battery receivers. I have heardof more than one listener who hastried to find a set with push-pulloutput, for instance, and there aretoo few sets with two stages ofscreen -grid amplification. If youwant a really good multi -valve set you

will still have to build it from instruc-tions in " Wireless Magazine."

On the whole, this supplementshowed that the listener who wantsto buy a new receiver has an amazingrange from which to make his finalchoice. There is no question of thepopularity of the three -valve set forA .C. operation-if the manufac-turers are gauging the public tastecorrectly I

Bari's NewTransmitter

Listeners whopick up the newhigh -power trans-missions from Bari,in Italy, will be in-terested to knowthat the equipmentwas actually madeby the MarconiCompany atChelmsford, as were

substantially flat between 30 and10,000 cycles. A crystal oscillatorwith temperature control is used tokeep the station exactly on itsallotted wavelength.

Other recent orders for Marconibroadcasting stations include instal-lations for the B.B.C. West Regionalstation near VVashford Cross, theIrish Free State, Cape Town, andBuenos Aires.

A FINAL POLISHCleaning up the King's microphone,which is kept by Marconiphone exclus-ively for public-address work when His

Majesty speaks

its predecessors at Trieste andFlorence.

The unmodulated aerial energy atBari is 20 kilowatts and the wave-length is adjustable between 250 and550 metres, the station at presentworking on 273.73 metres.

This station uses low -power modu-lation and the frequency response is

READY FOR THE PRINCETaking the King's special public-addressmicrophone to Belfast for the use of thePrince of Wales-the only other person

to use it apart from His Majesty

The Value of Fuse PlugsThere are on the market a number

of mains plugs that incorporate fuses.Several people have asked me whatis the use of such a device when everymains set is already provided with aninternal fuse.

The answer is that if the flexiblelead between the mains socket andthe set becomes frayed then quiteserious damage may be done beforethe house fuse blows. Of course,the smaller fuse in the set will not beaffected if the set is switched off.

I have never had this trouble witha radio set, but I did nearly have afire recently through the flex on atable lamp being broken and shorting.There was a horrible smell of burn-ing rubber and the cover was burntright through before the main5 -ampere fuse blew out.

Personally, I think it would be awise plan for everybody to fit a fuseplug to table lamps and radio sets.

London, W .C.1. BM/PRESS

753

Wireless Magazine. January1933

AMONG Tilt"MARC WAVif

MORTON BARR Discusses Some Important Developments

RECENT developments in radioshow that great interest is

being taken in waves less than ametre long. Two or three years agoit was thought that the limit in short-wave working had been reached withthe 15 -metre wave used for beamtransmission, but since then wireless -

using the capacity coupling betweenthe plate and grid as a means ofreaction, but the output is verysmall-only amounting to a fractionof a watt.

The method is therefore of littlepractical importance outside thelaboratory.

GENERATOR FOR MICRO -WAVESSpecial valve oscillator for the production of waves of the order of 30 centimetres. Suchvery low wavelengths are certain to assume a very great importance in the future. Inthis particular system electrons from the filament F travel along the narrow tube A,

swirl round B, and pass to the plate P

telephone messages have been sentacross the Channel on 20 centi-metres.

And within the last few monthsMarconi and others have coveredstill greater distances using wave-lengths which are more convenientlymeasured in inches than in metres.

Not An Easy ProblemIt is not easy to use an ordinary

back -coupled valve, or to employusual tuning methods, when produc-ing frequencies of this order.

A 30 -centimetre wave, for in-stance, corresponds to a frequency ofa thousand million cycles a second, sothat the inductance of even a shortlength of straight wire assumes largeproportions, whilst the capacityeffect across the electrodes inside thevalve has to be taken seriously intoaccount.

Wavelengths just under the metremark have in fact been produced by

A much larger output of energy onwavelengths of 10 centimetres-orroughly 4 in.-can be obtained bymaking what appears to be a verysimple change in the working condi-tions of the valve, though in fact itinvolves a profound dif-erence in the actual op-eration.

This consists in puttinga high positive voltage onthe grid instead of on theplate, the latter either beingnegatively charged or elseleft at substantially thesame potential as the fila-ment.

Under these conditions,the electrons leaving thefilament never succeed inreaching the plate, but arekept constantly oscillatingto and fro across the grid.Each time they pass thegrid they produce a vol-

tage swing and so build up oscillatingcurrents of very high frequency.

For instance, where the electronstream leaves the filament, it isurged at high velocity towards thepositively charged grid. Some of theelectrons are caught on the grid,momentarily reducing its voltage,but the rest pass through the openwindings and are carried on by theirown velocity towards the plate.

No Positive PotentialBut since the plate carries no posi-

tive voltage (sometimes in fact it isnegatively charged), the electrons arenow moving away from a point ofhigh attraction to an area of low orzero attraction.

Their flight is therefore quicklyretarded, and almost at once thedirection of the stream is reversedand it moves back again towards thegrid. Here some electrons are col-lected, as before, giving the gridanother voltage impulse, whilst therest pass through towards the fila-ment.

As they are now moving awayfrom the strongest centre of attrac-tion, they soon " about turn " againtowards the grid. In this way a rapidand sustained to-and-fro movement

COIL FOR 7 -METRE RECEPTIONA low -loss coil, made by Tunewell Radio, Ltd., forreception on the 7 -metre waveband. A simple setfor this purpose was described in the September

issue of " Wireless Magazine "

754

s set up, each " reversal " applying afresh impulse to the grid, which isdirectly coupled to the transmittingaerial.

The important point is that theaction of the electron stream has beenquickened. Instead of having totraverse the whole of the distancebetween the filament and plate beforeit can impulse the latter, it oscillatesover a short path on each side of thegrid. By cutting down the timefactor in this way, the frequency ofthe oscillation is increased, or, inother words, the wavelength isshortened.

Radiation SystemThe oscillations produced are

radiated from a short wire aerialinserted across the grid and plate,though in some cases radiation takesplace directly from the grid, which isextended outside the bulb for a shortdistance at each end.

This system of producing micro-waves, particularly the motion of mak-ing the electron stream vibrate acrossa highly positive grid, is usuallyreferred to as the Barkhausen-Kurzmethod, to distinguish it from cir-cuits using ordinary reaction.

Extra Large PowerWhere an extra large power out-

put is required, two valves can beconnected in push-pull to the sameaerial, the connecting wires being soarranged that they carry out -of -phase currents and therefore do notthemselves radiate. By ar-ranging several such aerialsin parallel (in the same wayas in beam transmission),a very powerful stream ofshort-wave radiations canbe produced.

The idea of dependingupon the movements of theelectron stream inside avalve, rather than upon the" tuning " of an externalcircuit, opens up manyingenious possibilities inshort-wave generation.

For instance, in the valveoscillator shown diagram-matically opposite, theelectron stream is made tointerrupt itself automati-cally, and at such a rate asto produce waves of theorder of 30 centimetres.

The glass bulb is shapedso that the electron streamfrom the filament F travelsat first along a narrow tube I


LEARNING ALL ABOUT BEAM TRANSMITTERSA group of Arabian students being shown the "feeder" box of a Marconi short-wa vebeam transmitter so that they will be able to maintain a wireless link throughout the

kingdoms of Medjax and Nedj in Arabia

A, as shown by the arrows. At thefar end, the tube flares out as shownat B. The plate is inserted at P so thatit lies at a tangent to the path of thestream, the high-tension supplybeing connected from the plate to acentre tapping on the filament trans-former T.

The flared part B of the tube iscovered internally with a thin coatingof metal which is carefully insulatedfrom the plate A by a bushing markedD. The arrangement operates as fol-lows :

As soon as the filament is energisedand the high tension applied to theplate, the electron stream starts out

2/ Wireless ParodyUnder the greenwood treeWho listens now with me ?And tunes his wireless set,A swanky super -het,

(See Shakespeare, 'Tis not Herrick's).Here we shall findAll to our mind

Save Morse and Atmospherics.Who doth ambition shun,Choosing a modest one,A little crystal setGood programmes oft doth get

From many far-flung stations.Here we shall findAll to our mind

Save Morse and Oscillations !LESLIE M. OYLER.

from the filament along the narrowpart of the tube. By the time ithas reached the positively chargedplate its velocity is such as to carryit past the plate and into the flaredportion B.

Electrons Curve BackHere it is in a region which is not

positively charged (in fact, a slightnegative charge may be given to themetal coating), so that it swirls pastthe end walls of the bulb B andcurves hack on itself, as shown by thedotted line, in an effort to reach theplate.

By the time the head of the streamcomes opposite to the plateP its momentum is suffi-cient to break through theoncoming stream, which isaccordingly interrupted un-til all the electrons in frontof the point of intersectionhave been swallowed up bythe plate. As soon as thishas happened, the electronstream starts to careerafresh around the flaredbulb, until it again inter-sects itself, and so causesanother momentary inter-ruption.

And so the process goeson indefinitely. Each newimpact on the plate sets upa current surge which isfed directly to a short-wave transmitting aerialsuitably coupled to theplate.

Great possibilities areopened up by these micro-wave developments.J

755

Wireless Magazine. January1933

Components As I Know Them -7.

The Variable CondenserThis month PERCY W. HARRIS, Minst.Rad.E., deals with one of the most importantcomponents to be found in any radio receiver-the variable condenser used for tuning.

Everybody who wants the best results should read what he has to say

THE variable condenser is acomponent which has reached

such a stage of perfection that theexperimenter rarely gives any thoughtto it. All variable condensers arenowadays assumed to be good andthey rarely give mechanical trouble.

So far as efficiency is concerned-

COMPLETELY SCREENED GANG MODELThis is the J.B. Unitune two -gang condenser. The metalcover is seen on the right. Note the star wheel for adjusting

the trimmer

well, we no longer worry aboutdesigning our oscillating circuit so asto have a very low damping and,as I pointed out in an article in" Wireless Magazine " last month,*the efficiency of the modern valve issuch that inefficiency in tunedcircuits goes unnoticed !

It has not always been so, and I amsorry that inefficiency is again creep-ing in. Only in ultra short-wavework do we find the faults of manymodern variable condensers showingup; in medium- and long -wavecircuits the faults are masked by themuch greater inefficiency of the coils.

Next Step ForwardProphecy is rather dangerous, but

I am very much inclined to thinkthat one of the next steps forward inradio design will be the re-establish-ment of an efficiency standard forcoils and condensers.

We shall then have the usual glutof articles from highbrow technicalwriters who never seem to be ableto forewarn us of trouble, but

"NeW Losses Balance New Gains," page 594of " Wireless Magazine" for December, 1932.

who are very wise after the event !Let us consider Fig. 1, which

shows the simplest oscillatory circuitwith an inductance L and a condenserc. In most cases such a circuit isset up in such a way that the voltagesinduced across the condenser ter-minals are applied to grid and

filament of a valve.To cover the

medium wave-band it is usual tohave the induc-tance L of theorder of 200 milli -henries; such acoil with a .0005-microfarad vari-able condenser andthe associatedcapacities will tuneover the band werequire.

The current inthe circuit will

depend, of course, upon the totalhigh -frequency resistance, whichwill be made up of the resistanceof the coils, of the condenser,and what is known as the" radiation resistance," that is thelosses by radiation (equivalent to aresistance loss) which can be ex-pressed for convenience in ohms.

The radiation resistance at thefrequencies used on the medium andthe long wavebands is for such acircuit very small and can be ignoredfor our purpose at this moment.

If the coil L is well designed itshigh -frequency resistance can bebrought down to 2 or 3 ohms, whilethe high -frequency resistance of thecondenser can be as low as half anohm over practically all of the scale,although at the bottom end it willrise appreciably, reaching somethingin the neighbourhood of 2 ohms.

Thus we see that even with thevery highest efficiencies most of thehigh -frequency resistance of thecircuit is found in the coil itself.

There was a time, during a periodwhen " low -loss " was the topic of

the day, when there was far too greata tendency to consider a circuit suchas this as if it could exist " on itsown " and as a consequence a propersense of proportion was lost.

Associated EffectsWe cannot deal with a circuit of

this kind by itself, and we mustconsider the effect of associatedinductances, couplings, dampingintroduced by the valve connectedto it, and so forth. Incidentally, Iwell remember carrying out anumber of tests at the time for thepurpose of finding out the high -frequency losses in the valve holdersconnected to such a circuit. Theywere always higher than that of thecondenser.

Reverting to thevariable condenser,there are quite a number on themarket the high -frequency resistanceof which is actually higher than thatof a good coil used with them,although even these have a relativelylow resistance compared with mostof the tuning coils in use at thepresent time.

InterdependenceFrom this it follows that if we

set out to make our coils really goodand of low high -frequency resistance,our efforts are wasted unless wechoose very good variable condensers,while on the other hand the virtuesof a good variable condenser are lostor rather masked with the majority

FOR SHORT-WAVE WORKA special J.B. condenser for short-wavereception. The vanes are more widelyspaced than usual for maximum efficiency

756

of tuning coils in use to -day.What must be looked for in a good

variable condenser? What has itto do ? The answer to this lastquestion sounds simple-as it reallyis ----but if we are not careful we shalloverlook certain important properties.

Capacity RatingVariable condensers are sold now-

adays on a maximum capacity rating.Thus if we say a .0005-microfarad,variable condenser we mean onewhich has a maximum capacity of.0005 microfarad with the fixed andmoving vanes completely inter-meshed.

Nothing is usually said, or evensuggested, about the minimumcapacity, which is of increasingimportance in view of the extensionof the working broadcasting band

LFig. I.-Skeleton tuning circuit showingcombination of Inductance L with Capac-

ity C

into the shorter wavelengths below250 metres.

So long as we only tuned to250-550 metres we could put upwith a condenser having a fairly highminimum, but nowadays a lowminimum is most important, 'other-wise our coil and condenser com-bination, while tuning to the maxi-mum wavelength satisfactorily, willnot get down to 200 metres.

Look at all the complaints one getsabout a receiver not being able totune down to the Newcastle wave-length or even to Fecamp.

Correct MaximumWe must look also for a correct

maximum capacity and in this regardI would like to point out that thewell-known and branded makesseldom err in this direction. I havemeasured hundreds and rarely foundany error of importance. Usuallythey are slightly above .0005 micro -farad.

With unbranded and cheap makes,sold in some of the back -street shops,there are very serious errors.

Not long ago a friend of minebrought to me a set built to one ofmy own designs which, whiteperfectly satisfactory so far as sharp-

-Wireless Magazine, January, 1933

ness of tuning and signal strengthwas concerned, gave readings whichwere quite different from thosepublished in my article, and the setwould not tune up even so far as theNorth Regional.

The coils were correct, but a quickglance at the variable condenserssuggested to me that probably thetrouble was there. I removed themand measured them on a capacitybridge, only to find that the maximumcapacity in each case was .00027microfarad !

Now in this case, as in manyothers of the kind, it is improbablethat the manufacturer really intendedthe capacity to be so low. It looksan easy matter to design and make avariable condenser, and I am afraida number of manufacturers merelytake an example of a rival maker andcopy it to the best of their ability.

In essence a variable condenserconsists of a number of metal platesthreaded on to a shaft and separatedfrom one another by washers, thewhole assembly being tightly grippedby locking nuts.

A second assembly is then madeup, also similarly spaced withwashers, or by some other method,and the two sets of plates are somounted that while they are com-pletely insulated from one anotherthey can be made to intermesh byrotating the spindle carrying themoving plates.

The capacity of the condenser isdependent upon the size of the inter -

CUT -AWAY END PLATESThis Lotus variable condenser has cut-

away end plates to reduce losses

meshed plates and their spacing.Double the spacing between theplates and you halve the capacity;similarly, decrease the spacing andyou increase the capacity. Theinexperienced " copyist " type ofmaker thinks only of the size andnumber of the plates and, buyinghis washers anywhere, may quitelikely get a wrong thickness and -soincrease the spacing between theplates and reduce the total capacity.

This is undoubtedly what hadhappened in the case I mentionedabove.

The minimum capacity of a variablecondenser can be greatly affected byits mechanical construction. If the

SLOW-MOTION INSTRUMENTAn Ormond condenser with an integralslow-motion device for fine tuning; a

very popular type

plates are so arranged that whenthey are turned to the minimumposition there is no actual inter-leaving at any point it does notfollow that there is no capacitybetween the two terminals of thecondenser, for there is what we maycall an " end capacity " between theplates.

Difficult to ManufactureIt is comparatively simple to design

a variable condenser with a very lowminimum capacity, but it may lackcompactness and be a difficult manu-facturing proposition.

Compactness in a variable con-denser is rather a virtue nowadayswhen receivers are made as small aspossible, but if in achieving thiscompactness we produce a condenserwith a high minimum our instrumentwill be very unsatisfactory in modemcircuits.

Capacity Between ConductorsWe must also remember that there

is capacity not only between thevanes, but between any other con-ductors connected to the vanes.Furthermore, if there is a soliddielectric material between theseconductors (as there is bound to bein every case, otherwise the con-denser would not hold together) weshall get a higher capacity for a givenspacing than would occur if onlyair separated the two parts.

For example, if we have two piecesof metal separated by an air spaceand we then insert in the air spacea piece of ebonite packed so asexactly to fill it, the capacity will go

757


THE VARIABLE CONDENSER Cont.

SOLID DIELECTRICA typical condenser for reaction circuits.This is a Lotus model with solid dielectric

to save space

up approximately twice, while if inplace of ebonite we introduce micait may go up as much as six toeight times. Nearly as high a figurewill also be given by glass.

We thus see that in our endeavourto get a low minimum of capacitywe need to be very careful how thetwo plates are supported. Ascapacity is reduced by increasingthe spacing between conductors itwill pay us in this regard to keep themetal supporting pieces wide apart.

High -frequency ResistanceAssuming that we have the correct

maximum capacity and a good lowminimum, what else must be lookedfor ? We must reduce the high -frequency resistance as low aspossible if we really want efficiency.To do this we must understandwhere the high -frequency losses canoccur.

Obviously there will be very littleloss in the plates themselves as theseare large pieces of metal connectedin parallel, hut we can if we are notcareful introduce considerable high -frequency resistance at points ofcontact.

Electrical ContactsIf, for example, aluminium plates

are used and these are threaded on aspindle and kept apart by aluminiumspacing washers, electrical contactbetween the plates will occur onlyat the point of contact between platesand washers, plates and spindle, andwashers and spindle.

All the resistances between platesand washers are in series and in apoorly assembled condenser theremay be comparatively small contactsbetween plates and spindle, andwashers and spindle.

Aluminium exposed to air immed-iately gains a transparent surfacelayer of oxide, -which in itself has afairly high resistance, and unless theplates and washers are screwed verytightly together we get quite con-siderable losses here.

Furthermore, aluminium cannotbe soldered by the ordinary method,so we cannot make sure of goodcontact by soldering the platestogether. However, with properdesign and construction, excellentcondensers can be made this way.

Far less trouble occurs if we usebrass both for plates and washers,while for laboratory condensers,particularly in Germany, both fixedand moving plates have been cut outof the solid ! This, of course, meansthat all our contact troubles areobviated.

A similar result has been obtained,but at much lower cost, by die-casting both fixed and moving plateassemblies. Die-cast condensershave, in fact, grown rapidly in popu-larity among set manufacturers.

TWO CONDENSERS-SINGLE TUNING DIALA Formo dual condenser with a single dial. One knob

adjusts both condensers, and the other adjusts one condenseronly for trimming

Brass assemblies can be solderedtogether to give good contact.

A very important source of high -frequency loss is in the solid di-electric material insulating the fixedand moving plates. In early variablecondensers it was quite usual tobring out the spindle connected tothe moving plates through a metalend plate connected to the fixedplates by a small ring of insulatingmaterial either forming the bearingor, in the better grades, carrying thebearing.

Mechanically such condensers arequite strong, but they have the gravedefect of placing this solid dielectric

material just at a point where theelectrostatic field is highly concen-trated.

Now air is a perfect insulator, itsdielectric losses being practicallyzero. Even the best ebonite is poorcompared with it, while many of thesolid insulating materials, particu-larly of the moulded variety, comparevery unfavourably indeed withebonite.

Concentration of FieldIt is quite possible for such a

variable condenser to have a high -frequency resistance of 20 or 30 ohmsdue to the concentration of fieldthrough poor quality material.

As an aside, but just to give you anidea of what may happen with asolid dielectric, some years ago whenone of the British high -powerstations was in an experimental statepure high-grade ebonite was usedas a mechanical support of aninductance coil in the transmittingcircuit.

When the full transmitting powerwas turned onthe heat set upin this ebonite wassuch as to causeit to melt andburst into flame !

All resistancelost in such a caseappears as heatalthough, ofcourse, the currentin the receivingcircuit of the kindwe are discussingis so small as notto make this heatappreciable. Theloss is there, how-ever, just thesame .

I am very sorry to see in severalcondensers produced recently thatthis old and pernicious method ofbringing out the connection from oneset of plates through a hole in theother set, with only a small insulatingwasher between them, is beingadopted.

Masking InefficiencyIn the modern case we usually

have metal end plates connected tothe moving vanes, the connectionfrom the fixed plates being broughtout through this washer. It is im-possible to make a good condenserthis way and the manufacturers are

758

Wireless Magazine. Januarx 1933

SPECIAL ARTICLE BY PERCY HARRISobviously relying upon the highlosses in modern coils to mask theinefficiency of their condensers.

If you take any modern high-gradecondenser (the Cyldon is typical ofthe best modern practice) you willfind that not only is very littleinsulating material used, but that thepath through the insulating materialfrom one set of electrodes to anotheris comparatively long.

Weak Field with Small LossesThis means that what field does

go through this insulating materialis very weak and correspondinglysmall losses are set up.

So far I have not mentioned any-thing about the shape of the plates,although this is a very importantmatter. If we use semi -circularplates in both assemblies and arrangethe moving plates in such a way thateach degree of the condenser inter-meshes an equal amount of plates,then we shall get what is known as a"straight-line capacity" condenser orone in which the capacity increasesproportionately with the turning ofthe dial.

Wrong MethodAlthough the first variable con-

densers were all made this way it isan entirely wrong method for tuning,as the wavelength to which a circuitwill tune is exactly proportional tothe square root of the capacity.

This means in practice that if wetry to tune our coil with a straight-line capacity condenser the stationswill be all crowded together at thebottom end of the scale and muchtoo widely spaced at the top.

A Better DesignWhen I first began to design wire-

less receivers for home constructionall of the condensers were of thesemi -circular kind, and then after ashort time a condenser was intro-duced having specially shaped platesso that as we got towards the topend of the scale the capacity increasedmuch more rapidly for an equalamount of turning. In this waythe stations distributed by wave-lengths were much better spaced out.

I thereupon decided that in futureI would no longer use any condenserthat did not comply with this law,and after some little difficulty Ipersuaded a second manufacturer to

embark upon the making of such acondenser.

For quite a time there were onlytwo makers and you would be sur-prised if I were to tell you how muchtrouble I had in persuading othersto take up the type. In time, ofcourse, they all did, but many foughtagainst the new kind for reasons Icould never understand !

Now although the straight -line -wavelength condenser was a bigimprovement we soon realised thatequal frequency rather than equalwavelength spacing of stations isdesirable and before long thestraight -line -frequency condenser wasintroduced, so that if stations wereequally spaced in frequency theywould become equally spaced on thedial.

This condenser, however, hasrather awkwardly shaped plates andhas never attained a wide popularityas, in common with all condensersfollowing a special " law," it will onlybe " straight-line " if the associatedcapacities are those for which thecondenser is designed.

About 1926 another form of con-denser, known as the " log -law," wasintroduced, giving a distribution ofstations on a line about half -waybetween that given by the straight-line -wavelength and the straight-line -frequency condensers respec-tively.

This condenser was designed notso much to give a uniform spacingof stations as to enable unmatchedcoils to be used with ganged con-densers.

The matter is not simple to explainin the space I have available, but itcan be said that if one coil in aganged set was slightly larger thanthe next the difference in tuning

A POPULAR "SERIES" CONDENSERAn "aerial series condenser" is used forcontrolling selectivity in nearly everymodern set. This model is the Formo-

denser with solid dielectric

positions of the two circuits can becompensated by setting the condenserconnected to the large coil backlittle.

A Good Deal of InterestI see I am getting to the end of

my space and there is still a gooddeal of interest which could be toldabout variable condensers ! I think,however, I have told you enough tosee that you cannot judge whether avariable condenser is a good one ornot merely by glancing at it, andthat a condenser may be excellentmechanically while poor electrically.

FOR REACTIONA Bulgin air -dielectric condenser forreaction circuits, a most efficient

component

The only safe guide, then, is to buyone of the makes which has alreadyestablished for itself a reputation-arule which applies just as well inevery other make and form of wire-less component !

South AfricanBroadcasting

AREADER in Cape Province,South Africa, sends us some

details of South African broadcast-ing. Johannesburg, 2TJ, is operatingon 49.2 metres (6,097.2 kilocycles)and the usual call is : " Good even-ing, everybody. This is Johannes-burg calling; the Johannesburg sta-tion of the African Broadcasting Co.,operating on 666.6 kilocycles and6,097.2 kilocycles, through Pretoriaon 1,000 kilocycles, and throughBloemfontein on 588.2 kilocycles."

In South African standard timethe daily programmes are from11.00 to 14.00 and from 16.00 to22.30; on Saturdays from 11.00 to14.00 and from 16.00 to 23.45 ; andon Sundays from 15.00 to 17.15 andfrom 19.15 to 22.00.

759


If You Didn't Build It for Christmas-Then Build It for the New Year!

1he1933 horlonyS.G3.

SCREENED DUAL -RANGE COILSTwo completely screened coils are used inthe 1933 Economy S.G.3, which was fullydescribed in the December issue of "W.M."

"GOOD afternoon, Henry 1 I'm

just looking you up becauseI want to know how you got on withthat little three -valve set I gave youdetails of. Is it working all right,or did you come up against anysnags ?"

" Oh, it's fine, thanks, George !Although it is the first set I have everbuilt, I managed to ferret it out allright. Several of my friends arethinking of building it now that theyhave been able to hear mine. Theywere amazed that such a cheap outfitcould give reception from so manystations."

A Popular Design" That's right ; the more the

merrier. I told you I was sure theset would be popular. Why, as soonas the Christmas Number of ' Wire-less Magazine ' was published wewere inundated with inquiries forblueprints of the 1933 EconomyS.G.3-that's the name we eventuallygave to your set, you know."

" Yes, George, I saw that. Thewife was tickled to death to thinkthat we had been able to build ourset from advance details before any-body else. You've no idea howpleased she is with the whole thing.

" But there are one or two things

George, of the "W.M." Tech-nical Staff, has another chatwith his friend Henry aboutthe 1933 Economy S.G.3, whichwas fully described in theDecember number. The setcan be built complete (that iswith valves, cabinet, batteriesand loud -speaker) for just under

five guineas

SIMPLE-BUT A STATION GETTER !Although it costs only five guineas complete withall accessories, the 1933 Economy S.G.3 is a realstation getter and provides plenty of entertainment

I should like to ask you about thewiring, if you have a few minutes tospare. I think I have done it all

right, but I am not quitecertain."

" Fire away, by all means.I'm not in a terrific hurry justnow. What is it you wantto know ?"

" Well, just look at thisblueprint. The connectionsnumbered 36 and 37 seem toend in mid-air. I lookedunderneath the coils, butcouldn't find anything thatlooked as if it needed con-necting up. I came to theconclusion that these wiresjust had to be pushed underthe metal bases of the coils tomake contact."

Earthing the Screens" That's right, Henry.

Those two wires actuallyearth ' the screens of the

coils so that the set is stablein operation. See, the sameapplies to the connectionsnumbered 31 and 34. Piecesof fine wire-without anyinsulation, of course-aretwisted round the outside ofthe metal -braided cable and

then connected to the coil screens.In that way the metal casing roundthe wire is earthed just as the coil

COMPONENTS NEEDED FOR THE 1933 ECONOMY S.G.3CHOKE, HIGH -FREQUENCY

1-Graham Parish, 2s. (or Lewcos, Telsen).COILS

2-Pressland dual -range, 9s.CONDENSERS, FIXED

2-Dubilier .0002-microfarad, type 665, ls.(or Lissen, Telsen).

CONDENSERS, VARIABLE2-Telsen .0005-microfarad, type W193, 5s.

(or Lissen, Polar).1-Telsen .0003-microfarad, type W194,

2s. 6d. (or Lissen, Polar).HOLDERS, VALVE

3-W.B. four -pin, ls. 6d. (or Lissen, Lotus).PLUGS AND SOCKETS

7-Eelex wander plugs, marked: H.T. +3,H.T.+2, H.T.-i-1, H.T.-, G.B.G.B.-1, G.B.-2, 10 Ad. (or Belling -Lee,Clix).

6-Belling-Lee terminals, type Q, ls. (orEelex, Clix).

RESISTANCE, FIXED1-Claude Lyons 2-megohm grid leak, 10Id.

(or Erie, Dubilier).SUNDRIES

1-Packet Goltone braided cable, 9d.Lengths of oiled -cotton sleeving (Lewcos).Tinned -copper wire for connecting (Lewcos).Length of rubber -covered flex (Lewcos).

SWITCHES1-Sovereign three-point wave -change, Is.

(or Bulgin, W.B.).1-Sovereign on -off, 7d. (or Bulgin, W.B.).

TRANSFORMER, LOW -FREQUENCY1.-Telsen Ace, ratio 1 to 5, 5s. 6d. (or Lissen

Torex, R.I. Dux).

ACCESSORIESBATTERIES

1-Ever-Ready 120 -volt high-tension,Winner type, lls. (or Lissen, Siemens).

1-Ever-Ready 9 -volt grid -bias, Winnertype, is. (or Lissen, Siemens).

1-Oldhams 2 -volt accumulator, type 025,5s. 6d. (or C.A.V., Exide).

CABINET1-Peto-Scott, 10s. 6d.1-Peto-Scott wood panel, baseboard and

terminal strip, 2s. 3d.LOUD -SPEAKER

1-Lissen plaque, type LN5077, 8s. 6d.VALVES

1-Mallard PM12, 16s. 6d. (or Cossor 220SG,Mazda 215SG).

1-Mullard PM1HL, 7s. (or Cossor 21OHL,Mazda HL2).

1-Mallard PM2A, 8s. 9d. (or Cossor 220PA,Mazda P220).

The prices mentioned are those for the parts used in the original set; the prices of alternatives I

as indicated in the brackets may be either higher or lower

760

screens are themselves earthed."" Good ! That's what I tried to

explain to one of my friends ; but,of course, I don't knowenough about it to be abso-lutely certain. Now thatyou have told me, I'll makesure he doesn't go wrong."

" I've been waiting tohear one criticism, Henry,but as you haven't men-tioned it I will. How doyou get on with the tuningknobs - I mean, theyhaven't any scales markedin degrees or anything, sohow do you know where thestations are ?"

Simple Solution" Ah, that was a bit of a

puzzle at first, but I got overit quite simply, as a matterof fact. I cut two semi-circular pieces of paper outand stuck them on the panel just overthe tuning knobs. You know thosehave white arrows on them? Well,when I had tuned in a station andmade certain what it was, I just


pencilled the name on the paperopposite the point where the arrowhead was. That's all right, isn't it ?"

NEAT CABINETMany readers have admired the appear-ance of the completed 1933 Economy

S.G.3

" Excellent, Henry; just what Iwas going to suggest if you hadn'talready thought of it ! Of course,another way would be to spring anextra three or four shillings and buy

two ordinary calibrated dials;it would not be difficult tofix them on to the condenserspindles and they would looka little neater than yourhome-made scales."

" I don't think I shall

LT

3"

SLUEPAIIITV/11 300

+3 +5 +1 -I -2MT .168

LAYOUT AND WIRING DIAGRAMFull-size blueprints of the set are still availableat Is. each, post free, if application is made to the^W.M." Blueprint Department. Ask for No.WM306 and address your letter to 58161 Fetter

Lane, London, E.C.4.

ideal in every respect-I don't any-way. All that really matters is thatit works as well as it does-and gets

so many stations. But I tellyou what I am thinking ofdoing, and that is to get oneof those gadgets you needfor playing gramophonerecords through the wire-less."

" Hullo, becoming quitea radio fan already, aren'tyou ? Well, you won't havemuch trouble about that.The set already has twopick-up terminals. All youhave to do is to connect apick-up to these and putthe records on."

" Need I get any specialkind of pick-up, or willany one do ?"

"Not exactly any one. Yousee, the set hasn't got agramophone volume control ;

so you had better get a pick-up thatis provided with its own volumecontrol. I should go along and seewhat your local dealer has got. BlueSpot make a pick-up with a volumecontrol, and there are the Harlie andthe B.T.H. Minor-you won't haveany trouble in getting one."

Up to Date !" That will be all right, then, for

I saw a second-hand clockwork motor

WHAT YOU CAN DO FOR FIVE GUINEASHere you see the 1933 Economy S.G.3 connected to the batteries all readyfor use. The price of five guineas includes set, valves, batteries, cabinet,

and loud -speaker !

trouble about that. You see,with the names of the stationsactually written on the papermy wife can tune at once tothe programme she wantswhen I am not about. Afterall, you can't expect a five -guinea set to be absolutely

and turntable going in a local junkshop for a few shillings. I think I'lldrop in and get it on the way hometo -night. That will have to be aNew Year treat for the wife. Shelikes the gramophone and will feelvery up-to-date with an electricone !"

761

Wireless Magazine, ,Janury. 1933

A POWERFUL SUPER -HET FOR USE IN THE CARGreat interest is being taken in the new H.M.V. portable super -het six-valver, which

is battery operated. This receiver has been found ideal for use in a motor car

AT this season of the yearlisteners who care to devote

a little time to the search for distanttransmissions in the later hours ofthe night may find their patiencerewarded by the capture of broad-casts from both North and SouthAmerican cities.

Reception of concerts broadcast onmedium wavelengths from theUnited States this year has beenfacilitated by the fact that many ofthe better-known stations are beingrebuilt with a view to an increase inpower.

This step has been taken in parti-cular by studios associated with theNational Broadcasting Company, asit is hoped that the new RockefellerCentre or Radio City at New Yorkmay be completed by August, 1933.

It is true that the change -over ofthe studios to the new site may onlybe gradual in order that there maybe no necessity to suspend operations,but in the meantime eight new sta-tions of the N.B.C. net will shortlyadd 297 kilowatts to their totaloutput.

Another IncreaseIn the same way, the competing

concern, the Columbia broadcastingchain, is being increased by some213 kilowatts. (To -day the com-bined power of the N.B.C. networkhas reached 900 kilowatts.)

Moreover, as a favour, the FederalRadio Commission has authorised

the Crosley Radio Corporation toconstruct an experimental 500 -kilo-watt transmitter to operate on 428.3metres (700 kilocycles) in replace-ment of the WLW, Cincinnati,station.

Stronger Than Any OthersIf the hopes of the engineers are

realised the signals from this giantbroadcaster will prove at least oneand one-halhimes stronger than anyother 50 -kilowatt station in existence,and they wills no doubt, be pickedup in the British Isles.

The possibility of hearing a greaternumber of U.S.A. programmes directwill be further increased by the factthat the following stations havealready stepped up their radiatingenergy, or are doing so within thenext few weeks.

They are WHAS, Louisville(356.2 metres), 25 kilowatts; WCCO,Minneapolis (370.2 metres), 50 kilo-watts; WCAU, Philadelphia (256.3metres), 50 kilowatts; and WBT,Charlotte (277.6 metres), 25 kilo-watts.

In addition, eight other studioshave also been authorised to putover their programmes at higherpower, namely, WSM, Nashville(461.3 metres); WSB, Atlanta (405.2metres); WOC-WHO, Des Moines(299.8 metres); KPO, San Francisco(440.9 metres); KOA, Denver (361.2metres). KVO, Tulsa (263 metres)and WAPI, Birmingham, on the

to theWorld!It Is often thought thatAmerican stations canonly be received with ashort-wave set. That isnot so, however, and inthis article J. GOD-CHAUX ABRAHAMStells you when to listen forthe New World on yourordinary broadcast set

same wavelength, have secured per-mits to use 25 kilowatts. WOR,Newark (N.J.), on 422.3 metres,may also be rated at 50 kilowatts.

During the past month reports onthe reception of Transatlantic broad-casts in the medium waveband havebeen frequent, and in many instancesthey were not confined to big stations.WPG, Atlantic City (N.J.), on 272.6'metres, rated only at 5 kilowatts(aerial),and WRVA, Richmond (Va),270.1 metres, of the same power,figure very prominently in theselists.

Curiously enough, WIOD, MiamiBeach (Flo.), on 230.6 metres, and ofmuch lower energy, appears to holdthe record, for its transmissions aremore frequently heard in the UnitedKingdom than those of many of itsbigger competitors.

Facilitating A SearchIn order to facilitate a search, I

have prepared a list of the moreimportant United States broadcastingstations; in those cases in whichshort-wave relays are associated withthem full particulars of wavelength,frequency, and times of transmissionhave been given.

In the same way you will also finda list of main Canadian stations,many of which simultaneously trans-mit on short waves.

Of the South American studios,there is no doubt that at least three,situated at Buenos Aires, are being

762

well heard on favourable nights onthis side of the Atlantic, although Ihave seen confirmed reports ofreception of such stations as LS9,LR8, LS5, LR9, and LR6.

As you will see from the list of theprincipal studios, we cannot rely onshort-wave intermediaries, as suchrelays are not carried out sufficientlyregularly. Now and again, however,a programme emanating from RadioSplendid is rebroadcast throughWABC, New York.

Publicity ItemsAlthough the number of broadcast-

ing stations operating in BuenosAires, in proportion to the popula-tion and to the area covered, is verylarge, programmes-the actual pro-grammes-are very poor, inasmuchas they are mainly composed ofgramophone records interspersed-as is the custom with, say, RadioToulouse nearer home-with fre-quently repeated publicity items.

The stations, with the exceptionof two which are run and operatedby the Municipality, are all privatelyowned, possess no fixed source ofincome, and consequently are com-pelled to rely on microphone adver-tising for revenue.

Poor PayNow and again, during the day, an

hour may be devoted to an orchestralor vocal concert, but, generallyspeaking, the pay offered to theartists is so small that few musiciansof repute are willing to broadcast.

In the case of the United States

Wireless Magazine. Januarx175331

studios, although no listening taxis levied and the stations are run bycommercial concerns, the annualamount expended on wireless enter-tainments, and solely derived fromsponsors of programmes, reachesvery high figures. Such organisa-tions as the National BroadcastingCompany and the Columbia Broad-cast Company, with their numberless

As a rule, the United States sta-tions do not devote much time to anyone particular broadcast; a featuremay last from fifteen to thirty min-utes. You will notice, however,that the time schedule is strictlyadhered to and there are no gaps inthe programme. It is also cus-tomary to introduce an item with amusical background even whilst the

NOT A RELIGIOUS TEMPLE-BUT A BROADCAST STATION!The transmitting buildings for the American station W C A U. It is located at Phila-

delphia and works on 256.3 metres. Why not listen for it P

associated transmitters linked up intothree or four separate networks,command big prices.

Experience has proved that theevening hours are more profitableto the advertisers than other periodsof the day, and most of the sponsoredprogrammes will be heard between10 p.m. and 2 a.m. G.M.T.

ONE OF THE BEST-KNOWN AMERICAN STATIONSA view of the WJZ transmitter at Bound brook, NJ. It works on 3944 metres and has

a short-wave relay on 16.878 metres ; it is frequently beard over here

preliminary announcement is beingmade.

Moreover, all stations are com-pelled to give their individual callevery fifteen minutes; this is ofconsiderable assistance to the distantlistener.

A Curious PointAnother curious point you may

observe is that, contrary to ourcustom by which we are told thatsuch and such a station is calling,the American announcer will informyou that your station is so-and-so, asif he were actually replying to aquestion put to him on the subject.Even announcers themselves areintroduced in this manner.

Typical ProgrammeOverleaf I have reprinted a

programme typical of many broad-cast by such stations as WEAF orWABC (New York), representingrespectively the " key " or " main "studios of the National BroadcastingCompany's system.

You may, of course, hear the sameentertainment through a number ofassociated transmitters or throughtheir respective short-wave stations:

763


LISTEN TO THE NEW WORLD!-Cont.

AMERICA'S GIANT RADIO CITYThe building of Radio City, a broadcasting and entertain-ment centre in New York, is proceeding apace. Here is a scalemodel of the completed scheme. It is hoped to start opera-

tions in August, 1933

A Typical American Programme(Times have been converted to G.M.T.)

ItemPhysical ExercisesHill Billy songsOrgan RecitalInspirational (?) TalkGlee ClubString TrioPoetry, Songs, OrganSketchFood TalkPiano and Song RecitalSpecial Artists

Time11.4513.0013.1513.3014.0014.1514.3015.0015.1515.3015.4516.0016.15 Household Talk16.30 Band17.00 Songs17.15 String Trio18.00 Market Reports18.15 Orchestra

01.4502.0002.3003.0003.3004.0004.1505.0005.30

19.15 Sketch19.30 Choral

Concert20.00 Orchestra20.30 Woman's

Review21.00 Orchestra21.30 The

Dansant21.45 Sketch22.00 Sponsored

Programme22.1522.30 Interview22.45 Sponsored

Programme23.00 Orchestra23.30 Songs23.45 Talk00.00 . Interview00.15 . Dramatic

Sketch00.30 Songs00.45 Sketch01.00 Mystery

Drama01.30 Political

Talk(relayed)

Paul Whiteman's BandConcertSpeeches (relayed)Sponsored ProgrammeConcertInterviewOrchestraSongsOrchestra

The " high lights " or specialfeatures of these broadcasts areusually given between 19.00 and23.00 Eastern Standard Time andare, therefore, heard by us between23.00 G.M.T. and the early morninghours.

The entertainments offered by theCanadian stations are not so lavish

as those of their immediate neigh-bours and although the time allottedto the various items is also aboutfifteen minutes or half an hour,stations such as CKAC and CFCF,Montreal, do not give much pro-minence to publicity.

CKAC opens up at 09.00 (14.00G.M.T.) with a special feature;CFCF, as early as 07.30 (12.30G.M.T.), with a recital by trouba-dours; the former station includingin its daily transmissions a percen-tage of talks or songs given in theFrench language.

Toronto ProgrammeSome privately owned Canadian

studios broadcast only in the eveninghours. As a rule, the close -downtakes place after a news bulletinbetween 23.15 and 23.30 (G.M.T.04.00-04.30). Here is a CKGWToronto programme taken at random:

G.M.T. 22.45, Little Orphan Annie;23.00, Orchestra; 23.45, LowellThomas (Explorer and Journalist);24.15, Revellers; 01.00, Cities Ser-vice Concert Orchestra ; 02.00, JoyceTrio ; 03.00, The Country Doctor'sAdvice; 03.15, CPRY bro:-dcast ;03.45, Luigi Romanelli's Orchestra;04.15, Cesare Sodero and Orchestra ;05.00, Close down.

Finally, apart from XEP, NuevoLaredo and XEW, Monterey, ofwhich transmissions have beenpicked up through their short-waverelays, it is seldom that listeners inthe British Isles hear broadcastsfrom Mexico.

Principal New World StationsMetres.Kilo-

cycles 1Call Station Metres Kil°-cycles Call Station

NORTH AMERICAN STATIONS 260.7 1,150 WHAM Rochester (N.Y.), N.B.C., Blue Net.(United States) 270.1 1,110 WRVA Richmond (Va.).

214.2 1,400 WCGU Brooklyn (N.Y.) relayed by W2XBH, 270.1 1,110 WPG Atlantic City (N.J.), C.B.S.54.52 metres. 275.1 1,090 KMOX St. Louis (Mi.), C.B.S.

230.6 1,300 WIOD Miami Beach (Florida), N.B.C. BlueNet, relayed by W4XB on 49.67

280.2 1,070 WTAM Cleveland (Ohio), N.B.C.; relayedthrough WJZ, Boundbrook.

metres. 282.8 1,060 WTIC Hartford (Conn.), N.B.C.; relayed243.8 1,230 WHAS Boston (Mass.) Columbia Broad- through WJZ, Boundbrook.

casting System, relays WABC,New York.

293.9 1,020 KWY }KFKx .Chicago (Ill.), N.B.C. Blue Net.

249.9 1,200 WBHS Hunstville (Ala.), 50 kw. 302.8 990 WBZ Boston (Mass.), N.B.C.; Blue (re -252 1,190 WOA1 San Antonio (Tex.), N.B.C., 50 kw. layed by WIXAZ, 31.35 metres.256.3 1,170 WCAU* Philadelphia (Pa.) C.B.S., 50 kw.; G.M.T. 11.30-03.00 daily.

relayed by W3XAU, 31.28 metres.G.M.T. 21.00-06.00 (except Thurs.and Fri.); and on 49.5 metres,G.M.T. 14.30-21.00 daily; 14.00-

305.9 980 KDKA East Pittsburgh (Pa.), N.B.C., Blue;relayed by W8XK, 13.92 metres,40 kw. G.M.T. 11.30-16.00 daily;and on 19.72 metres G.M.T. 11-

06.00 (Thurs. and Fri.).

764


WHEN TO LISTEN FOR AMERICAMetres Kilo-

cycles Call Statimi

309.1

344.6

970

870

WCFL

WBCNWENR

344.6 870 WLS348.6 860 WABC361.2 830 KOA*370.2 810 WCCO*374.8 800 WFAA374.8 800 WBAP379.5 790 KGO379.5 790 WGY

389.4394.5

399.8405.2416.4

422.3428.3

440.9454.3

461.3468.5

770760

750740720

710700

680660

650640

Stations markedin article.

291.1

312.3329.5

1,030

960910

WBBMWJZ

WJRWSB*

WGNWLIB IWOR*WLW*

KPO*WEAF

WSM*KFI

30-22.00 daily ; and on 25.27 metres.G.M.T. 20.00-02.00 daily and on48.86 metres, G.M.T.22.00-04.00.

Chicago (Ill.) relayed by W9XAA,16.57 metres, and on 25.34 metres;and on 49.34 metres, G.M.T.14.30-03.00 (Wed. and Sat.); 14.30-02.00 (Tues. and Thurs.) 19.00-03.00 (Sun.).

Chicago (Ill.), N.B.C. Blue; relayedthrough WJZ, Boundbrook. Re-layed by W9XF, 49.83 metres,G.M.T. 05.00-07.00 ; 13.00-17.30;20.30-23.00 (Sun.); 01.00-06.00(Mon.); 15.15-16.45; 20.30-24.00(daily); 13.30-18.00 (Sat.).

Chicago (Ill.), N.B.C. Red.New York, main C.B.S. station.Denver (Col.), N.B.C. Red.Minneapolis (Min.), N.B.C.Dallas (Tex.), N.B.C.Fort Worth (Tex.), N.B.C.San Francisco (Cal.).Schenectady (N.Y.), N.B.C., relayed

by W2XAD, 19.560 metres. Callannounced every 15 minutes.Daily G.M.T. 18.00-20.00 (exceptSat. and Sun.); 18.00-21.00 (Sat.and Sun.), and on W2XAF, 31.48metres. Beamed on S. America.G.M.T. 22.15-04.00 (except Sat.and Sun); 21.00-04.00 (Sat. andSun); aerial directed on S. America.Advice of relays of importantevents not mentioned in pro-grammes is made at 22.15 everyday. During the season W2XAFand W2XAD relay sporting broad-casts at about 18.00.

Chicago (Ill.), C.B.S.Boundbrook (N.J.), N.B.C.; relayed

by W3XAL, 16.878 metres. DailyG.M.T : 12.00-20.00 and on49.18 metres from 22.00 daily.

Detroit (Mich.), N.B.C.Atlanta (Gol.), N.B.C.Chicago (Ill.), C.B.S.Newark (N.J.).Cincinnati (Ohio), N.B.C. Blue,

relayed through WJZ, Boundbrook.Relayed by W8XAL, 49.5 metres,G.M.T. 19.30-21.30 daily.

San Francisco (Cal.), N.B.C.New York, N.B.C., main station

Red Net, relayed through WGY,Schenectady, and/or WJZ, Bound -brook.

Nashville (Tenn.).Los Angeles (Cal.), N.B.C.

* are those of which power is being increased as explained

CNRV

CNRRCJGC

CANADAVancouver (B.C.), occasionally re-

layed by VE9CS on 49.43 metres.Regina (Sas.).London (Ont.) relayed by VE9BY on

34.68 metres, G.M.T. 21.00-22.00(irreg.) and on 46.67 metres,G.M.T. 02.30-03.30 (Thurs.);01.00-01.55 (Sat.) 02.00-04.00(Sun.) and on 62.56 metres,G.M.T. 06.00 (Sun.).

Metres Kilo-cycles Call Station

357 840 CKGW1 Toronto (Ont.), linked up withCPRY J National Broadcasting Company of

America (N.B.C.) network andoccasionally relays WEAF, NewYork; WJZ, Boundbrook; andKDKA, East Pittsburgh. Relayedby VE9GW, Bowmanville, on 25.4metres. Daily G.M.T. 18.00-21.00(except Sun.), and on 49.22 metres.Daily G.M.T. 22.00-04.00; 17.30-01.00 (Sun.).

385 780 CKY Winnipeg (Man.) linked up withCNRWI N.B.C. Relayed by VE9JR on 25.6

metres, G.M.T. 17.45-19.30 (ex-cept Sat. and Sun.).

411 730 CKAC 11CNRMJ

St. Hyacinthe (Que.) linked upwith Columbia Broadcasting Sys-tem of America (C.B.S.).

411 730 CFCF Montreal (Que.) relayed by VE9DR,Drummondville (Que.), on 49.96metres G.M.T. 01.00-05.00.

435 690 CFRE ll Toronto (Ont.), linked up withCNRX J C.B.S.

435 690 C FCN Calgary (Alta.).517 580 CHMAI

CKUA f Edmonton (Alta.).555.5 540 CKWO Windsor (Ont.), linked up with

C.B.S.

SOUTH AMERICAPrincipal Stations at Buenos Aires

(Argentine Republic)215.8 1390 LS9 La Voz del Aire.231.5 1,295 LR7 Radio Patria.243.9 1,230 LS8 Radio Sarmienito.252.1 1,190 LS2 Radio Prieto260.9 1,150 LR8 Cind Paris.270.3 1,110 LS5 Estagion Rivadavia.291.3 1,030 LR9 Radio Fenix.303 990 LR4* Radio Splendid.316 949.2 LR3f Radio National.330- 910 LR2 Radio Prieto.345 870 La Nacion.361 830 LR5 Radio Excelsior.423 710 LS1 Broadcasting Municipal.448 669.4 LP4 Radio Portena.509 590 I,P6 Casa America.

Times of transmission : Generally from G.M.T. 14.00-18.00 and from 21.00-03.00 or 04.00.*Concerts are occasionally relayed to WABC, New York.t Sometimes relayed by LSY, Hurlingham, on 14.47 metres on Sun. (G.M.T.

21.00) and irregularly by LSX on 28.98 metres.lOccasionally relayed to Paris or Madrid.

RIO DE JANEIRO (BRAZIL)400 PRAA Radio Sociedade de Rio de Janeiro,

occasionally relayed by PRAB on31.58 metres (9.500 kcs). and PPQ,25.72 metres (11,660 kcs.)PERU

380 789 OAX Lima.MEXICO

214 1,400 XEP Nuevo Laredo, relayed by X26A on39.4 metres, G.M.T. 16.00-17.00(Thurs.)

265 1,130 XEH Monterey. .311 965 XED Reynosa.330 910 XEW Monterey, relayed on 49.8 metres,

G.M.T. 01.00-05.30.408 735 XER Villa Acuna Coahuilla.

(Studios are in U.S.A.).CUBA

411 730 f CMK Havana, relayed by CMCI on 49.5metres daily, G.M.T. 02.00-04.00.

765

II


Radio As FurnitureBy WALTER H. CLARK, L.R.I.B.A., F.I.B.D.

Since radio has now entered into the home almost universally, it becomes interestingto consider the place which it is filling, and is likely to fill, in the appointment of the

future home

sideboard, or artfully disguised as a picture or wallornament.

Owing to the greater mechanical perfection of thesets, the designer now has compact units with whichto deal. To disguise our radio as something else willnot help us to arrive at a satisfactory solution ofour problem; we must design to get the best expressionof the individuality of our new acquisition.

A PERIOD DESIGNFig. 1.-The radio cabinet designed to be inkeeping with period furniture. Particularattention is not paid to its special function

as radio

A FEELING OF MODERNITYFig. 2. (right).-The radio cabinet designedto be not out of harmony with the furnishingof the average home. It occupies a positionsimilar in importance to that of a useful

ornament such as a clock

WE have seen how the gramophone has developedfrom its early form into the radiogram console

cabinet which is to -day an important item in our furnishingscheme. Let us approach our subject, however, from theradio rather than from the gramophone side of the question.

In the radio we have, not merely a musical box, butsomething in the nature of a modern Oracle or, to use afurther simile, we find ourselves listening much in the samespirit as did the ancient Greeks and Romans when gatheredin the Agora to hear their poets, singers, and philosophers.

Still Closer ContactPrinting was the first broadcast of knowledge and enter-

tainment to the public; radio moves on a further step,making still closer contact between the author and his public.

Radio has happily passed out of the stage when the" box of tricks" was placed in some ignominious positionwith the loud -speaker perilously poised on mantelpiece or

A COMPLETE UNITFig. 3.-The radio cabinet designed onmodern lines in conjunction with a suitableand useful piece of furniture, the whole

forming one complete unit

766

Our first illustration (Fig. 1) makes use of periodstyle as a basis of design. This, however, does

not seem to give radio its best thence of selfexpression, though as a cabinet it may be pleasingenough.

Fig. 2 picks up a feeling of modernity, but our cabinetfinds itself somewhat ill at ease owing to the fact thatit has not achieved any certainty of position in thegeneral scheme of things; it is too large a piece to beconsidered merely as an ornament.


round it, incorporating such treasures as will be inharmony.

Perhaps in the not far -distant future the architect,when planning, will make special provision for theinstallation of radio in the home, and the manufacturerwill offer furniture particularly suitable in characterfor our purpose. That may seem a startling prophesy,but it is almost certain to come true.

It seems that a new type of room may well be evolved--where we may listen, read, write, or dance. Our

CENTRAL FEATURE OF THE FURNISHING SCHEMEFig. 4.-The radio treated as a central feature of a furnishing scheme-appearance, convenience.

and such matters as acoustics being considered

The third illustration introduces the idea of designinground the cabinet, and producing a useful piece offurniture of character, which holds our radio set muchas our bookcase holds our books or our dresser holdschina. This is a type of cabinet that would be useful inmany homes.

The next illustration (Fig. 4) takes us still a stepfurther. Considering our radio set as a centre, weproceed to form our decorating and furnishing scheme

illustration pictures a radio -library recess which maybe closed off from the rest of the apartment by curtains.Practical and (esthetic points may thus be achievedwithout additional expense if the scheme is originallycontemplated.

One well-known firm of manufacturers is alreadyproceeding with designs embracing these views, andthey find that their mass -production methods of cabinetmaking are in no danger of being interfered with.

767

Wireless Magazine. Januaty. 1933

IT was mentioned last month thatthe oscillator coil used in the

Seventy-seven Super had been speci-ally developed by Lewcos. Con-structors should be quite clear thatthe coils needed are a type TOS/GRoscillator and a type BPF/GRband-pass filter. It is of vitalimportance that coils with thesuffix " GR " are ordered.

In order that the tracking of theoscillator section of the three -gangcondenser shall keep in step withthe two sections used for band-passtuning a fixed padding condenserof .0025 microfarad is connected inseries with the oscillator tuningcondenser.

For Long Waves OnlyIn addition to this, there is another

condenser, of .0011 microfarad,between terminals 1 and 6 of theoscillator coil; this is automaticallythrown in and out of circuit by theoscillator switch. It is used onlyfor long -wave reception.

Unfortunately in the circuit dia-gram that appeared on page 622of the last issue, and in the quarter -scale reproduction of the blueprintthat appeared on page 621, thesecondensers were reversed. Thecorrect arrangement is to place the.0025-microfarad condenser underthe figures 59 and 58 on the blue-print, while the .0011-microfaradcondenser is placed under the

Ganging theSeventy- seven

SuperHere the "Wireless Magazine" TechnicalStaff gives some further hints regardingthat ganging of the Seventy-seven Super,the one -knob super -het radio gramophonefor A.C. mains of which full constructionaldetails were given in the December issue

figures 65 and 63. This is shownclearly in the portion of the blue-print reproduced on this page. Allblueprints supplied to readers havehad the necessary correction made.

It should be noted that the.0025-microfarad condenser is ob-tained by using a .002 in parallel

-r

BLUEPRINT

nro.NIDEMSER

IIMIs RATED

©a

el4C101APO [004 r 4lo o.,

VIVIC)141gm

g---- P' ip[*

TRACKING CONDENSERSA portion of the layout diagram showingthe correct positions of the .0011- and.0025-microfarad combination trackingcondensers. Full-size blueprints areavailable for Is. 6d. each, post free

with a .0005, while the .0011 isobtained by using a .001 in parallelwith a .0001-microfarad condenser.

A number of readers have writtento us because they seem to be in

some difficulty regarding the correctganging of the set. The procedureis really very simple and expertmanipulation is not required toadjust this set. Rather the reverseis the case, since the ganging of theSeventy-seven Super is considerablyeasier than with most " straight "sets having a stage of high -frequencyamplification.

In order to make the procedurequite clear, even to the beginner,we give here the four steps inganging. If the set is adjusted inthe following way it is a simplematter to obtain equal sensitivityover all parts of the two wave ranges :

Sequence for Ganging1.-Tune to the local station and

adjust the trimmer of the oscillatorsection of the three -gang condenser(that is the front section, nearest thedial) so that the transmission istuned in at approximately the readinggiven in the log that appeared onpage 627 of the December " Wire-less Magazine."

2.-With the volume control turnedas far down as possible (consistentwith still hearing the transmissionfaintly), adjust the other trimmersfor maximum volume.

3.-Next tune to a more distantstation, preferably about 300 metres(if you are in the London district asuitable station is Midland Regionalon 398.9 metres) and adjust the

768

oscillator trimmer so that the dialreading is exactly that given in thetest log on page 627 of the lastissue (for Midland Regional thereading is 53 degrees).

4.-After this has been done, thetwo other trimmers controlling theband-pass circuit are again adjustedfor maximum volume with thevolume control turned as far downas possible as explained in note 2.If still further accuracy of trimmingis desired, a more distant station


can be tuned in, preferably between250 and 300 metres, and the sameprocedure carried out.

It is not advisable to trim the setwhen receiving long -wave stations,because tuning is inherently flatter

A RADIOGRAM FOR THE CONNOISSEURThe Seventy-seven Super shown complete inits Osborn cabinet-an absolutely up-to-the-minute mains super -het receiver with amazing

selectivity

brackets specified in the list of partsunder "Sundries." These are usedfor mounting the two poten-tiometers placed on the underside ofthe baseboard. Two of the bracketsare placed near the front edge of

THE SET YOU WANT IF YOU HAVE A.C. MAINS!A view of the Seventy-seven Super showing the compact nature of thelayout. Although it is a large set, it is not difficult to construct with

the aid of a blueprint

on that waveband. Bytrimming on the mediumwaveband only, consider-ably greater accuracy isobtained and the set willautomatically be trimmedon the long waves.

There has also beensome confusion regardingthe use of the four

the set and act as supports for thetwo expansion spindles attached tothe potentiometers.

The other two brackets are usedfor holding the potentiometers them-selves in position. These pointsshould be clear from a glance at thelower photograph on page 623 ofthe December issue and also fromthe blueprint.

COMPONENTSCHOKE, HIGH -FREQUENCY

1---Lewcos, type MC, Is. 6d.CHOKES, LOW -FREQUENCY

2-Ferranti, type 81, £2 2s. (or Varley, R.I.).COILS

1-Lewcos bandfilter, type BPF/GR, 12s.1-Lewcos oscillator, type TOS/GR, 8s. 6d.3-Lewcos super -het intermediates with

pigtails, type IFTP, lls. ed. (orWearite).

CONDENSERS, FIXED1-T.C.C..00005-microfarad, type 34, ls. 6d.3-T.C.C. .0001-microfarad, type 34, 4s. 6d.

(or Dubilier, Telsen).2-T.C.C. .0005-microfarad, type 34, 3s.

(or Dubilier, Telsen).I-T.C.C. .001-microfarad, type 34, ls. 10d.

(or Dubilier, Telsen).1-T.c.c. .002-microfarad, type 34, Is. 10d.

(or Dubilier, Telsen).2-T.C.C. .01-microfarad, type 34, 3s. (or

Dubilier)9-T.C.C. 1-microfarad, type 50, £1 5s. 6d.

(or Dubilier, Telsen).2-T.C.C. 2-microfarad, type 50, 7s. 8d.

(or Dubilier, Telsen).2-T.C.C. 2-microfarad, dry electrolytic

200 -volt working, type 561, 6s. (orDubilier).

1-T.C.C. 5-microfarad, 400 -volt D.C. work-ing, h,. (3d. (or Dubilier, Peak).

1-T.C.C. 8-tnicrofarad electrolytic, 9s. (orDubilier).

CONDENSER, VARIABLE1-British Radiophone .0005-microfarad

NEEDED FOR THE SEVENTY-SEVEN SUPERthree -gang with cover and disc drive,type 344C, £1 13s.

HOLDERS, VALVE11 -Li ssen five -pin, type 593, 13s. 9d. (or

W.B., Lotus).RESISTANCES, FIXED

1-Packet of 18 Erie fixed resistors, 1 -watttype, values 400, 500, 600, 750, 5,000,7,500, 10,000, 20,000 (3), 25,000, 30,000(2), 50,000 (3) ohms, .5 and 1 megohm,18s. (or Claude Lyons, Dubilier).

RESISTANCES, VARIABLE1-Multitone graded, 3s. 6d.1-Lewcos 10,000 -ohm potentiometer, 3s.

(or Wearite, Colvern).SUNDRIES

Tinned -copper wire for connecting (Lewcos).Lengths of oiled -cotton sleeving (Lewco3.Length of shielded cable, 9d. (Goltone).Length of rubber -covered flex.1-Baseboard-chassis assembly with 18% -in.

by 14 -in. sheet of aluminium foil(Peto-Scott).

4-Peto-Scott brackets to specification, ls.2-Utility 10 -in. rods and insulated couplers,

4s.1-Belling-Lee twin fuseholder and fuses,

2s. 6d.SWITCHES

1-Tunewell radio -gram, ls. 9d.1-Becker double -pole on -off, type 462,

2s. 3d.TERMINALS

4-Belling-Lee, type B, marked : Aerial,Earth, Pick-up (2), 2s.

2-Belling-Lee terminal blocks, ls. 4d.TRANSFORMER, LOW -FREQUENCY

1-Multitone, 17s. 6d.TRANSFORMER, MAINS

1-Parmeko, type WMD, £2.

ACCESSORIESCABINET

1-Osborn radio -gramophone, type 234, inmahogany, £6 5s.

LOUD -SPEAKER1-Baker permanent -magnet, standard type,

with matched output transformer,£3 10s.

GRAMOPHONE MOTOR1-Garrard No. 201 induction with auto-

matic stop, £4 17s. 6d.PICK-UP

1-B.T.H. minor with volume control, Ll 6s.VALVESOscillator

1-Mazda AC/HL metallised, Us. 6d.First Detector

1-Mazda AC/SG metallised, 19s.Screen -grid Intermediates

2-Cossor MVSG metallised, £1. 18s.Diode Detector

1-Cossor 41MHL, metallised, 13s. 6d.First Low -frequency Stage

1-Cossor 41MHL, metallised, 18.1.14.Pentode Output

1-Cossor MP/Pen, £1.Mains Rectifier

1-Cossor 506BU, 12s. 6d.The prices mentioned are those for the parts used in the original set; the prices of alternatives

as indicated in the brackets may be either higher or lower.

769


Radio Music imetiteNewYearIT is human nature to grumble.

No matter how good the pro-grammes are, some fault or anotheris certain to be found. Many saythat the programmes now are terrible,and probably think they are perfectlyjustified. But has it occurred to youthat if you were to have the pro-grammes of a few years back youwould grumble still more ?

A Little InvestigationThe average listener is usually

fond of one type of entertainmentand thoroughly detests another. Ihave been doing a little investigation

Every dance -music enthusiast has heardof Paul Whiteman, whose dance orchestrais one of the biggest in America. Hisband was relayed to British listeners

recently

work, the results of which havebeen surprising. Wandering roundthe roads at night, eavesdroppingoutside windows and listening toloud -speakers has given me someuseful information concerning thetastes of the majority.

I have made these tours when oneprogramme has been a Queen's Hallsymphony concert and the other avaudeville programme or some otherkind of light entertainment. Remem-ber that the big orchestral concertsinvolve the greatest expense-theB.B.C. Symphony Orchestra costsover £100,000 a year to maintain.

By T. F. HENNThe number of sets tuned to the

symphony concert was small com-pared with the number tuned to thelight programme. Relay exchangeswhich provide alternative pro-grammes in some towns are, Ibelieve, finding the same state ofaffairs.

The B.B.C. is a little one-sidedin its general programme arrange-ments. Mid -day concerts are almostall of the light -music type, while theevening concerts do definitely favourthe highbrows.

The alternative programme systemdoes not relieve the situation as muchas it could. However, the listenerwith highbrow tastes must be con-sidered. My New Year request tothe B.B.C. is simply : " Arrange yourprogrammes, still maintaining theirhigh standard, so that light items

One of the earliest of broadcasters,Hilda Bor is a splendid classical pianist.She has been heard from London Regionalplaying music by Liszt and Chopin

play a more prominent part in themain evening entertainment."

Percy Pitt, one of the best lovedmen in the musical world, died duringNovember. He was musical directorof the B.B.C. before Adrian Boult.No one ever called Percy Pitt" Mister." He was known to the

great men of the musical world asPercy," and to the musical world

at large as " The Maestro."His greatest work as B.B.C.

Musical Director was the arrange-ment and presentation of theNational concerts, first at the CentralHall, Westminster, and later at theAlbert Hall. Afterwards these con-certs grew into the present B.B.C.Symphony Concerts at Queen's Halland the concerts at the People'sPalace, Mile End.

Opera and Operatic ConcertsWhilst on the B.B.C. staff he made

a feature of the presentation of studiooperas and operatic concerts. Manylisteners will remember the series ofoperas arranged by Percy Pitt someyears ago which were, I believe,relayed from the Parlophone record-ing studios.

At the time of his death he wasbusy preparing a new series ofpopular operatic concerts which isto be given in the New Year.

Percy Pitt was a composer as wellas conductor. He was responsiblefor' the incidental music to SirHerbert Tree's productions, Richdrd ,

the Second and Flodden Field, at HisMajesty's Theatre. He also wrote

The orchestra relayed from the PavilionCinema, Shepherds Bush, is conducted byHarry Fryer. His choice of music isreputed to fit both pictures and micro.

phone

770

a symphony for the 1906 MusicFestival and a Ballade for Violin andOrchestra which he dedicated toYsaye, the famous Belgian violinvirtuoso.

The B.B.C. and listeners generallywill miss his great services to broad-cast music.

.The first season of Christmas

Promenade Concerts opens at theQueen's Hall on New Year's Eve,and goes on nightly until January 14.Although I am certain a greatmajority of listeners hate the verysound of the word " Prom," theseconcerts are going to appeal to many.Providing the B.B.C. gives some goodvariety and vaudeville concerts asalternatives, everyone will, or atleast should, be well pleased.

Popular Classical MusicIn brief, this new season is to be

a feast of the best and most popularitems in the huge repertoire ofclassical music. Sir Henry Wood,who already has thirty-eight seasonsof summer " Proms " to his credit,is to conduct a section of the B.B.C.Orchestra consisting of ninetyplayers, with Charles Woodhouse asprincipal violin.

The opening concert will bepopular in the best sense of the word.Berlioz's overture, Le CarnavalRomain, opens the concert, whichincludes Moussorgsky's famous song,The Song of the Flea, to be renderedby Harold Williams ; Liszt's Wan-derer Fantasia for piano andorchestra, with Soloman as soloist;

A classical singer of importance, ClairaCroiza has broadcast recently severalrecitals of French and Continental songs


A well-known tenor who has given severalrecitals lately-Herbert Cave. His last

broadcast was from London

Scheherazade, Rimsky Korsakov'smusical impression of an ArabianNights story; and the beautifulInvitation to the Waltz by Weber.The evening will conclude with thesinging and playing of Auld LangSyne. This will be a fine concert.

Composer nights will follow an

Gretyl Vernon, known as "The VienneseNightingale," broadcast during the B.B.C.birthday week. She is widely known on

the Continent

arrangement similar to that of thesummer " Proms." Both Mondaysand Fridays will be devoted to theworks of Wagner and Beethovenrespectively. In the second half atthe first Wagner night, Paul Hinde-muth's Philharmonic Concerto willreceive its first performance in thiscountry.

A famous operatic singer who will beheard during the new Christmas" Proms" at the Queen's Hall-Evelyn

Scotney

A Russian concert has beenarranged for January 3 in whichTchaikowsky will be represented byhis Symphony No. 5 in E minor andthe Piano Concerto No. 1 in B flatminor; the soloist will be Poushinoff.

Handel is one of those unfortunatecomposers whose works have beenneglected to some extent lately.The B.B.C. has arranged a specialconcert of his works for January 7.

Special Handel ConcertThe programme will include

choruses from the Messiah, the over-tures to the Messiah and Samson, andthe Organ Concerto No. 9 in B flat.The solo organist will be ThalbenBall. The Sheffield Musical Unionwith its veteran conductor, Sir HenryCoward, renowned for its singing ofHandel, will perform at this concert.

The short season is to have anumber of " star " works, chosenapparently for their novelty ratherthan their musical value. Ravel'sBolero, an exciting and noisy com-position you should certainly makea point of hearing, is down for per-formance on January 12. In thesame programme five Catalan folksongs will be given their first per-formance in this country.

A First PerformanceDame Ethel Smyth is to conduct

the first London performance of herFite Galante (A Dance Dream) at amiscellaneous concert on January 10.

I have endeavoured to cataloguebriefly the most interesting items you

771


RADIO MUSIC FOR THE NEW YEAR-Cont.can hear. The orchestra is reallysplendid, and with such first-rateartists as Albert Sammons, Lamond,Walter Widdop, Arthur de Greef,in addition to others I have mentioned,you will gather that the concerts aregoing to provide a fortnight of goodmusic properly executed.

Enthusiastic AudienceWhatever your musical tastes, you

should make a point of listening tothe last " Prom " on January 14.The audience will be very enthu-siastic and will shout their applause

The death of Percy Pitt, late musicaldirector of the B.B.C., has robbed broad-casting of one of its greatest workers.He was a great believer in studio operatic

performances

after every item. But, remember,they are shouting not so much forwhat they have heard but as a meansof showing their appreciation of oneof England's greatest conductors,Sir Henry Wood, a man who hasdone more to popularise good musicthan anyone.

An Old FavouriteThe last concert will finish with

an item that has been included inevery last " Prom " for many years,Liszt's Second Hungarian Rhapsody.

Quite recently I explained thevarious sub -divisions of the bigB.B.C. Orchestra. I hope you havefully digested the meaning of " TheB.B.C. Orchestra, Section C." Nowthis A -B -C method has spreadto the B.B.C. choruses.

Again I will try to explain whatit all means. Firstly, the B.B.C.Chorus is not affected by the newclassification system. This seems acontradiction. When you hear anannouncement to the effect that theB.B.C. Chorus will sing it meansthat you are about to hear a choir of260 amateur singers drawn from theranks of London and district choraland operatic societies.

Any amateur singer, providing- heor she can attend the weekly rehearsalin London on Friday evenings,- iseligible for membership. If youwould like to try your hand at chorussing;ng write to the Hon. Secretaryof the B.B.C. Chorus at BroadcastingHouse for an audition.

It is the Wireless Chorus, a pro-fessional organisation of forty voices,that has been divided into classifiedsections. Section A is the fullchorus consisting of thirteensopranos, eight contraltos, seventenors and twelve bass singers.Sections B and C consist of twenty-six and fifteen members respectively,in roughly the same proportions oftypes of voice.

The Revue Chorus consists ofthree sopranos and two contraltos,tenors and basses-nine singers in all.The members are 'drawn from theWireless Chorus. In addition theMale Voice and Ladies Choir, offifteen and twelve voices respectively,are obtained from the same source.

.By the time these notes are

published you will know all aboutthe Christmas programmes. I feelI ought to comment on one pro-gramme to be broadcast on BoxingDay. There is a chamber -musicconcert in the second half of the mainevening programme. I wonder whowas responsible for this judgment oflisteners' tastes ?

Henry Hall and his " hotted -up "band are taking a good share in theChristmas week programmes. Sincethe change in personnel, which Imentioned last month, the perform-ances of the band are certainly muchbetter. In fact their " hot " numbersare really good. But I still thinkthe band needs either anotherdouble -bass or a sousaphone to givebetter balance.

Les Allen, the new vocalist, whowas formerly a saxophonist inHoward Jacob's band, is an improve-ment. His fresh Canadian accent

and remarkably good diction havedone wonders in a short time. ValRosing, the late vocalist, is forminga stage band.

Among the best events in theJanuary programmes is a concertby the Royal Air Force Band onJanuary 7-always a popular item.

Gunther Ramin, the celebratedorganist of St. Thomas' Church,Leipzig, is giving a recital from AllSaints, Margaret Street, on January 3.

A Listening HintTalking of Leipzig reminds me to

give a hint on listening. If you gettired of the B.B.C. programmes tunein Leipzig, a big German station justbelow Midland Regional. Itsstrength and clarity after dark, andthe fact that it can be heard withalmost negligible interference, makesit an ideal alternative.

The programmes from this stationare well varied, but the chief itemsare concerts by the Leipzig Sym-phony Orchestra two or three timesa week and very tuneful light musicin the late evening. I think youwill thoroughly enjoy the fineprogrammes.

No doubt there are a few listenerswho miss the Bach cantata relays onSunday afternoons. These enthu-siasts will be interested to know thatthe principal German stations relaya Bach cantata from St. Thomas'Church, Leipzig-Bach's own church -every Sunday at 10.30 a.m.

Florence Castelle, pupil of Marches', hassung in all the principal concert halls ofLondon and the provinces. She sings in

German, French, and Italian

772

GRAMO-RADIO SECTION Wireless Magazine. January -1933

"WirelessMagazineA Special Section for Those Interested in Radio -gramophone Technique

Here is another article by one of thegreatest authorities on gramo-radio mat-ters. By following the advice given in theprevious articles of the series you will beassured of obtaining the very best resultswhen you reproduce gramophone recordselectrically. Many significant features havealready been dealt with, and this monthMr. Wilson considers some of the dyna-

mical problems affecting reproduction

SO far in our examination of thevarious factors which affect the

contact between needle and recordwe have confined attention almostentirely to statical, I might even saygeometrical, considerations.

We have not inquired into theeffects that are created by themotion of the record or the trans-mission of vibrations from thegroove to the needle.

Significant FeaturesYet we have found a number of

very significant features, and nodoubt at this stage it would be wellto summarise the important pointsthat have appeared in the course ofthe examination.

Before I do so, however, I wantto give an important warning. Ibelieve that some of the illustrations

This is the fourth article of aseries. Previous articles ap-peared in the August, Septem-ber, and November issues of"Wireless Magazine." Readersare recommended to read thesearticles if they have not already

done soo

ellecordUlf P. 1)114v-p,

M.A

I have given furnishconclusive evidencethat these staticalconsiderations, as itis convenient to callthem, are a sinequa non of goodreproduction a n dminimum recordwear.

They are so vital, indeed, thatmany an investigator has beencontent to rest on his oars at thispoint in the delusion that there islittle more to be discovered. Thatit is a delusion, however, it is com-paratively easy to show.

One can take a pick-up, or agramophone soundbox, mount themin the ideal fashion as indicated bythese statical considerations, takeparticular care over needles, etc.,and yet not only obtain bad repro-duction but encounter the mostviolent record wear as well, just asviolent, it seems, as one wouldget if all the statical rules weredisobeyed.

The truth is that there aredynamical considerations connectedwith the passing on of mechanicalvibrations which are, or may be,

much more important than any ofthe matters so far discussed.

I have left them out of considera-tion up to now, partly because theyare not quite so easy to grasp andpartly because they really concernthe adjustment and the design of thepick-up, which is a very largequestion.

Put shortly, the statical consideni-tions we have been concerned withare as follows :-

(1). The vertical plane in whichthe needle lies should be as nearly aspossible tangential to the groove atall points of the track of the needleacross the record. This considera-tion, which was dealt with fully byP. K. Turner some months ago inthese pages, is referred to as" needle -track alignment."

Wrong Spelling !The word should be spelt " aline-

ment," but the other form has beenhallowed by use.

(2). The needle should rest asnearly vertical in the groove as canbe managed without the creation of" needle -drag." This needle -dragconsists of vibrations in a verticalplane which are quite distinct from

773

Wireless Magazine. January:1933 1 GRAMO-RADIO SECTION

THE NEEDLE AND THE RECORD Cont.

CENTR I FUGALFORCE

Fig. 1.-A free bead placed on the turntable, so that it canrotate with it, will be acted upon by a centrifugal force tend-

ing to throw it off

the transverse vibrations which wewant to pass on to the pick-up.

There is, unfortunately, atpresent no definite rule by whichone can determine what is the bestneedle angle. It depends on theshape of the needle and the shape ofgroove cross-section as well as onthe design of the pick-up.

With modern records, pick-upsand needles, a needle angle of 70 to75 degrees is not impossible. Withthe older records 60 degrees or evenless was advisable.

Better High Notes(3). The steeper the needle can

be made without risk of needle -drag, the less up-and-down motionthere is of the needle point withinthe groove. This means lessattenuation of high notes, accom-panied by less surface noise of araucous kind and, of course, smallerrecord wear.

(4). Probably the best criterionof the most satisfactory com-promise between the rival con-siderations dealt with at (2) and (3)above is the amount of chatterbetween needle and groove.

Chatter and Surface NoiseTangential vibrations due to

needle -drag produce chatter; so alsodoes the up-and-down motion ofthe needle point in the groove, andboth increase surface noise withoutreal increase of high notes.

The best needle angle thereforeis the one where there is the least

needle chatter ondifficultpassages.Dance recordsare the best fortesting this.

This needlechatter, how -ever, should notbe confused withthat due to faultygripping of theneedle in theneedle socket.

(5). To de -t er mine theoptimum pres-sure betweenneedle and re-cord is again amatter of com-promise.

Needle angle and up-and-downmotion are factors to be borne inmind, but as there are other im-portant factors not yet discussed,no final conclusion on this pointhas yet been reached.

(6). In any event, it is folly to usean ordinary steel needle more thanonce. When a shoulder has formedon the needle, record massacreensues. The ear gives the firstindication of a shoulder by a certainmuffling of the tone.

It is well to make oneself familiarwith this sign by careful observa-tion and practice.

(7). The design of a permanentgramophone needle which willgive minimum wear by virtue ofthe fact that the business endwill fit the groove, will wearvery slowly and will be symmetricalabout a vertical line, whilst needle -drag will beavoided by theuse of a slopingshank, does notappear to be be-yond the boundsof possibilitynow that thegroove cross-section has beenstandardised atapproximately asemi -circularshape.

But, as thesergeant - majorsaid, we must" wait for it !"

Now let us come on to thedynamical considerations, as I havecalled them. So far as I knowthere is only one untoward effectcaused by the rotation of the recorditself under the needle point; apart,that is, from the transmission of themusical vibrations from the grooveto the record.

At one time it used to be thought,and some people may have thenotion still for aught I know, thatthe record exerted what they calleda centrifugal force on the needle,always tending to press it outwards.This is a complete delusion.

They argued from the fact thatif one puts a small article, say asmall bead, on the rotating turntableit is immediately thrown off. So itis, and there is no doubt that in thiscase centrifugal force is broughtinto play.

Bead on a ThreadBut now thread a string through

the bead and place it on the turn-table, holding the string taut in thedirection, approximately, of thetangent to the groove at the pointof contact of the bead. In this casethe bead is certainly not thrown off.

Indeed, if the direction of thestring is ever so slightly towards thecentre of the turntable, the beadwill actually be drawn inwards.

An examination of the diagrams(Figs. 1, 2 and 3) will probably makethis point clear.

The difference between the twocases is that in the former the beadbegins to move round with theturntable, whereas in the latter thebead is prevented from doing so.

TRACK ALIGNMENT IS MOST IMPORTANTEvery pick-up must be correctly tracked for the best resultsand most makers supply a template for this purpose. Hereis a typical pick-up with volume control-the Blue Spot

774

GRAMO-RADIO SECTION Wireless Magazine. Jam/alai:1933

GETTING THE BEST RESULTSCentrifugal force is only created byangular motion, and if the bead doesnot move round with the turntablethere is no centrifugal force.

The position of the gramophoneneedle on the record is much thesame as that of the tied bead ; thereis no centrifugal force, but there isan inward drag. The reason forthis is easily seen from Fig. 3.

The friction between needle andrecord exerts a force on the needlepoint in a direction at right anglesto the record radius at the needlepoint, that is, tangential to thegroove.

Forces AnalysedThis force is resisted by the

refusal of the carrying arm to heelongated, and the effect of this isa force acting in the direction fromthe needle paint to the place wherethe carrying arm is fixed to thebaseboard, that is, to the back pivotof the carrying arm.

But these two forces are not inline, and so cannot completelycancel out. A little considerationwill show that the net result is asmall force tending to drag theneedle -point towards the centre ofthe turntable.

There can be no doubt that thisdrag is undesirable since it meansthat there will always be a sidepressure between the needle andthe groove, and this cannot butimply record wear and impairedreproduction.

It is significant in this connectionthat the point of a fibre or othernon-metallic needle will readilybreak down, even on comparativelyeasy passages, if there is any sidepressure.

The amount of the inward dragdepends principally upon the settingof the carrying -arm in relation tothe turntable.

Drag IncreasedIt is an easy matter to show that

it is increased when the needle-point is made to overlap the spindle,for then the tangent to the grooveturns further away from the linejoining the needle point to thecarrying -arm back pivot.

This is very unfortunate becausein order to get the best needle -trackalignment we must make the needle-

point overlap the spindle, in somecases by quite considerableamounts.

Is there no way out of thisdilemma ? We cannot possibly getrid of the inward drag, no matterhow we set up our carrying -arm.Can we then neutralise it in someway or other ? Fortunately we canand, even more fortunately, theneutralisation is particularly effec-tive at the setting for good align-ment.

First of all we should noticethat something in the right direc-tion could be accomplished bymeans of a little friction at the backpivot of the carrying -arm.

This would tend to oppose the

packed up on the left-hand side insuch a manner that the tone -arm,when the needle was not in contactwith the record, should have atendency to swing away from thecentre.

Simplest MethodThis was the simplest method,

but it was often not aestheticallysatisfactory since it might meanlifting up the cabinet legs on theleft-hand side by as much as in.No one likes to see a piece offurniture on the tilt. There wereother methods, but they were alittle troublesome.

With pick-up carrying -arms,however, a completely satisfactory

A NEAT MOTOR -BOARD LAYOUTIt will be found a great convenience to provide cups for used and unused needles. The

model shown here is the Bulgin Duplex

motion across the record, and onemight expect with a little luck toeffect complete neutralisation bythis means.

But this method is unsatisfactorybecause, however cunning we maybe in our friction device, it willalmost inevitably operate in aseries of little jerks.

Moreover, a freely movingcarrying -arm, though one with con-siderable inertia, is desirable forreasons which we shall see lateron. We must reject this idea, then,and look about for something else.

That something else is simplygravity, and no one can complainthat gravity does not act sufficientlysmoothly.

In the old days, with gramo-phones, one used to advise that thegramophone cabinet should be

method can be devised which is alsovery simple. Incidentally, it hasother advantages, which 1 willexplain when I come to discuss thetransmission of vibrations.

Use of RubberThis method is simply to put a

piece of rather soft indiarubberbetween the base of the carrying -arm and the baseboard of thecabinet. The rubber may be any-thing up to in. thick, though itshould be noticed that the insertionof rubber in this way will increasethe needle -angle. So don't be toogenerous!

Holes should be made throughthe rubber as a clearance for thescrews holding down the carrying -arm to the baseboard, and also, ifdesired, to take the pick-up leads.

775

Wireless Magazine. January. 1933 GRAMO-RADIO SECTION

THE NEEDLE AND THE RECORD Cont.

Fig. 2.-A bead held by a string on a rotating turntable inposition A will remain steady ; held in position B it will bedrawn inwards towards the spindle S. In either case, there is

no centrifugal force

The correction of the drag is thendone by slackening the screws onthe left and tightening those onthe right, so that the back pivot ofthe carrying -arm, instead of beingquite vertical, is inclined slightlyto the right.

The amount of tilt required willbe found to be so slight that onecannot tell by eye alone that it isthere.

Gauging the TiltHow then do we find out how

much tilt is required ? The methodis quite simple. I get a 12 -in.record which has a good marginof unrecorded surface both on theoutside and also inside the run -outgroove at the centre of the disc.The turntable is set running and aneedle is put into the needle socketin the ordinary way.

I then set the needle on the outerunrecorded space and adjust thescrews until the pick-up remainssteady without any tendency forinward or outward drag. I thenput the needle on to the innerunrecorded surface very gingerlyand watch to see if there is anydrag there.

Digging Itself In !It is necessary to be particularly

careful here because if there isinward drag the needle may bedrawn across the record, past theturntable spindle, and so over tothe other side, where it will immed-iately begin to dig itself in.-andgoodbye record 1

Usually, how-ever, I find thereis little or nodrag if the carry-ing -arm ismounted in thecorrect positionto give the mini -

'B mum trackingerror. There is agood mechanicalseason for this,but that I will

A pass over. Factalone matters.

If there is anydrag left I re-adjust the screwsuntil it disap-pears and thencheck up again

on the outside of the record. Onesoon gets into the knack of the thing,and it is really quite easy to find anadjustment where there is no drageither at the inside or outside.

And if you happen to have an oldsingle -sided record and try the teston the blank side of that, you willfind that when you have effectedthe neutralisation at both insideand outside you have also done it

Fig. 3. --Force diagram showing inward drag on needle due tothe friction (F) and reaction (R) not being always in line

for all the intermediate points.In order to facilitate this process

of " dynamic levelling," as it hasbeen called, I found it desirable longago to have three fixing screws, nomore, for the base of the carrying -arm arranged at the corners of anequilateral triangle, with No. 1 onthe left and Nos. 2 and 3 on the right.

One can then screw up No. 1,but not too tightly, and in thelevelling process operate on Nos.2 and 3 only.

I have laid stress on this matterof dynamic levelling because it isa matter of far more importancethan even gramofans realise. Itmakes a considerable differencewith an acoustic gramophone; andwith a pick-up the existence of side -pressure between needle and groovehas additional disadvantages.

I will explain these more fullylater when I come to discuss pick-upcharacteristics.

Effect of Side PressureBriefly, however, the effect of a

steady side pressure is preciselyanalogous to over -biasing a valve.A pick-up has a magneto -mechanicalcharacteristic similar in shape to theanode-current/grid-volts character-istic of a valve.

The best " operating point " isobtained when the armature ismagnetically and mechanically inequilibrium when in its centralposition; side pressure displaces theoperating point just as increasingor decreasing the bias does in

the case of avalve.

And now, onlooking throughwhat I havewritten above, Inotice that I saidthat I know of

PIVOT only one un-toward effectcaused by therotation of therecord. I waswrong. There isanother, thoughit is usuallyclassified as arecord defect. Irefer to the" swinger," as itis called.

This effect occurs when therecord is placed on the turntable insuch a way that the centre of thegroove circles does not coincidewith the axis of rotation of theturntable.

An error of even so little as1/100 in. here can have some verydistressing results.

776

GRAMO-RADIO SECTION Wireless Magazine, January ,1933

I %yell 14E14er-oldsSACRED MUSIC

(a) Christians Awake, (b) Harkthe Herald Angels Sing,Royal Choral Society, 2s.6d.

H.M.V. B4305Very well done, particularly

the Mendelssohn-I mean" Harkthe Herald." If you want thesecarols really well sung, youcannot do better than buy thisedition of them.

(a) Holy City, (b) Star ofBethlehem, (Adams) Rich-ard Crooks, ten, 6s.,

H.M.V. D.B. 1798Marvellously sung and pro-

duced, but who on earth wants

RICHARD CROOKS

either song? A bit antedilu-vian, but not yet a classic.Still, if you can stand them, Ipromise you some fine singing.

Moody and Sankey Favourites(d.s.) Gospel Singers withOrg tn, 4s. COL DX416

A medley of Messrs. Moodyand Sankey of the" Count YourBlessings" type. Quite welldone, and I heartily recommendit to all who will appreciate it.I am not among the number,but you may be !

(a) 0 For a Thousand Tonguesto Sing, (b) Soldiers ofChrist, Methodist UnionConference, Royal AlbertHall, Sept., 1932, 25. 6d.

COL DB988The recording is a bit heavy

in this. The tunes are not thegeneral hymn -book tunes-oneis Handel-and the singing isgood. I am not too happyabout the recording. It" blasts"a bit in places.

(a) Silent Night, Holy Night,

HEDDLE NASH

Here are reviews of the latest releasesby WHITAKER-WILSON, the" W.M." Music Critic. Outstandingrecords are indicated by an asterisk (*)

against the title

(b) Sleep, My Saviour, Sleep,Isobel Baillic, Muriel Brun -skill, Heddle Nash andNorman Allin, with StringOrch., as. 6d. COL DB976

An effective quartet. Themusic is quite pleasantly arrangedto suit their voices. I. thoughtI was in for a "dud," but waspleasantly surprised. There issome good bass on both sides.In that sense, the record mightbe useful for test purposes.

Te Deum Laudamus, (d.s.)sung at the MethodistUnion Conference, RoyalAlbert Hall, Sept., 1932, 4s.

COL DX419Ten thousand voices with

organ on one record ! Fairlygood. The setting is a simpleone and has some uplift aboutit. I wish they would not talkabout an infynyte Majesty.Why not pronounce the wordcorrectly-tnfinnit? Otherwisethe rendition is good.

CLASSICALORCHESTRAL MUSIC*Children's Overture, (d.s.),

Sir Henry J. Wood conduct-ing the London Philhar-monic Orch., 2S. 6d.

COL DB95I -952This is a very charming work.

SIR HENRY WOODI have always liked RogerQuilter's music. I recommendthis as a delightful light orches-tral record. The kiddies willrecognise some of their favouritetunes pleasantly varied.

*Concerto No. 1 in B FlatMinor, (d.s.), (Tchaikovsky)Arthur Rubenstein and theLondon Symphony Orch.,6s. H.M.V. DB1731-4

This is one of the favouritepiano concertos with modernaudiences. Rubinstein's readingis not in advance of others I haveheard, but it can be taken asbeing authoritative. I enjoyedthe exquisite slow movementparticularly. Four discs in all.

*Pomp and CircumstanceMarch, No. 1 in D Major,

No. 2 in A Minor (Elgar),B.B.C. Symphony Orch.,6s. H.M.V. DB1801

All good and noble " Prom-oters" must invest in this. Itis one of the most popular or-chestral works of later years.Sir Edward Elgar himself is theconductor. The surface of one of

Medley of Popular Tunes, (d.s.)John Firman and His SalonOrch.,is. 6d. ZONO 6223

A medley of " 0, Listen to theBand" style. I am always indif-ferent to medleys, but I canhonestly say that this one isquite acceptable owing to itsbeing produced so well. JohnFirman's salon orchestra is agood orchestra, which is morethan some salon orchestras are!

" Once Upon a Time "-Selection (d.s.) New MayfairOrch., 2S. 6d. H.M.V.B4323There are some good old

ABBREVIATIONS USED IN THESE PAGESbar baritone H.M.V. HIS MASTER'S

VOICEBRUNS.. BRUNSWICK orch. .. orchestraCOL COLUMBIA PARLO PARLOPHONECOM. comedian sop. soprano

con. contralto ten. tenor

d.s. . double -sided w. waltz

f. fox-trot ZONO ZONOPHONE

(a) and (b) indicate the ti es of each side of a record.

the sides-I forget which-appealed to me as being extra-ordinarily fine.

OPERATIC SONGS*(a) Vesti La Guibba (Leon-

cavallo), (b) M'appari (Flotow), Enrico Caruso, ten.,6s. H.M.V. DB1802

ENRICO CARUSOThis is one of the most out-

standing records of the year.Buy it! This is the first electricalrecording of Caruso's voice. It istaken from an acoustical record-ing and a new orchestral accom-paniment has been added by anew H.M.V. process.

LIGHT ORCHESTRALMUSIC

(a) Marcheta, (b) You LovingMe, Albert Sandler and hisOrch., as. 6d. COL CB871

An Albert Sandler recordgenerally recommends itself.Here you will find him just as heis when you hear him on a Sun-day evening by wireless. Soif that appeals to you, you cantake my word for it that therecord is worth having.

favourites here: " DorothyDear," "Old Flo." " As YourHair Grows Whiter," and heapsmore I have not heard for longenough. A very good selection !

*Overture "1812 " Op. 49(Tchaikovsky) (d.s.), Leo-pold Stokowski and thePhiladelphia Orch., 6s.

H.M.V. DB1664This is always popular. Here

It gets a perfect rendering on twodiscs. Every record has theoriginal date on it -1812 I

" Snacks in Bars " (d.s.), NewMayfair Orch., 4s.

H.M.V. C2486Rather a "snappy" title.

You will recognise much of it.It is an orchestral medley inwhich Wagner gets mixed upwith everyone else. Very good,if you like this sort of thing.

What's Yours) --A convivialMedley (d.s.), DebroySomers Band, 4s.

COL DX385A medley :" Tavern in Town,"

" Simon Cellarer," "King Cole,"" Here's a Health," " BrownJug," "Dead Men" (downamong same), " Barley Mow,"and a host of other new works.Much band, some chorus. Splen-didly produced; excellently re-corded.

SONGS AND BALLADSHarry Lauder Medley (d.s.)

Sir Harry Lauder, 6s.H.M.V. DB4015

Sir Harry Lauder, in excellentvoice, sings you six songs oneach side of this record-twelvein all. So you must not miss it.He is just the same as ever !

777

Wireless Magazine, x :1933 GRAMO-RADIO SECTION

CHOOSINGIndian Love Lydon, (d.s.)

Harold Williams with Orch.,ss. bd. COL DB980

These delightful new songs-you cannot possibly have heardthem-are sung charmingly byHarold Williams, one of ourbest baritones. The general pro-duction is beyond reproach.I hope Columbia will introducesome more unknown songs. Itis nice to have a change fromhackneyed numbers.

*(b)a) MaMah

CuLinrly-HdyeadedLou,

BPaulaby,

(

Robeson, as. 6d.H.M.V. B4809

A very good specimen ofRobeson's voice. I like him somuch better in coon songs thanin those wretched spirituals.The orchestra plays beautifullyIn this record. 1 recommend itfervently, particularly as I haveso often condemned his recordsin the past. Buy this on myrecommendation, it is splendid.

Negro Spiritual Medley, (d.s.),Layton and Johnstone, 4s.

COL DX418They sing some rather hack-

neyed items, but sing them intheir own inimitable fashion.I think you will hear many ofyour favourites. The record isworth a trial, at all events.

*(a) Ninon, (b) Red Lips Un-kissed, Richard Tauber, 43.

PARLO RO 20208Both sides excellent. A

Tauber record is always worthbuying; this is no exception.

Once Upon a Time (d.s.),

YOUR RECORDS-continuedPavement Artists, is. 6d.

REGAL MR724Rather a pleasant little

medley of well-known songs ofpast years. Quite suitable forthe season and very well done.

*Swallows, (d.s.), Gitta Alpar,Sop., with orch., 4s.

PARLO RO'0202A very charming light -music

record, very well played andsuperbly recorded. The" effects"in it are singularly arresting andthe singer (Gitta Alpar) pos-sesses a beautiful voice. A verygood record.

MILITARY BANDMUSIC

"1812 " Overture, (d.s.) GrandMassed Brass Bands, xs.6d.

REGAL MR718I don't know what Tchaikov-

sky would have said to thisedition, but it has pleasingpoints. As a military bandrecord, apart from the overtureitself, I consider It a goodproduction.

Poppies For Remembrance,(d.s.), Foden's Motor WorksBand, is. 6d. ZONO 6226

This is a medley, including(on the first side) such songs asLong Long Trail, Pack Up YourTroubles, etc.; on the other sideit is devoted to hymns likeAbide With Me. You can formsome opinion from that. Theband is quite a good one butthe singing is distinctly poor.Sorry, but I cannot say anythingkinder than that except, per-haps, to say that the recordingis up to Zono standard.

NOVELTY RECORDSA-Hunting_We Will Go, (d.s.)

Empire Novelty Band,is. 6d. REGAL MR719

As a stirring hunting scenethis is really good. It alldepends, of course, whether youare interested in such things.The recording is amazingly good.Very good surfaces, these Regalrecords!

*(a) Animal Alphabet, (b)Noah's Ark, George Baker,2S. 6d. H.M.V. B4824

A splendid record for thetiny tots. I welcome it as I havealways maintained there are notenough kiddies' records. Thisis a guessing game. Animalnoises are made on one side andthe children are expected toguess them. The other sidegives the answers. Well worthhaving; the children will love it.

(a) Bed Time Story, (b) BigBen's Saying Good -night,Singing Twins, is. 6d.

REGAL MR 726The title suggests the type of

record. Children-very youngones-will like it. Not a badidea letting your records tellfairy stories for you I Saves alot of breath!

Columbia On Parade (No. 2),(d.s.), 4s. COL DX410

Useful for the children. Ina sense it is a skit at the old-fashioned pantomime and yetis quite modern in its outlook.I think we could do with morereal children' records.

Making a Record, (d.s.), CarsonRobinson and his Pioneers,

is. 6d. ZONO 8224This is a scene supposedly in

the No. 1 Recording Studio ofthe Zonophone Company inwhich some negroes arrive tomake a record. I am not surewhether they are intended to beparticularly humorous or not.Not, I imagine. The wholescene seems to be an excuse forintroducing Carson Robinsonand his Pioneers. It is certainlynovel and they are very good,but I do not think the result,as a whole, justifies the scene assuch.

HUMOROUSRECORDS

*(a) Christmas Presents, (b)Kiddies Go Carolling, HarryHemsley, 25. 6d.

PARLO 111868Quite amusing. Harry Hems -

ley is always worth hearing.Child-lovers-children them-selves, for that matter-willenjoy this. It is quite the best

"juvenile" record 1 have heardrecently.

*(a) Dance of the Cuckoos,(b) He's Dead, But HeWon't Lie Down, LeonardHenry, coin., Is. 6d.

ZONO 4227Personally, I do not think you

can beat Leonard Henry for realhumour. His lines would allbear writing down. He is anexample of my contention amonth or two ago when I sug-gested that recorded humourmay be anything but satis-factory. Unless the lines are Mereno record will stand the acidtest of separated performance.


H.T. CURRENT & GRID BIAS fromL.T. BATTERY !

IMPORTANT PRICE REDUCTIONSOwing to the steadily Increasing demand for M -L ANODE CONVERTERS we havefound it possible to reduce our production costs, allowing a SUBSTANTIAL RE-

DUCTION IN LIST PRICES amounting to approx. 25%.New prices of ANODE CONVERTERS:-

CAT. No. INPUT VOLTS (D.C.) OUTPUT VOLTS (D.CJ OUTPUT MA. TYPE WEIGHT (LBS.) PRICE REDUCED TO

*200'201

202203204

-6.12. 32. 50 or 110v.6, 12, 32, 50 or 110v.6,12, 32, 50 or 110v.12, 32, 50, 110 or 220v.12. 31 50. 110 or 220v.

150150200400500

1530404030

BBCCC

1313141414

£8- 0-0£8. 0 -0£8.10.018-13-0£8.10.0

ALL ABOVE ARE SINGLE OUTPUT MODELS. TWO EXTRA H.T. TAPPINGS AND TWO G.B. TAPPINGS 30/- EXTRA.*226 6, 12, 32, 50 or 110v. To suit PHILIPS 2802 or 2805. BX 14 0 -10-0*227 6, 12, 32, 50 or 110v. To suit MeMICHAEL Colonial. BX 14 £9-10-0228 6, 12, 32, 50 or 110v. To suit EDDYSTONE All Wave 4. B 13 13 - 5 -0*229 6, 12, 3Z 50 or 110v. To suit GECOPHONE 6 -Valve SuperIset. BX 14 0 - 10 -0

ABOVE COMPLETE WITH ALL TAPPINGS.

WRITE NOW FOR FULL Dr.TAILS1 2 and 4 volt models available. Ask for details.

ROTAX LTD., DEPT. 7, WILLESDEN, LONDON, N.W.10778


SUPER HET PORTABLE SIX-

all stations without overlap

a he Portable of your dreams "-strong praise, that, for anyset nowadays, but it's how the " Daily Telegraph " radioexpert sums up the " His Master's Voice" Superher Portable

' Six ' -while Captain Robinson, radio critic of the " Observer"calls it "the finest portable on the market." Actually it is the firstbattery set " His Master's Voice " have made, and, as such, wasnot put on the market until proved as nearly perfect as modernresearch and methods could make it. As to selectivity-" almostevery station on the European map at full volume, and evenAmerica" (" Daily Telegraph" again). The set complete withbatteries-price 17 guineas or by hire purchase.

"His Master's Voice""TRUE - TO - LIFE" RADIO

The Gramophone Co.. Ltd., London, W.aSpeedy replies result from mentioning " Wireless Magazine "

779

(Price does not apply in I.F.SJ

Wireless Magazine, January, 1933 GRAMO-RADIO SECTION

CHOOSING YOUR RECORDS--Cont. from page 778

THREE FAMOUS BRITISH ARTISTSLeft to right, Jack Hulbert, Cicely Courtneidge, and Claude Hulbert. They are all famous for'their records, broadcasts, and film work. Their latest records are reviewed in the first column

on this page*(a) Double Damask, (b) I'll

Give Her a Ring, CicelyCourtneidge, as. 6d.

H.M.V. B4314Very good, as she always is.

The whole cast in these twoexcellent sketches is really good.A very good humorous storyvividly told. Well worth having.

Four Ale Bar Concert, (d.s.),Boozy Bill and His Pals.is. 6d. REGAL MR732

I think the title is enough togive a good indication of thecontents 'of the record. It isjust what I expected. And Iwas not amused ! A good surfacewasted !

Gracie's Christmas Psrty.(d.s.),Gracie Fields and Company,4s H.M.V. C2487

Very good, You will find thelady in excellent form and herfriends are equally jolly. Ithink this will have a good sale.

Hulbert Brothers in Chicago,(d.s.), Jack and ClaudeHulbert, as. 6d.

H.M.V B4332Well up to their admirable

standard. You will recognisetheir voices; they sound exactlyas they do when they broadcast.They are quite amusing whenthey come up against somegangsters. I have heard themdo it on the wireless. It comesout very 'well.

*Insubordination, (d.s.), Ar-thur Prince and " ,Jim,"4s. COL DX4i2

Perfect, of course. There isno difference between his recordsand his broadcasts. All youmiss in either is the pleasure ofseeing Mr. Prince and thecharming "Jim." Well worthhaving; really funny !

(a) Laughing Bassoon, (b)Laughs and Frills, CharlesJolly and Kaye Connor,is. 6d. REGAL MR723

The laughter records are withus again-a bassoon, this time.If you liked the other lhughterrecords, you will like this. Thatis all I can honestly say.

Mum, Dad, and the -Nipper(d.s.), George Buck, BerthaWillmott and Company,is. 6d. REGAL MR720

Bad-definitely so. Sorry, butI cannot honestly recommendlow-down family quarrels punc-tuated with sloppy soup. I hadno patience to hear the secondside, so I do not know how itended. No, Regal; your recordsare really good. Give this sortof thing up. I hope you willpardon my frankness !

National Programme, (d.s.),(Broadcasting Burlesque),4s H.M.V. C2504

This is a skit at a broadcastingprogramme. Some of it isquite good. The only point Ifind to criticise is that it is ratheroverdone. The humour is quitegood in places, but I must warnyou that some of it is ratherfeeble. Still, hear it and judgeit for yourself.

*Our Village Pantomime,(d.s.), 4s. H.M.V. C2503

Very funny. Do you remem-ber "Our Village Concert?"This is by the same cast. It isa"scream" in pasts. The village

orchestra is appalling as in theother record; this time it accom-panies the amateur theatricals.Buy it. I am sure you willenjoy it.

Village Concert, (d.s.), RoostersConcert Party, 4s.

COL DX390This is typical of the Roosters

-vociferous and noisy. Thoseof you who appreciate thebroadcasts by this concert partywill like this. Some of thehumour is pretty feeble, butthere are some amusing lines.

ADDITIONAL RECORDSREVIEWED by CHOPSTICK

LIGHT SONGS(a) Isn't It Romantic? (b) Love

Me To -night, Jeanette Mac-donald with orch., as. 6d.

H.M.V. B4288Jeannette Macdonald is Che-

valier's leading lady in his newfilm, Love Me To -night. Do notmix this film with Tell MeTo -night. Both films have somesplendid musical numbers; (a)and (b) are from Love MeTo -night. This is one of thosefifty-fifty records, half orches-tral and half vocal. JeanetteMacdonald's singing is quitegood.

(a) It Was So Beautiful, (b)I Love a Parade, Harry

Richman, ten., as. 6d.COL DB981

There is a definite demand forsuitable records to fill in gapsat home dances where recordsare used. This record is just thetype for the job. Both aremodem love ballads sung in anemotional way. Richman has asplendid voice, but the record-ing could be better.

(a) Mimi, (b) Poor Apache,Maurice Chevalier, as. 6d.

H.M.V. B4289This record needs little com-

ment. Maurice Chevalier's styleis inimitable; his broken Englishis very amusing. Of course, hiswhole personality is infused intothe songs, which are from his

RECOMMENDED DANCE RECORDS FOR

YOUR PARTIES

A Great Big Bunch of You (f.), The Clouds Will SoonRoll By (f.), Jack Hylton and His Band.

DECCA K3109How'm I Doin' (f.), Moon (slow f.), Roy Fox and

His Band. DECCA F3198I Can't Believe It's You (f.), The Roses are Red, the

Violets are Blue (f.), Gene Kardos and HisOrchestra. H.M.V. B6227

I'm In Good Form To -day (f.), And Then? (f.),Jack Bund and His Orchestra. PARLO R1276

La Flor Del Camino (tango), Caminito (tango),Orquesta Tipica Don Alberto. BRUNS 1342

Let That Be A Lesson to You (f.), I Don't BlameYou (f.), Savoy Orpheans. COL CB479

Oh, How I Love My Darling (f.), Sweet Little You (f.),Edgar Jackson and His Band. DECCA F3156

Ooh ! That Kiss (f.), You're My Everything (slow f.),Roy Fox and His Band. DECCA F3099

new film Love Me To -night. Thisis one of the best Chevalierrecords I have heard.

(a) Say It Isn't So, (b) Night-fall, Leslie Hutchinson.as. 6d. PARLO R1350.

Leslie Hutchinson, or'Hutch," as he is better known,

is a regular broadcaster andvery popular at London cabaretshows. He always plays his ownpiano accompaniments.''Hutch" has an appealing typeof voice, but his remarkable giftof combining his singing andplaying is his strong point.Both of these numbers are popu-lar hits at the moment. I tho-roughly enjoyed listening to thisrecord.

(a) While We Danced at theMardi Gras, (b) The NightWhen Love Was Born.Anona Winn, sop.,is. 6d.

REGAL MR727Anona Winn is, of course, a

popular broadcaster. Her voiceis extremely fresh; there is no"crooning" huskiness. Bothtunes are popular dance hits,especially (a), which appears tobe one of the season's greatfavourites. The most out-standing point of the record isthe arrangement in (b), wherethe melody is taken by the saxo-phone whilst Anona Winn soarsinto the top notes. The effectis well produced,

PIANO SOLO*Flirting With Annie Laurie,

(d.s.), Patricia Rossborough,as. 6d. PARLO R1359

This is an excellent record !Patricia Rossborough, the syn-copated pianist, puts some real"pep" into Annie Laurie. Thearrangement, which is by GeorgeScott -Wood, is clever, especiallywhere the theme is changed tomodem rumba time. Recordingis exceptionally good.

CINEMA ORGANMUSIC

*(a) Big Ben's Saying Good-night, (b) Song of the Bells,Harry Davidson, is..6d.

REGAL MR725Harry Davidson believes in

giving good straight tone with-out an excess of frills. I amstrongly recommending thisrecord because the effects arenot too elaborate; the vocalchoruses are sung, not"crooned"; and the recordingbrings out all the delicate pointsof a fine cinema organ. (b) iswritten by Jack Hylton.

Round the World in EightMinutes (d.s.), Sydney Gus-tard, 4s. H.M.V. C2498

This is a medley of tunes,mostly classical, including 'LaPaloma," "Blue DanubeWaltz," "Liszt's HungarianRhapsody No. 2," "Rule Bri-tannia," "01' Man River," andsimilar pieces. I am not enthu-siastic. Such works are hardlysuitable for cinema -organ music.The playing is rather lifeless.Gustard does not put enoughvariation in his style.

DANCE RECORDS(a) He's in the Infirmary Now

(f.), (b) I'm Writing a Letterto Heaven, The Blue Lyres,is. 6d. ZONO 6205

A splendid record for parties.(a) is a comedy quickstep inwhich we are told some of the

(Cont. on pew: 782)

780


IF YOUHAVE ELECTRIC LIGHTYOU NEED THIS BOOK

Ask your DealerIf you have any difficulty in obtaininga copy of this book, fill in the couponand post to us with six penny stamps.We will send you a copy by return.

COUPONTo Publicity Dept., The Telegraph Con-denser Co., Ltd., Wales Farm Rd.,N. Acton, W.3.

Please send me a copy of your book "TheDesign and Construction of Radio PowerUnits," for which I enclose six penny stampsto cover cost and postage.

Name

Address

0NLY mains power can provide your set with thatconstant voltage essential to pure and powerful repro-duction. Get a copy of this book and see how you can

run your set off the electric light-how you can be sure ofadequate power-always-how to dispense with costly andinefficient batteries. If you are on. A.C. supply there are fourpower units described-one of which is suitable for your set.If you are on D.C. there is an informative chapter on D.C.apparatus. The book also includes a useful Rotating ResistanceCalculator. Ask your dealer to -day or fill in and post this coupon.

CONTENTSRADIO POWER UNITS-and howto build them.

NOTES ON A.C. POWER UNITS.

OPERATING RECEIVERS ON D.C.MAINS.

ALL-BRITISH

CONDENSERS

ABOUT T . C C . ELECTROLYTICCONDENSERS.

ELIMINATION OF INTERFERENCE.

FOUR T.C.C. POWER UNITS (A.C.)with full constructional Details.

(e75)

ROTATING RESISTANCE CAL-CULATOR.

V 1670

781

Wireless Magazine, January 1933GRAMO-RADIO SECTION

CHOOSINGextraordinary reasons why somepeople manage to visit infirma-ries. Admittedly, the worms arenonsense, but the record has allthe"pep" needed for party use.(b) is a dreamy type of tuneplayed at correct waltzing time.The Blue Lyres have an excel-lent "sax" player. The record-ing brings out the saxophone'smellow tones well.

*(a) I Guess I'll Have to ChangeMy Plan (f.), (b) Let's PutOut the Lights (f.), Ambroseand His Orch., 2S. 6d.

H.M.V. B6261Ambrose at the top of hi,

BERT AMBROSE

form 1 The saxophone playingin (b) is -brilliant and wellrecorded, too. (b) is one of thosecatchy tunes that once you haveheard it, you cannot get it outof your mind for days. Both areAmerican numbers.

YOUR RECORDS-Contd. from page 780*(a) How Do You Do, Mister

Brown? (f.), (b) Confetti (f.),Jack Bund and His BravourDance Band, as. 6d.

PARLO R1220Parlophone's best fox-trot

record this month. It is veryrefreshing to hear a dance bandwhich favours light arrange-ments and plenty of piano solowork. (a) is too well known toneed comment. (b) is bestdescribed as a first-rate synco-pated piano solo with dance -band accompaniment in quick-step time. If you make a pointof hearing this disc, the tempta-tion to buy will, I am sure, hirresistible.

Jug and the Bottle (f.), (d.s.),Ray Noble and his NewMayfair Orch., 2S. 6d.

H.M.V. B6268This is the second double -

sided comedy number this monthso apparently some people mustbuy them. The time of this oneis quite good for dancing, butthe noise is unbearable. Thereis not one scrap of melody oneither side. A disappointing disc.

(a) " Let's All Dance thlPolka " (polka), (b) March-ing Along Together (six -eight), The Blue Lyres,is. 6d. ZONO 6204

Dancing the polka is good funfor us moderns, although somemay find it too strenuous. Thisis a good record for those whomay be interested. (b) is a fine

tune, but I think it needs a bigband to do it justice, "orches-trally" speaking. The BlueLyres version is suitable fordancing purposes, of course.

(a) Lotus Flowers (w.), (b)Moonlight on the Colorado(w.), Orchestra Mascotte,2S. 6d. PARLO R1349

Here are two delightful tunessuitable for the old-fashionedwaltz. Both are freshly pre-sented; guitar, xylophone, andwell -sung vocal choruses beingthe strong points of the orches-tration.

Old Moore's Almanac (d.s.),Ray Noble and his NewMayfair Orch., 2s. 6d.

H.M.V. B6269This is a comedy six -eight

RAY NOBLE

number. I do not care for suchthings. The record has some

good humorous lines concerningprophecies for 1933. If you carefor such records this one-I'll befair-is well up to Ray Noble'susual standard. His straightdance numbers are usuallyexcellent.

*Paul Jones (d.s.), RayNoble and his New MayfairOrch., 45. H.M.V. C2497

An ideal record for parties !There are all the modern dances,with the usual gallop interludesbetween each. Ray Noble hasmanaged to change the style ofhis playing for each dance; acommendable point. The num-bers chosen are all well known.Ooh That Kiss ! , Mona Lisa,Gipsy Moon, and The FliesCrawled up the Window areexamples. A fine production!

*(a) When You Say " Yes "(tango), (b) Good Morning,My Lady, Good Morning,Madame (w.), Dajos BelaDance Orch., 20. 6d.

PARLO R1348A really outstanding dance

record. The tango is beautifullyplayed; the arrangement isunique. Snatches of pianoplaying, clever whistling, piano-accordeon solo, and saxophonesolo, all with a fine strong bassbackground, is the main idea ofthe orchestration. As a matterof interest, the tune is from theGerman film, Madame hasAusgang. (b), the waltz, has afine melody. I thoroughlyrecommend this record to alllovers of good dance music.

MAKE EVERY SET A

SHORT-WAVE

MAGNUM SHORT-WAVEA DAPT OR

Price, in U.K., including coil 40/80 metres, cordand plug, .. .. 39/6.

Extra Coil, if required, 18/40 metres, 3/-.Price, including packing and freight abroad, 47/-

NMNever mind if your present set,or the receiver you are thinking

of buying, does not reach the shortwaves. The latest Magnum Short -Wave Adaptor will convert it im-mediately into an amazingly efficientshort-wave set.MODEL T.-For sets using British

valves.MODEL TA.-For sets using Ameri-

can valves.MODEL TSG.-For sets using British

screen -grid valve as detectorMODEL TASG.-For sets using Ameri-

can screen -grid valve as detector.All the above models are suitable for both

battery and A.C. mains sets.If in doubt as to model suitable, send full

details of set

Send at once for full particulars with a list ofshort-wave stations and Free Trial offer.

SET!

IBURNE-JONES & CO. LTD.," MAGNUM" HOUSE, 296, BOROUGH HIGHST., LONDON, S.E.I. Telephone: Hop. 6257 & 6258.Scottish Agent : Mr. ROSS WALLACE, 54, Gordon St., Glasgow, C. I .

The LatestSTENODEThese high -quality instru-ments are now availableas Radio -gramophonesand Radio Receivers. Afully descriptive Bro-chure is now readyand free on applica-tion.

MAGNUM differential reactioncondenser has been selected byMr. Percy Harris for his "ETHER -GRAM", where reliability andefficiency are required from everyccmponent. Magnum .0003-mfd.differential reaction condenser,Price 2s. 6d.

782

Wireless Magazine, Jam/a/x/933

Set bolts from OurbdeisHere we are able to presentreports from five enthusiasticreaders on five " WirelessMagazine " sets. These reportswill be of value to prospectiveconstructors of the sets in

question, as they will be ableto form a good idea of what per-formance they can expect in

different localities

CALIBRATOR(October, 1932)

Edinburgh (Scotland).-I havenothing but praise for the set. Ifound it easy to build and it gives awonderful performance. I will giveone example only of its selectivity.Scottish Regional and Hamburgwere almost separated here-a featwhich is often wellnigh impossible.

The quality and volume from theBaker permanent -magnet moving -coil loud -speaker are well up to thestandard of " Wireless Magazine "sets-indeed very high.

The Calibrator is now inCaithness -shire, near John O'Groats,and, from a report I have received,the set has made listeningthere worth while. It easilycuts out the high-poweredNorthern European sta-tions whose strength atnight is often terrific.

EASYTUNE 60(May, 1932)

Belfast (Ireland).-I feel Imust write to say how wellmy Easytune 60 is perform-ing. Results are morethan good ; they areexceptional. Last night or,rather, at 1.45 this morning,I switched on to see whatwas doing.

On turning the dial-asingle knob is a great help-I got Fecamp very faintlyon the loud -speaker.This seemed very unusual.On examining the aerial

lead-in I discovered that it wasdetached from the lead-in tubeand the only aerial on the setwas a 3 -ft. length of rubber flex.Fecamp is nearly 500 miles away.But that is not all.

On tuning further up the dial Isucceeded in getting seven Americanstations at fair strength-with aerialconnected, of course-but atmo-spherics were so bad that I onlymanaged to identify WJB, New York,on about 400 metres ; WGY, 380metres ; and Newark, New Jersey,about 430-440 metres.

The other American stations wereheard on 355, 445, 460, and 515metres. The single -dial tuning is anasset which the rest of the householdgreatly appreciates.

FIVE -POINT FOUR(November, 1930)

Deltota (Ceylon).-Thank your fora truly remarkable set l After mid-night (Ceylon time) the Five -pointFour will bring in over fifteenEuropean stations, including LondonNational, North National, and Lon-don Regional, all at moderate loud-speaker strength. Heilsberg, Breslau,Prague, and Mithlacker are bestreceived (all identified with one ofyour excellent station -finder charts)

and by 1 a.m. are as loud as, if notlouder than, the local station,Colombo.

As sensitivity is more importantthan selectivity out here, I haveomitted the pre-set condenser. Adja-cent stations are, however, easilyseparated. I have made two otheralterations in the construction of theset.

I have omitted the wave -changeswitch. Atmospherics are bad outhere for long -wave reception, al-though on a good night some of thelong -wave stations come in quitewell.

The other alteration is that thefirst low -frequency valve is trans-former coupled instead of resistancecoupled, otherwise the layout isexactly as specified. Again manythanks for a wonderful set.

SUPER 50(March, 1931)

Ratnapura (Ceylon).-I am using aSuper 60 with an extra super -poweroutput. Our alternative programmecomes from Bombay (10 kilowatts),nearly 900 miles away, but we donot hang out the flags when we getit at R9.

AN IDEAL SET FOR EMPIRE BROADCASTSThis is the" W.M." Short-wave Super, of which a Walthamstowreader has sent us an enthusiastic report. This set is ideal

for the B.B.C.'s new Empire transmissions

M." SHORT-WAVE SUPER(November, 1932)

Walthamstow (Essex).-Iwish to commend the"W.M." Short-waveSuper designed by W. G.Hill. This set is the ninthshort -waver I have built,and I am convinced that itis the real " easytune "short-wave set. I haveinstalled it as a regularprogramme supplier in myhome. I did not realisethat there were so manylanguages in the world untilI toured on the " W.M."Short-wave Super. Thelog to date is twenty-threestations, all at good strength.W8XK provides a realgood programme from 9p.m. onwards. It is trulythe last word in short-wave sets.

783

Wireless Magazine, January; 1933 1

TESTSPF NEWAmplion

USLoud -speaker :: Goltone Coupling Unit :: J.B. Unitune

Clarion Screen -grid Valve :: Pressland Cop

NEW LOUD -SPEAKERThe Amplion permanent -magnet moving-ccil reproducer is very efficient. The

magnet weighs 61 lb.

AMPLION LOUD -SPEAKERAPPARATUS : Permanent -magnet moving -

coil loud -speaker, type MC2.PRICE: £1 19s. 6d.MAKERS: Amplion (1932), Ltd.

WE have recently tested theAmplion, model MC22, per-

manent magnet moving -coil repro-ducer. The loud -speaker is quiteconventional in appearance, a veryrigid metal cone Chassis being em-ployed. A large E -shaped permanentmagnet is bolted direct to the backof the chassis.

The magnet is constructed of.5 -in. chrome steel and weighs6.5 lb. The diaphragm is of the one-piece type, the outer edge beingturned over to act as a suspensionand ribbed to give the necessaryflexibility.

The usual web type of centeringdevice is employed, this being fixed infront of the diaphragm and held onto the polepiece. The moving coil isof the low -resistance type, but thenecessary multi -ratio transformer ismounted on the loud -speaker chassis.This transformer is suitable formatching up with all types of powerand pentode valves.

On test the loud -speaker wasmounted behind a 2 ft. 6 in. baffle -

board. The overall reproductionwas very pleasant. Besides beingvery sensitive, the loud -speaker ap-peared to be capable of handlinglarge inputs to the order of 3 or 4watts without any sign of distress.

This reproducer certainly meritsconsideration.

GOLTONE COUPLINGUNIT

APPARATUS : High -frequency coupling unit.Price: 105. 6d.MAKER : Ward & Goldstone, Ltd.

AN interesting high -frequencycoupling unit which we have

tested this month is that marketedunder the well-known name ofGoltone. This unit comprises ahigh -frequency choke, a couplingcondenser, a 600 -ohm decouplingresistance and a by-pass condenser.

A unit such as this may, of course,be used in aperiodic high -frequencyamplifiers, but undoubtedly itsgreatest use will be in circuitsemploying what is termed " tuned -grid " high -frequency amplification.For this type of amplification a first -.class high -frequency choke is essen-

H.F. COUPLING UNITA special unit incorporating high -fre-quency choke, coupling condenser, re-sistance, and by-pass condenser. It is

particularly efficient

Condenser

tial if proper operation of thereceiver is to be ensured.

In order to verify this point thechoke employed in this unit wastested in accordance with our usualpractice and was found to have areally excellent performance. Asreaders will remember, we normallygive a curve indicating the per-formance factor over wavelengthsfrom 200 to 2,000 metres. In thiscase such a curve would prove oflittle use as the performance factoris well over 99 per cent. over thewhole range.

The choke, resistance and con-denser of this unit are mounted inan aluminium screening can, lugscarrying the necessary terminalsprotruding through insulatingbushes. The anode connection ismade by means of a spade terminaland screened lead through the topof the can.

UNITUNE GANG CONDENSERAPPARATUS: Two -gang .0005-microfarad

variable condenser with cover.PRICE: 18s. 6d.MAKER: Jackson Bros., Ltd.

THE name of Jackson Bros. is sowell known in connection with

condenser design that we werespecially interested in their newUnitune two -gang model.

The two sets of fixed vanes of thiscondenser are built into a metalchassis, 'being supported and insu-lated from this by means of bakelisedpaper supports. The moving vanesare carried on a brass shaft, on oneend of which is fixed a slow-motionfriction drive, this latter giving areduction ratio of approximately7 to 1.

The back section of the condenseris fitted with a trimmer operated bymeans of a small star wheel fitted tothe side of the condenser chassis.The front section is trimmed bymeans of a small single -vane solid -dielectric condenser operated bymeans of a shaft passing through


784

iii

Wireless Magazine. Janualy 1933

THE 66 A.C. CALIBRATOR "BULGIN " TRANSCOUPLER " is again incorporated in this month's best set,further proof that it justifies its popularity with well-known set -designers. Every dealer should be able to supply the "Transcoupler" 1116from stock. Make no mistake when ordering. LIST No. L.F.10BULGIN ENCLOSED TWIN FUSEHOLDER, also specified, andgives full protection to every mains set. Complete with glass -enclosed fuses. LIST No. F.9/14THE SENATOR. Supplies now avail-able of this wonderful Nickel AlloyCore Transformer. The latest 619in L.F. design.

LIST No. L.F.12

" SIMPLE TWO -THREE " KIT.Full-size diagram, layout, and fullinstructions for building the newBulgin Battery Set ; available onrequest FREE.

A. F. BULGIN & GO., LTD., Abbey Road, Barking, EssexTelephone: Gra ngcwood 3266.

London Showrooms : 9, 10, 11, Cursitor Street, E,C.4. Telephone : Holborn 2072

SEND FORLATEST

CATALOGUE B

SPECIFIED FOR THEA.C. "CALIBRATOR"

2/. Complete

M.K. FUSE PLUGFor real protection ofMains Radio, it is neces-sary to fit an M.K. FusePlug for connecting tothe Mains Supply.The flexible is thenadequately safeguardedagainst damage (due toexternal short circuit)by the small cartridgefuses, fitted in theconnecting Fuse Plug.

Ask your dealer to show you this new M.K.safety device which safeguards your Mains

Radio and the connecting flexible.

Recommended Fuses : M.K. I amp. for RadioM.K. 2 amp. for Radio -Grams

See the TRADE MARK

CAO(Ce of CrilicS

MODEL A.O.2Charging 2, 4 or 6 volt accu-mulators at % amp. fromthe electric supply plug.Complete and 35f..guaranteed ...Neat Metal Cases for powerpacks and units. Supplied inthree sizes : Small, medium,and large.

Prices : 9/-, 12/6 and 17/6

E MANUAL80 PAGES (4-

ENCLOSE /*POSTAGE

SPECIFIEDfor the

W.M." A.C.MAINS UNITThis is the L.T. BatteryCharger specially chosen by theTechnical Experts of "WirelessMagazine." like all Heayberdproducts, it is selected becauseit stands up to a very severe test,is constructed from the finestmaterials, and is the work ofMains Specialists. ModelA.O.2 incorporates a HeayberdTransformer and WestinghouseRectifier in a neat crystallinesteel case. Convenient screw -onterminals are provided, clearlymarked for input and output."Wireless Magazine" designershave also used a HeayberdMetal Case because they foundit the only one suitable for thejob. These cases are hand-somely finished in crystallineblack, and include a bakelitepanel and steel base. Writefor the Handbook of MainsEquipment.

- - - - -POST COUPON------------I enclose 3d. stamps for new

Handbook packed with hints,tips and diagrams, and givingfull details of Chargers, Units,Kits, and Components.

Mr.

Address

W.M. MONARCH OF THE MAINS.

'M.K." ELECTRIC LTD., WAKEFIELD STREET, EDMONTON, N.18Telephone : Tottenham 3056 (4 lines) Telegrams : "Multiconta, Tottlane, London."

10 FISSRI1RY ST.. I ONPON. E.( .2 (One min. row Moorgate)

Advertisers like to know whence the business comes-please mention "

785

Wireless Magazine. January/933

TESTS OF NEW APPARATUS-Continued from page 784

the centre of the main drivingspindle.

A high -frequency test (at 400metres) was made on the frontsection of the condenser, the trimmerhaving first been set in the minimumposition and then in the maximumposition. With the trimmer atminimum the resistance was approxi-mately 2.3 ohms, while with thetrimmer in the maximum positionthis value increased to 2.8 ohms.

With both trimmers at the mini-mum position the two sections of thecondenser were matched within 1

per cent., the maximum capacitybeing 25 micromicrofarads and theminimum approximately 30 micro-microfarads.

(See illustration on page 757.)

CLARION SCREEN -GRIDVALVE

APPARATUS : 2 -volt screen -grid valve.PRICE: 12s. 6d.MAKER : Clarion Radio Valve Co.

WE have tested this month aClarion SG2 high -frequency

amplifying valve. The valve is con-

ventional in appearance, employinga moulded bakelite base and anodecap. The electrode system is justvisible through the heavy getteringof the bulb and appears to be quiteusual in construction.

The ordinary characteristic curvesof the valve were taken. The ampli-fication factor of the valve was foundto be 140, the mutual conductance.5 ma/volt and the anode impedance240,000 ohms. The makers ratingfor the valve is as follows : Ampli-fication factor 200 ; mutual conduc-tance .8 ; and the anode impedance250,000 ohms.

The valve was also tested in athree -valve receiver and was foundto operate satisfactorily.

A USEFUL GADGETA useful component, the Pressland Cop incorporates an aerial

condenser and lightning safety device

PRESS' AND COPAPPARATUS: Aerial -control tube.PRICE: 6 -in. size, 2s. 6d. ; 9 -in., 3s. ;

3s. 6d.MAKER : Clifford A. Pressland (Sales), Ltd.

THE Pressland Cop is a newversion of the well-known lead-

in tube made by this firm. It incor-porates useful features in additionto its ordinary duties as a lead-in tube.

There is an earth disc mountedconcentrically with the metal rodthrough the middle of the tube, buthaving a hole slightly larger than therod so that the two are not in con-tact. In the event of a lightningdischarge the voltage will jumpacross this gap and be conducted toearth.

The inside to -mina' of the deviceis not in direct con-tact with the outsideterminal, being actu-ally connected to ashort length of rodwhich slides in andout of a metal collarin the end of thetube. This formsan adjustable seriescondenser.

Nillit0 VARIABLE COLVERSTATCISpecified for the "W.M." A.C. MAINS UNIT

Make your set All -Electric by constructing the Mains Unitdescribed on page 708 which employs the Variable Colverstat.They are wire wound smooth in movement and ideal forMains Units and A.C. Receivers.

Type S.T.5C. 25,000 ohms at 5/3 each.

TYPE T.D.

PAW'T.D.COILThe Colvern T.D. Coil is completely screened and incorpor-ates tapped aerial coupling and reaction.Four alternative aerial tappings are arranged as sockets witha wander plug.The first two tappings give aerial couplings similar to thosenormally employed but with greatly increased selectivity.Numbers 4 and 5 give a high degree of selectivity with weakaerial coupling suitable for use in a swamp area. There is nobreak through on the long wave -band from B.B.C. stations.

Price 8/6Suitable for detector L.F. type of screen -grid receivers.

COLVERN LIMITED, Mawneys Rd.,

Type S.T.5C. Pro-tected Windings.Ratings, 5 watts.Standard values, 250to 25,000 ohms. 5/3

Send for theColvern cir-cuit Booklet, R.L.IO.

Romford, Essex

786

DESIGNED BYTHE SPECIALISMIN SHL)R1 WAVE

APPARAIUS

SMITH'SAnodex Dry Batteries whichhave been specified for theHarris Ethergram are manu-factured by a special High-pressure Process, ensuringlong life and absolutely trouble -free performance. Extra powerand Triple Power Types are alsoavailable.

Wireless Magazine, thnuara:1933

BRING IN THE WORLDAt Full Loud -speaker Volume!

The Kilodyne 4 is the voice of the world; it receivesstations from every Continent and operates at loud-speaker volume. It opens up a vast new field ofinterest to the wireless fan.Tunes down to 12 metres and is adaptable up to2,000 metres, incorporates S.G. H.F. amplification,absolutely no hand capacity, perfectly smoothreaction, one -dial tuning, has been designed byshort-wave specialists and praised by leading short-wave critics. It is supplied complete ready for anyhome constructor to assemble easily, or the individ-ual components are obtainable separately.TOTAL COST OF ALL PARTS (not includingvalves ... ... £6 17 6Full constructional details and wiring diagrams fort "Kilodyne 4" are contained in the Eddystoneshort-wave manual.

Sole Manufacturers :STRATTON & CO., Ltd.

BROMSG OVE ST. THEBIRMINGHAMLondon Lervice Depot:WEBB'S Radio tom164, i haring Cross load

W.0 2Teta TootBar2944.

RADIO'ANODEX'120v. H.T.

at 11/ -and

GRID BIAS9 Volt

Speciallychosenfor theHARRISETHERGRAM

BATTERIESThere is a Smith Accumulatorboth H.T. and L.T. for every typeof receiver and a special rangeJelly -Acid Cells for portables.Below : Type R.G.C.9, 48 amps.

Price 12/6(complete with metal carrier)Please write for Folders

S. SMITH & SONS (Motor Accessories) LTD., CRICKLEWOOD, LONDON, N.W.2Advertisers take more interest when you mention " Wireless Magazine "

787


otes audjottintsMAGNAVOX announce a new

Magna series of energisedmoving -coil loud -speakers, which areclaimed to have 50 per cent. bettersensitivity, to be devoid of undesir-able resonances, and to give definitelybetter quality. These results are dueto the lavish use of copper and iron.Details of the new models are con-tained in leaflet D635, which can beobtained from Magnavox (GreatBritain), Ltd., of 89 Kingsway,London, W.C.2.

From Ferranti, Ltd., of Hollin-wood, Lancashire, we have receiveda constructional chart of a battery -operated band-pass four. No com-plete kit is to be supplied for thisset. Copies of the chart can beobtained for 1-0., if " WirelessMagazine " is mentioned.

We are asked by Lotus Radio,Ltd., to make clear that the hire-purchase price of the 20 -guineaLong-range 4 is £1 19s. 3d. downand eleven instalments of the sameamount, a confusion having occurredin their advertisement on page 563of the December " Wireless Maga-zine."

The Rothermel Corporation, Ltd.,makers of Sonochorde loud -speakers,ask us to point out to constructors ofthe Prosperity Three (fully describedin " Wireless Magazine " for Octo-ber last) that model SF6500 shouldbe used when the mains voltage isbetween 200 and 250 volts, whilemodel SF2500 is for mains of 100 to190 volts.

Radio sets may now be taken intoItaly by British visitors on paymentof a licence fee of five lire a month(approximately ls. 6d.) to the ItalianBroadcasting Company. Payment ismade through the customs offices atthe frontiers.

All that is necessary is the com-pletion of a form, either in advanceor at the frontier station, giving thevalue of the set, the number ofvalves in it, and a statement whetheror not it is fitted with a loud -speaker.The maximum per:od for which sets

may be used in Italy on these termsis three months.

From Mavox Radio, of 17 MaddoxStreet, W.1, we have received aninteresting folder describing Mavoxreceivers. Two models are made;the Table Grand Four at £13 13s.and the Table Grand Three at£10 10s.

The price of the Portadyne MC2battery two-valver, listed on PageSix of last month's Set -buyers'Supplement, should be £6 19s. 6d.instead of £6 9s. 6d.

The British Clarion Co., Ltd.,announce that their well-knownpick-up, of which the standard modelsells at £1 is., can now be obtainedwith a volume control for £1 5s. 6d.

Canvas travelling covers for theMarconiphone Super -het Portable(Model 255) can now be obtainedat 10s. 6d. each.

NEW PLATE -LESS ACCUMULATOROne of the new Block accumulators, whichis made without any plates. Further detailsof this battery will be found in thismonth's " In Tune with the Trade" fea-

ture on page 700

From Lectro Linx, Ltd., of 254Vauxhall Bridge Road, S.W.1, wehave received samples of a newinsulated socket for metal mounting.The socket sells at 2d., and is foruse with a Clix Master Plug at 14d.

From Charles Letts & Co. wehave received a copy of a wirelessdiary for 1933 that should be of useto every listener. It contains agreat deal of information useful toeverybody concerned with radioreception. The price in clothbinding is ls., and in leather binding2s. 6d.

The Zetavox model AT receiveris listed at £16 16s., and not £19 19s.as indicated on Page Fourteen oflast month's Set -buyers' Supplement.

Fox Industrial, Ltd., are producinga new receiver which will be sold inthree different forms-table model,console model, and an all -electricradio gramophone with automaticrecord -changing device.

Sonochorde Reproducers, Ltd.,of 1 Willesden Lane, N.W.6, sendus a folder dealing with the range ofSonochorde moving -coil loud-speakers. It is claimed that thisrange of reproducers is the mostcomplete now available.

Readers should note that the priceof the Atlas type RB2 battery set( £6 10s.) does not include batteries;the price of the RA2 receiver is£10 10s., and a mains aerial isincluded. These receivers werereferred to on Pages Four and Eightof last month's Set -buyers' Supple-ment respectively.

Those people with D.C. mainswho desire to operate A.C. receiverswill be interested to learn that thewhole range of Rotax rotary trans-formers made by Rotax, Ltd., hasrecently been substantially reducedin price. These instruments whenconnected to a D.C. supply givean output of A.C. suitable forrunning a radio set or a radio


788

KIT AMPLIFIER.

-Wireless Magazine. January 1933

QUALITYREPRODUCTIONThere is a growing tendency amongst thediscriminating trade and public for betterquality reproduction. The "Parmeko" 25watt Kit of parts enables you to buildyour own amplifier from specially selected"Parmeko" components and know that youare going to get the best results.

Sold complete (except Valves) with every-thing necessary and two full sized blue

prints, price £14: 10:0.

Please write for further particulars.

PARTRIDGE & MEE LIMITED,Parmeko Works, LEICESTER,AYLESTONE 487.

74, New Oxford Street, LONDON, W.C.I.MUSEUM 5070.

STENICABINETSPECIFIED FOR THE "WIRELESSMAGAZINE" `A.C. CALIBRATOR'Model No. 19. A Radio -Gramophone Cabinet,3 ft. 3 in. high, 2 ft. 2 in.wide, 1 ft. 41n. deep,will take a baseboard24 in. by 15 in., orsmaller. The Top Panelabove the Fret w willcut to your specifica-tion.

ifica-tion. Should you beusing an ebonite panel,a paper pattern must beforwarded. Will accom-modate any type ofOratnoplIone Motor.Hand -polished Oak. Mahogany, Walnut. Write forFree Catalogue of Latest Afodela, Post Free.

STENIBAC LTD.(I1.1.816T,,N.

LONDON, N.I

lepl 313 Essex Rd.

'Phone: Clissold 8065.

PRICES :OAK

£4.10.0MAHOGANY

£4 . I .0WALNUT

LS .0 .0

BAC

Simpson's Electric Turntable"nothing to go wrong"

1. Only 2i, in. deep.2. Sizes 10 in. and 12 in.3. 50 Cycles, 100,150 and 200,250

volts A.C.4. Fits any Gramophone.5. Costs less than 4d. per week.6. Correct speed of 78 revs. per

minute.7. Goes by itself.8. Anyone can fit it.

The most remarkable gramo-phone invention of the age-agramophone turntable that" goes by itself." In a fewminutes you can convert anordinary gramophone into anautomatic electric one. It takeslittle longer, following the simpleinstructions supplied, to convertyour present Radio Set into aSuper Radio -gram.The total cost is 39/6only ...It lasts a lifetime with noadditional coat. Ask your Dealerfor illustrated leaflet anddemonstration.

SIMPSON'S ELECTRICALS LTD.,GRANGE ROAD - LEYTON E.10

"We're Fluxiteand Solder-he reliable

pair; Papoosefar soldering --known every-

where/

Ley..

'

When fixing opWireless-there'eno need to fret;Just call 113 tohelp you-thenperfection you'll

yet "

See that Fluxite and Solder are always by you-in the house-garage-workshop - anywhere where simple, speedy soldering is needed.

ALL MECHANICS WILL HAVE

,FLUXITEIT_SIMPLIFIES ALL SOLDERING

MI Ironmongers sell Fluxite in tins: 44., 8d., ls. 4d. & 2s. 8d. Ask to see theFLUXITE POCKET SOLDERING SET-complete with full instructions-7s. 6d. Ask also for our leaflet on HARDENING STEEL with Fluxite.FLUXITE LTD. (Dept. 332), ROTHERHITHE, S.E.16

FOR ALL REPAIRS!

It helps us if you mention " Wireless Magazine

789


CHOSEN FOR TI -17

ETHERGRAM"KINVA9! STANDARD

SCREENED H.F. CHOKE

YieldsMaximumDeflection

of H.F.CurrentsWherever

used.

OxydIsedScreen

BeautifullyMade.

An ideal H.F. choke, for H.F. ordetector anode, fieldless, and perfor-mance curve not below 95% over its

50-2,000 metres range.A Choke for exacting conditions.

Send stamp for list of-

"KINVA" SCREENED "MAJOR "TYPE FOR SUPER-HETS

"KINVA' SHORT WAVE CHOKESand the now famous

" KINVA " H ETERODYNE-WH ISTLE FILTERS

PrvsTLETI-t wft F"KINVA" WORKS, KINVER, STOUREIRIDGE

SPECIFIEDby "Wireless Magazine"Technical Staff for the

"77 SUPER"BELLING -LEE " B "TYPE TERMINAL.Non -rotating name, bakeliteinsulated, soldering elimina-ted, anti -twist wedge oncollar, highly polished blackwith white letters.

Price 6d. each.TWIN SAFETYBASEBOARDFUSE -HOLDER.Fuses carried on the lid, ren-dering shocks Impossible.Complete with two I -amp.fuses. Price 2/6TERMINAL MOUNTTakes two terminals of anymake. Can be mounted

vertically or horizont-ally. Particularly suit-able for " B " typeterminals. Price 8d.

each

BELLING -LEEFOR EVERY RADIO CONNECTION

Adtert of Belling & Lee Ltd., Cambridge Arterial Rd., EnfieldMiddleeez.

NOTES ANDJOTTINGS

(Continued from page 788)

gramophone. They are made in avariety of sizes and there is amodel for almost every radio need.

Rotax, Ltd., also make a range ofanode converters-machines which,when connected to an accumulator,give a constant supply of hightension. These machines are ofconsiderable utility in places wherefor any reason dry high-tensionbatteries cannot be used.

Anode converters as well as rotarytransformers have also been reducedin price. Further details can beobtained on application to the makersat Willesden, N.W.10.

Constructors who are interestedin making their own mains receiversshould look out in next month'sissue of " Wireless Magazine "-which will be published on Friday,January 20-for a special articleby W. James. In this article hegives particular attention to the useof the new electrolytic condensersMake a note of the date now 1

DRY BATTERIES

SUPERSEDEDIt costs nothing to know howto get better results with

STANDARDPERMANENTH.T. BATTERYWe provide personal attention and show evenBigger savings on your battery expense. Installthe Standard which lasts for years, because it re-charges itself when the set is shut down. ThisPERMANENT saving is enjoyed by thousandsof enthusiasts. Ample level current brings indifficult stations without background. Eventualreplacements merely a matter of changing cart-ridges at a few pence each. Such great promisedeserves your investigation. DO IT NOW.

STANDARD BOOKLET POST FREEPopular Type Battery for Ordinary Sets

Any voltage,Any capacity. Model H. No. 3 size. 12.500 milli -

amp, capacity, 126

complete withoutIts. 84 cells, Price,

Down trays.

Tray containers extra if required.

Other capacities 2,000 to 25,000 milliamps.

sTANDARI) BATTERY CO.,(Dept. W.M.)

184-188 Shaftesbury Avenue, London, W.C.2

5/

ryps_Viectratity:'

447-H: BATTERY111111110111111I/W1

F:i5m

'o

SUPERSEDER

.T.

No H.T. Batteries needed with aSUPERSEDER

even if you are not on the mainsS. G. Brown's device gives you 8o v.D.C. from your 2 -volt battery and lastsindefinitely.A boon and blessing to all H.T. batteryusers. Reduced from L3 r5s. to

,40111.1111111 ..... 11,000 other

bargains in ourSALE LIST .'1%1.2."

37/6from us only.

ELECTRADIX RADIOS,218, Upper Thames Street, E.C.4

ENJOYyour Radio Music during1933-and onward-by using

THE THE

PER AGBAKER BAKER

MOVING COIL SPEAKERThousands sold every week by

B \ KER SELHUI,S1' eCADIO75 & 77 Sussex Road, Croydon,

Surrey - - 'Phone: Croydon 3441/2

Write for IllustratedCatalogue of

Radio dramopluneCABINETSexclusivert modern

design, made bycraftsmen, In highlyfigured Oak, Wal-nut, or Mahogany,post free.

hemariatie taluscauincoi made toI der a sp yMaker, underlicence

of theHowe an Balls

Recommended by L:the B.B.C.C. Fulldetails on reque.t.G LBERT -CABINET MAKER.S W I NI )0 EstimePsF Ie. Estd 18611

YOUR OLDCOMPONENTSare worth money. Sort out thespare radio parts you no longerequire and advertise them in the

" Miscellaneous Columns " ofAMATEUR WIRELESS. Youwill be surpiised how quickly theywill be snapped+ up.

Your announcement will coat you3d. a word. Send your list of parts,together with your name, addres,and remittance, to:

"Small Advertisement" Dept.,

AMATEUR WIRELESS58-61 Fetter Lane,

London, E.C.

790

TUNEWELL

A TYPICAL

TUNEWELL

I .F.

c -

SPECIFIEDfor the

A.C. MAINS UNITDescribed in this Issue

Tunewell Components are consistentlyrecommended for successful circuitsbecause of their technical efficiencyand reliability. Wherever good cpaiityis the keynote, you will find them.The Tunewell L.F. Smoothing chokeS.70/50, price 20/-, is specified forthe A.C. Mains Unit described in thisissue. Use it and other Tunewellcomponents wherever you can-for anycircuit-and you will guarantee super -results and save yourself money, too.Send the coupon now for the Tunewell" Guide to Super -Radio," which tellsyou about the whole range of thesefamous quality components and in-cludes

8 FREE BLUEPRINTS(All -Mains Bandpass 3, S.G.3, etc.)

I 932's greatestRadio Achievementis the new TUNEWELL A.G. RADIO -GRAMOPHONE. No mass-producedinstrument can approach its glorious tone,which technical experts agree is unrivalledin radio to -day. 27 ens. ( plus 251- royalties).Send coupon for illustrated Brochure giving

NAM MIMI

To Tunewell Radio, Ltd.,54 Station Road, London,

Please send m,:-) "Glide to Super -Radio."

*04 Radiogram Brochure.

N.11

I Name

Address

L *Cross out if not required. W.M 6..J


If youBuild the

HarrisfEthergrani

Terminalsand Plugs should

be your choice . . .EELEX 2DM WANDER PLUG

As specified by the designers for the Harris" ergram." The Ee lex 2DM MidgetWander Plug. Supplied In six

I dColours. P' -ice each 2-

NEW TYPEA.1.

TERMINAL

The aon-omical way to buy ter-minals for the Hard=" Ethergram." Set of 4tern:dais and 24 Indi-cating tale. 40 letteringsa, allahle. Unwantednameplates can be ex.changed at your dealer',.prodded thev are en.need. at the rate of 2 fogevery 3 retained.

Price per set 2/6Write for lid Eli.

J. J. EASTICK & SONS,Erlex POLse 118 " einhi I Pew 1. ndOil, E.C.1

Panne Illetropolilaw 0314 5 5

asnous wainUtter 1

CCARINiTfor %,/5/-

7 DAYS' FREE TRIAL

10/ -if

You save 36/-1 A few only atseekers' prices. Web Brown OakMaster Grand" tae made torRadio Presto carriage paid. Ahue Bantam. P II OTOUltAPilsand LosTs FREE.

All Models from 351- to £15

vxt0*C:t

intent 8123 improve-iacoustics yields mellow.Itch, lull volume thatyour speaker is reallyvaPable of. Makorsto

(Radio -Pesos. B.B.O.,',I:AD FOR LIST 3,000 eilenteie)

PICKFTTS'"° Tune Cabinets (M.8.Albion ill.. Begleyneath. Kent

Party Decora-tions, holly,mistletoe, thoseattractive,pleasing littlecoloured lights -

et- 'QZiZV.V33".

6A1771X MI A S

e"

All these and manyother things can bequickly and easily

fixed in -any positionneatly, by simplypressing a Kniffy PinInto wood, wall orceiling

temporary wiringto lamp standards,

Ideal for hook-ups,

etc.

PFrom your dealer, or KI;Vet"g11111send 7d, stamps to "'"""End - Middlesex

3i4c it with a WNIFFY'.."TAY11-eX WET H.T. dATTERIES.'-'

Give long service. improved volume and tone. Veryeconomical. Replacements for Taylex or Standardbatteries at low prices; details post free. Also BargainList, Radio Kits and parts at luwest prices.B. TAYLOR. 57 Studley Rotel, PRY/EWELL. LONDON

A uthor'sL st of

FIRST specified Parts includingBaseboard with foil ready.mounted. but less Panel,Valves, and Cabinet. Set ofspecified valves £3 5 0.KIT "B" AB kit "A" but with valves only.Lash or C.O.D. carriage paid £13 16

Ur demon £1 his. lid. and 11 monthly payments of 24/.PETO-SCOTT Walnut Console .. 13 2PETO-SCOTT 1933 Adaptagram "Model C" £7 7

CASH r r C.O.DCarriage Paid

CIO :11 :6or 12 monthly payments

of LIM

CALIBRATOR BMODEL

6

00

KIT "A"cabinet,A %tell:: urta

otor,Pick-up. and speaker.

Cash or C.O.D.Carriage Paid £6:7 :7Or 12 monthly payments of 1118

Valves, E2-2-6. Cabinet. E4-15-0RADIOPHONE RADIOPAK. Cash or C.O.D., carriagepaid, £3, or 12 monthly payments 01 5/6.

ETHER GRAMKIT "A"Author Kit, but lessvalves, cabinet, motorpick-up and speaker

or 12 monthly payments of 1:2,8Bet of specified vanes £2 1 0Peto-Scot Model " B" Alaptagram'.. £6 6 0W.B.P.M. 4 Speaker £2 2 0Formo Triple -gang Type 69C Condenser and

Coil Asse bly .. £2 6 6

CASH OR C.O.D.

g6 : 18 0

ECONOM V S.G.3KIT '`A"

FOR EVERY SET-there's a

PILOTAUTHOR KIT

CASH-C.O.D.-or H.P.

A.C. CALIBRATORAs described in this month's issue

1 Siektan H.F. choke, standard type1 Igranic constant inductive L.F. choke, CH2 ..1 Eavenset L.F. choke, type 101 .. .. 181 Dubilier fixed condenser, type 670, .0001 mfd. .. 11 Dubilier fixed condeneer. type 670, .001 mid. .. 11 Dubilier fixed condenser. type 610, .005 mid. 21 Dubilier fixed condenser, centre tapped. BE256 .1 mid. 36 Dubilier fixed condensers, type 9200. 1 mid. .. 161 Dubilier 2 mid. fixed condenser. type 92001 Dubilier 2 mid. fixed condenser, type LSA, 400 v.

Dubilier 2 mid. type LBA 400v. D.C. working,lined condensers .. 36 0

1 Polar Uompar variable condenser, .0000 mid. .. 2 91 British Radiophone knob .. . 61 Bulgin twin fuse, type F9 with fusee. 2 31 Readi-Bad grid leak holder .. 63 Tellies 5 -pin valveholders .. 3 01 Telsen 4 -pin valve bolder . 9I Erie fixed resistances as specified .. 5 0I Linen 1-megohm grid leak .. 6

Erie 400 -ohm, 1 -watt resistance .. 1 01 Erie 200-olun. lwatt resistance . . 1 0Tinned copper rhea lengths of insulated sleevtn.y.

Lengths of rubber -covered Sex, Welded cable forpick-up leads. a. 'Teethed .. 3

1 4 -volt flash -lamp bulb for dial1 Pets -Scott baseboard with sheet of aluminium fedi

(16 In. by 12 ln.) ready mounted .. .. 31 Peto-Scott bracket for mounting reaction condenser1 ME fuse plug, type 640 .

3 Lissen marked terminal blocks sa specified 81 British Radiophone Radiopak . 3 01 Bulgin Transcoapler L.P. Transformer, type LF1.0 111 R.I. mains transformer, type EY3uKIT "A" Cash or C.O.D. .. £7611 6

KIT "A"

6

a306

4 6

Cash or C.O.D.Delivered carriage paid

Author's Kit of specified wAparts. including ready- 1 17 3drilled plywood panel, but aless valves and cabinet.

Or 6 monthly payments of 610.

PETO-SCOTT CO. LTD. 77 City F d London, E.0.1Telephone t CLEEKENWELL 9400/7.

Dear Sus, Please send me CABH/C.O.D./H.P

........for which I enclose

£ e d essurit.r. Deposit. Also sendyour FREE, 1933 Radio Catalogue.

I NAME

ADDRESS W.51.1/33.Mention of the "Wireless Magazine" will ensure prompt attention

791

Wireless Magazine. Januwx to.33

BLUEPRINTCOUPON

Valid only until January 31,1933 (or until February 28,

1933 for overseas readers)

FOR ONE BLUEPRINT ONLY

If you want a full-size blueprintof any ONE of the sets construction-ally described in this issue for halfprice, cut out the above coupon andsend it, together with a postal order,to Blueprint Department, WIRE-LESS MAGAZINE, 58-61 FetterLane, London, E.C.4.

This coupon is valid for a blue-print of any ONE only of the follow-ing sets at the prices indicated :-

HARRIS ETHERGRAM (page713), No .WM3o8,price 6d. post free.

A.C. CALIBRATOR (page 746),No. WM3o9, price 6d., post free.

A.G. MAINS UNIT (page 708),No. WM.31o,price 6d., post free.

INFORMATIONCOUPON

Valid only until January 31,1933 (or until February 28,1933, for overseas readers)

If you want to ask any quest -tons,cut out the above coupon and send it,together with a postal order for is.and stamped -addressed envelope, tothe Information Bureau, WIRE-LESS MAGAZINE, 58-61 FetterLane, London, E.C.4.

Note that not more than twoquestions may be asked at a timeand that queries should be writtenon one side of the paper only.

Under no circumstances can ques-tions be answered personally or bytelephone. All inquiries must bemade by letter so that every readergets exactly the same treatment.

Alterations to blueprints or specialdesigns cannot be undertaken; nor canreaders' sets or components be tested.

If you want advice on buying aset, a stamped -addressed envelopeonly (without coupon or fee) shouldbe sent to the Set Selection Bureau,WIRELESS MAGAZINE, 58-61Fetter Lane, London, E.C.4.

Australian Short - waveTransmissions

FOLLOWING are details of theshort-wave transmissions made

by Melbourne and Sydney, Australia:VK3ME, Melbourne (Vict.) on

31.55 metres. Wednesday, 8 to9.30 p.m.; Saturday, 8 to 10 p.m.(local time).

VK2ME, Sydney (N.S.W.) on31.28 metres. January : 4 to 6 p.m.;8 p.m. to 2 a.m. February : 4 to6 p.m.; 8 p.m. to 2 a.m. March :4 to 6 p.m.; 8 p.m. to midnight ;12.30 to 2.30 a.m. April : 4 to 6 p.m.;8 p.m. to midnight; 12.30 to 2.30a.m. May : 4 to 6 p.m.; 8 p.m. tomidnight; 1.30 to 3.30 a.m. June :3 to 5 p.m.; 8 p.m. to midnight;2.30 to 4.30 a.m. July : 3 to 5 p.m.;7.30 to 11.30 p.m.; 2.30 to 4.30 a.m.August : 3 to 5 p.m.; 7.30 to 11.30p.m.; 1.30 to 3.30 a.m. September :3.30 to 5.30 p.m.; 7.30 to 11.30 p.m.;12.30 to 2.30 a.m. October : 3.30 to5.30 p.m.; 7.30 to 11.30 p.m.;12.30 to 2.30 a.m. November :4 to 6 p.m.; 7.30 to 11.30 p.m.;midnight to 2 a.m. December : 4 to6 p.m.; 8 p.m. to 2 a.m. (All timesare local.)

SCOTTSESSIONS

FOR EXPERTWORKMANSHIPHave your " WirelessMagazine " set built, re-paired or overhauled byexperts.You will be amazed atthe wonderful improve-ments in performance.No matter what your re-quirement, send us detailsand ask for free quotation.

SCOTT SESSIONS &RADIO ENGINEERSMUSWELL HILL

LONDON, N.ioTele¢hone No. Tudor 5326

Contractors to H.M. Office of Works, etc.

INDEX TOADVERTISERS

BBaker Selhurst RadioBecker, Geo., Ltd. ..Belling & Lee, Ltd. ..Block Batteries, Ltd...British Blue Spot Co...British Radiphone, Ltd.Burne-Jones & Co., Ltd.Bulgin, A. F., & Co. ..

Page790

.. 701

.. 790687

er iii.. 703.. 782.. 785

Carrington Mfg. Co., L td. .. 689Clarke, H., & Co. (M/cr.), Ltd. 692Clifford A. Pressland (Sales), i.td. .. 688Columbia Graphophone Co., Ltd. Cover ivColvern, Ltd. .. .. 786Cossor, A. C., Ltd. .. 685

DDubilier Condenser Co., Ltd. .. 695

E

Eastick, J. J., & Sons .. 791Electradix . .. 790Ever Ready Co.. (G.B.), Ltd. .. 697

FFluxite, Ltd. .. .. 789Formo Co .. 682, 683

aGeneral Electric Co., Ltd. ..Gilbert, J. C. ..Gramophone Co., Ltd., The..

Heayberd, F. C., &

JJackson Bros...

Kniveton Cable Works, Ltd.

.. 691

.. 790

.. 779

.. 785

698

.. 791

Lectro Linx, Ltd. . 688Limit Radio, Ltd. .1 .. 688London Electric Wire Co., and Smiths,

Ltd. .. Cover ii

MMcMichael, L., Ltd. .. .. 701Microfuse, Ltd. .. .. 688M.K. Electric, Ltd. .. .. 785Multitone Electric, Ltd. .. 692

0Osborn, Chas. .. 692

PPartridge & Mee, Ltd. 789Partridge Wilson & Co. 6it9Pertrix, Ltd. . .. 7,2Peto-Scott, Ltd. .. .. 791Philomel Radio Equipment Co. 6;3Pickett Bros. .. .. 791Postlethwaite .. .. 790

RRadio Resistor Co. ..Reproducers & Amplifiers, Ltd.Rotax, Ltd. ..

Scott SessionsSimpson's Electricals, Ltd. ::Smiths Cabinets, Ltd.Smith M/A, Ltd. ..Stenibac, Ltd.Stratton & Co., Ltd. ..

TTaylor, A. ..Telegraph Condenser Co., Ltd.Tunewell .

V

Varley .. 704

wWard & Goldstone, Ltd. .

Westinghouse Brake & Saxby *SignalCo., Ltd.

Whiteley Electric Radio Co., Ltd.Wingrove & Rogers, Ltd. ..Wright & Weaire, Ltd. ..

.. 701

.. 693

.. 778

.

792789701787789787

688, 791.. 781.. 791

698

699689688700

la

792


Make sure of

Perfect Reproductionfor 1933 Programmes

A new and modern speakerwill make

all the differenceto your enjoyment

of

the broadcastprogrammes

and wherewill you find more modern, more perfect,

more reliable spzakersthan those in the fatuous Blue Spot R.ange.

Blue Spot

Speakers are known and respectedthroughout

the country as the best that money

can buy.In spite of their high quality, Blue Spot Speakers

are not expensive

and the range is so wide that you. will certainlyfind one at the price you want to pay

31K316

CeieWeee0WeMf.b4:CertWee:PMReOWt rte$Wetazi'e4*elgeOrtiCeO*IC6CblebrtN4

Another splendid cabinet in fine qualityoak. The movement is the world-famous 66K and its performance issuperb. It gives you song and speechand music without a blemifih. Nobetter speaker value exists.

OUCb14%-'eA,K%P*CkeVOQ.MS%Vo?Wtle*:0,,%$::±1Ce*Ii:g4VefO,rCtAViOgACk04WD

MOD5216

Here is a speaker that will be prized. Its hand-some exterior of first -quality oak is worthy ofthe movement-the famous 100U-that itshelters. 100D reproduces every word and noteto perfection. It is the admitted equal of all butthe very highest quality moving -coil speakers.It can be used with battery or all -mains sets andwith normal or pentode valves. No matchingtransformer is needed.

ft MO, MCtelo igZSI~, Mgt rtt't caIttM% MCI, MOD Mee ifgteke)/ .%,*1, W(A beautifully designed cabinet in fine -quality oak. The movement is thewonderful Blue Spot 66R, which iscapable of handling enormous outputswithout distress. Every item repro-duced is crystal clear and true to life andthe volume is such that it will fill thelargest room with ease.

.'er:*1C4,00CeP*OAtCetWe ittWee4ICLOOge ve, IAZCele4tgele*4%WeteiWe eVEe =VIDA* tr.Ask your dealer to demonstrate these and other products in the Blue Spot range ofunits, loud -speakers and receivers. If any difficulty send for our Catalogue No.W.M.24S.

All Blue Soot Products are guaranteed for 12 months and may be purchased by instalments.

44R521

BRITISH MADE

THE IBIRITIni EWE /FOY COMPANY LTDBLUE SPOT MOUSE 94/96 ROSOMAN STREET - ROSEBERY AvENuE. LONDON E C

Telephone: Clerkenwell 3570. Telegrams: " Bluospot, 'sling, London."Distributors for Northern England, Scotland and Wales: H. C. RAWSON (Sheffield and London), Ltd.,100 London Road, Sheffield ; 22 St. Mary's Parsonage, Manchester ; 44-46 High Bridge, Newcastle ;

37. 38, 39, Clyde Place, Glasgow.

ri'/ZO,Ies4''b'OVRtIZW,Iftlebgi$C6FItil'ANIVaele*CkAtIO-.1%ck3/41$1:::cb

HI

ti

0


TONEtells

you make this simple test ? to hearColumbia Radio alongside any other make.With 30 years' experience in sound reproduc-tion our claim is that Columbia tone isunsurpassed. But we ask you not to take ourword for it-Test it ! Let your own ears proveit ! Above you see the Columbia Radiograph Four (Model 620)a new in( xpensive radio -gramophone of rare beauty, carrying everymodern dev,ce to meet present broadcasting conditions and rendergramophone music at its best. Four valves, including rectifier.One knob tuning. Illuminated station guide and flood lithorizontal scale calibrated in wave -lengths. Columbia CradleChassis. Electric induction motor. Field -excited moving coilspeaker. Handsome walnut cabinet. Marconi valves standard.The price is 32 gns. (A.C.), 34 gns. (D.C.), and there arefourteen other Columbia models from .4. 7. 6 to 90 gns.

Obtainable onfirst payment of £3. I S

ColumbiaTEN -POINT RADIO andRADIO - GRAPHOPH ONES

Get the Craziest Recordon Record!

CRAZY PANTOMIME(Columbia on Parade No. 2.)

What a Cast!CHESNEY ALLEN and BUD FLANAGANCinderel'a - - - PEGGY WOODPrince Charming - - NORMAN LONGBaron Fyffe - STANLEY HOLLOWAYUgly Sisters - BINNIE and SONNY HALEButtons - - BILLY LEONARDThe Fairy Queen - - HARRY TATEThe Demon King (afterwards Dandini)

NAUNTON WAYNEAccomnanied by

DEBROY SOMERS and HIS FORTY THIEVES.12 inch DX410 (4/-)

(UT OUT FOR FREE HOME TRIAL(Write in block capitals)

* Flease arrange a demonstration of Model 620, freeand without obligation, in my home.

* Please send me a free Magazine Catalogue of the 15Columbia Models (54. 7. 6 to 90 Gns.)

* Please send me free a copy of Columbia RecordCatalogue for December.

* Cross out if not required.

NAME

ADDRESS

W.M.. Jan 4933

Cut this out and post it in an unsealed envelope bearingid. stamp to Columbia, 98/108, Clerkenwell Rd., E.C.1.

41111ft.

Mir

percy harris radiogram · percy harris radiogram gets j stations shillingsworth in radio january...

Documents