laser output meter - americanradiohistory.com...ation of 2400mhz using a doubler. i have programmed...

A Publication for theRadio Amateur Worldwide

Especially Covering VHF,UHF and Microwaves

Volume No.35 . Spring . 2003-Q1 . £5.15

Laser Output MeterAlexander Meier, DG6RBP

Contents

K M Publications, 63 Ringwood Road Luton, Beds, LU2 7BG, UKTelephone / Fax +44 (0)1582 581051, email : [email protected]

web : http://www.vhfcomm.co.uk

Paolo Pitacco Micro transmitter for L band 2 - 7IW3QBNWolfgang Schneider Control logic for a switchable 8 - 13DJ8ES attenuatorPeter Greil Amateur use of the optical 14 - 24DL7UHU spectrum (above 300GHz)

Part 1André Jamet 2m direct conversion transceiver 25 - 29F9HX

Index of Volume 34 (2002) 31 - 33Sigurd Werner Frequency multiplier for 76GHz 35 - 41DL9MFV with an integrated amplifierAlexander Meier Laser output meter 42 - 51DG6RBPBernd Bartkowiak Coax cable and connectors 52 - 55DK1VAE Chicken A 10.7MHz i.f. probe 56 - 58G3BIKGunthard Kraus Internet Treasure Trove 60 - 61DG8GB

A packed issue this time with topics from theoretical to constructional that will, Ihope, interest all readers. Some of the articles are a result of the request for newauthors, these are most welcome. I am always interested to receive new articles fromnew authors.I am working on a new RSGB book, due to be published in April. A more detailedversion of the article by André Jamet on a direct conversion 2m transceiver will be inthe book.I have been asked to publicise the 2003 Microwave Update. This will be a joint eventwith The Pacific North West VHF Society held in the Seattle, Washington area onSeptember 25-28th 2003. Full details are shown on page 59 and on the VHFCommunications web site.73s - Andy

VHF COMMUNICATIONS 1/2003

1

Following the invitation to write per-sonal experience and ideas from VHFCommunications, this is my solution togenerate a stable signal on L-band. Itis useful to transmit ATV, high speeddigital signals or simply as local oscil-lator for a transverter.

1.Introduction

Most amateurs refuse to go on SHFbands because of the difficult to easilygenerate a stable and reliable signal.Normally this is achieved using an ex-pensive chain of multipliers from a crys-tal oscillator. Tuning is the big obstacle,especially when only a simple test meteris available in the ham-shack. The projectpresented here will demonstrate that it ispossible to do all that is required in asimple and easy manner.Due to the growth of wireless technologyand related applications, today it is easyto access complex circuitry without anydedicated instruments. I refer to develop-ments in the field of micro-controllersand rf modules, today we can havecomplex functions ready to use in asingle package:

• Microprocessors are made smallerhaving more peripherals and are

re-programmable “in circuit”.

• Wide band amplifiers, MMIC arematched to 50 ohms.

• Voltage controlled oscillators(VCO) and the components for thecontrol of these (PLL).

Using these technological solutions, it isvery easy to design a stable and re-programmable oscillator with few parts.The result is shown in the Fig 1, a smallpcb gives a great circuit.

2.Circuit description

The circuit diagram is very simple (seeFig 2), a major note is the absence of anyvariable (externally tuneable) elements.The RF part is built around a commercial(ready-to-go) smd VCO functioning be-tween 1100 and 1400MHz, ALPS modelED18-A. A buffer transistor and anMMIC amplifier are used for an outputstage.VCO control is achieved using a Na-tional PLL, LMX1501, programmed by asmall and inexpensive micro-controllerfrom Atmel, AT90S2343. This is thelittle member (dimensionally speaking)of the AVR family from Atmel, and hasonly 8 pins! With an internal oscillator

Paolo Pitacco, IW3QBN, e-mail: [email protected]

Microtransmitter for L-band(microtx)


2

(RC), this device does not require anexternal oscillator or crystal. Two pinsare used for frequency selection. I wrotethe program for this small micro-control-ler to select one of 4 frequencies used forATV traffic in my country (Italy). Theseare 1224, 1240, 1256 and 1272MHz.Any change in the switch position duringoperation changes the output frequency,because the switch setting is checkedcontinuously by the micro-controller.The loop filter is calculated for a VCOsensitivity Kvco=32MHz/V and a refer-ence frequency Fref=25KHz, using Na-tional’s information from the LMX1501datasheet [3], all values were used toobtain a good carrier for ATV transmis-sion. The LMX1501 is a good device thatworks well from VHF to SHF withenough sensitivity. It is fully programma-ble (pre-scaler, reference and divider) inserial mode using National’s Microwireinterface (3 wire: clock, data and latch).The PLL uses a 6MHz crystal for internalreference oscillator. Any other frequen-cies in the VCO’s range of operation arepossible by re-programming the micro-controller. For this reason I have madeprovision on the pcb for a connector usedby the Atmel ISP dongle, this is notinstalled for normal and “standard ATV”

versions. Software tools are availabledirectly from Atmel [1] moreover a lot ofsuggestion and applications are availableon the internet [2].

3.Construction

To make the circuit as simple as possible,I decided to use a mix of componenttechnology, normal insertion parts formicro-controller, power regulation andloop filter, smd parts for the rf side. Thepcb is designed in the same way: acomponent side with all insertion parts,and a solder side with all smd parts. Thisdesign reduces interference between rfparts and micro-controller without greatscreening or filtering. The bottom side isshown in Fig 3. Another design criteriawas to use the minimum smd part’swhich are not currently accepted by radioamateurs. After component installation,no tuning is required for stable andcontrolled operation, this represent a bigsatisfaction for all! Measured power out-put (on my HP432A) is greater than+10dBm in all cases, and is suitable to

Fig 1: Pictureof top side ofcompletedMicrotx.


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fully drive a power amplifier (e.g. Mit-subishi model M67715) to reach 2Woutput. The pcb, shown in Fig 4 (bottom)and Fig 5 (top), and all parts, are avail-able by sending an email for the attentionof IV3KAE to [email protected]

4.Applications

The primary use is an ATV transmitterand it is good practice to use a filterbetween base-band signal and modula-

tion input (R13) as shown in Fig 6, butsome others are possible (and tested). Inorder to have audio capability, you canuse the circuit shown in Fig 7 as a6.5MHz sub-carrier, and using the sec-ond half of U4 as audio amplifier. Set theinductor coil for centre frequency, RV2for enough deviation and RV1 to set thesub-carrier level 14dB down from videocarrier (with spectrum analyser). A pro-totype has flown on some model aero-planes (RC) with good performance.I have done a test as high speed digitaltransmitter simply by substitution ofvideo base-band signal with a stream of38400 Baud Manchester encoded data.

Fig 3: Pictureof bottom sideof pcb showingsmd parts.

Fig 4: Bottom side of pcb for Microtx with smd component layout.


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Another test was carried out for gener-ation of 2400MHz using a doubler. Ihave programmed an output frequency of1200MHz and connected the tx output toa simple doubler using a diode (HP2800)followed by a Murata filter for ISM band(2400-2480MHz), the filtered secondharmonic was amplified by an MMIC(ERA3). In this manner a simple beaconfor S-band was realised, again withouttuning elements (Murata filter are smallboxes without screws!).For the satellite enthusiast, it is possibleto use this circuit as local oscillator for a

transverter for 144 - 1268MHz “mode L”up-link of satellites (i.e. AO-40). With aprogrammed 1124MHz output fre-quency, I feed a double balanced mixer(ADE-12 from Mini Circuits) in the LOport, and my 144MHz transmitter (with aVERY low level, controlled!) in the RFport and obtained a 1268MHz signal.Another Murata filter followed the mixerand a couple of MMICs amplified thissignal to a +10dBm to drive the M67715(2W, linear), usable for up-link to thesatellite (together with a good antennasystem).

Fig 6 : Filter for use as ATV transmitter.

Fig 5: Top side of pcb for Microtx and normal insertion componet layout.


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5.Conclusion

From my viewpoint, this is a simplesolution, but demonstrates how it ispossible to reach good results with lowcomplexity for the experimenter. I hopethat my idea will be useful to other radioamateurs.

6.References

[1] www.atmel.com[2] www.avrfreaks.net[3] www.national.com

Fig 7 : Circuit for using 6.5MHz sub-carrier sound.

PUFF Version 2.1 MicrowaveCAD Software

• Complete with full Englishhandbook

• Software supplied on 3.5 inchfloppy disc

• £20.00 plus shipping (UK £1.50,Surface mail £3.00, Air mail £5.00)


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Commercial switchable attenuatorsfrequently require a binary codeddrive for the integrated switchingstages. In order to set a value of, forexample, 10dB, a 2dB and an 8dBattenuator must be activated. A simplelogic circuit can handle the necessaryconversion from decimal into binarysignals. When a key is pressed, theattenuator can be switched in 1dBsteps from 0dB up to a maximum of127dB.The circuit has deliberately been madediscrete, with no micro-controller, thissimplifies any modifications to indi-vidual requirements which may be-come necessary.

1.Introduction

The most effective method for assem-bling switchable attenuators is to arrangethem in binary coded stages. The 1dB,2dB, 4dB, 8dB, 16dB, ... structure allowsall possible combinations of values to beput together with the least expense. Theindustrially manufactured, programmableattenuators from Weinschel, are built inthis way. The models from the 3200-1range are switchable, in 1dB steps, from0dB up to a maximum of 127dB, with thefrequency range extending from DC to 2(3)GHz.

2.Circuit description

The drive logic circuit for programmableattenuators (Fig 1) consists of three sec-tions.First is the ICM 7217A (IC5) counter,with integrated display driver for sevensegment displays. A three digit display issufficient for the attenuation range setbetween 0dB and 127dB.The second section consists of the driversIC6 and IC7, together with the twocounters IC2 and IC3.The programmableattenuator is driven by means of twodrivers, each being an LM324 quadrupleoperational amplifier (IC6, IC7). Theoperational amplifiers operate as compa-rators in this circuit. The switchingthreshold lies at approximately 1.4V,defined by the voltage drop through thelow-current LED D1.The binary coding is generated by of two4 bit 4516 counters (IC2, IC3). These areprogrammable forward/reverse counterswith a reset system. The pre-set optionfor a desired value is not used in thisversion of the circuit.The third section consists of the inputcircuit, the keys and the timer IC4. Threekeys are sufficient to operate the drivelogic: Up (S2), Down (S3) and Reset(S1). Each key has an anti-bounce circuit

Wolfgang Schneider, DJ8ES

Control Logic for a SwitchableAttenuator


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consisting of an R/C combination(10kOhm, 100nF). The control signalsact on the counter modules either directlyor as inverted signals (IC1, 4011) forresetting and up/down counting.The timer, IC4, generates the actualcounting pulse (with auto-repeat func-tion). This pulse is controlled through thelogical sum of the up/down keys, S2 andS3, using IC1a. If either of these twokeys is pressed, then the output of IC1agoes to high signal and the NE555 timeremits counting pulses. The frequency isdefined, at approximately 1 pulse/second,through the capacitor C1 (22µF) and thetwo resistors R1 and R2 (each 22kOhm).

3.Assembly instructions

The drive logic circuit, including theattenuator, can be mounted on a double-sided copper coated epoxy printed circuitboard with the dimensions 102mm x100mm (Figs 2 and 3).When holes have been drilled in theboard with a 0.8mm or 3.2mm drill forthe fastening screws of the switchableattenuator, the components are mountedin any order, in accordance with Fig 4. Itmakes sense to use sockets for the sevensegment displays and the correspondingcounter/multiplex integrated circuits(IC5: ICM7117AIPI). All SMD compo-

Fig 2 : Bottom side of Printed Circuit Board.


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nents are mounted on the underside ofthe board (Fig. 5).The board is through hole connected atvarious points, either with the leads forthe components or with a thin copperwire. These points are to be soldered onboth sides!

3.1. Parts listIC1 4011, CMOS NAND gateIC2, IC3 4516, CMOS counter

moduleIC4 NE555, TimerIC5 ICM7217A, counter/display

moduleIC6, IC7 LM324N, operational

amplifierIC8 78L05, 5V voltage regulator

D1 LED green, low currentLD1-LD3 D350PK seven-segment

displayC1 22µF, SMD, tantalum

electrolytic capacitorC7 1µF, SMD, tantalum

electrolytic capacitorC8 10µF, SMD, tantalum

electrolytic capacitor5 x 100nF, SMD 1206, ceramic1 x 1.8kΩ, SMD 12063 x 10kΩ, SMD 12062 x 22kΩ, SMD 12062 x Yellow Digitast key1 x Red Digitast key3 x 1mm. terminal pin1 x DJ8ES 061 printed circuit

board

Fig 3 : Top side of Printed Circuit Board.


11

Fig 4 : Component layout showing non SMD parts.

Fig 5 : Component layout showing SMD parts.


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4.Putting into operation

No calibration is required for the drivelogic assembly for programmable attenu-ators. The counter and the attenuator areset to 0dB using the Reset key. Thedesired attenuation value can now be set,using the Up and Down keys.The current consumption of the assem-bly, including the attenuator, is only50mA in the initial position, which corre-sponds to the 0dB position, with anoperational voltage of +12VDC. For thispurpose, the terminal pin K11 is con-nected to K9 with the operational volt-age. The total current consumption risesby about 10mA for each switching stage,up to a maximum of 130mA .

5.Literature references

[1] Model 3200 data sheet, Programma-ble Attentuators www.weinschel.com[2] INTERSIL Data book/ApplicationsSection ICM7217 Series INTERSILINC., 1983

Fig 6 : Photograph of completed attuenator.


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Nowadays, large quantities of data aretransmitted in built up areas usingoptical directional radio links. Theoptical transmission technology forthis is perfected and operationally reli-able. Optical transmission has beenused for telephone links for over 100years. Recently radio amateurs havealso devoted attention to this subject.The basic principles and the technol-ogy are described below.

1.Introduction

The optical range has been used fortelephone transmissions for over 100years, and in Germany the term “Lich-tsprechen” (“optical speech”) was coinedfor it. During the Second World War, thetechnology was used mainly for militarypurposes, and in the Cold War period itwas widely utilised by agents and spies.Nowadays, enormous amounts of dataare transmitted in the Gbit range in builtup areas over links that are up to 5 kmlong, and several thousand kilometresbetween satellites.Individual radio amateurs were experi-menting in this field in the sixties. Thelevel of activity increased when it be-came possible to use lasers.The range that can be covered is essen-

tially dependent on the location and,above all, on the weather. If visibility isvery good, the power level is a lessimportant factor.National and international regulations arecurrently being revised, or introduced,and co-ordinated in order to provideunambiguous definitions for amateur ra-dio in this area.

1.1. HistoryAlexander Graham Bell applied for apatent for his “photophone” back in1880. This projected sunlight onto anacoustical recording diaphragm by meansof a reflector and a lens system. Thereception equipment was made up of aselenium detector and a telephone ear-piece [16].This process doubles the frequency atdemodulation therefore meaningful un-derstanding can only be achieved for ofmodulation of <20 % and then with“errors”.In Germany, the first time any practicaluse was made of this technology was fortelephony during the First World War.The range was approximately 8km, andfor telegraphy it exceeded 8km. By 1929various types of apparatus were beingmanufactured in Germany and marketedunder the description of “optical tel-ephones”.The receiver cell in use was the Thal-

Peter Greil. DL7UHU

Amateur use of the opticalspectrum (above 300GHz)Part 1


14

lofide (Tl2S) cell, developed in 1917.This is made from partly oxidised thal-lium sulphide, and used in a narrowrange at approximately 950nm. Thal-lofide is toxic with the lower toxic limitfor Tl2S being 92.7µg/m³. It is a photo-resistor and is used with a screen and ared filter, and is easy to replace.A selection from the 24 or more knowntypes of equipment:The OF 80, manufactured from 1934 orearlier, was the forerunner of the LiSpr80 (supplied to the U.S.S.R. until 1939)The OF 130, which contained only onecommon lens, with a diameter of 130mm,for transmission and reception, and usedas a telescope objective.The predecessor of the Li Spr 60/50 wasthe LiSpr a.Whether it was deliberate or not, thedescriptions of equipment and types wereused for various applications (and notalways correctly used) by manufacturers,users and other interested parties.A silicon PIN diode is at least 1,000more sensitive than the Tl2S photo-resistor [3]. Although the receiver for theequipment consisted of nothing but theTl2S photo-resistor and a low-frequencyamplifier, relatively long ranges werespecified. For example, depending on thetype of equipment and the diameter ofthe reception lens (50mm - 130mm),daylight telephony ranges for Germanequipment used in the Second WorldWar period were specified as being be-tween 2km and >15km. Messages wereindeed reliably transmitted over thesedistances in normal weather.Experiments in telegraphy using Italianoptical telephone equipment from theSecond World War period have yieldedranges of 30km or even 50km, whileonly 6 - 7 km. were specified, or 9km fortelephony [4]. We shall discuss rangespecifications later.Equipment was also manufactured thatwas equipped with a high-pressure gas

filled lamp as a transmitter, which wasdirectly modulated and could transmit onseveral channels.Until as late as May 1951, development,manufacture and operation was prohib-ited in the allied zones and the subse-quent Federal Republic. The author doesnot know when it became possible, forexample, to apply for, and perhaps ob-tain, licenses from the Central Office forTelecommunications Technology inDarmstadt or the MPF in Berlin.At the end of the fifties, assembly in-structions for optical speech equipmentbegan to appear in non-technical publica-tions. They were intended for games andexperiments to amuse the young. In thesixties, the “ASTRO Infraphon 6611”optical speech equipment was licensedby the Federal Post Office, and couldtherefore be operated without any licenseor fee. A permit was still required if theremote station was not on the sameproperty.In 1967, Conrad Electronic developedthe “NORIS 6611 optical speech equip-ment”. It was sold in pairs for DM59.50in kit form and for DM110 as a finishedunit The “JO 4.01 optical speech equip-ment” was produced in the D.D.R. in1985, it contained a “diaphragm” whichcould be used for recording.With the coming of the laser, radioamateurs also began to intensify theirexperiments, often only in order to set upa one-way link to receive telegraphy.No official licenses appear to have beenissued, either there were simply no appli-cations submitted, or a decision wastaken on principle to issue no licenses.(Please contact the author via the pub-lishers if you have any information onthis).At least one license was applied for inthe D.D.R., the applicant being informeda year later that the application had beenrejected.In the sixties, experiments were carried


15

out with Manfred (now DD6VGM) in-volving filament bulbs, which veryquickly led to the conclusion that aminimum level of optical knowledge anda minimum expenditure on the mechan-ics is necessary to obtain consistent re-sults.The first fee paying licence was issuedfor radio experiments in the optical rangeof 400 to 420GHz on 10th June, 1996, toMichael Kuhne, DB6NT, and a later oneto Helmut Neidel, DL1IN. On 6th Janu-ary 1998 the two of them created theirfirst link at 411GHz. Michael Kuhne didnot use an LED, he used a Russianbeam-lead diode, which was mounted atthe focal point of a 16cm mirror. Thisacted as a nine times multiplier of theoriginal quartz signal during transmissionand as a mixer diode during reception.Helmut Neidel used a 51.4GHz Gunnoscillator signal in a mixer PLL, follow-ing eight times multiplication and a 4λ“long wire” the same diode illuminated a16cm Fresnel lens.My own attempts to gain licences in thenineties simply made no progress, al-though suitable provisions were made bythe BAPT for commercial use.Things really began to move forward in1997, when a friend was found (RainerWilhelm, DH7RW, in BAPT Abstract123). Links could be established at fre-quencies exceeding 300GHz under verygood clear conditions. The first licencewas issued on 22nd June 1998, and thecallsign DA5FA was allocated. Follow-ing the later allocation of callsignDA5FB to Hans (DL7VJB), a two-wayA2A link was established, on a lovelysunny day, on 5th June, 1999, over adistance of 680m. Since a station con-sisted of a separate transmitter and re-ceiver, tuning to the remote station wasvery tedious. The quality of the link ledme to think that there must be sufficientreserves available for greater distances.I subsequently worked alone, usinghouse walls and, in the hours of dark-ness, and listened to foliage of a poplar,

as at a distance of 140m. FM experi-ments with a modified ELV kit at 30kHz/60kHz and again at 30kHz, were carriedout in the middle of 2000. The resultswere documented and were also madeavailable as “specifications” to other ra-dio amateurs.Hellmuth Cuno (DL2CH) developed theFM link further, and managed to create acomplete laser transceiver. My areaswere the mechanics and optics required,the basic principles and regulations forcontests, and the regulations for neigh-bouring countries.With regard to the approval required,conditions were subsequently adjustedthrough practice and experience, andapproval became possible without theallocation of a special callsign.

2.Basic principles

2.1. Wavelengths and frequencyrangesThe optical range begins at 300GHz,which corresponds to a wavelength of1mm. Specifying the wavelength is nor-mal for the practical frequency specifica-tion and thus the band description do notcoincide with the wavelength specifica-tion in every case. The Ångström shouldno longer be used as a unit of measure-ment. Current bands are listed in Tables1 to 3, without reference to nationalrestrictions.In order to avoid any clashes that mightarise, the band classification shownshould be used. The gaps between 3µmand 12µm, or 760nm and 780nm, may benecessary for reasons of classificationuntil the IARU can impose a clarificationthroughout Europe, or all over the world(?). They are available for amateur radio,insofar as national restrictions do notapply (Table 3).


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Table 1 : Europe [5]

300GHz - 100THz 1mm - 3µm Infrared C100THz - 214THz 3µµµµm - 1.4µm Infrared B214THz - 384THz 1.4µµµµm - 780nm Infrared A384THz - 750THz 780nm - 400nm Visible750THz - 952THz 400nm - 315nm Ultraviolet A952THz - 1071Thz 315nm - 280nm Ultraviolet B107THz - 1667THz 280nm - 180nm Ultraviolet C

Frequency Wavelenghts Description

Table 2 : USA [20]

300GHz - 25THz 1mm - 12µm FIR (Far Infrared)25THz - 214THz 12µµµµm - 1.4µm IR (Infrared)214THz - 394THz 1.4µµµµm - 760nm NIR (Near Infrared)394THz - 750THz 760nm - 400nm VIS (Visible)750THz - 3000THz 400nm - 100nm Ultraviolet


Table 3 : Reception [5]

300GHz - 25THz 1mm - 12µm100THz - 214THz 3µµµµm - 1.4µm Infrared B214THz - 384THz 1.4µµµµm - 780nm Infrared A384THz - 750THz 780nm - 400nm Visible preferred

660nm ± 15nm750THz - 952THz 400nm - 315nm Ultraviolet A952THz - 1071Thz 315nm - 280nm Ultraviolet B107THz - 1667THz 280nm - 180nm Ultraviolet C

Note for all tables: Band descriptions are in bold



17

The verbal descriptions are a small selec-tion from descriptions that sometimescontradict each other. In order to avoidthe duplicated use of a wavelength and/ora frequency for 2 adjacent bands, the “>”sign was used.

National restrictionsThe following restrictions apply in the300GHz band, the operation of amateurradio equipment on the following fre-quencies will not be permitted in Ger-many in future, so please take this intoaccount now:

300GHz to 444GHz453GHz to 510GHz546GHz to 568GHz623GHz to 711GHz730GHz to 732GHz795GHz to 909GHz926GHz to 945GHz951GHz to 956 GHz

2.2. Modes and types of transmissionA list of the modes and sound frequen-

cies used can be found in Table 4 below.The 625Hz frequency was selected inorder to reduce interference from themains (50 / 60Hz) and its harmonics at(100 / 120Hz), for example, from illumi-nation. The effect of the magnetic inter-ference from the mains frequency withits harmonics, e.g. during experiments inbuildings, is reduced.

2.3. Signal strength specificationIt is not practicable to specify the inputvoltage for the “S-Meter” in relation tothe input resistance. It is important, andhelpful, to include the input power.Above 30MHz, 5µV into 50Ω corre-sponds to an S-Meter reading of S9. Thisgives an input power of 5 x 10-13W,corresponding to 500pW.However, specifying the input poweralone still says nothing about the “fieldstrength” present at the receiving point.It is expedient to relate the input powerto the reception area, which gives the“field strength”. Thus the remote trans-

Table 4 : Operating and transmission modes.

AM Telegraphy Rx: 625Hz Optimal low frequency bandwidthdependant on speed

Tx: 625Hz ±1Hz Square wave 1:1 medium power A3modulation

AM Telephony Rx: 350Hz - 2.7KHz Low frequency bandwidth 2.35KHzTx: 350Hz - 2.7KHz Speech

FM Telegraphy Rx: 32.769KHz Fixed frequency between 32 and 38KHz625Hz High frequency bandwidth 3KHz625Hz Optimal low frequency bandwidth

dependant on speedTx: 32.768KHz Carrier adjustable between 32 and 38KHz

625Hz ±1Hz Sound modulation index 2

The modulation index for telephony has not been optimised

FM Telephony Rx: 32.768KHz Fixed frequency between 32 and 38KHzHigh frequency bandwidth ?KHzOptimal low frequency bandwidth2.35KHz

Tx: 32.768KHz Carrier adjustable between 32 and 38KHz350Hz ±2.7Hz Speech


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mitting station can determine the inten-sity of irradiation from itself at thereceiving point. You should determinewhether there may be a risk to your eyes.So we return to what was normal inamateur radio by specifying of the re-ceived field strength, and move awayfrom specifying the input voltage [17].This means that specifying the signalstrength for the remote station is moremeaningful, and the receiving pointknows the sensitivity of the receiver thatis being used. To specify signal strengthto two decimal places in the RST/Msystem, the radiation is measured in theusual 6dB steps. The description shouldsimply be left to the RST/M system.With a high irradiation, the suffix (+ xdB) is required. The reception of weaksatellite signals has been taken into ac-count.If we take dm² as the reception area, or around area with a diameter of 1.13dm,we obtain the readings below. Here weare in the range of specifications S 1 to S9 only for very sensitive receivers, andotherwise we are at S 9 + x dB.Perhaps this will start people thinkingabout putting more energy into develop-ing increasing receiver sensitivity:

S 1 7.63 x 10-16 W/m²S 2 3.05 x 10-15 W/m².S 3 1.22 x 10-14 W/m²S 4 4.88 x 10-14 W/m²S 5 1.95 x 10-13 W/m²S 6 7.81 x 10-13 W/m²S 7 3.13 x 10-12 W/m²S 8 1.25 x 10-11 W/m²S 9 5 x 10-11 W/m²

The S0 specification indicates that nomeaningful data can be obtained.The receivers S-Meter can be calibratedat no great expense see also vacuumrange.

2.4. Signal generationA laser does not have to be used as the

transmitter, even if the classification re-fers to laser classes [5]. An LED, an LEDgroup or another source may need to beallocated to a laser class to make thecorresponding risks apparent. This alsoapplies to transmitters that are driven byfrequencies below 300GHz or generatetheir signals in another way.

2.5. Laser classesIf we purchase laser diodes, laser point-ers or laser diode modules, we find alaser class specified on the equipment, orsome other indication of possible risks.This has also begun to happen withLEDs.The laser classes are clarified in DIN EN60825-1, with particular reference to anypossible health risk to the eye. Thelicence to use a laser class includes thecorresponding indications regarding thesafety required.The specification of the maximum poweras a limiting value, normal in amateurradio, is useful only under extreme con-ditions, due to the physiological effect inthe optical range, and so is meaningfulonly in special cases for the radio ama-teur. Depending on the conditions, forlaser class 3B, a power level of between1.58mW and 150MW is permissible forour experiments. For an emission lasting1ns, we can probably not carry out aQSO, but we can receive a reflectionfrom a remote sphere in the sky.The following numerical values do nottake any modulation and/or keying intoaccount. They are based on continuouswave power plotted against the angle ofradiation, the duration and the wave-length, which is not given in full in everycase. This is a simplified representationbut the corresponding standard (DIN)should be utilised in every case, in orderto detect the framework conditions.Limiting value for accessible radiation,abbreviated to GZS (Grenzwertzugänglicher Strahlung), see Tables 5and 6.


19

2.6. Daytime visibility rangeMeteorological visibility, as observed inweather stations, is defined as the great-est distance from which a black object ofsufficient size (angle of vision 0.5° to 5°)can be seen against the horizon with thenaked eye and at which it's outlines arerecognisable. Telescopes and the likemay not be used here.A normal pencil at the end of an out-

stretched arm can be seen at an angle ofvision of approximately 0.5°.Television masts, church towers, highchimneys, monuments, etc. can be usedas visual markers.The “black object” in the above defini-tion should not be taken too seriously.The difference in luminance is a physi-ological factor in visual observation. Thehuman eye recognises a difference if theobject has about 95 to 98% of the

Table 5 : Old version of Laser Classes. (March 1997, expires 1/1/2004)

Laser Class 1Sources that are safe under reasonable operating conditions

λ660nm α < 11mrad t 1ks at 125µWλ940nm α 5mrad t 1ks at 360µWλ400 - 550nm α < 11mrad t > 10ks - 500min GZS 3.9µWλ550 - 700nm α < 11mrad t > 10ks - 500min GZS 3.9 - 125µWλ700nm - 1.05µm α < 11mrad t > 1ks - 500min GZS 120 - 600µWλ 1.05 - 1.15µm α < 11mrad t > 1ks - 500min GZS 600µWλ 1.15 - 1.4µm α < 11mrad t > 1ks - 500min GZS 4.8mWλ 1.4 - 4µm α < 11mrad t > 10s - 500min GZS 10mW

Laser Class 2Sources of visible light only, in the range from 400nm to 700nm. In this range the eyeis protected by natural reflex reaction.

λ400 - 700nm α < 11mrad t > 10s at 1mW

Laser Clas 3ASources of visible light as in class 2 or other wavelenghts, viewed directly usingoptical aids (binoculars, telescope etc.) can be dangerous.

λ400 - 700nm α < 11mrad t > 10s - 500min GZS 5mWλ700nm - 1.05µm α < 11mrad t > 1ks - 500min GZS 0.6 - 3mWλ 1.05 - 1.15µm α < 11mrad t > 1ks - 500min GZS 3mWλ 1.15 - 1.2µm α < 11mrad t > 1ks - 500min GZS 3 - 8mWλ 1.2 - 1.4µm α < 11mrad t > 1ks - 500min GZS 8mWλ 1.4 - 1mm α < 11mrad t > 10s - 500min GZS 50mW

Laser Class 3BSources that are usually only safe when viewed as diffuse reflections. A beam fromthe source is usually dangerous.

λ400nm - 1mm α < 11mrad t > 10s - 500min GZS 500mW


20

luminance of the background (the hori-zon). The reference value for visibility isthe horizon, even if it's luminance ischangeable, e.g. for the morning sky andevening sky in the East or the West.The range reported at a weather station isthe worst visibility at any compass pointon the horizon, so there should be poorvisibility over approximately a 30degreesector. The code 89 in the SYNOP codefor visibility (VV) means, “visibility ex-ceeds 70km”. If we look at this critically,the very fine sub-division of visibility inthe weather code is not adhered to at allweather stations. The range of visibilityhas no decisive significance for theweather forecast. Yet the differences invisibility are taken very seriously forvisibility ranges of up to approximately5,000m, since they are particularly im-portant for flying (visual flight).

2.7. RangeIn the following, daytime visibility rangeis understood as having the meteorologi-cal definition given above, so visibilityrange does not necessarily refer to seeingan object.It makes sense to be within the visibilityrange to begin with. Eyesight, the lasersfrequency and the frequency dependentsensitivity of the detector, the attenuationproblems in the atmosphere due to watervapour, carbon dioxide and other gasesin the infra red are the criteria. Theatmosphere is always a non-homogenousmedium as the distance increases, due tothe different temperature layers. Thelight beam becomes “curved”, even ifonly the effects of this can be observed.This often happens when making meas-urements using a theodolite in cities,therefore these measurements are there-fore restricted to short distances. For thisreason, measurements over greater dis-tances are carried out on 2 days with asmuch variation in the weather as possi-ble. Links parallel to the ground at thenormal distance can be extremely mis-leading, so please choose the right links

for experiments.If the stations are 20m above the ground,the beam is displaced, at a distance of6km, by 1m in the course of a day. At aheight of 4m, the displacement is 5.1m,and at the standard height of 1.5m. it isconsiderably more. The displacementchanges with the distance, double thedistance equals four times the displace-ment! As long as your eye is on thefinder and your finger is on the sightingdevice, or as long as effective control canbe exercised using a 4 quadrant detectoror the like, the process can and will bestabilised.It is usually not possible to distinguishwhether the “mechanics” and/or the op-tics and/or the atmosphere has/have“moved”. So reliable links can be usedonly up to 3km (5km), but then they canbe used almost permanently. As theheight increases, the attenuation is re-duced more and more. At a height of4,000m, the attenuation is only 1/1000 ofthe attenuation at sea level. For thisreason, no attempt was made to carry outprecise observations concerning theweather, the height and other parametersto determine the range. This would beoutside the framework and would be oflittle use in practice, since we are in factworking in “real time”.It is expedient to specify the vacuumrange. For a daytime visibility range of500km, 99% of the vacuum range isobtained. If we take the equipment pa-rameters as given and use the equipmentsensibly, the range depends on theweather and the condition of the atmos-phere. A pre-condition is that the siteshave been sensibly selected. Informationin [1] is highly recommended. It containscomprehensive basic principles, withcomprehensive calculations and alsomeasurements for Berlin, Karl-Marx-S-tadt (Chemnitz), Dresden (highest attenu-ation), Greifswald, Leipzig andWarnemünde (lowest attenuation).


21

Table 6 : New version of Laser Classes (Issued November 2001, valid inGermany since 1st November 2001).

Laser Class 1Sources that are safe under reasonable operating conditions.

λ315nm - 400nm t 1ks - 500min GZS 7.9µWλ1.4µm - 4µm t 10s - 500min GZS 10mWλ4µm - 1mm t 10s - 500min GZS 1000W/m2

Laser Class 1MSources that are safe under reasonable operating conditions except when opticalequipment is in use.

λ315nm - 400nm t 1ks - 500min GZS 7.9µWλ1.4µm - 4µm t 10s - 500min GZS 10mWλ4µm - 1mm t 10s - 500min GZS 1000W/m2

Laser Class 2Sources that are safe under reasonable operating conditions. Eye protection normallyensured by lid closing reflex.

λ400nm - 700nm α <1mrad t>0.25s GZS 66.7mW

Laser Class 2MSources that are safe under reasonable operating conditions. Eye protection normallyensured by lid closing reflex except when optical equipment is in use.

λ400nm - 700nm α 100mrad t>0.25s GZS 66.7mW

Laser Class 3RSource that could be dangerous if anyone looks directly into the beam.

λ315nm - 400nm t 1ks - 500min GZS 40µWλ1.4µm - 4µm t 10s - 500min GZS 50mWλ4µm - 1mm t 10s - 500min GZS 5000W/m2

Laser Class 3BSource that are normally dangerous if anyone looks directly into the beam.


22

Attenuation at 920nm per km. for:50%-70% of time attenuation <1.3dB82%-90% of time attenuation <4dB98%-98.5% of time attenuation <40dB

A 99.9% certainty for transmission in theopen air is possible only over a fewhundred metres at an acceptable cost.Equipment for serious users is commer-cially advertised and used only at dis-tances of up to 3km and in exceptionalcases up to 5km.As radio amateurs, we must use the timesand the weather when the attenuation isrelatively small.Range specifications for a combinationof transmitter and receiver (Tx/Rx) arerarely meaningful, since the specifica-tions for this usually do not include theweather and the attenuation required, orelse they can not be reproduced.For commercial equipment in the DDR,ranges were specified at a visual range of5km and a signal-to-noise ratio of 10dB.For the JO 4.02 unit (specified range5km), this gives a range of 15km for avisual range of 70km. The vacuum rangeis 20km for the signal-to-noise ratiomentioned. This gives a considerablygreater range under amateur radio condi-tions. It is necessary to specify thevacuum range because this completelydispenses with the weather and thus theatmosphere. It is expedient if it is basedon equipment with the same characteris-tics as the remote station. The vacuumrange can be calculated theoretically ordetermined practically.If you can not use a second transmitter,receiver or transceiver of the same type,a combination can be used. This might bea telescopic sight, LED/Laser diode mod-ule with a short length, so that you canignore the attenuation. Good visibility isneeded and it is important that the radia-tion cross-section of the transmitter ex-ceeds the receiver area. It must be possi-ble to reduce the receiver area by adefined amount, for example by means ofa 3 section screen. Once contact has been

made, the receiver area should be re-duced while the signal received corre-sponds to the values expected for thesignal-noise ratio and the limiting range.At first the maximum daylight visibilityrange was given for VV = 89 as >500km.It is anyone’s guess why it was changeddown to 70km. With a daytime visibilityrange of 18km, for two items of equip-ment with different vacuum ranges of30km and 100km, a relative range isobtained usually only a range describedas being of 10km or 16km. The longerthe vacuum range, the closer the relativerange comes to the visibility range. Ifyou can see the remote station, that doesnot always mean that you can also workwith it, and vice versa.

To be continued.

X.References

[1] Kube, Erhard: News transmissionusing light beams in the atmosphere,VEB Verlag Technik, Berlin Nachrich-tentechnik, vol.19 (1969), no. 6, pp.201-207[2] Greil, Peter, DL7UHU: Appendix:The right location, CQ DL, (2001) no.12,pp 908, 909[3] Megla, Gerhard: News transmissionusing very high frequencies, Fachbuch-verlag Leipzig, (1954)[4] Galasso Mario, Gaticci Mario: LARADIO GRIGIO-VERDE, pp. 185ff.[5] DIN EN 60825-1[6] Greil, Peter, DL7UHU: Transceiversfor the 394 ...750 THz-Band, CQ DL(2001) no. 8 pp. 605[7] Greil, Peter, DL7UHU: Funkamateur(2001) no. 10 pp. 10201023.


23

[8] Schwarz, Hans, DK5JI: The radioamateurs yearbook[9] Franke, Michael: Receiver head forminimum luminous power, radio fernse-hen elektronik, 38 (1989) no. 6 pp. 398[10] Hüster, Herbert, DL1ZBP: DARCpaper on future technologies: E-Maildated 07.10.2001, DWD: Guidelines fortraining in German meteorological serv-ice, no. 6: Instrument news, 2nd edition,Offenbach am Main, 1973[11] Cuno, Hellmuth, DL2CH: Proceed-ings of 46th Weinheimer VHF Congress2001, pp. 5.1 5.11, CQDL 10/2001 pp.727 - 730, 11/2001 pp. 810, 811. AATiSe. V., Praxisheft 12, pp. 102-109,[12] Drischel, H.: The human pupil appa-ratus - a biological intensity regulator, inOppelt/Vossius: The human being asregulator, VEB Verlag Technik, Berlin,1970, p. 113[13] Müller, Winfried: Optoelectronictransmitters, receivers and couplers,Militärverlag der DDR (VEB), 1986, p.37[14] DUBUS 1/2000, p. 46[15] DUBUS 3/2001, p. 35[16] Bergmann, H.: 100 years of opticalnews technology, radio fernsehen ele-ktronic, 29 (1980) no. 10, p. 633[17] Fuchs~Fasching: Signal book forshortwave traffic, second edition (revisedand supplemented), Vienna 1929[18] Stahl, Konrad; Miosga, Gerhard:Infra-red technology Heidelberg: Hüthig,1980; p. 163[19] Zimmermann, Erich, HB9MIN: VH-F-UHF 2002, Munich, 9. 10. March2002, Proceedings of 14th Congress ...,Upper Bavaria District in DARC, pp. 71- 76[20] Lilburn R. Smith, W5KQJ: AmateurCommunications Using Lasers[21] Reg TP, Letter dated 24.04.2002

[22] Kainka, Burkhard: Elektor 6/2002,LED power lamp, regulation through100-Ohm potentiometer to battery[23] Kondraschkow, A. W., Electro-opti-cal range finding, VEB Verlag für Bau-wesen - Berlin 1961, pp. 261 ff[24] Isaac I. Kim, Bruce McArthur, EricKorevaar, http://www.opticalaccess.com[25] Kube, Eberhard, Dipl.-Ing.: Finalreport, INT Berlin, 1969[26] Dr.-Ing. Klaus Sander, Modulatabledrivers for almost all laser diodes.Funkamateur 51 (2002) no. 8, pp. 804 -806[27] Meier, Alexander, DG6RBP; Pro-ceedings of VHF Congress Weinheim2002, pp. 17 ff[28] Cuno, Hellmuth, DC2CH: Simpletester for laser diodes, CQDL 11/2002,pp. 810, 811


24

1.Why make your owntransceiver for the 2 meterband?

In fact the purpose of this transceiver isto drive an SHF transverter and to re-place the familiar IC202 used for thisjob. This old friend is a very simple,robust, low phase noise rig, without thebells and whistles found on modernequipment. My IC202 is at the end of itslife after years of transporting to the topof mountains so it is time for a replace-ment.The aim of this design is to get the samegood characteristics as the older one withsome useful additional accessories.

2.Specifications

We need to cover the most frequentlyused range for an SHF tunable IF,144.000 to 144.200MHz. As for theIC202, we will use a VCXO to get thesame low phase noise characteristic. Aset of four crystals provides four rangesin accordance with our needs. A fre-

quency meter is useful to arrange acontact on a given frequency. The sensi-tivity required is not as critical as for anEME receiver. It is very convenient tohave variable selectivity to improve thesignal/noise ratio mainly in CW. A stableand accurate S meter is needed to allowreliable signal strength reports. The audiooutput power must be high enough toovercome the ambient QRM when wework with a team! For the transmitter onewatt power output (+30dBm) is enoughto drive an SHF transverter in CW andSSB modes. Some accessories are desir-able to make contacts easier, a “roger”beep at the end of the message, “dots” toidentify a very weak signal and a “par-rot” for calling CQ.One important thing is the ergonomics.When we are at the top of mountains andit is freezing we have to wear gloves orto have numb fingers. In both cases it isvery uncomfortable to manage with verysmall push buttons. Therefore, our trans-ceiver must have large knobs!

3.Principles

It would be easy to retain the samearchitecture as the one used in the IC202:

André Jamet F9HX

2m Direct ConversionTransceiver


25

Receiver with:

• A simple conversion with a 10MHzintermediary frequency including acrystal filter, followed by a productdetector

Transmitter with:

• SSB generation by filtering, using thesame filter as in receiver.

The direct conversion with ZIF (zerointermediate frequency) has recentlyfound its way into wireless and cellularmobile communications systems. Since itis in the aim of amateur radio to investi-gate new fields, I thought it could beinteresting to try the direct conversionconcept with a 2m transceiver. As far Iknow, the only work in this field hasbeen done by S53MV who describedWeaver based transceivers for 1.3, 2.3,5.7 and 10GHz [1].

4.Description

The block diagram (Fig 1) shows twosections, receiver and transmitter. Thecommon circuits are the local oscillator,the power supply, the auxiliary circuitsand the antenna relay.For receive, the antenna is matched to alow noise FET by a simple LC circuit.The output is fed to an MMIC through abandpass filter. This is followed by aMini Circuits demodulator that generatesI and Q audio signals. Two identicalchannels amplify these to give a com-pressed and filtered signal. These consistof a two stage AGC amplifier withpass-band filtering. These feed Hilbertfilters providing different phasing to pro-duce the single side band required afteradding.An elliptic 8th order filter using a capaci-tor switching IC gives an adjustablebandwidth from one to three kilohertz. A

one watt audio amplifier ensures a loudsignal from the speaker.The demodulator is fed by the LO thatconsists of four VCXO switched fromthe front panel and multipliers to get aVHF signal at the receive frequency. Ahigh dynamic range logarithmic IC isused for the S meter.In the transmitter, modulation is obtainedfrom a microphone or a one kilohertzsignal for CW, TUNE or DOTS, thesesignals being produced by an auxiliaryoscillator. A compressor stage is in-cluded to improve the efficiency andavoid splatters. A Voice Record andPlayback IC allows a twenty secondsmessage for CQ.

5.Construction

The photographs (Figs 2 - 4) show thatthe transceiver is housed in a case largeenough to hold eight PCB including threethat are shielded for the VHF, LO andfrequency meter PCBs. A 4 to 5 inchloudspeaker is fixed to the top of thecase. Many holes ensure suitable ventila-tion. All knobs to be used during acontact are located on the front panelwith an LCD display for frequency andthe strength signal. On the rear panel,there are knobs and jacks not often used.

6.Result

Compared to the old IC202, the actualsensitivity is at least equal, -120dBm for10dB S/N ratio. Accessories are a veryconvenient plus. The modulation qualityis very good and efficient both for re-ceive and transmit. The carrier and unde-sirable side band emissions are in line


26


27

Fig 2 : Photograph of the completed 2m direct conversion transceiver.

Fig 3 : Photograph showing the internal construction of the 2m directconverasion transceiver.


28

with common practice.The use of the transceiver as a receiverfor 144MHz gives two familiar prob-lems. As in all direct conversion receiverwe can see the LO injection at theantenna. In fact, it is not illegal since thesignal is our band and the level is quitelow. On the contrary, in a classicalsuperhet, the LO is not in an amateurband and any radiation is illegal! Thesecond drawback is a lack of protectionagainst very strong signals in or out ofthe received band. This is due to a poorlinearity of the demodulator and it isdifficult to improve it.When used to drive a transverter, none ofthose problems are significant and ourchallenge is won!

7.Conclusion

The aim of this article is not to give fullconstructional detail of the transceiversince it would take to much space inVHF Communications! For those inter-ested, a comprehensive one hundred pageFrench document is available on thefollowing web site http://perso.wana-doo.fr/f5cau with a mailing facilitythrough [email protected]. The documentincludes all circuit diagrams, PCB draw-ings, photographs, details of construc-tion, list of suppliers for special compo-nents, advice for adjustment and result ofmeasurements is available. A more com-prehensive version of this article is dueto be published in a new RSGB publica-

Fig 4 : Photograph showing the rear panel of the 2m direct conversiontransceiver.


29

tion called Practical Microwaves, beingedited by the editor of VHF Communica-tions. The transceiver contains two PICmicro controller, one for general controland one for the frequency counter. TheHEX code for these two PICs can bedownloaded from the VHF Communica-tions web site.

8.References

[1] No-tune SSB transceivers for 1.3,2.3, 5.7 and 10 GHz, S53MV, Dubus, 3,41997 and 1,2 1998 and RSGB/ARRLInternational Microwave HandbookISBN 1-872309-83-6[2] Un transceiver 144 MHz … pour lesSHF, F9HX, Radio-REF December 2001

Fig 5 : Picture of the author, André Jamet, F9HX/P, and F6BEG/P, 27th May2001, Mont Pilat, France (JN25HV), operating on 144MHz and 10GHz.


30

Index of Volume 34 (2002)

Article Author Edition Pages

2m BandFM Receiver For Miroslav Gola, 2002/3 130 - 150137 - 141MHz OK2UGS

2-Tone Generator For Wolfgang Schneider, 2002/4 216 - 227145MHz DJ8ES

47GHz BandAmplifier For 47GHz Sigurd Werener, 2002/3 160 - 164Using Chip Technology DL9MFV

Amateur TelevisionVideo Signal Recognition, Alexander Meier, 2002/4 232 - 241ATV Squelch DG6RBP

Antenna TechnologySimple Speed Control Michael Kuhne, 2002/2 66 - 68for Rotators DB6NT

Audio Frequency TechnologySpeech Store With Wolfgang Schneider, 2002/2 87 - 94Integrated Sequencer DJ8ES

FiltersModern Design of Stripline Gunthard Kraus, 2002/1 35 - 62Low Pass Filters DG8GB

FundamentalsS12 Geoff Pike, GI0GDP 2002/2 111 - 115

An Interesting Program, Gunthard Kraus, 2002/2 69 - 85MSTRIP40 DG8GB

The Sensitivity of Radio Prof. Gisbert 2002/2 95 - 104Equipment Glasmachers


31

The Transmission Of Wido Schak 2002/3 151 - 159Electro-Magnetic Wavesin Rectangular Waveguides

Determination Of Received Gunthard Kraus, 2002/4 194 - 202Field Strengths In UHF DG8GBRange

Measuring TechnologyA Simple Proceedure for Dipl. Ing. Detlef 2002/1 17 - 21Measurements Burchard

Frequency Generator Wolfgang Schneider, 2002/1 2 - 16(Wobbler) to 4GHz DJ8ES

Pre Divider (:10) up to 5GHz Alexander Meier, 2002/1 22 - 26DG6RBP

A Simple Noise Figure Meter Carl G Lodstrom, 2002/2 105 - 110KQ6AX

Direct Mixer for a 1-65MHz Wolfgang Schneider, 2002/2 120 - 123Short Wave Synthesiser DJ8ES

Precision Directional Coupler Bernd Kaa, 2002/3 165 - 174For Matching Measurements DG4RBF

2-Tone Generator For Wolfgang Schneider, 2002/4 216 - 227145MHz DJ8ES

Frequency Indicator For Robert Tyrakowski, 2002/4 243 - 250Portable Radio Equipment DK7NT

MiscellaneousInternet Treasure Trove Gunthard Kraus, 2002/1 28 - 29

DG8GB

In Memory of Eberhard L Smolka, 2002/2 116 - 118Alois Pendl, OE6AP DB7UP

International Microwave Andy Barter, 2002/2 125Handbook G8ATD

Internet Treasure Trove Gunthard Kraus, 2002/2 126 - 127DG8GB

CW Modulator Using Wolfgang Schneider, 2002/3 176 - 180Pin Diodes DJ8ES


32

BALUNs For Microwave Winfried Bakalski, 2002/3 181 - 187Applications Part 1 DL5MGY


BALUNs For Microwave Winfried Bakalski, 2002/4 203 - 214Applications Part 2 DL5MGY

Problems with Running Puff Gunthard Kraus, 2002/4 229 - 231On Windows 98/ME/XP and DG8GBhow to eliminate them


Weather Satellite ReceptionFM Receiver For Miroslav Gola, 2002/3 130 - 150137 - 141MHz OK2UGS

A complete index for VHF Communications from 1969 to the current issue isavailable on the VHF Communications Web site - http://www.vhfcomm.co.uk.The index can be searched on line or downloaded in pdf of Excel format so thatit can be printed or searched on your own PC. If you are not connected to TheInternet you can write or fax K. M. Publications for a printed copy of the indexwhich will cost £2.50 plus postage.

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Fax +44 (0)1582 581051


33

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34

This article describes a simple designfor a 76GHz transmitter. It comprisesa multiplier circuit from 9.5 to 76GHzand a final amplifier, built with justtwo semiconductor chips from UnitedMonolithic Semiconductors. The out-put is relatively broadband giving14mW at 76,032MHz. The article dem-onstrates the extraordinary efficiencyof this new chip technology plus theminiaturisation of the construction.

1.Introduction

In my scientific work, I am concernedwith the non-thermal effects of modu-lated high frequency [1]. Due to possible“molecular resonances”, the range be-tween 70 and 80GHz is of special inter-est. To be able to research this a suitablesignal source is needed such as a Gunnoscillator. Unfortunately these have asmall “pullable” range (frequencychange). This meant that we needed touse a standard low frequency OCXO(around 100MHz) with a suitable fre-quency multiplier.The frequency multiplier described be-low (9.5 to 76GHz) with integrated finalamplifier is a typical spin-off productfrom this scientific project. It is demon-strated that, with just a very few GaAs

semiconductor chips, efficient signalsources can be manufactured for thisfrequency range (both broad band andnarrow band). They are very suitable, forexample, as GHz radio beacons, butaccess to “Bond technology” is a pre-condition for their manufacture.

2.Concept and selection ofsemiconductors

The block diagram for this design isshown in Fig 1, it comprises:

• A stable OCXO with an outputfrequency of 99MHz e.g. the designby DF9LN [2], which is very popularwith radio amateurs.

• A frequency multiplier to 9.5 GHze.g. a modified version of the designby DB6NT [3].

• An eight times multiplier circuit to76GHz with an integrated finalamplifier.

Since the first two blocks are alreadydocumented [2, 3] and are already famil-iar to most microwave constructors,therefore only the last block is describedbelow.This multiplier, from 9.5 to 76GHz uses

Sigurd Werner, DL9MFV

Frequency multiplier for 76GHzwith an integrated amplifier


35

just two semiconductor chips fromUnited Monolithic Semiconductors(UMS).The feed frequency of 9.5GHz is firstquadrupled, using the CHX 2092a chip,to 38GHz. Then the signal is doubled to78GHz by the CHU 2277 chip, andfinally the signal obtained is amplified.Both GaAs multipliers were initially as-sembled separately and their perform-ance is described in the following sec-tion.

2.1 10 - 40GHz frequency multiplier:Type CHX 2092aThe multiplier works with feed frequen-cies of 8 to 10GHz. The signal is doubledtwice here and finally amplified [4].Monitoring the output signal with aspectrum analyser (HP 8565A and mixer11517A), shows that the basic frequency(e.g. 9.5GHz) and the third harmonic areattenuated by more than 25dB. The sec-ond harmonic is suppressed by at least afurther 15dB (in ratio to the 38GHzsignal). This gave grounds for hopingthat a 38GHz output filter could bedispensed with.An output of 6mW was obtained withoutany trouble from a drive input of ap-proximately 15mW at 9.5GHz. The biasvoltage supplied to gates 1 and 2 wasminus 0.6V in each case, and to gate 3minus 0.15V. The drain voltage was setat plus 3.6V (60mA; without selection20mA!). A negligible increase in output

tuning and a simultaneous increase in thedrain voltage to 4V (80mA) gives anoutput exceeding 15mW at 38GHz.

2.2 W band multiplier and PA type:CHU 2277A drive power like this would mean thatthis semiconductor was over driven. Itstypical drive power would be less than3mW. In addition to the frequency dou-bler, the chip is also has a four stageamplifier. Due to the internal bias net-work, we only need two voltages [5],minus 3.8 - 4.5V (about 13mA) and plus4.5V (130mA). The chip has two outputports. The power measured at the mainport was approximately 11mW, meas-ured using the Anritsu MP 416Awaveguide head or a calibrated detector,including an isolator from Millitech forthis frequency range. Since only oneoutput signal is needed, the secondaryport was terminated with a 50Ohmdummy load.

3.Eight times multiplier from 9.5to 76GHz

3.1 Mechanical and electricalstructureBased on the values measured in theindividual models, it was decided toconnect the two chips in series with no

Fig 1: Block diagram of a complete 76GHz source.


36

filter. A housing, about the size of amatchbox was milled from brass(35.5mm x 31mm x 13.5mm, Fig. 2) andgold plated. A simple SMA plug with athin connecting pin (0.3mm) wasmounted at the input (9.5GHz),. The76GHz output at the main port of theCHU 2277 is a 50Ohm microstrip on aceramic substrate (1.1mm wide, 0.25mmhigh). This is inserted into a WR-12waveguide (3.1mm x 1.55mm, cut-off

frequency 48GHz) (see Fig 3). Theground plane of the substrate is insertedinto the waveguide (approximately0.9mm long) was ground using a mini-ature mill.The waveguide is made from the twobrass blocks of the housing at this point.A 4/40 screw (diameter approximately2.85mm) is fitted in a small cover, acts asa non-contact piston (see Fig 4).

Fig 2 :Construction ofthe frequencymultiplier in abrass housing. Thepositions of thesubstrates and thetwo semiconductorchips can be seenin the milledchannels.

Fig 3 : Detail viewof the outputcircuit with thecover of thewaveguideremoved.


37

The carrier substrate for the quadruplerchip (9.5 to 38GHz) is a thin (0.25mm)ceramic plate made from aluminium ni-tride (AlN, ε = 9.0). The microstrips arebutted up to the chip surfaces, as in the47GHz project, [6], using transitionpieces. Underneath the chip surface is agroove approximately 2mm deep fittedwith a thin attenuation mat (1mm thick).The AlN substrate was glued onto thehousing using a mat impregnated withsilver conducting adhesive [7].The 38GHz signal is fed through a short

50Ohm microstrip, made from ceramic,to the W band doubler. This chip sits ona miniature platform (height 0.15mm) inthe brass base of the housing, in order tobalance the height difference between thechip (height 0.1mm) and the ceramicsubstrate (height 0.25mm). This chip andall additional substrates were fixed di-rectly onto the housing using silver con-ductive adhesive.The secondary port of the CHU 2277 isterminated with a 50Ohm network (seeFigs 3 and 4). The resistors used for this

Fig 4 : Detail viewof the circuitshowing bothsemiconductorchips and theinterconnections.

Fig 5 : Rear viewof the completedunit showing thewaveguide port.


38

were etched out of the conducting layerof the substrate.The main port is connected to thewaveguide through a short microstrip asdescribed above. The connection for ad-ditional waveguide segments is locatedon the rear of the housing (Fig. 5 and 6).An adjuster screw (M1) in the waveguide part of the housing, about 6/4λfrom the feeder point, had no positiveeffect and was omitted from later assem-blies.The power leads for the chips are firstdecoupled by 100pF single layer capaci-tors and subsequently by 100nF ceramiccapacitors, and are then taken out, usingfeedthrough capacitors (approximately3nF), through the base of the housing.The chips were “bonded” using thermo-compression (supported by ultra-sound)in the so-called wedge-wedge process[6].Because of the relatively low currentconsumption of the semiconductors andthe good thermal conductivity of the AlNsubstrate, and/or of brass, special meas-ures for additional temperature controlcan be omitted.

3.2 ResultsThe following control voltages and HF

lines were selected for optimised drive ofthe multiplier:Quadrupler chip CHX 2092a:

• Gate 1 and 2, minus 0.85V (preciselythe “pinch-off” of the semiconductor)

• Gate 3, minus 0.1V, drain, 3.8V(60mA)

• Drive power at 9.5GHz approxi-mately 4mW.

W Band chip CHU 2277:

• minus 4.8V (approximately 13mA)

• plus 5.0V (approximately 210mA).The signal source is operating almostoptimally under these conditions. Theoutput at 76,032MHz was 12mW. Byfitting small metal lugs (0.5mm x0.25mm!) to improve the chip matching,a higher output of a good 14mW(11.5dBm) was attained.The 13dBm referred to in the data sheet[5] (measured on the wafer!) was thusnot quite attained. By optimising thetransition from the stripline to the WR-12waveguide, and by improving the match-ing of the subsequent waveguide curve,undoubtedly a few more mW can beobtained.

Fig 6 : Rear viewof the completedunit showing theexternal waveguidefitted.


39

It is not necessary to apply attenuationmaterial in the 4.1mm deep “brass bath”since cover effects were scarcely measur-able. The relatively wideband character-istics of the circuit layout is astonishing.The -3dB range of the un-optimisedoutput extends from 72.7 to 78.7GHz(see Fig. 7).Other examples of the signal sourcereached the “sound barrier” of 13dBmoutput and indeed comfortably exceededit, with 14.2dBm (26.4mW).

3.3. Conclusion and future projectsUsing only two semiconductor chips, a9.5GHz signal is quadrupled to 76GHzand amplified to an acceptable outputexceeding 13dBm.An interesting 76GHz transceiver couldbe constructed by combining a suitableW band mixer (e.g. CHM 2179a fromUMS [8]) and using both output ports ofthe CHU 2277 chip.The possibility of using a chip with a Q

band VCO (output frequency 38GHz)and integrated Ku band oscillator(12.7GHz, with subsequent tripler),which are characteristics offered by theUMS chip CHV 2243 [9], is currentlybeing investigated to replace almost allcomponents before the 38GHz doubler.Finally, I would like to thank the numer-ous people who have assisted me andcontributed to making the project a real-ity:

• Mr. Evers and Dr. Hechtfischer(DG4MGR) for very kindly allowingme to work in the clean room

• Dr. Jünemann (DK7AH) for the useof the ceramic substrates

• Most of all Mr. W. Hohenester (allFa. Rohde & Schwarz, Munich), mymentor and helper for all RFproblems, who introduced me to thistechnology.

I would also like to thank J. Ehrlich(DF3CK), who provided support when

Fig 7 : The output characteristic of the un-optimised frequency multiplier.


40

mechanical problems occurred and wasalways available for discussion and con-structive criticism. And finally, I am alsoindebted to M. Münich (DJ1CR, MPI forPlasma Physics, Munich) and Dr.Massler (Institute for Applied SolidBody Physics, Freiburg), who were agreat help to me in calibrating my meas-uring equipment.

4.References

[1] Project at Institute for PhysiologicalChemistry of University of Munich[2] U. Nietschke, DF9LN, Oven stabi-lised XO for VHF, DUBUS 3/1997, pp.36 - 40.[3] M. Kuhne, DB6NT, 12 GHz LO,

DUBUS 2/1996, pp. 5 - 13.[4] Data sheet from United MonolithicSemiconductors, S.A.S.; Ref.: DSCHX20921074, 15th March, 2001[5] Data sheet from United MonolithicSemiconductors, S.A.S.; Ref: DS-CHU22770089, 29th March, 2000[6] Sigurd Werner, DL9MFV, Amplifierfor 47 GHz in Chip technology, VHFCommunications 3/2002 pages 160 - 164[7] Technical Data Sheet, Ablebond. 84-TLMI, Electrically Conductive EpoxyAdhesive, 9/91.[8] Data sheet from United MonolithicS e mic o n d u c to r s , S . A . S . ; Re f . :DSCH21790192, 22nd June, 2000[9] Data sheet from United MonolithicS e mic o n d u c to r s , S . A . S . ; Re f . :DSCHV22431074, 15th March, 2001

VHF CommunicationsBlue Binders

• Attractive blue plastic

• Holds 12 issues (3 years)

• Allows you to findrequired issue easily

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41

Using laser light for communicationhas aroused new interest in amateurradio circles since Hans-HellmuthCuno (DL2CH) published his views[1]. However measuring equipment fordetermining the optical output of alaser is usually very expensive and/orthere are no instructions for assem-bling it as a DIY project. In addition tothe theoretical principles, the articlebelow also describes a simple DIYapparatus for measuring laser output.

1.Introduction

1.1 The optical spectrumThe optical spectrum range begins at awavelength of 100nm with ultravioletlight (UV) and ends after the infraredrange (IR) at 1mm. Between these is therange of visible light, from about 380 to780nm. Fig 1 clarifies this and can alsobe used to identify important laser wave-lengths. This diagram can be down-loaded, in colour, from the Internet. [2]The human eye does not perceive allwavelengths in the visible spectrum withthe same intensity. In the daytime, we seegreen light best at a wavelength of555nm. At night, this is displacedslightly into the blue-green at 507nm. Fig

2 represents the sensitivity of the eye fordaytime and night-time vision, the datafor this can be found in [3]. Now it canbe understood why, in spite of identicaloutput, that we perceive red laser light at635nm to be approximately seven timesbrighter than laser light at 670nm, whichis also red!

1.2 Laser diodesIn order to imprint information onto alaser beam, the beam must be modulated.This is very easily using laser diodes, andmore importantly, it doesnt cost much.This is why laser diodes are used almostexclusively in amateur radio. It should bepointed out that in practice specific lightdiodes are also often used for opticalcommunication. In [4], we find a com-prehensive article describing practicaloperations for communications withLEDs and lasers.In the optical spectrum range, we nor-mally refer to wavelengths in nm and notfrequencies. By contrast in amateur radioit seems that specifying the frequency inTHz is becoming generally accepted.The wavelengths of the most frequentlyused laser diodes are typically 635, 650,670 and 780nm. Table 1 shows typicalapplications.Laser diodes with a wavelength of635nm are very close to the wavelengthof the familiar red, helium-neon gas laser(632.8nm).

Alexander Meier, DG6RBP

Laser output meter


42

Special care should be taken with laserbeams in the near infra-red range. Thehuman eye cannot see this light very well(see sensitivity of the eye, Fig 2), butnevertheless it is focused onto the retina!Even if we see nothing, or just a weakpoint of light, the beam can be powerfulenough to cause serious damage to theeye.Thus the basic principle is that you neverlook into a laser beam, even for wave-lengths outside the visible spectrum!

2.Values and units in photometry

In the measurement of optical radiation,we differentiate between radiometric andphotometric values. In contrast to radio-metric values, photometric readings usethe degree of spectrum sensitivity tomake evaluations (Fig 2).Consequently, photometric values aremainly used for the characterisation oflamps or light diodes. The luminousintensity (light flux per solid angle) isexpressed in candelas, or the intensity oflight (light flux per area) in lux.The power of a laser is measured inWatts as a radiometric value, the so-called radiation capacity, P. The sensorused for measurement must acquire theentire laser beam, i.e. the diameter of thesensor must be greater than that of thelaser beam.Because of its divergence, a laser beam

Fig 1: The optical spectrum frominfrared through visible light to ultraviolet.

Table 1: Typical applications for laserdiodes.

635nm Red DVD player/laser pointer650nm Red DVD player/laser pointer670nm Red Laser pointer780nm Infra- CD player, CD writer

red

Wave- Type Applicationlength


43

has a relatively large beam diameter aftertravelling a great distance. At a distanceof several kilometres, the beam has adiameter of one or more metres. Thus itis no longer possible to easily acquire theentire laser beam with a sensor. Bycontrast, it is possible to measure theoutput per sensor area. This is a furtherradiometric value and is designated asthe intensity of irradiation, E (output perarea). The unit is consequently W per m²or W per mm².The power levels for the laser diodes inmost frequent use are typically between 3and 5mW. These laser diodes are put touse in equipment such as CD players,CD-ROMs, DVDs and laser pointers.Depending on the operating current andthe optics (lenses) used, we typicallymeasure an optical output between 0.5and 3mW for laser pointers, and usuallyfar less than 1mW for CD players. Otherequipment such as laser printers or CDwriters uses laser diodes with a power ofseveral tens of milliwatts.Lasers with an output of less than 1mWare usually relatively harmless. On theother hand, when using lasers withhigher outputs, you should clearly beaware of what you are doing and have asuitable knowledge of protection againstlaser radiation [5,6]. Irrespective of the

output of a laser, the basic principlenaturally applies, never look into thebeam, and certainly not using whenoptical instruments e.g. magnifyingglasses!

3.Laser output meter

Various items of professional measuringequipment are available for optical out-put measurement. Measuring equipmentthat can only measure individual laserwavelengths is frequently described aslaser output measuring equipment. Withmore universal equipment it possible toadjust the wavelength between 400 andover 800nm in small steps e.g. 1nm.These are called optical output measuringequipment.Depending on the application (continu-ous-wave lasers, pulsed lasers, laserswith lower or higher output levels, etc .),there are sensors of varied kinds: bolom-eters, calorimeters, pyroelectric equip-ment, photoelectric equipment, etc.The equipment used for amateur radioconsists almost exclusively of modulatedlow-powered continuous-wave lasers (

Fig 2 : Sensitivityof the eye for daytime and nighttime.


44

<5mW) operating at specific wave-lengths. This considerably simplifies thedevelopment of laser output measuringequipment.The most suitable units for use as sensorsare photo diodes, optical outputs fromthe nW range right up to several mW canbe detected. The problem is that thesensor area must acquire the entire laserbeam to measure the radiation capacity.Also the sensor should not be over-loaded. Thus in practice the choice isusually a large surface photo diode,something like the IPL 10050 [7] with asensor area of 41.3mm². The price ofsuch a diode is about 50euros.If light falls onto a photo diode, a currentflows through it from the cathode to theanode. If we operate the photo diode witha large (infinitely large) load resistor andmeasure the voltage, this increases in alogarithmic relation with the intensity ofirradiation. If, on the other hand, thephoto diode is short circuited, then thecurrent passing through it increases pro-portionately with the density of illumina-tion!Thus short circuit operation is best suitedto the development of output measuringequipment. In practice, we use an opera-tional amplifier for this purpose andoperate it as a current/voltage converter(Fig 3).If we want to measure very low levels ofradiation (nW range), we should use anoperational amplifier with FET inputs,

because of it’s lower input currents. Thephoto diode is located directly betweenthe two inputs. Since the inverted inputforms a virtual earth, the diode is effec-tively short circuited. When the diode isirradiated, a current then flows, depend-ing on the polarity of the diode, from orto node 1. The operational amplifier thenadjusts its output voltage accordingly, sothat the entire current flows through theresistor, R. The size of the resistancedirectly determines the transfer ratio. Forexample, a resistance of 1kOhm gener-ates an output voltage of 1V for aphoto-current of 1mA.One big disadvantage of photo diodes isthe dependency of the photo-current onthe wavelength of the radiation. Depend-ing on the structure of the photo diode, ithas maximum response at approximately800 to 900nm. Fig 4 shows the spectrumresponse for the IPL 10050 photo diodein the visible spectrum range. As theA/W unit suggests we obtain, for exam-ple, a photo-current of 0.5mA with aradiation capacity of 1mW on the sensorarea.To be able to acquire various wave-lengths with laser output measuringequipment, we need a switching option.The four wavelengths that are usuallysufficient for the requirements of radioamateurs are 635, 650, 670 and 780nm.Unfortunately, even with photo diodes ofthe same type, the spectrum responsefluctuates by several percent from photodiode to photo diode. In practice, thismeans that every photo diode (and thusalso every output meter) has to be indi-vidually calibrated!To measure the spectrum response and tocalibrate the equipment, we need anexpensive measurement rig (Fig 5).Using a monochromator, an individual,adjustable wavelength (or a narrowrange) is filtered out of a lamp spectrum.With the help of a subsequent lenssystem, a parallel beam is formed, so thatthe sensor area of the photo diode is

Fig 3 : Current/voltage converteramplifier.


45

completely and uniformly irradiated.Now we measure the density of illumina-tion at the desired wavelengths with acalibrated optical output meter and aknown sensor area, Aref. Then we re-place the sensor of the output meter withthe unknown photo diode (DUT) andindividually measure the photo-current atthe same wavelengths. Since the area ofthis photo diode is also completely irradi-ated we are measuring the photo-currentper sensor area, ADUT. From this, thespectrum response, S, can be calculated:

Due to the high expense, radio amateurscan hardly carry out this measurementthemselves. On the other hand, calibra-tion by a calibration service is much tooprecise for amateur purposes, and theassociated costs exceed 500euros.Another option is to calibrate the output

meter using a diode laser with a suitablewavelength and a known and regulatedoutput. There are only four wavelengthswhere this is more effective than measur-

Fig 4 : Spectral response of the IPL 10050 photo diode from 400 to 800nm:635nm 0.295A/W650nm 0.307A/W670nm 0.326A/W780nm 0.434A/W

DUT

ref

ref

DUT

AA

PIS ⋅=

WA

Fig 5 : Method used to measure thespectrum response of a photo diode.


46

ing each photo diode on the monochro-mator.

4.The simple LPM-10 laseroutput meter

4.1 Circuit descriptionThe circuit diagram of the laser outputmeter is illustrated in Fig. 6. It’s design isvery simple and, with the exception ofthe photo diode, requires no specialcomponents. The measurement range andthe calibrated wavelengths were chosenfor the measurement of laser diodes, asused in amateur radio. This meter is alsosuitable for checking laser pointers ormeasuring the output of a He-Ne gaslaser.D4, the photo diode is in short circuitmode in this circuit. The MAX495 isused as an operational amplifier, it’sinput and output swing covers the entiresupply voltage range (Rail-to-Rail). U2,the voltage regulator reduces the batteryvoltage to 5V to supply the operationalamplifier, it must not be operated at morethan 6V. Other rail-to-rail operationalamplifiers with operational voltages ex-ceeding 5V have proved to be inferior tothe MAX495.C2 acts as a simple low pass filter for thecurrent/voltage converter. It thus pro-duces the average when modulated lasersare being measured. It is not necessary tomeasure the peak value for use in ama-teur radio, and therefore this facility hasnot been provided. Using a moving coilmeter, modulated lasers can be measuredwith modulation frequencies of between50Hz and 50kHz, with a 20 to 80% pulsewidth.The display is calibrated for the wave-lengths in question using the adjustableresistors, R1 to R4. In normal mode, thewavelength is selected using switch S1.

The readings are displayed on a 100µAmoving coil meter scaled for a full-scalevalue of 5mW. A high quality metershould be used. A digital meter has moredisadvantages than advantages in thissituation, readings are displayed with aprecision that is not present, or the valuedisplayed oscillates so much that it cannot be read off if you shake while thelaser pointer is pointed at the sensor.Two suitable small lamps (e.g. T1, 5V/60mA) are wired in series to illuminate themoving coil meter.Switch S2 acts as an on/off switch,illuminates the moving coil meter andalso has a position for checking thebattery voltage. An arc at the end of themeter scale shows the battery voltage, thebattery voltage indicated being between 8and 9V. Should the battery voltage fallbelow 8V, the battery should be replacedto make sure that the voltage regulatorhas a sufficient input voltage.A 9V alkaline battery is used for thepower supply allowing the meter to beused on the move. If it is used exclu-sively in the laboratory, a stabilised 9Vplug in power supply can be used insteadof the battery.The two diodes, D1 and D2, act as areverse battery protection and for isola-tion if the power supply is connectedwhile a battery is installed.To suppress external light interference,the photo diode is mounted at the end ofa 25mm long, black plastic tube. Anadjustable zero point is not required withthis meter.The version described here can beadapted to ones own requirements e.g.for other wavelengths or measurementranges.

4.2 Assembly instructionsInitially all the wired components areassembled on the printed circuit board(Fig 7). The size of the PCB is 100mm x40mm, as shown in the component layout(Fig 8). There are no special features to


47


48

be taken into consideration here.Next, the photo diode is fitted on theround sensor printed circuit board (Fig9). The small marking on the photo diodeidentifies the anode.The sensor board and the main board areconnected by a short piece of RG174 orRG316 coaxial cable.To house the sensor board, a blackplastic tube is prepared, with a diameterof 30mm and a length of 25mm. This hasa 14.5mm hole drilled in the centre. Tomount the photo diode, the tube is turnedinwards a little at one end. Two M2screws are used to fasten both the sensor

board and the sensor tube behind a frontplate. The precise form of the sensor tubecan be left to ones own devices.After an initial function test with a laserpointer, the meter can be calibrated. Thisis most easily done using regulated diodelasers of a suitable wavelength and witha known power.

4.3. Parts listR1-R4 5kΩ Trimmer 64Z,25 turnR5 1.2kΩ 1/4WR6 39kΩ 1/4WR7 47kΩ 1/4WR8 3.3kΩ 1/4WC1,C2,C4,C5 100 nF, MKS-2, RM5

Fig 7 : Printed circuit board layout for the laser output meter (DG6RBP-004).

Fig 8 : Component layout for the laser output meter.


49

C3 100µF 63V, RM5D1,D2 1N4001D3 LED green 3 mm, low currentD4 IPL 10050 [7]U1 MAX 495 + IC base, 8-pinU2 78L05, 5V voltage regulatorS1,S2 Rotary switch, 3x 4 positions2 Knobs for rotary switch1 Holder (Clip) for LED1 DG6RBP meter PCB1 DG6RBP sensor PCB1 Moving coil instrument,

100µA, with 2 small lamps,T1, 5V/60mA

1 Battery compartment for 9Vbattery

1 DC socket 2.5mm1 Plastic tube for sensor5-10 cm RG-316

4.4 Technical dataMeasurementrange: 0 to 5mWWavelengths: 635, 650, 670 and

780nmMeasurableLaser types: CW and modulated

(50Hz - 50kHz, 20 -80% pulse width,display of average

Precision: Dependent oncalibration, typically

±5...10%Sensor area: 41.3mm²Display: Iluminated moving

coil instrument(100µA)

Power supply: 9V battery orstabilised 9V plug-inpower supply

Currentconsumption: max. 10mA or 70mA

(illuminated display)

5.Use of measuring equipment

For output measurement, the angle thatthe laser beam illuminates the sensor areais one factor of decisive importance. Ifthe beam illuminates sensor at an angleof 90°, the laser beam is reflected by thephoto diode back to the laser. Part of thiswould enter the laser, and the remainderwould be reflected back to the sensor(multiple reflection).With diode lasers, this can lead to a dropin the output, while with He-Ne gaslasers it can lead to an increase. Thisleads to quite enormous errors in the testresults, quite apart from the fact that itcan also lead to a fault in the laser.Precise readings are obtained when theangle between the laser beam and thesensor is approximately 5°. The bestsolution is to erect a low wall made ofblack cardboard near the laser, in order toidentify the position of the reflectedbeam. This is still a powerful beam andhas no business in anyones eyes!For the measurement, the laser is dis-placed and/or tilted until the reflectedbeam appears on the cardboard wall ashort distance from the laser. The slightlytilted laser should be in line with thecentre line of the sensor. It is extremelyimportant that the sensor captures theentire laser beam. Otherwise, the outputreading displayed will be too low! With a

Fig 9 : Printed circuit board forsensor (DG6RBP-005).


50

little practice, youll quickly get the hangof it. Fig 11 shows the test rig clearly.

6.Literature

[1] Cuno, Hans-Hellmuth (DL2CH): Aversatile, reproducible laser-transceiverPaper at Weinheim VHF Congress 2001,Section 5[2] Website of Alexander Meier Ele-ktronik, www. ame-engineering.de[3] Naumann/Schröder: Optics compo-

nents, Carl Hanser Verlag Munich, Vi-enna, 1992[4] Greil, Peter: Amateur radio in the(optical) range >300GHz, Open-air opti-cal communication Paper at WeinheimVHF Congress 2002, Section 8, www.lichtsprechen.de[5] Sutter, Ernst: Protection against opti-cal radiation, VDE-Verlag GmbH Berlin,1999[6] DIN EN 60825-1: Security of laserdevices, German Standards Institute[7] Data sheet IPL 10050, IntegratedPhotomatrix Ltd., Dorchester, Dorset,UK

Fig 11 : LPM-10test rig.

Fig 10 : The prototype of the LPM-10 laser output meter.


51

Time after time, one has the alarmingexperience of realising just how care-less many radio amateurs are when itcomes to plugs for coax cable. At anyfrequencies exceeding 1GHz, cable at-tenuation plays a considerable role inthe power loss and thus in the effi-ciency of a radio installation.

1.Introduction

Low attenuation coax cables of around10mm in diameter, e.g. AIRCOM PLUSand ECOFLEX are available to the radioamateur at reasonable prices. But whatabout coax connectors? The connectorsdesigned for these coax cables are knownto be rather expensive so can't we save abit here?The subject of N type connectors isunfortunately not considered to be veryimportant by some radio amateurs. Peo-ple stock up with low price connectors atflea markets, in the firm belief that theyhave got a bargain. The cable is then laidfor the installation, the connector is justfitted on and the jobs done.

2.Search for reasons

Only later comes the great awakeningthat the signals are getting weaker andweaker, the links are getting poorer, etc.The cause: Water is getting into thecable!Water penetrates further and further intothe cable due to capillary action. Oxida-tion colours the cable green or black. Thecable attenuation is multiplied manytimes over.If we look for an explanation, we fre-quently find the following reasons.

2.1. The cable sheath is damaged!This happens quickly if the cable is notlaid carefully enough.The sheath can be damaged on sharpedges. A cut a few millimetres long issufficient to set off the disastrous proc-ess. Water penetrates in and even infil-trates the screen.One should be aware of the fact that thecoax cables used in amateur radio are notwater tight along their length. This isirrespective of whether they are the fa-miliar RG type of cable or the moremodern versions with film and sheathscreening.

Bernd Bartkowiak, DK1VA

Coax cable and connectors


52

This means that through capillary actionthe water penetrates deeper and deeperinto the cable along the outer conductor,and so meter after meter is destroyed.In contrast to this, professional low losscoax cables are usually water tight alongtheir length. A corrugated copper sheetreplaces the screen sheath. This is woundaround the dielectric, it overlaps and isseamlessly welded. The welds are thentested for air tightness.So please take care: Coax cables withscreen sheath are not water tight, so youmust be careful when laying them!

2.2. Unsuitable N type connectors or“Not all connectors are the same!”This starts with electrical values. Whatsthe situation with return loss (VSWR)?Some extremely poor values have beenmeasured, less than 5dB. If we examinethis more closely, we find that the con-nectors simply have the wrong dimen-sions!

The diameter ratio of the internal pin tothe bore in the connector body is incor-rect, which has caused an embarrassingimpedance jump within the connectorhousing.What about the connector dimensions?Are the rubber gasket, the contact socketand the nut exactly right for the cable inquestion? Are there any installation in-structions for the connector with dimen-sioned sketches showing the exact cut-ting lengths for the cable?If these questions can not be answeredwith an unambiguous “yes”, then cautionis needed!For coax cables such as AIRCOM PLUSand ECOFLEX, there are specially de-veloped connectors, their dimensionshave been precisely matched to the di-mensions of the cable. They have beenelectrical optimised using TDR analysis,so that the position of any impedancejump can be pinpointed precisely.Elongated connector housings and pre-

Fig 1 : N type plug with extended body and improved clamp. This plug wasspecifically designed for use with AIRCOM plus cable.


53

Fig 2 : Laboratory test on ECOFLEX 10 cable fitted with the plug designedfor this cable.


54

cisely dimensioned rubber gaskets pro-vide the required strain relief and watertightness.These connectors are carefully tested. Todo this a finished cable is exposed to apressure of 2 bars in a water container fora period of 60 minutes. No air bubblesshould be detected and no water shouldpenetrate. Only then is the new connectorsatisfactory (See Fig 2).

3.Conclusion

Hundreds or thousands of euros are paidfor a complete radio station, includingantennas and cables. Saving just a feweuros by buying a connector at what isassumed to be an advantageous pricecan, however, under certain circum-stances, put the entire installation out ofoperation.Thus, in our own interests, we should use

only connectors tested and released forthe individual coax cable. Greater careshould be exercised in the laying of thecable, so that the cable is not bent and thesheath is not damaged.

4.Literature

[1] AIRCOMplus data sheet[2] ECOFLEX-10 data sheet

Fig 3 : The teflon inner part of a plug designed for use with ECOFLEX 15cable. It is specially designed to reduce impedance jumps in the plug body.


55

1.Introduction

Despite the advent of synthesisers thistype of probe is still often used inprofessional circles for setting up crystalcontrolled uhf/vhf communication re-ceivers such as in the PMR field (or theirconversion by radio amateurs). The cir-cuit diagram for a 10.7MHz i.f. probe(crystal heterodyne oscillator) is shownin Fig 1. It is used as an aid to adjust thereceive frequency in any crystal control-led radio receiver that has a 10.7MHzfirst intermediate frequency.

2.Constructional notes

C1,2 and 3 are silver-mica capacitors. C4and 5 are ceramic capacitors. All resis-tors are 1/8 watt metal film. Fig 2 showshow to cut the copper tracks to constructthe i.f. probe on stripboard. Suitable10.7MHz crystals are readily available atlow cost. The completed unit should beenclosed in a small non-metallic box(e.g. plastic) with the push-button switchmounted on the box.

3.Adjustment of the probe'sfrequency

This is a once and for all adjustment,after which the probe is ready for use atany time. A non-metallic trimming tool isrequired, and some means of measuringthe 10.7MHz crystal's frequency withoutphysically contacting the oscillator cir-cuit. If you have access to a synthesisedhf broadcast receiver and a synthesised rfsignal generator, a satisfactory method is:

• Tune the receiver to 10.7MHz

• Tune the signal generator to10.7MHz with an un-modulatedoutput

• The un-modulated carrier shouldbe discernible on the receiverwithout an inter-connecting cable

• Press the activate button on the i.f.probe, it will probably cause aheterodyne tone to be heard on thereceiver

• Adjust the probe's trimmercapacitor (CV1) to give a zerobeat of the heterodyne tone,

E. Chicken MBE, G3BIK

A 10.7MHz i.f. probe


56

thereby setting the probe'sfrequency to exactly 10.7MHz

Alternatively use a frequency counterwith a high impedance rf probe to meas-ure the output frequency of the i.f. probe

while CV1 is adjusted to give a 10.7MHzreading on the counter.The i.f probe is now ready for use.

Fig 1 : Circuit diagram of 10.7MHz i.f. probe.

Fig 2 : Stripboard layout for 10.7MHz i.f. probe.


57

4.Using the probe

Connect the un-modulated output of asynthesised rf signal generator to theantenna input of the radio receiver to betuned. Set the signal generator to pre-cisely the intended receive frequency.With it's activate button pressed, hold the10.7MHz i.f. probe in close proximity tothe receiver's 10.7MHz crystal filterstage.

If a heterodyne tone is heard from theloudspeaker, it means that the receiver isnot quite on tune, hence the frequency ofits local oscillator needs to be adjusted.To do that, adjust the receiver's own localoscillator crystal trimmer for zero beat ofthe audible heterodyne tone. This willbring the receiver exactly on tune at thechosen frequency.

Visit the VHF CommunicationsWeb site www.vhfcomm.co.uk

•••• Text of some past articles

•••• Pdf files of some recent articles

•••• List of overseas agents

•••• Secure forms to subscribe and order back issues or kits

•••• Full index of VHF Communications from 1969 to thecurrent issue, this can be searched on line or downloaded

•••• Up to date list of back issues available

•••• Links to other sites including all of those from InternetTreasure Trove

•••• Downloads for some articles including the Hex code forthe PIC processors used in the 2m direct conversiontransceiver described in this magazine


58

Microwave Update 2003 in Seattle

Microwave Update 2003 organisers and the Pacific Northwest VHFSociety are joining forces to host a joint conference in the Seattle,Washington, area on September 25-28, 2003. Registrations for thejoint conference will be accepted beginning April 1, 2003. Cost ofthe registration will be $40 prior to September 12, 2003, and coversall three days. Single-day or single-event registrations are notavailable. Late registrations, including at the door, will be $50.Registration forms can be downloaded at www.microwaveupdate-.org or send a SASE to John Price, N7MWV, at 12026 81St AveNE, Kirkland, WA 98034, and a form will be mailed to you.Completed registration forms and payment should be sent to thesame address. Make checks payable to “Microwave Update 2003”.Joint conference sessions and the Saturday evening banquet will beheld at the Everett Holiday Inn and Conference Centre, a short drivenorth of downtown Seattle. Special rates have been arranged withthe hotel for conference participants. Rooms are $69 per night plustax…a real bargain for the Seattle area! It is suggested that earlyreservations be made directly with the hotel at (425) 337-2900. Besure to mention “Microwave Update” to get this rate. Reservationsmust be made by August 21 for this rate.“White papers” are currently being solicited from potential authorsand speakers for publication in the 2003 conference proceedings.Topics specifically of interest to Microwave Update attendees, aswell as those on VHF and UHF subjects usually associated with theannual Pacific Northwest VHF Conference are solicited. Papers willbe accepted until July 1, 2003, to allow enough time for printing.White papers should be sent directly to Jim Christiansen, K7ND, viae-mail at [email protected]. MS Word format is preferred. MicrowaveUpdate 2003 and the Pacific Northwest VHF Society respectivelywill be the sole judges of whether presentation requests and whitepapers are accepted.If you are interested in making a session presentation at one of theMicrowave Update 2003 sessions, please respond to NU7Z ([email protected]); for presentations at the Pacific Northwest VHFConference sessions, contact N7CFO ([email protected]). LCDprojection equipment will be available for those using PowerPointpresentations. Slides and video presentations can be accommodatedwith advance notice.


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Antenna Design Calculator

Anyone who visits the homepage of“Q-Par Angus” is entering a forest ofmicrowave antennas. Innumerable micro-wave antenna types, up to 100GHz, aredesigned, manufactured and marketedthere, and there are detailed descriptionsas well. One very nice gesture is a free“Antenna Design Calculator” in the formof two slide rules that can be down-loaded. One deals with the connectionsbetween gain, efficiency, antenna diam-eter, frequency and beam width. Theother can be used to investigate therelationships between antenna diameter,frequency and far field range. These arevery informative and very easy to use.Highly recommended, you simply musthave this on your own computer.Address: http://www.q-par.com

AppCad , Version 3.0

This is brand new, the most recentWindows version of the “Personal De-sign Assistant for RF, microwave andwireless applications”. A very long timeago, when Agilent was still calledHewlett Packard, this program existed ona 5 ¼ inch diskette. This ancient versioncan also still be downloaded, but it wontwork properly except with pure DOS.But it still contains some things that weredeleted later such as spiral inductor de-sign, etc.In the most recent version 3.0, not onlyhave many details been improved, butalso a new tool has been incorporatedknown as “Everything S-Parameters”. It

lives up to its name, for you can use it toanalyse the S-parameter file of a compo-nent or a circuit, right down to the lastdetail. You can calculate some interest-ing facts from the analysis and thendisplay them (e.g. to demonstrate stabil-ity circuits or noise factor curves, carryout matching procedures, etc.). This freepackage has grown to 14Mb and merits amore detailed description at some time inour section on “An interesting program”.Address: http://www.hp.woodshot.com

Antenna Systems Laboratory

Another source for antenna literature isin the form of a “Technical Journal”. Arange of scientific articles is on offerhere, covering horn antennas, patch an-tennas, propagation experiments, etc.This is certainly very interesting for thespecialist.Address:http://www.ee.fit.edu/electrical/asl_page/journal.htm

Radio Waves below 22kHz

Have you heard of Schumann reso-nances? Or can you sketch a Whistlerreceiver? If you want to close such gapsin your education, visit this Italianhomepage. It is compulsory reading forthose people who want to get involvedwith VLF, ULF or ELF. Anyone landingup here will find innumerable recom-mended links to follow.Address: http://www.vlf.it

Gunthard Kraus, DG8GB

Internet Treasure Trove


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Transmitter Tour

What would it be like to go on a tourthrough various radio stations such as“Voice of America” etc. To savour thetechnical details of such high poweredtransmitters, as revealed in many illustra-tions and detailed explanations? Just goto “Jim Hawkin's Radio and TechnologyPage”. The author has assembled morethan 300 photos, and there's also plentyof material on the history of wirelesstransmission technology. Naturally, thereare links for such modern subjects asDAB, etc. Extremely entertaining andnever boring! If you want to learn a bitabout the principles, then just enjoy“Electromagnetic Radiation explained”Address:http://hawkins.pair.com/radio.shtml

A Site for the practising RFengineer

A lot of stuff has been assembled herethat people need more and more fre-quently. Two very fine and well pro-duced features are the tutorials on directconversion receivers and fractional Nsynthesisers. But there is also a completepage containing nothing but links tocompanies who offer application notesfor downloading. Another importantthing, here you can finally download thestandards for the various modern com-munications systems such as GSM, 2G,GPRS, WLAN, WDCDMA etc. ontoyour own computer.Address: http://www.rfengineer.cc/

RF-WEB

As down-to-earth as the name implies. A

very comprehensive but very unimpres-sive site greets you, containing nothingbut links to interesting aspects of radiofrequency technology. But if you take acloser look at this list, then you will verysoon be mentally begging the author'spardon, because not only is there anunbelievable amount available here, butit is a real Treasure Trove.Address: http://www.rfweb.com

Online Education

Internet learning is continually on theincrease, in our specialist subject as well,so we're giving two interesting links forbetter information here. The materialavailable there is not intended for imme-diate downloading but for on screentraining and/or further education. Profes-sors, teachers and specialists have cre-ated the splendid lessons or learningpackages, which makes for willing pu-pils. You'll have no trouble getting stuckin here, so to speak.Address 1:http://www.educatorscorner.com/tools/rf_corner/index.shtmlAddress 2:http://www.iec.org/online/tutorials

RF-Cafe

This, as you might expect, is a site whereyou just sit back and have a good oldrummage around. You will undoubtedlyknow of, or you'll already have, a lot ofthe literature or software mentioned here,but the author never sits still and isalways on the lookout for interesting newitems (such as a waveguide filter de-signer).Address:http://www.rfcafe.com


61

With over 1000 members world-wide, the UK Six Metre Group is the world’slargest organisation devoted to 50MHz. The ambition of the group, throughthe medium of its 60-page quarterly newsletter ‘Six News’ and through it’sweb site www.uksmg.org, is to provide the best information available on allaspects of the band: including DX news and reports,beacon news, propaga-tion & technical articles, six-metre equipment reviews, DXpedition news andtechnical articles.

Why not join the UKSMG and give us a try? For more information, contactthe secretary Iain Philipps G0RDI, 24 Acres End, Amersham, Buckingham-shire HP7 9DZ, UK or visit the web site.

The UK Six Metre Group

www.uksmg.org


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Year Q1 Q2 Q3 Q42002 Y Y Y Y2001 Y Y Y Y2000 Y Y Y Y1999 Y Y Y Y1998 Y Y Y Y1997 Y Y Y Y1996 Y Y Y Y1995 Y Y Y Y1994 Y Y Y Y1993 Y P Y P1992 Y Y Y Y1991 P P P P1990 P P Y P1989 P P P L1988 P P P L1987 P P P P1986 Y Y Y Y1985 Y Y Y Y1984 Y Y Y Y1983 Y Y Y Y1982 P P P P1981 L L P P1980 P P P P1979 L P L P1978 P L P P1977 L P P L1976 P P P P1975 P L L P1974 L P P P1973 P P P P1972 P P P P1971 P P P P1970 P P P P1969 P P P P

VHF CommunicationsBack Issues Available

KeyY = Available L = Low quantity P = PhotocopyThe back issue sets contain issues marked Y, issues marked L or P must beordered separately.


63

AUSTRALIA - W.I.A. South Australia Division, GPO Box 1234,Adelaide, SA 5001, Australia. Tel/Fax: 8 8522 4859BELGIUM - UKW-BERICHTE, POB 80, D-91081 BAIERSDORF,Germany. Tel: 09133-77980. Fax: 09133-779833 .Postgiro Nbg. 30445-858.DENMARK - KM PUBLICATIONS , 63 Ringwood Road,LUTON, LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] - Christiane Michel F5SM, Les Pillets, 89240 PARLY,FranceFax: (33) 03 86 44 08 82 Tel: (33) 03 86 44 06 91FINLAND - KM PUBLICATIONS , 63 Ringwood Road, LUTON,LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] - UKW-BERICHTE, POB 80, D-91081BAIERSDORF, Germany. Tel: 09133 7798-0. Fax: 09133 779833.GREECE - KM PUBLICATIONS , 63 Ringwood Road, LUTON,LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] - KM PUBLICATIONS , 63 Ringwood Road, LUTON,LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] - R.F. Elettronica di Rota Franco, Via Dante 5 - 20030Senago, MI, ItalyFax 0299 48 92 76 Tel. 02 99 48 75 15NEW ZEALAND - KM PUBLICATIONS , 63 Ringwood Road,LUTON, LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] - WAVELINE AB, Box 60224, S-216 09 MALMÖ,Sweden. Tel: +46 40 16 42 66. Fax: +46 40 15 05 07.GSM: 0705 16 42 66e-mail: [email protected] http://www.algonet.se/~wavelineSOUTH AFRICA - KM PUBLICATIONS , 63 Ringwood Road,LUTON, LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] & PORTUGAL - JULIO A. PRIETO ALONSO EA4CJ,Donoso Cortes 58 5° -B, MADRID 15, Spain. Tel: 543 83 84SWEDEN - WAVELINE AB, Box 60224, S-216 09 MALMÖ,Sweden. Tel: 040 16 42 66. Fax: 040 15 05 07. GSM: 0705 16 4266 e-mail: [email protected] http://www.algonet.se/~wavelineSWITZERLAND - KM PUBLICATIONS , 63 Ringwood Road,LUTON, LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected] KINGDOM - KM PUBLICATIONS , 63 Ringwood Road,LUTON, LU2 7BG, UK. Tel: +44 1582 581051.Fax: +44 1582 581051. Email: [email protected]. - GENE HARLAN, ATVQ Magazine, 5931 Alma Drive,Rockford, IL 61108, USA. Tel: Toll free USA only: 800 557 9469;Elsewhere: +1 815 398 2683; Fax: +1 815 398 2688Email: [email protected] - KM PUBLICATIONS, address as for the U.K.

WWW: http://www.vhfcomm.co.uk

KM PUBLICATIONS,63 Ringwood Road, Luton,LU2 7BG, United KingdomTel: +44 1582 581051Fax: +44 1582 581051

Email:[email protected]

Andy Barter G8ATDThe international edition of theGerman publication UKW-Berichteis a quarterly amateur radiomagazine, especially catering forthe VHF/UHF/SHF technology.It is owned and published in theUnited Kingdom in Spring,Summer, Autumn and Winter byKM PUBLICATIONS.The 2003 subscription price is£20.60, or national equivalent.Individual copies are available at£5.15, or national equivalent each.Subscriptions should be addressedto the national representative shownin the next column. Orders forindividual copies of the magazine ,back issues, kits, binders, or anyother enquiries should be addresseddirectly to the publishers.NOTICE: No guarantee is giventhat the circuits, plans and PCBdesigns published are free ofintellectual property rights.Commercial supply of these designswithout the agreement of theAuthor and Publisher is notallowed. Users should also takenotice of all relevant laws andregulations when designing,constructing and operating radiodevices.

All rights reserved. Reprints,translations, or extracts only withthe written approval of thepublishersTranslated by: Inter-Ling Services,62 Caldecott Street, Rugby,CV21 3TH, UKPrinted in the United Kingdom by:Cramphorn Colour Printers Ltd.,15a Boughton Road IndustrialEstate, Rugby CV21 1BQ, UK.

Publishers

Editor

VHFCOMMUNICATIONS

© KMPUBLICATIONS

ISSN 0177-7505

A Publication for the Radio Amateur Worldwide

Especially Covering VHF, UHF and Microwaves

Volume No.35 Spring Edition 2003-Q1

VHFCOMMUNICATIONS

The microwave bands arean excellent area for radioamateurs who want to ex-periment and constructtheir own equipment. TheRSGB in partnership withthe ARRL has producedthis invaluable source ofreference information forthose interested in thisarea, along with excellentdesigns from around theworld to fire the imagina-tion. Material has beendrawn from many sourcesincluding the RSGB jour-nal RadCom and theARRL publications QST& QEX. Alongside thismaterial a truly interna-tional range of sourceshave been used includingitems from Germany,Denmark, New Zealand,Slovenian and many more.The earlier chapters of thebook provide invaluablereference material re-quired by all interested in

this exciting area of experimentation. Techniques and devices are covered indepth, leading the reader to understand better the wide range of equipment andtechniques now available to the microwave experimenter. This book contains awide selection of designs using the latest technology that can reasonably beused by radio amateurs and ranges from ones that can be reproduced by mostradio amateurs to those that require a high degree of skill to make.With the explosion in consumer electronics using microwave frequencies theopportunity to experiment has never been greater and this book is simply thebest guide to the area of microwave radio.

Available in the UK for £24.99 from www.rsgb.org/shopAvailable in the USA for $39.95 from www.arrl.org

The New International Microwave Handbook

COMPLETE KITS, PCB's & ICs ARE AVAILABLEFOR RECENT PROJECTS

If the kit or PCB is not in this list please contact K. M. Publications

READY MADE DESCRIPTION ISSUE No. PRICEDG6RBP Pre Divider (:10) up to 5GHz 1/02 £ 140.00DG6RBP ATV Squelch 4/02 06006 £ 55.00

KIT DESCRIPTION ISSUE No. PRICEDJ8ES-019 Transverter 144/28MHz 4/93 06385 £ 120.00DJ8ES-019/50 Transverter 50/28MHz 2/95 06392 £ 120.00DJ8ES-020/50 10W PA for 50MHz 2/95 £ 140.00DJ8ES-047 Log Amplifier up to 500MHz with AD8307 2/00 06571 £ 42.00DG6RBP-002 Pre Divider (:10) up to 5GHz 1/02 £ 115.00DB6NT-Rotor Simple Speed Control for Rotators 2/02 06533 £ 35.00

PCB DESCRIPTION ISSUE No. PRICEDJ8ES-019 Transverter 144/28MHz or 50/28MHz 4/93 06384 £ 10.00S53MV Set of PCBs for Matjaz Vidmar Spectrum Analyser 4/98-4/99 S53MV £ 55.00DJ8ES-047 Log Amplifier up to 500MHz using AD8307 2/00 06569 £ 6.50DG6RBP-002 Pre Divider (:10) up to 5GHz 1/02 £ 18.00DJ8ES-053 Frequency Generator to 4GHz - mixer 1/02 £ 10.50DJ8ES-054 Frequency Generator to 4GHz - oscillator 1/02 £ £9.50DJ8ES-054 Frequency Generator to 4GHz - microcontroller 1/02 £ 15.50DB6NT-Rotor Simple Speed Control for Rotators 2/02 06532 £ 5.50DJ8ES-056 Speech Store With Integrated Sequencer 2/02 £ 7.00DG6RBP ATV Squelch 4/02 06542 £ 3.50

ICs DESCRIPTION ISSUE No. PRICEDJ8ES AT90S2313 For Digital Speech Store 2/02 £ 17.25DJ8ES/DL5HAT AT89C52 For GPS Control Of 10 MHz Standard 1/01 10353 £ 21.50

Please note that due to component supply problems some items have along delivery time, please ask for advice on delivery.

Minimum shipping charge £5.00K. M. Publications, 63 Ringwood Road, Luton, Beds, LU2 7BG, U.K.

Tel / Fax +44 1582 581051 email [email protected] Site http://www.vhfcomm.co.uk

laser output meter - americanradiohistory.com...ation of 2400mhz using a doubler. i have programmed...

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