January 15, 192515 Cents a Copy

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PUBLISHED TWICE A MONTH

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GI LINRAD I 0 APPARArIFTJ S

The Giblin Broadcast ReceiverTHE Giblin Radio Frequency Broadcast

Receiver makes it possible to obtainradio entertainment without the necessityof erecting outside antenna wires or usinga troublesome ground wire. A small, loopaerial placed near the set will pick up sig-nals, which, though they have come longdistances, and are weakened by bills, val-leys, trees and buildings, will be clear andof great volume. Many families, living inapartments where it is undesirable or im-possible to erect antenna wires, can nowhear enjoyable, ever-changing programsthrough the day and evening by "listening -in" with a Giblin Radio Frequency Broad-.ast Receiver.

The Giblin Audio -FrequencyAmplifying Transformer

Price $4.50

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"A"SIVITC11AMPLIFIER

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The set comprises two stages of radio frequency ampli-fication, a detector and three stages of audio frequencyamplification. The parts are mounted on a sub -base towhich a Bakelite panel is attached. It is enclosed in ahandsome solid mahogany cabinet.

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The Giblin Radio -FrequencyAmplifying Transformer

Price $5.00

Buy Giblin Products from your dealerWrite for descriptive circulars

STANDARD RADIO &ELECTRIC CO.PAWTUCKE T, RHODE ISLAND

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JANUARY 15, 1925 RADIO PROGRESS 1

UNITED STATES BROADCASTING STATIONSARRANGED ALPHABETICALLY BY

CALL LETTERSAbbreviations: W.L., wave length in meters; K.C., frequencies in

kilocycles; W.P,, wattpower of station.W.L. K.C. W.P.

KDKA-Westinghouse Elec. & Mfg. Co., East Pittsburgh 326- 920-1000KDPM-Westinghouse Elec. & Mfg. Co.. Cleveland, 0 270-1110- 500KDPT-Southern Electrical Co., San Diego, Cal 244-1230- 100KDYL-Salt Lake Telegram, Salt Lake City, Utah 360- 833- 100KDYM-Savoy Theatre, San Diego, Cal 280-1070- 100KDYQ-Oregon Institute of Technology. Portland, Ore 360- 834- 100KDZB-Frank E. Seifert, Bakersfield, Cal 240-1250- 100KDZE-The Rhodes Co., Seattle. Wash 270-1110- 100KDZF-Auto. Club of So. Cal., Los Angeles, Cal 278-1080- 500KFAB-Buick Auto Co., Lincoln, Neb 240-1250- 200KFAD-McArthur Bros. Mercantile Co., Phoenix, Ariz 360- 908- 100KFAE-State College of Washington, Pullman, Wash 330- 910- SOOKFAF-Western Radio Corp., Denver, Col 360- 833- 500KFAJ-University of Colorado. Boulder, Col 360- 833- 100KFAQ-City of San Jose, San Jose, Cal 360- 833- 250KFAR-Studio Lighting Service Co., Hollywood, Cal 227-1320- 100KFAU-Boise High School. Boise, Idaho 270-1110- 150KFBB-F. A. Buttrey & Co., Havre, Mont 275-1090- 100KFBG-Search Light Publishing Co., Fort Worth, Tex 254-1180- 100KFBK-Kimball-Upson Co., Sacramento, Cal 283-1060- 100KFCF-Frank A. Moore, Walla Walla, Wash 360- 833- 100KFCL-Los Angeles Union Stockyards, Los Angeles, Cal 236-1270- 500KFCM-Richmond Radio Shop, Richmond, Cal 244-1220- 100KFCZ-Omaha Central High School, Omaha, Neb 259-1160. 100KFDH-University of Arizona, Tucson, Ariz 268-1120- 150KFDM-Magnolia Petroleum Co.. Beaumont. Texas 306- 980- 500KFDX-Frst Baptist Church, Shreveport, La 250-1200- 100KFDY-So. Dakota State College, Brookings. So. Dakota 273-1100- 100KFEL-Winner Radio Corp.. Denver, Col 254-1180- 100KFEQ-J. L. Scroggin, Oak. Neb 268-1120- 100KFEX-Augsburg Seminary, Minneapolis, Minn 261-1150- 100KFFV-Graceland College, Lamoni, Iowa 360- 834- 100KFFY-Louisiana College, Alexandria, La 275-1090- 100KFGC-Louisiana State University, Baton Rouge, La 254-1180- 100KFGD-Chickasha Radio & Elec. Co 248-1195- 200KFGH-Leland Stanford Jr. Univ., Stanford Univ., Cal 273-1100- 250KFGJ-Mo. Natl. Guard, 138th Infantry, St. Louis, Mo 265-1130- 100KFGX-First Presbyterian Church, Orange, Tex 250-1200- SOCKFGZ-Emmanuel Missionary Col., Berrien Springs, Mich 268-1120- 500KFHD-Utz Elec. Shop Co., St. Joseph, Mo 226-1365- 100KFHJ-Fallon & Co., Santa Barbara, Cal 360- 833- 100KFHR-Star Elec. & Radio Co., Seattle. Waqh 263-1140- 100KFI-Earle C. Anthony, Inc., Los Angeles, Cal 469- 640.1500KFIF-Benson Polytechnic Institute, Portland, Ore 360- 8.33- 100KFIX-R. C., Jesus Christ of L. D.Stas., Ind'p'nd'n'e,Mo 268-1120- 250KFIZ-D'ly C'm'nw'h & S. Radio C'p., Fond d'L'c, Wis 273-1100- 100KFJC-Seattle Post Intellegencor, Seattle, Wash 270-1110- 100KFJF-National Radio Mfg. Co., Oklahoma, Okla 261-1150- 225KFJK-Delano Radio & Electric Co., Bristow, Okla 233-1290. 100KFJM-University of N. Dakota, Grand Forks, N. Dak 280-1070- 100KFKB-Brinkley-Jones Hospital Assn., Milford, Kans 286-1070- 500KFKQ-Conway Radio Laboratories, Conway, Ark 250-1200- 100KFKX-Westinghouse Elec. & Mfg. Co., Hastings, Neb . .. 285- 880-1000KFLE-National Education Service, Denver, Col 268-1110- 100KFLR-Korber Wirelss Station, Albuquerque, N'. Mexico 254-1180- 100KFLZ--Atlantic Automobile Club, Atlantic, Ia 273-1098- 100KFLV-Swedish Evang. Mission Church, Rockford, Ill . . . 220.1310- 100KFMQ-Univ. of Arkansas, Fayetteville. Ark 263-1140- 100KFMX-Carleton College, Northfield, Minn 283-1071- 500KFNF-Henry Field Seed Col, Shenandoah, Iowa 266-1145- 500KFOA-The Rhodes Co., Seattle, Wash 454- 660- 500KFOC-First Christian Church, Whittier, Cal 236-1290- 100KFON-Echophone Radio Shop, Long Beach, Cal 2341290- 100KFOU-Hommel Mfg. Co., Richmond, Cal 254-1180- 100KFOX-Technical High School, Omaha, Neb 248-1210- 100KFOZ-Taft Radio Co., Hollywood, Cal 240-1250- 250KFPG-Garretson & Dennis, Los Angeles. Cal 238-1260- 100KFPL-C. C. Baxter, Dublin, Texas 252-1190- 100KFPO-Colorado Nat'l Guard. Denver, Col 231-1300- 500KFPR-L. A. Coukty Forestry Dept., Los Angeles, Cal 231-1300- 500KFPT-The Deseret News, Salt Lake City, Utah 360- 833- 500KFPX-First Presbyterian Church, Pine Bluff, Ark 242-1240- 100KFPY-Symons Investment Co., Spokane, Wash 283-1060- 100KFQC-Kidd Brothers Radio Shop, Taft, Cal 227-1320- 100KFQD-Chovin Supply Co.. Anchorage, Alaska 280-1070- 100KFQG-Southern Cal. Radio Assn., Los Angeles, Cal 226-1330- 100KFQI-Thomas H. Ince Corp., Culver City, Cal 234-1280- 100KFQM-Texas Highway Bulletin, Austin, Texas 268-1120- 100KFQU-W. Riker, Holy City, Cal 234-1280- 100KFQV-Omaha Grain Exchange, Omaha, Neb 231-1300- 100KFQX-Alfred M. Hubbard, Seattle, Wash 233-1290- 502KFRA-Marvin S. Olsen, Carver. Minn 240-1250- 100KFRB-Hall Brothers, Beeville, Texas 248-1210- 250KFRN.-United Churches of Olympia, Olympia, Wash 220-1360- 100KFSG-Echo Park Evangelistic Ass'n, Los Angeles, Cal 278-1069- 500KGO-General Electric Co., Oakland, Cal 312- 960.1000KGU-Marion A. Mulreny, Honolulu, Hawaii 360- 833- 500KGW-Portland Morning Oregonian, Portland, Ore 492- 610- 500KHJ-Times-Mirror Co., Los Angeles, Cal 395- 760- 500KHQ-Louis Wasmer, Seattle, Wash 360- 833- 100

W.L. K.C. W.P.KJR-Northwest Radio Service Co.. Seattle, Wash 270-1110- 100KJS-Bible Institute of Los Angeles, Los Angeles, Cal 360- 833- 750KLS-Warner Brothers, Oakland, Cal 360- 833- 250KLX-Tribune Publishing Co., Oakland, Cal 508- 590- 500KLZ-Reynolds Radio Co.. Denver, Col 283-1060- 500KNT-Grays Harbor Radio Co., Aberdeen, Wash _263-1140- 250KNV-Radio Supply Co., Los Angeles, Cal 256-1188- 100KNX-Los Angeles Express, Los Angeles, Cal 337- 890- 500KOA-General Electric Co.. Denver, Col 323- 930-1500KOB-N. M. C. of Agri. & Mech. Arts. State Col., N. M 360- 833- 500KOP-Detroit Police Dept., Detroit, Mich 286-1050- 500KPO--Hale Bros., San Francisco, Cal 422- 710- 500KQV-Doubleday-Hill Electric Co., Pittsburgh. Pa 275-1090- SOOKSD-Post Dispatch, St. Louis, Mo 545- 550- 500KTHS-New Arlington Hotel, Hot Springs, Ark 375-....- 500KTW-First Presbyterian Church. Seattle, Wash 360- 833- 750KUO-Examiner Printing Co., San Francisco, Cal 360- 833- 150KUS-City Dye Works & Laundry Co., L. Angeles, Cal 360- 833- 100KUVQ-Kreetan Co., Johnswood Drummond Island, Mich 450- 666-1000KWG-Portable Wireless Tel. Co., Stockton, Cal 360- 833- 100KWH-Los Angeles Examiner, Los Angeles, Cal 360- 833- 500KYQ-Electric Shop, Honolulu, Hawaii 270-1110- 100KYW-Westinghouse Elec. & Mfg. Co., Chicago, Ill 535- 560-1500KZM-Western Radio Institute, Oakland, Cal 360- 833- 100KZKZ Electrical Supply Co., Manila, P. I 270-1110- 100KZN-The Desert News, Salt Lake City, Utah 360- 834- 500WAAB-Valdemar Jensen, New Orleans, La 26.8-1120- 100WAAC-Tulane University, New Orleans, La 360- 833- 400WAAF-Chicago Daily, Drovers Journal, Chicago, Ill 278-1080- 200WAAM-I. R. Nelson Co., Newark, N. J 263-1140- 250WAAW-Omaha Grain Exchange, Omaha, Neb 286-1050- 500WAAZ-Hollister-Miller Motor Co., Emporia, Kans 360- 833- 100WABE-Y. M. C. A., Washington, D. C 283-1060- 100WABI-Bangor Ry. & Elec. Co., Bangor, Me 240-1250- 100WABL-Conn. Agri. College, Storm, Conn 283-1060- 100WABM-F. E. Doherty Auto. & R'dio Co., Saginaw, M 254-1180- 100WABP-Robert F. Weinig, Dover, Ohio 265-1130- 100WABT-Holliday-Hall Elec. Engineers, Washington, Pa 252-1190- 100WABU-Victor Talking Machine Co., Camden. N. J 225-1330- 100WABX-Henry B. Joy, Mount Clemens. Mich 270-1110- 150WAHG-A. H. Grebe & Co., Richmond Hill, N. Y 316- 950- 500WBAA-Purdue University, West Lafayette, Ind 283-1060- 250WBAD-Sterling Electric Co., Minneapolis, Mimi 360- 833- 100WBAK-Penn. State Dept. of Police, Harrisburg, Pa 400- 750- 500WBAN-Wireless Phone Corp., Paterson, N. J 244-1230- 100WBAP-Wortham-Carter Pub. Co.. Fort Worth, Tex 476- 630-1000WBAV-Erner & Hopkins Co., Columbus, Ohio 390- 770- 500WBAW-Marietta College, Marietta, Ohio 246-1220- 250WBAX-John H. Stenger, Jr., Wilkes-Barre, Pa 254-1180- 100WBAY-American Tel. & Tel. Co., New York, N. Y 492- 610- 500WBBF-Georgia School of Technology, Atlanta, Ga 270.1110- 500WBBG-Irving Vermilya, Mattapoisett, Mass 248-1210- 500WBBL-Grace Covenant Church, Richmond, Va 283-1060- 100WBBM-H. Leslie Atlass, Chicago. Ill 226-1330- 200WBBR-Peoples' Pulpit Ass'n, Roseville, N. Y 244-1230- 100WBL-T. & H. Radio Co., Anthony, Kansas 254-1180- 100WBN-Ott Radio, Inc.. La Crosse, Wis 244-1230- 500\VBR-Penn. State Police, Butler, Pa 286-1050- 250WBS-D. W. May, Inc., Newark, N. J 360- 833- 100WBT-Southern Radio Corp., Charlotte, N. C 360- 833- 500WBU-City of Chicago, Chicago, Ill 286-1050- 500WBZ-Westinghouse Elec. & Mfg. Co., Springfield, Mass 337- 890-1500WCAD-St. Lawrence University, Canton, N Y 263-1140- 250WCAE-Kaufmann & Baer Co., Pittsburgh. Pa 461- 650- 500WCAH-Entrekin Electric Co., Columbus, Ohio 286-1050- 100WCAJ-Nebraska Wesleyan Univ., Univ. Place, Neb 280-1070- 500WCAL-St. Olaf College, Northfield, Minn 360- 833- 500WCAP-Chesapeake & Potomac Tel. Co., Washingt'n, D. C 469- 640- 500WCAR-Alamo Radio Elec. Co., San Antonio, Texas 360. 833- 100WCAS-W. H. Dunwoody Ind. Inst., Minneapolis, Minn 280-1220- 100WCAT-S. Dakota State Sch. of. Mines, Rapid City, S. D 240-1250- 100WCAU-Durham & Co., Philadelphia, Pa 278-1080- 500WCAX-Univ. of Vermont. Burlington, Vt 360- 834- 100WCAY-Milwaukee Civic Broad. Assn., Milwaukee, Wis 266-1130- 250WCBC-Univ. of Michigan, Ann Arbor, Mich 229-1310- 200WCBD-Wilbur G. Voliva, Zion, Ill 345- 870- 500WCBI-Nicoll, Duncan & Rush, Bemis, Texas 226-1330- 100WCBN-Chicago, Ill. 266-....- 500WCBQ-First Baptist Church, Nashville, Tenn 236-1270- 100WCBT-Clark University, Worcester, Mass 238-1260- 250WCCO-Washburn-Crosby Co., Minneapolis, Minn 417- 720- 500WCK-Stix, Baer & Fuller Dry Goods Co., St. Louis, !do' 360- 833- 100WCX-Detroit Free Press, Detroit, Mich 517- 580- 500WCKB-E. Richard Hall. St. Petersburg. Fla 266-1130- 500WCM-Texas Mkts. & Warehouse, Dept., Austin, Tex 268-1120- 250WDAE-Tampa Daily Times, Tampa, Fla 273-1100- 250WDAF-Kansas City Star, Kansas City, Mo 411- 730- 500WDAG-J. Laurance Martin, Amarillo, Texas 263-1140- 100WDAH-Trinity Methodist Church. El Paso. Texas 268-1120- 100WDAR-Lit Brothers. Philadelphia, Pa 395- 760- 500WDAU-Slocum & Kilburn, New Bedford, Mass 360- 833- 100WDAX-First National Bank, Centerville, Iowa 360- 833- 100WDBH-C. T. Sherer, Co., Worcester, Mass 268-1120- 100WD B R-Trem on t Temple Baptist Church, Boston, Mass . 256-1170- 100WDBY-North Shore Cong. Church, Chicago, Ill 258-1160- 500WDWF-D. W. Flint, Providence, R. I 286-1050- 500WEAA-Frank D. Fallon, Flint, Mich 234-1280- 100WEAF-Amer. Tel. & Tel. Co., New York, N. Y 492- 610-1500

2 RADIO PROGRESS JANUARY 15, 1925

W.L. K.C. W.P.WEAH-Wichita Board of Trade, Wichita, Kas 280-1070- 100WEAI-Cornell University, Ithaca, N. Y 286-1050- 500WEAJ--Univ. of S. Dakota, Vermillion, S. Dakota 283-1060- 100WEAM-Borough of N. Plainfield, N. Plainfield, N. J 261-1150- 250WEAN-Shepard Co., Providence, R. I 273-1100- 100WEAO-Ohio State University, Columbus, Ohio 360- 834- 500WEAP-Mobile Radio Co., Mobile Ala 263-1140- 100WEAS-Hecht Co., Washington, D. C 360- 833- 100WEAU-Davidson Bros. Co., Sioux City, Iowa 275-1090- 100WEAY-Iris Theatre, Houston, Texas 360- 833- 500WEB-Benson Radio Co., St. Louis. Mo 273-1130- 500WEBH-Edgewater Beach Hotel Co., Chicago, Ill 370- 810-1000WEBJ-Third Avenue Ry. Co., New York, N. Y 273-1100- 500WEBL-R. C. A. United States (portable) 226-1330- 100WEBW-Beloit College, Beloit, Wis' 268-1120- 500WEEI-Edison Elec. IlEm'n't'g Co., Boston, Mass 303- 990- 500WEV-Hurlburt-Still Electric Co., Houston, Texas 263-1140- 100WEW--St. Louis University, St. Louis, Mo 280-1070- 100WFAA-Dallas News & Dallas Journal, Dallas, Tex 476- 630- 500WFAB-Carl F. Woese, Syracuse, N. Y 234-1280- 100WEAN-Hutchinson. Elec. Serv. Co., Hutchinson, Minn 286-1050- 100WFAV-Univ, of Nebraska, Dept. of E. Eng., Lincoln, Neb 261-1250- 250WFBB-Eureka College, Eureka, Ill 261-1250- 150WFBG-William F. Gable Co., Altoona, Pa 261-1150- 100WFBH-Concourse Radio Corp., New York. N. Y 273-1100- 500WFBI-Galvin Radio Supply Co., Camden, N J 236-1270- 100WFBK-Dartmouth College, Hanover, N. 11 256-1170- 100WFBL-Onondaga Hotel, Syracuse, N. Y 286-1050- 100WFBM-Merchants Heat & Light Co., Indianapolis, Ind.. 268-1120- 250WFBN'-Radio Sales & Service Co., Bridgewater, Mass 226-1330- 200WFBR-5th Infantry, Maryland, N. G., Baltimore, Md 254-1180- 100WFBW-Ainsworth-Gates Radio Co., Cincinnati, Ohio 309- 970- 750WFI-Strawbridge & Clothier,* Philadelphia, Pa 395- 760. 500WGAQ-Youree Hotel, 406 Market St., Shreveport, La 263-1140- 100WGAY-Northwestern Radio Co., Madison, Wis 360- 833- 100WGAZ-South Bend Tribune, South Bend, Ind 275-1090- 250WGBS-Gimbel Brothers, New York, N. Y 316- 950-1000WGI-Am. R'dio & Res'ch Corp., Medf'd Hillside, Mass 360- 833- 100WGL-Thomas F. J. Rowlett, Philadelphia, Pa 360- 833- 500WGN-Drake Hotel (Whitestone Co.), Chicago, Ill 370- 710-1000

Co., Buffalo. N. Y 319- 940- 750WGY-General Electric Co., Schenectady, N. Y 380- 790-1000WHA-University of Wisconsin; Madison, Wis 275-1090- 500WHAA-State Univ. of Iowa, Iowa City, Iowa 484- 620- 500WHAD-Marquette University, Milwaukee, Wis 280-1070- 100WHAG-University of Cincinnati, Ohio 233-1290- 100WHAM-University of Rochester, Rochester, N. Y 283-1060- 100WHAR-Seaside Hotel, Atlantic City, N. J 275-1090- 200WHAS-Courier-Journal & Louisville Times, Louisville, Ky 400- 750- 500WHAV-Wilmington Elec. Spec. Co., Wilmington, Del 266-1130- 100WHAZ-Rensselaer Polytechnic Institute, Troy, N. Y 380- 790- 500WHB-Sweeney School Co., Kansas City, Mo 411- 730- 500WHK-Radiovex Co., Cleveland, Ohio 283-1060- 100WHN-Loew's State. Theatre Bldg., New York, N. Y 360- 833- 500WHO-Bankers Life Co., Des Moines. Iowa 526- 570- SOOWHQ-E. M. Tellefson, Mackinac Island, Mich 300- 999- 200WIAC-Galveston Tribune, Galveston, Texas 360. 833- 100WIAD-Howard R. Miller. Philadelphia, Pa 234-1180- 100WIAK-Journal-Stockman Co., Omaha Neb 278-1080- 250WIAR-Paducah Evening Sun, Paducah, Ky 360- 833- 100WIAS-Home Electric Co., Burlington, Iowa 283-1060- 100WIK-K. L. Electric Co., McKeesport. Pa 234-1280- 100WIP-Gimbel Brothers, Philadelphia, Pa 508- 590- 500WJAB-American Electric Co.. Lincoln, Neb 229-1310- 100WJAD-Jackson's Radio Eng. Laboratories, Waco, Tex 360- 833- 150WJAG-Norfolk Daily News, Norfolk, Neb 283-1060- 250WJAN-Peoria Star, Peoria. III 280-1070- 100WJAR-The Outlet Co., Providence, R. I 360- 833- 500WJAS-Pittsburgh Radio Supply House, Pittsburgh, Pa 286-1050- 500WJAX-Union Trust Co., Cleveland, Ohio 390- 770- 500WJAZ-Zenith Radio Corp., Chicago, Ill. (portable) 268-1120- 100WJH-Wm. P. Boyer Co., Washington, D. C 273-1100- 100WJJD-Supreme Lodge Moose, Mooseheart, Ill 278-1080- 500WJY-R. C. A., New York, N. Y 405- 660- 500WJZ-Broadcast Central, New York, N. Y 454- 660- 500WKAA-H. F. Parr, Cedar Rapids, Iowa 278-1080- 100WKAF-W. S. Radio Supply Co., Wichita Falls, Tex 360- 833- 100WKAQ-Radio Corp. of Porto Rico, San Juan, P. R 360- 833- 500WKAR-Michigan Agr. College, E. Lansing, Mich 280-1070-500WKY-WKY Radio Shop, Oklahoma, Okla 360- 833- 500WLAG-Cutting & Radio Wash. Corp., Minneapolis, Minn .417- 720- 500WLAH-Samuel Woodworth, Syracuse, N. Y 360- 834- 500WLAL-Naylor Electric Co., Tulsa, Okla 360- 833- 100WLAN-Putnam Hardware Co., Houlton, Me 283-1060- 250WLAW-Police Dept.. New York City, N. Y 360- 834- 500WLBL-Wisconsin Dept. of Markets, Stevens Pt., Wis 278-1080- 500WLS- ears, Roebuck & Co., Chicago, Ill 345- 870- 500WLW-Crosley Radio Corp., Cincinnati, 0 423- 710-1000WMAC-Clive B. Meredith, Cazenovia, N. Y 275-1090- 100WMAF-Round Hills Radio Corp., Dartmouth, Mass 360- 833- 500WMAH-General Supply Co., Lincoln, Neb 254-1180- 100

W.L. K.C. W.P.WMAK-Norton Laboratories, Lockport, N. Y 273-1100- 500WMAP-Utility Battery Service, Easton, Pa 246-1220- 150WMAQ-Chicago Daily News, Chicago, Ill 448- 670- 500WMAT-Paramount Radio Corp., Duluth, Minn 226-1130- 250WSY-Alabama Polytechnic Institute, Auburn, Ala 250-1200- 500WMAY-Kingshighway Presbytern Church. St. Louis, Mo 280-1070- 100WMAZ-Mercer University, Macon, Ga 261-1150. 100WMC-"Commercial Appeal," Memphis, Tenn 500- 600- 500WMH-Ainsworth-Gates Radio Co.. Cincinnati, Ohio 309- 970- 750WMU-Doubleday-Hill Elec. Co., Washington, D. C 261-1150- 100WN'AC-Shepard Stores, Boston, Mass 278-1080- 100WNAD-University of Oklahoma, Norman. Okla 254-1180- 100WNAP-Wittenberg College, Springfield, Ohio 275-1090- 100WNAT-Lenning Brothers Co., Philadelphia, Pa 250-1200- 100WNAX-Dakota Radio Apparatus Co., Yankton, S. D 244-1230- 100WNYC-City of New York, New Vogt, N. Y 526- 570-1000WOAC-Pagan Organ Co., Lima, Ohio 265-1130- 150WOAI-Southern Equipment Co., San Antonio, Tex 384- 780- 500WOAL-William E. Woods, Webster Groves, Mo 229-1310- 100WOAN-Vaughn Conserv't'y Music, Lawrenceb'rg, Tenn 360- 833- 200WOAR-Henry P. Lundskow, Kenosha, Wis 229-1310- 100WOAV-Penn. Nat'l Guard, 2d Bat., 112th Inf., Erie, Pa 242-1240. 100WOAW-Woodmen of the World, Omaha, Neb 526- 570- 5U0WOAX-Franklyn J. Wolff, Trenton, N. J 240-1250- 500WOI-Iowa State College, Ames, Iowa 360- 833- 500WOO-John Wanamaker, Philadelphia, Pa 508- 590. 500WOQ-Unity School of Christianity, Kansas City, Mo 278-1080- 500WOR-L. Bamberger & Co., Newark, N. J 405- 740- 500WOS-Mo. State Marketing Bureau, Jefferson City, Mo 441- 680- 500WPAB-Pennsylvania State College, State College, Pa 283-1060- 500WPAC-Donaldson Radio Co., Okmulgee, Okla 360- 833- 100WPAH-Wisconsin Dept. of Markets, Waupaca, Wis 360- 833- 500WPAJ-New Haven, Conn 268-1120- 100WPAK-North Dakota, Agri Col., Agri. College, N. D 283-1060- 250WP'AL-Avery & Loeb Elec. Co., Columbus, Ohio 286-1050- 100WPAM-Auerbach & Guettel, Topeka, Kansas 275-1090- 100WPAZ-John R. Koch (Dr.), Charleston, W. Va 273-1100- 100WQAA-Horace A. Beale, Jr., Parkesburg, Pa 220-1360- 500WQAC-E. B. Gish, Amarillo, Texas 234-1280- 100WQAM-Electrical Equipment Co., Miami, Fla 268-1120- 100WQAN-Scranton Times, Scranton, 250-1120- 100WQAO-Calvary Baptist Church, New York, N. Y 360- 833- 100WQAQ-Abilene Daily Reporter, Abilene, Tex 360- 833- 100WQAS-Prince-Walter Co., Lowell, Mass 265-1130- 100

-WQAX-Radio Equipment Co. Peoria, Ill 248-1210 100WQJ-Calument Rainbo Broadcasting Co., Chicago, Ill 448- 670- 500WRAL-No. States Power Co., St. Croix Falls, Wis 248-1210- 100WRAM-Lombard College, Galesburg, Ill 244-1230- 250WRAV-Antioch College, Yellow Springs, Ohio 242-1240- 100WRAX-Flexon's Garage, Gloucester City, N. J 268-1120- 100WRBC-Immanuel Lutheran Church, Valparaiso, Ind 278-1080- 500WRC-Radio Corp. of America, Washington, D. C 469- 640- 500WREO-Reo Motor Car Co., Lansing, Mich 288-1040- 500WRK-Doren Bros. Electric Co., Hamilton, Ohio 270-1110- 200WRL-Union College, Schenectady, N. Y 360- 833- 500WRM-University of Illinois, Urbana. Ill 273-1100- 500WRW-Tarrytown Radio Research Lab., Tarrytown, N. Y 273-1100- 500WSAB-State Teachers College, Cape Girardeau, Mo 275-1090- 100WSAC-Clemson Agri. Col.. Clemson College, S. 'C 360- 833- 500WSAD-J. A. Foster Co.. Providence, R..1 261-1150- 100WSAH-A. G. Leonard, Jr., Chicago, Ill 248-1210- 500WSAI-U. S. Playing Card Co Cincinnati, Ohio 309- 970-1000

-WSAJ-Grove City College, Grove City, Pa 25.4-1180 250WSAP-7th Day Adventist Church. New York, N. Y 263-1140. 250WSAR-Doughty & Welch Elec. Co., Fall River, Mass 254-1181- 100WSAV-Clifford W. Vick Radio Const. Co., Houston, Tex 360- 833- 100WSAY-Chamber of Commerce, Port Chester, N. Y 233-1304- 100WSAX-Chicago Radio Laboratory, Chicago, Ill 448- 670-1000WSB-Atlanta Journal, Atlanta, Ga 428- 700- 500WSK-Reiss Steamship Co., Sheboygan, Wis 300- 999-1000WSL-J. & M. Electric Co.. Utica. N. Y 273-1100- 100WSOE-School of Eng. of Milwaukee, Milwaukee, Wis 246-1220- 100WSY-Alabama Power Co., Birmingham, Ala 360- 833- 500WTAB-Fall River Daily Hearld, Fall River, Mass 248-1130- 100WTAC-Pennsylvania Traffic Co., Johnstown, Pa 275-1090- 150WTAM-The Willard Storage Battery Co., Cleveland. 0 489- 770-1500WTAN'-Orndorff Radio Shop, Mattoon, Ill 2401250. 100WTAQ-S. H. Van Gorden & Son, Ossea, Wis 254-1180- 100WTAR-Reliance Electric Co., Norfolk, Va 261-1150- 100WTAS-Charles E. Erbstein, Elgin, Ill., near 286-1050- 500WTAT-Edison Electric Ilium. Co., Boston, Mass 246- 1220- 100WTAW-Agri. & Mech. College, College Station, Texas.. -270-1110- 250WTAY-Oak Leaves Broadcasting Station, Oak Park, Ill 283-1330. 500WTG-Kansas State Agri. Cot, Manhattan, Kas 485-620-1000WWAD-Wright & Wright, Inc., Philadelphia. Pa 250-1200- 500

-WVVAE-Alamo Ball Room Joliet, Ill 242-1240 500WWAF-Galvin Radio Sup. Co., Camden, N. J 236-1260- 500WWAO-Michigan College of Mines, Houghton, Mich 244-1230- 250WWI-Ford Motor Co., Dearborn, Mich 273-1100- 500WWJ-Detroit News, Detroit, Mich 517- 580- 500

268-1120- 100WWL-Loyola University, New Orleans, La

RADIO PROGRESSHORACE V. S. TAYLOR, EDITOR

Volume 1 Number 21

Contents for

JANUARY 15, 1925PAGE

I \1TED STATES BROADCASTING STATIONS 1

N-DERSTANDING A HOOK-UP 5

AMERICAN RADIO RELAY LEAGUE. S

WAVING PHOTOGRAPHS 3,000 MILES 9

THE YEAR 1924 IN RADIO HISTORY 12

FIFTEEN WORTHWHILE HOOK-UPS:1-SIMPLE CRYSTAL DETECTOR. 15

2-TWO-CIRCUIT CRYSTAL SET 15

3-SINGLE REGENERATOR-VARIOCOUPLER 16

4-SINGLE REGENERATOR--VARIOMETER 17

5-TWO CIRCUIT REGENERATIVE TUNER 17

6-THREE-CIRCUIT TUNER 19

7-FOUR-CIRCUIT TUNER 20

8-HONEYCOMB (SPIDER WEB) REGENERATIVE 21

9-AUDIO FREQUENCY AMPLIFIER 2210-COMPLETE THREE -TUBE REGENERATIVE 23

11-RADIO FREQUENCY AMPLIFIER 24

12-FOUR-TUBE REGENERATIVE SET 25

13-THREE-TUBE REFLEX CRYSTAL14-THREE-TUBE INVERSE REFLEX 28

15-FIVE-TUBE NEUTRODYNE 30

WILL THE MOON SHADOW SHUT OUT RADIO`' 31

Because of so much space taken by "Fifteen Worthwhile Hook-ups."regular departments are omitted for this issue only.

km() PROGRESS is issued on the 1st and 15th of each month by the Oxford Press at 8 Temple Street,idence. Rhode Island. John F. O'Hara, Publisher. Yearly subscription in U. S. A., $3.00. Outside

I :. A.. $3.50. Single copies, 15 cents. Entered as ,eeond-class matter, April 4, 1924, at the Post Officeat Providence, R. I., under the Act of March 3, 1879. Address all communications to RADIO PROGRESS,8 Temple Street (P. 0. Box 728), Providence, R. I. Title registered at United States Patent Office.

The publishers of this magazine disclaim all responsibility for opinions or statements of contributorswhich may at any time become subjects of controversy.

4 RADIO PROGRESS JANUARY 15, 191

Good Things inNext Issue

So much has been done intesting receiving sets that thesending end, particularly theaerial, has seemed somewhatneglected. This is to beremedied shortly, as describedin "53 Acres of TestingAerial."

The large amount of ma-terial in this issue on Hook-ups forced the postponementof two very interesting articles,"Silencing Ether Squeals," byGoldsmith, and "Taking Por-traits of Heart Beats," by Ar-nold. They will appear in theFebruary 1 issue.

You.know by now that 1924was a banner year in the ad-vance of radio. What can weexpect for the coming year? Agood prophecy will be found in"1925 A Forecast of Radio,"by Dunlap.

The "A" battery is alwaysa problem. Even with drycell tubes one or two cells ofstorage battery are often anadvantage. To charge themyourself read "Build YourOwn Charger," by Rados.

Many a good hook-up is

spoiled by the wrong wiring."How to Wire Your Hook-up," by Taylor, tells whatkind of wire is used and howto use it.

(Patent Applied For)

a newFour WayProduct!\

rLoud Speaker

Extension Unitl

COMPLETE

HIS Complete Unit enables those whowant to use the loud speaker in otherparts of the house to do so without re-

moving set. Insert plug from loud speakerinto jack; place plug on end of cord, into set.This can be done readily and saves the troubleof using tools or soldering iron.

PRICES, including Jack, Plug and Cord

10 foot cord $2.25 40 foot cord ....$3.00

20 foot cord 2.50 50 foot cord .. 3.5030 foot cord 2.75 100 foot cord ... . 5.75

Manufactured by

FOUR WAY CO.Myrick Building, Springfield, Mass.

AT THE BEST DEALERS EVERYWHERE

RADIO PROGRESS" ALWAYS ABREAST OF THE TIMES "

Vol. N. 21 JANUARY 15, 1025 15c PER COPY, $3 PER YEAR

416

Understanding a HookupIt is Easy to Read a Dia-gram When You Know How

By HORACE V. S. TAYLOR

T first sight many people think thatn. 'a, hookup is perhaps a new kind of

crossword puzzle. Once you get the hangof it however, reading such a diagramis as easy as picking out your route ona road map. The only difference is thatyou are already accustomed to the signsfor streets, rivers, railroads and cities,while the symbols for the various radioparts may seem strange to you.

The signs have been built with theidea of making them depend on commonsense. For instance. we have all seenhow the rotating plates of a variablecondenser turn in and out of the sta-

MAIN CONO.

VERNIER COND

Fig. 1. Rotor and Stator

tionary ones. A sign for such a unit isshown in Fig. 1, which represents amain condenser with a small vernierunit connected in parallel. Of course,the flat part represents the straight orstationary plates and the curve, theround or movable ones.

Coils May be AdjustableThe drawing for a coil is shown in

Fig. 2. At the left appears a coil with

p arrow pointing to it which meanshat the number of turns can be varied.

Such a -coil is frequently used connectedbetween the aerial and ground. Whenmade adjustable, a tap switch ordinarilypicks out which turn is wanted by con-tacting with a switch point as shownin the right hand part of Fig 2. Sucha diagram takes up too much space sothe left hand is used to represent thesame thing.

A rheostat is made by wrapping aresistance wire around a strip of fibrewith a turning arm sliding on the wire tomt more or less into the circuit. This

is well represented by Fig. 3. In the-mne way .a transformer consisting ofNo windings, primary and secondary, is

suggested by the symbols of Fig. 4. Thenumber of turns are specified here butordinarily they are not given as a trans-former has to be bought ready madefrom the manufacturer.

The symbol for a vacuum tube is acircle with grid, plate. and filament asshown in Fig. 5. Here also are seen thetuning condenser at the left, and thesymbol for phones and by-pass conden-ser at the right. This takes up most ofthe ordinary signs. In well constructeddiagrams any unusual markings are ex-plained.

When Wires CrossMany diagrams are somewhat confus-

ing as they do not show at a glancewhether two wires which touch are con-nected together or not. To make thiseasy we are using the scheme shown inFig. 6. At A is shown a cross connec-tion-a main wire with two branches.

Such a connection is oftentimes indicatedby the lines at B which has a dot overthe intersection. Indeed some hookupsdo not even show the dot and that some-times leaves the reader in doubt whetherit was intended to join the wires togetheror not. Diagram A in Fig. 6, cannotpossibly mean that the wires are cross-ing each other without touching, andso no doubt is felt by the reader. Whentwo lines cross without being connectedthey appear as shown in C.

The "A" and "B" batteries are repre-sented as ill Fig. 7. The long line is

Fig. 2. Signs of Tapped Coil

always to represent the positive (plus)although so many people make a mis-take here that it is well to indicate thepolarity by the signs and -. Itmakes no difference in operating the setwhether the negative side of the "B"battery rums to the + or - of the "A."It is customary to hook up the "A"and "B" - as the lower part of Fig. 7shows. When, however, a diagram makesa better looking job by showing the two

RADIO PROGRESS JANUARY 15, 1925

negative terminals hooked together as atthe top of Fig. 7 then this is done. Itshould be understood that in construct-ing the set either connection may beused.

The General Hook-upWhen you see a hook-up of several

tubes, which look at first sight rathercomplicated, there is one way of runningthe wires down which will give you agood idea of the whole thing. The firstthing to do is to notice the filament con-nections. These will run from the "A"battery through one or more rheostats,to the filament of the different tubes.As a general thing the rheostat shouldbe in the negative line of the "A" bat-tery. Occasionally it will work just aswell in the positive. but even in suchcases it might be put in the former withequally good results. A rule which willalways work is a good one to follow,and that is why we always show therheostat connected to the "A" minus inour diagrams.

frOFF

4

ONMM 1-9,

Ti

Fig. 3. Rheostat Has Two Terminals

After the circuit of the "A" batteryand filament has been traced through for

the tubes, you are ready to pick outthe grid and the plate circuits for eachtube. The general scheme is shown inFig. 5. Ordinarily a coil will be foundrunning from the grid to the filament.This coil may be the stator of the vario-coupler, or a variometer, or it may bethe secondary winding of a radio oraudio transformer. In a few hook-upsthe opposite end from the grid does notgo to the filament. (See Hook-up No. 71.In such cases, however. the oscillationsget back to the filament through theleakage capacity of the set, and indeedit is likely that a positive connection tothe filament would increase the volumeof the music.

Tuning the GridIf the tube in question is handling

radio frequency, it is quite likely that atuning condenser will be shown con-

nected in parallel across this coil. Insuch a case the stator should always

run to the grid.The output of the tube always runs

from the plate through the receiver tothe "B" battery. The receiver may bethe phones (if it is the last tube) or theprimary of the transformer, if a furthertube is used.

(3F -CO N DARY

PRI MARY

1-000TURNS

91,40 WIRC

'RON CoRF-----1

Fig. 4. Transformer Symbol

These three circuit-. Marmot!, grid analplate, will be fmind in every hook-up,and if taken for each tube in that order.will make a reading of the diagrainmuch simpler.

The By-pass CondenserWhenever radio and audio frequency

are present in the same wire, it is neces-sary to put a by-pass condenser aroundthe unit which is operated by the lowspeed audio vibration. The reason isthat the inductance or electrical weightof such a device is so great that it can-not be made to oscillate at a milliontimes a second or so, corresponding tothe radio frequency. This stopping con-denser may have a value of .001 or .002mfd. (microfarad) interchangably. It isshown around the phones in Fig. 5. Forthat reason it is sometimes called a"phone condenser." That is not a goodname for it, because the same condensermust be used around the primary of thefirst audio transformer when one step ofamplification is used.

This condenser may be connectedaround the phones in either way asshown in Fig. S. The first method is theone usually drawn out in a hook-up. Itby-passes the high frequency around thephones only. The second way is, how-ever, better as by this connection thehigh frequency does not have to passthrough either phones or "B" batteries.In this way the bad effect of a "B" bat-tery in poor condition is removed fromthe radio frequency circuit.

Size of CondensersAs just mentioned, whenever a by-

pass condenser is used, it may be either

.001 or .002, with equally good resultsIn any hook-up where you see one calk(for, the other may be substituted. Thvariable air condensers may be specifieseither by the number of plates or by thcapacity. When an 11 or 13 plate variable is called for it is understood tha.00023 mfd. is meant. If your brand acondenser happens to have wider spacings between the plates than usual, yolmay need a 17 plate unit to get thicapacity. The 23 plate condensers armeant to have a value of .0005 mfd.43 plate condenser should never be usesexcept in very special work, as that capacity is too big for use with coils whielare properly made unless wave lengthof over 600 meters are to be brought in.

Size of Wire to UseIn general the size of wire for radii

work is not very important. One or twnumbers larger or smaller can be substituted in almost any hook-up without ma

a

Fig. 5. Basic Tube Circuits

terially changing the inductance of thcoil. Small differences in this value arcompensated for by a slight difference iithe setting of the dials. For this reasanany diagram calling for, say No. 23 DC(double cotton covered) wire, can be followed just as well with No. 22 or No. 24About the only time when this is impoltant is when a spool of a certain size ito be wound full. In such a case thsmaller wire will require more turns tfill the space and this will run up thinductance too high. In such a caswinding on the same number of turns acalled for of a smaller size will not filthe space full, but will give the HOvalue of inductance.

Dials are not mentioned by size, as thdiameter should be made to harmonizwith the general appearance of the setThree and one-half inch dials are abetsright for ordinary work, although 4units make a little easier tuning. Focontrols which are not at all critical

JANuAriy 15, 1925 RADIO PROGRESS 7

and so do not need very accurate set-tings, 3" or even 2,A" are big enough forsatisfactory service.

As already explained, the tap switch(Fig. 2) selects the number of turns ina coil so as to vary its useful value.Since it is impractical to change the

pt number of turns by less than one turnsteps, it follows that fine tuning cannotbe done with a tap switch. Where in-ductance must be varied continuously,instead of in steps, a variometer is used.The tap switch may come as a singleunit with the switch points mounted ina disk of ibakelite or the switch pointsmay be bought separately and the paneldrilled to take them.

What Kind of Vacuum Tube?When you consider that there are four

different styles of tubes on the marketwhich are very popular, besides a num-ber of others, made by different kinds offactories, it is something of a problemto know which one to use. These fourtubes may be called the 199, 200, 201A,

Fig. 6. Cross-overs and Connections

and WD. These are the numbers as-signed by the Radio Corporation, but inthis discussion it should be understoodthat equivalent tubes of other manufac-ture are included in these names.

For use with storage batteries the 200makes the best detector and the 201Athe best amplifier. For dry battery usethe 199 takes three volts from three cellsin series. The WD is operated by 1.1volts from a single cell. The WD11 andthe WD12 are electrically just alike. Theonly difference between them lies in thebase. For those who do not mind theexpense and bother of keeping up thestorage battery the 200 and the 201Atubes will be the proper selection as theygive louder volume particularly on localstations. Those who prefer the great ad-vantages of dry cells will use the 199or WD. Of these two, the former is thebetter radio amplifier and also uses lessfilament energy than the latter. Forsets using three tubes or more we recom-mend the 199 tubes. If only one or two

are called for in the set then the WDwill have the advantage that a singlecell will serve for an "A" battery, whilethree cells are necessary to give the vol-tage required to operate from one to six199 tubes.

1_11111111+

"A" "f?

9- 11-t-

"i3"

Fig. 7. Two Ways of Connecting "B"

ohms6 ohms

ohms30 ohms20 ohms

4 to 6 199 Tubes 6 ohms1 to 3 WD Tubes 6 ohms3 to 6 WD Tubes 2 ohmsThe rheostat may be used as a switch

to turn off the set or a filament switchmay he inserted in either of the "A"battery leads to do the same thing. Thishas the advantage that the rheostatsmay he left at about the correct. settingwhen the current is turned off.

Different Kinds of JacksIn any hook-up a jack may be used to

connect the phones or loud -speaker intothe circuit at either detector first or sec-ond step of audio. The intermediatejacks may he omitted if desired. Forthe last tube a jack with from one tofour springs is needed. The intermediatetubes require jacks that have at leasttwo springs.

This was explained at length in"Judging Jacks for Real Results" in theSeptember 1, 1924, issue of RADIO PROG-RESS. The two -spring unit is better than

Rheostat to FitNotice that in the hoop -ups the re-

sistance of the rheostat is not mentioned.This is because different values areneeded depending on what style is em-ployed. When using the various tubesas described above the following valuesof resistance are suitable. The numberof tubes means those connected to onerheostat.

1 200 Tube 6

1 or 2 201A Tubes3 to S 201A Tubes1 199 Tube2 or 3 199 Tubes..

the four since it does not have as manyunsoldered contacts which might causetrouble. The method of connecting sucha jack into any audio circuit appearsin Fig. 9.

The most popular sizes of panels atthe present time are the 7x14, 7x21, and7x26.. These are the ones specified in ourlists of material. If you have some othersize which is similar it will do just aswell. The preferred material is eithersome form of hard rubber or else thesynthetic product like bakelite, conden-site, or the like.

Testing a, SetWhen building a set it is well to test.

it as it is being put together. First con-nect the "A" battery and filament cir-cuits. Put the tubes in and make surethat the rheostats control their bright-ness. When the wiring for each tube iscompleted it is best to insert it and thenconnect the "B" battery to see whetherthere is a short circuit or not. Touchthe wire to the "B" battery for only an

Q.

=--1111111 --411111" 13., .13.0

Fig. 8. By-pass is Around "B"

instant while looking at the tube. Ofcourse it should not light up, and if itdoes, it shows a mistake, which shouldbe corrected immediately. This test willsave you from burning out your tubesby a wrong connection.

When operating a set be sure to re -tune for the station you are listening toafter every change or adjustment that ismade. This is necessary, because evensuch a simple thing as adjusting therheostat may cause a slight shift in wavelength. This must be corrected orelse the music will be faint because ofincorrect tuning.

Prices of MaterialIt is not an easy matter to put prices

on radio parts which will represent goodvalue all over the country, there are somany different grades of parts. We havetried to give the figures for the cheapervariety of good parts in the simple sets,while the elaborate hook-ups call for

Continued on Page 8

8 RADIO PROGRESS JANUARY 1Z, 1925.

American Radio Relay League"SIX WEEKS," SAID THE JUDGE

In some respects it is not as pleasantto live in Czechoslovakia as it is in theUnited States. They do things different-ly there.

According to information received bythe American Radio Relay League froma correspondent, a radio fan in thatcountry was recently sent to prison forsix weeks because he built a radio receiv-ing set and occasionally sold parts with-out a license. The accused fan filed anappeal but the court would not change itsjudgment on the sentence.

In order to obtain a license for operat-ing a receiving set under the governmentregulation of April 17 of last year, onemust furnish a diagram of the set with alist of units employed, pay the tax andadvise whether the receiver is home -built,or obtained from a manufacturer of

radio equipment. The law of December20. 1923, requires the applicant to be asubject ofand a permanent resident of the country.

Despite these requirements. there areat present in that country about 1,000receiving sets. The correspondent fur-ther tells us that enthusiasm among lis-teners is not very high as governmentrecognition and privileges were long incoining and the present programs arepoor. Most of the receivers come fromFrance, England and Germany.

While the prices for radio parts andcomplete sets are about the same as thosein the United States, they are far be-yond the reach of the poor farmers, in-dicating that it may he a long time be-fore radio becomes as popular generallyamong all classes of people as it is in

this country. There is a great demand.however. for radio text hooks and maga-zines.

PRIZE BY MYSTERY MANThe amateur radio operator who han-

tiles the greatest number of radio tele-graph messages for three consecutivemonths will receive a valuable plaque,suitably engraved with the name of thewinner. it was recently announced by theAmerican Radio League Traffic Depart-ment. Only members of the A. R. R. L.

who hold an amateur operator's licenseand operate a transmitting station, areeligible to compete.

The man who offers the prize is him-self an amateur, but as he does not wishhis name to be known, we cannot tell youwho it is. The object of the gift is tostimulate the amount of message trafficon the short waves and to allow for im-provement in the quality of the messageshandled. The contest will start with thebeginning of the March operating monthin each of the A. R. R. L. Divisions.Amateurs in doubt as to the exact timeshould write their Division Manager.The reader for each month will be an-nounced.

The provision is made that all mes-sages must be transmitted in accordancewith the usual A. R. R. L. practice withrespect to prefix, number and date. Ab-breviations will not be permitted andmessages held more than forty-eighthours for relay cannot be counted. Con-testants will be permitted to send "ap-plause messages" for broadcast listeners.

To give some idea of the traffic, it wasannounced at the American Radio RelayLeague that Ralph Barnett of St. Louis,Mo.. operator of amateur station 9AUI,had handled 333 private radio messages

during December, which is the best indi-vidual record of any amateur operatorfor that period.

DOUBLE YOU BE ZEDNo, the call letters of the Westing-

house station at Springfield, Mass., havenot been changed. They are still WBZ.But on the air the letter "Z" sounds likemany other possible letters. It mightbe mistaken for a "V," a "C," a "D," ora "G." All radio fans like to know thestation they are listening to. So theannouncers were instructed to try pro-nouncing "Z" like "Zed." The proposalwas tried, and met with the immediateapproval of listeners. Many fans aretickled with the idea. They say that"Zed" leaves no room for doubt. Thescheme was tried during internationaltests for the benefit of listeners on theother side, but United States fans werequite enthusiastic over the new pro-nunciation.

STILL GOING STRONGThe total value of radio apparatus

and tubes manufactured in this countrylast year aggregated $48,032,927.

HENAGONALNoT

514011T SPRING

A

Fig. 9. Connecting aUNDERSTANDING A HOOK-UP

tMitinued from Page 7.prices on the best equipment. The ideais to give a set builder some idea ofwhat it will cost him to put together

Pc V \

TP,ANSF 0 P\K

jack in Audio Circuitsuch a hook-up. He can always paymore than what we have indicated andsometimes good parts may be procuredfor less. These figures will be found ingeneral to be about average.

-w

JANUARY 15, 1925 RADIO PROGRESS 9

Waving Photographs 3000 MilesA New Process That StaticDoes Not Bother Much

YOUhave probably seen in the news-

papers some reproductions of photo-graphs that have been sent across theAtlantic by radio. There have also ap-peared with them some so-called explan-ations of how they work, but most sucharticles have not given a very clear de-scription of what happened.

Part of the apparatus which is usedis comparatively old. Pictures have beencarried over telegraph lines for somelittle time. The principle of such trans-

FILM

Osca.LALAvA CyzmiDER

FA7.14 OF LIGHT RAYS174Rouort f1 AM

Fig. 1. Film is Clipped to Roll

mission is that each illustration hasbeen broken up into a large number ofsmall dots by photographing it througha screen. That is the same processwhich is used in making portraits formagazines and newspapers. The difference between the appearance of the figures in these two mediums is that mag-azines use high priced, smooth finishedpaper, and so are able to use' screenshaving 120 wires per inch, while news-papers are printed on much cheaper andcoarser paper which will not print wellif more than half that number are used.

Big and Little DotsBy this method, which is called the

half tone process, a dark part of the pic-ture consists of a group of large blackdots. They are so large in fact that theyoverlap oftentimes, and leave only smallwhite spaces between them. A gray partof the picture appears as smaller dots,completely surrounded by white apace.The sky will be represented by dots so

By VANCE

small that they are hardly visible at all.Naturally, there are all sizes of thesedots in any picture, depending on theamount of light and shade in the origi-nal.

In transmitting pictures over a tele-graph line the mechanism transmits aseries of electrical impulses or waves,corresponding with the various dots.The sending mechanism takes one afteranother right straight across the pic-ture, and where the spot is large andblack, a heavy current flows. A lightspot, on the other hand, causes only asmall current through the wire. If asixty mesh screen is used, then whensixty of such current changes have oc-cured, a single inch of the photographhas been transmitted.

3600 Points Per Square InchBut notice that this is not a square

inch of photograph. It is only a lineone -inch long. To complete a squareinch there must be sixty of such 'ices.That means, sixty times sixty, or 3600separate current impluses to one squareinch of picture. Naturally by usinga coarser screen, the number may becut down a great deal, but the appear-ance of the completed photograph ismade correspondingly rougher. By com-paring the illustrations in magazineswith those in newspapers a good ideacan be obtained as to the result of in-creasing the mesh of the screen in thisprocess.

When it comes to sending by telegraphlines, it is a problem, to know just howbig a mesh it is best to use. If we em-ploy a screen with twice as many wiresper inch, then it will take four timesas many current changes to completethe figure. From this it is easily seenthat the time of reproducing a good sizednegative will be very long if we try tomake it out of very small dots.

Static Gives a Black EyeThe same process of sending can be

used as well in radio as over a wire asfar as theory is concerned. But justthink what would happen if interfer-ence should occur. If static came injust while the eye of the subject hap-pened to be transmitted, he would cer-tainly get a black eye. And if a neigh-bor started oscillating while his facewas being printed, each squeal would

LAMP I -EMS

4,15 1)PHOTO-EL-AcrRic CELL

Fig. 2. Light Strikes Electric Eye

show up as a freckle, with the resultthat not even a mother could love theface which would appear.

This new invention was created withthe idea of getting away as far as pos-sible from the disturbance of static andinterference. And results show that ifconditions are favorable, pictures willcome through which do not show theblemishes from small disturbances andinterference which might be expected.Of course, if static gets to be too bad,then it is advisable to postpone sendinguntil a time when the atmosphere quietsdown a bit.

Preparing the PictureThe first step in the process is to

make a negative like those which youtake in the ordinary camera. If a regu-lar negative is obtainable, no furtherwork on it has to be done, but if it isan ordinary picture, an illustration in amagazine, or the like, then it is hungup on the wall and a studio camera takesa photograph of it, thus making a regu-lar negative on a film. A plate nega-

10 RADIO PROGRESS JANUARY 15, 1925

tive will not do, since the film is nextbent around a glass cylinder, to whichit is held firmly by metal clips alongeach edge.

This glass cylinder with the film on itis shown in Fig 1. Inside the cylinderis a very powerful electric light and

lens. The light naturally shines throughthe glass of the cylinder and alsothrough the film. It is concentrated in-to a beam by the lens between the lampand the film itself. The lens is designedso that the rays of light come to asharp focus or point at a single spot onthe film about as big as the head of apin. From there the rays go on (see

Fig. 2) spreading out until they strikea second lens.

CARNARVON- WALES -

STANDARD HIGH POWERTRANSMITTING APPARATUS

This photo -electric cell is found tohave the curious property that whenlight shines upon it, it reduces the re-sistance as measured by an electricalcurrent, to a very low value. The

brighter the light the more current willflow when a voltage is impressed on thetube. You will see that this becomesan electrical eye and transforms thechanges in light into variations in elec-tric current.

Following the Zigzag TrailThe glass cylinder, with the film at-

tached to it, turns on its axis slowlyback and forth without making a com-plete revolution. When the light beamgets to the edge of the film, as Fig. 1

shows, the rotation reverses and so it

EiV6L A A'oTRANSMITTING

--ANTENNA

notLio"oats goo

CARNATVON.Y4XLES220

\`... AUTOMATICSIGNALLING RELAYS

is a standard apparatus. Fortunately,the amount of light which strikes thecell causes an instantaneous change inthe current flowing so there is no lostmotion. As the light creeps back andforth across the film its variations arepicked up and at the same moment theradio waves crossing the Atlantic re-spond to the slightest changes in theoriginal picture. As the film rocks backand forth and keeps advancing a notchat a time, the record of what the photocell sees is broadcast to the world andso line by line the picture is put on the

air.Getting on the Air

The modulator feeds the radio wavesto an ordinary amplifier to increase

AMPLIFIER MODULATOR CAMERA GLASSCYLINDER

POWERFULLIGHT

PICTURE TO BETRANSMITTED

MARCONI HOUSE "STRAW-LONDON -

Fig. 3. London Puts Picture on Air from Aerial 200 Miles Away

The Electrical EyeThis second lens concentrates the rays

again on a special tube, called a photo-electric cell. This is a kind of vacuumtube which contains a special form ofthe metal "sodium." You never see sucha metal in its pure state, because it hassuch a strong affinity or desire for oxy-gen, that if a piece of the pure metal

is dropped into water it breaks thewater molecules up into its ingredients,oxygen and hydrogen, and seizes on theoxygen with such violence that it getsred hot and sets fire to the hydrogen.It can be preserved without oxidizingin a vacuum, where there is no oxygerand that is why a vacuum tube is used.Although you never see any pure so-dium, still you are very familiar wit!,the element in combination as when so-dium and chlorine unite in equal partsthey form ordinary table salt, (sodiumchloride ) .

rocks back and forth first to the leftand then to the right. Every time itchanges its direction, however, the wholebusiness moves endwise on its axis fora distance of about 1/134th of an inch.This makes a path for the beam oflight through the film of a lot of par-rallel lines connected on the ends, as il-lustrated.

From this you can see that the elec-tric -eye (photo -electric cell) is gettinga continuous series of bright and darkrays of light as the patches of blackand white film let more or less lightthrough. The current, passing throughthe cell, varies up and down in a waythat corresponds with the shading ofthe negative being transmitted. Thiscurrent is fed to a modulator of a broad-casting station, which works just likeany ordinary transmitter such as isused to send out radio concerts. Thisis not described in detail here, as it

their volume. From there they mightgo directly to the aerial, but in the re-cent tests the pictures were sent fromMarconi House in London, and thetransmitting antenna was located atCarnavon, in Wales, so a telephone line220 miles long was used to conduct thewaves between the two stations. See

Fig. 3. This is the same idea as hadbeen employed recently in the UnitedStates when land lines linked up fromtwenty to thirty different sending sta-tions to give out the same program onseveral different occasions.

At Carnavon, is located the 200kilowatt transmitting station of the

Marconi Company. This amount ofpower is 200 times as great as the big-gest broadcasting stations which havebeen allowed in the United States up tillvery recently. However, broadcast lis-teners will not have "heard" this picturesince it is sent out at very long wave

JANUARY 15, 1925 RADIO PROGRESS 11

CENTRAL RADIO OFFICEBROAD STREET - NEW YORK CITY

SPECIAL RADIO AMPLIFIER.PHOTOGRAPHIC RECEIVER

ELECTROMAGNET

PEN

RECORDINGSHEET

e-&_4_-=

CYLINDER MOTOR. =-

LAND LINEi- 70 MILESRIVERHEAD TO NEW YORK

9 MILERECEIVING ANTENNA

\ STANDARD VACUUM'-TUBE AMPLIFIER. IN

RECEIVING BUILDING

RIVERHEADLONG ISLAND

Fig. 4. Using 9 -Mile Antenna Brings Photo to Cylinder in New York

lengths-far above the range of any or-dinary receiving set.

At this sending station the electricwaves from the land line stretchingfrom London, operate small relays whichturn the aerial current on and off. Thistremendous electrical power radiatesfrom the aerial in interrupted blocks ofenergy, very much like the dots and

'9'4,44:474,0 C.

clashes of telegraph code, except that required. Of course, the wave length isthe latter has dashes all of equal length, much longer, as has been explained, butwhereas in sending a picture if a large this was for two reasons; the absorp-dark part of the negative comes intofocus the dash transmitted will be a verylong one.

No Special Broadcasting StationYou will notice that at the sending

station no particular new circuits are

Fig. 5. Our President as Flashed from London

tion by the atmosphere on such low fre-quencies is less than the ordinary speedsof oscillation, and furthermore it wouldnot do to blanket ordinary broadcastprograms by using such tremendouspower at regular wave lengths. Thereis nothing in the actual requirement,of the transmission which necessitatessuch lengths.

It is also worth observing that anyof the powerful trans -Atlantic stationscould use such a system of sending. Itis not confined to special apparatuswhich requires a lot of expensive equip-ment and special trained operators.This is a very good point in favor ofthis system.

Snatching Pictures from the Air.We now come to the receiving sta-

tion, which pulls in the ether vibrationsand makes a photograph out of them.An aerial nine miles long, (Fig. 41. isinstalled at Riverhead, Long Island. topick-up the Carnavon transmitter. Thisis the regular equipment used for com-mercial messages. An amplifier equip-ment at Riverhead increases the vol-ume of the electrical impulses enough,so that they can be transmitted 70 milesover the land to the New York offi,,e onBroad Street.

Another amplifier makes up for theweakening effect of the 70 miles of cable.The waves are then fed to a detectorwhich operates in the usual manner.The output, instead of running througha telephone or loud speaker, is connectedto an electro magnet, which pulls a

Continued on Page 14

12 RADIO PROGRESS JANUARY 15, 192

The Year 1924 in Radio HistoryWestinghouse Tells of .Progressin Radio and Electricity

By H. W. COPE, Assistant Director of Engineering, WestinghouseElectric and Manufacturing Co.

DURING the year 1924 a great dealof progress was made in radio as

well as along other electrical lines. Ofcourse, many improvements were of adetail nature which do not sound likevery much when described, althoughthey make a great deal of differencein the smoothness and efficiency withwhich a device may operate. However,there were a large number of basicimprovements, which make interestingreading. Some of these are describedhere as seen by the Westinghouse Com-pany.

In making such a review of its elec-trical engineering achievements of thepast year the company has reportedonly the most noteworthy improve-ments. 'Some developments are of greatpopular interest. Others, of apparent-ly little significance to -day, are un-doubtedly the start of achievements tocome in the future.

Every Night in EuropeIn the radio field, KDKA, the world's

pioneer station, at East Pittsburgh,Pa., and its sister stations, KYW atChicago, Ill., WBZ, at Springfield,Mass., and KFKX, at Hastings, Neb.,added new laurels to a crown alreadywell -filled. Through the use of short-wave repeating, KDKA was heard con-sistently in all parts of the North andSouth American continents, in GreatBritain and continental Europe andeven in such remote places as SouthAfrica. In the International listeningtests, recently completed, KDKA wasthe only United States station to beheard in Europe every night of thetests. Such a record speaks well forthe reliability of radio broadcasting.

Two Giant GeneratorsIn electrical lines other than radio

great improvements are noted. Forinstance, two generators, having a rat-ing of 62,500 kv-a (kilovolt -amperes),

1,200 revolutions per minute (r. p. m.)each were placed in operation. Thesewere the largest single generator unitsever built. The rotor had a net weightof 230,000 pounds. The output of thissingle machine is enough to light alarge city. Using the ordinary 25 wattbulbs, this unit would light two andone-half million (2,500,000) lamps. Thelargest 3600 r. p. m. generator yet con-structed also went into service duringthe year. It had a rating of 12,500kv-a.

As a result of the careful studygiven to the various problems enter-ing into the design of large machines,it has been possible to place in servicea frequency changer, converting 25 into60 cycles, having an efficiency for eachof the two machines comprising theset of better than 98%. This is thehighest efficiency that has ever beenobtained in a 60 -cycle motor or gen-erator. This frequencies changer isused to tie together two different sys-tems, one working at a frequency ofsixty cycles and the other of twenty-five cycles. Very few twenty-five cyclegenerators are built for new installa-tions, since the higher rrequency ismuch more popular. However, exist-ing systems which use twenty-five cy-cles and need new apparatus naturallycontinue at that speed of oscillation.When such a system grows until itstrikes the territory of a sixty cycleinstallation, it is necessary to use afrequency changer to tie the two linestogether.One Motor Drives Two Generators

A notable advance has been madein motor -generator sets for steel mills.This consists in the use of a singlemotor driving two generators connect-ed in parallel. One set of this type isnow in very successful operation, hav-ing capacity for a 5000 h. p. reversing

mill motor. Two other sets of 500and 7500 h. p. capacity are under cotstruction and will be delivered shortb

A new type of high speed contnhas been perfected, which allows a loudispatcher in a central office to opeand close circuit breakers, which mabe located in various sub -stations. Tb

position of each separate breakershown on a control board in the di:patcher's office. Of course, such a sy:tern has been in use in a small way faa long time, but the trouble in the pahas been that the large numberbreakers has required a prohibititequipment in the way of separate winfor each breaker. The new system rduces the number to a small fractio

Keeping Ends in StepThis new form of supervisory coi

trol selects entirely by relays. Itcalled the "synchronous relay type," bcause the contacts on the two ends(the system operate in step with oranother. This system is acknowledgethe best yet developed. As a result(its remarkable efficiency, it is possibfor a company to use a selective meteing equipment whereby 52 current au54 voltage readings are obtained ovlonly two pairs of telephone wires.

The largest automatically controlhmotor -generator set in the world 1

Edison service was placed in successfoperation in St. Louis under full autmatic control. Such a machine haalmost human intelligence as it startoperating automatically when needeand shuts itself off when no longer neessary. If one of the bearings gelhot, instead of wrecking it, it immedately comes to a stop. If for any re:son the speed gets too high it is takecare of automatically. If the wansupply cooling the transformers shoulcease to flow, they would not be burne

.art

JANUARY 15, 1925 RADIO PROGRESS 13

out as the wise generator would imme-diately shut itself off.

No Oxygen Touches ItThe Inertaire Transformer marks

one of the most progressive steps for-ward in transformer engineering yettaken. These transformers make im-possible either explosions or fire fromthe oil insulation in transformers. Ni-trogen taken from the air is used toact as a cushioning blanket betweenthe transformer oil and the air, pre-venting oxygen from reaching the oil.

Auto -valve lightning arresters havebeen built for voltages up to 140,000volts. Another type of arrester hasbeen developed for use on lines wheresurges of dangerous magnitude or dur-ation may appear.

When You Visit the "Follies"When you see some of the musical

comedies you may be surprised at themarvelous lighting effects. Up to re-cently it was possible for the electri-cian to set his levers to control thevarious lights just one step ahead ofthe time he wanted to use them. Thenby pressing a button the correct changein all the circuits would occur at once.He was then required immediately toget ready for the next set. A "multi -preset" stage lighting system has beendeveloped with twenty preset switches,each controlling 95 pilot circuits. As aresult the stage electrician workingfeverishly between each lighting ef-fect, opening and closing the switchesis no more seen. With this board, all

4. the lighting effects for every scene of atheatrical production may be set up inadvance and remain undisturbed for

I jo. the run of a production.The rapid expansion in transmission

systems has made it necessary to de-velop some means for obtaining infor-mation of the nature of voltage dis-turbances. To meet this need, theKlydonograph was developed. It workson the basis of an electrical stressthrown on the emulsion of an ordinaryphotographic plate and which, whendeveloped, shows figures that give de-tails concerning the voltage impressed.The instrument will show whether thevoltage was alternating or not, and ifnot, will show whether it was positiveor negative. Voltages of extremelyshort duration can be recorded. Adescription of this instrument and sam-

ples of its records appeared in theApril 1, 1924, issue of RADIO PROGRESSin, "A Lifetime in a Second."

A Throb -less Mill MotorAn accurate method of balancing

rotating machinery has been developedthat can be operated by almost any-one. A means has been devised foreliminating the vibration caused by thepulsating torque of single-phase ma-chines. New methods for driving steelmills, rubber mills, paper mills and thedrilling of oil wells have been per-fected.

Several new types of instrumentshave been developed, among which arethe Klydonograph and the kv-a meter,while others such as the oscillographand the watthour meter have beengreatly improved.

A number of marked improvementshave been made in stoker design byWestinghouse engineers the past yearas follows :

A new model underfeed stoker foruse with preheated air.

A modified clinker grinder equipmentfor the successful handling of lowgrade coal.

A device to prevent the formationof clinkers.

Hats Off to the "Colorado"In the field of marine applications,

1924 was a notable year of achieve-ments. The U. S. battleship Coloradowas given her final trials during thesummer and accepted by the Navy De-partment. This is the mightiest dread-naught afloat and surpasses all othercapital vessels in striking power, rapid-ity of action, facility of control andthoroughness of protection. Her elec-tric drive permits the use of her fullpower for both forward and reverseoperation, thus providing the highestdegree of maneuvering power. As aninstance of this latter, is the abilityto stop this great ship, from a fullspeed of. 21 knots to standstill, in threeminutes.

Four Diesel electric hopper dredges,built for the U. S. War Department,Corps of Engineers, were completedand put through their trials. Eachvessel is fitted with the largest Die-sel electric plant ever installed on aship. Trial runs have been completedon the first Diesel electric tanker togo in service on the Atlantic Coast.

Also the first Diesel electric tug in theworld went into operation in New YorkHarbor the past year.

Henry Ford's Railroad EquippedDeliveries of power house and sub-

station equipment for the VirginianRailway, the greatest single order everplaced for complete electrification, arenearing completion. Locomotives willbe ready for shipment as soon as thetrolley line is erected and has hadvoltage applied to it. The first motor -generator type locomotive ever built isjust on the point of completion. It hasbeen designed and built by the jointefforts of the engineers of the FordMotor Company and those of the West-inghouse Company. The initial electri-fication of the Detroit and IrontonRailroad Company consists of approxi-mately 17 miles of double track rail-road, extending from the River Rougeplant of the Ford Motor Company toFlat Rock, Mich.

High Speed ElevatorsIn elevator equipment, the necessary

apparatus and controls have been de-veloped which makes speeds of 1,000feet per minute entirely possible. In

order to test all elevator apparatus,and develop and demonstrate new sys-tems of control, a new elevator towerwas built at East Pittsburg. Thistower is designed and equipped to testany kind of hoisting apparatus forduties up to 10,000 pounds and speedsof 1,000 feet per minute.

The phenomenal growth of streettraffic and the increased demand forornamental types of street lighting fix-tures has stimulated a careful study ofthe lighting of city thoroughfares. Not-able in engineering development wasthe BI -Lux refractor which divides thelight flux into two wide beams whichdiverge in opposite directions up anddown the street, resulting in a higherillumination evenly distributed be-tween lighting units and with the glarereduced to a minimum.

To Charge Your "A" BatteriesFurther refinement in the design and

manufacture of rectigon bulbs havebrought the average service life of thisproduct up to 4,000 hours under fullload conditions. These are the bulbswhich contain a heavy tungsten fila-ment which burns in the rare gas Ar-gon. It is used as a rectifier for charg-

14 RADIO PROGRESS JANUARY 15, 1925

ing "A" and "B" batteries, as electric-ity will flow from the carbon electrodeto the tungsten, but not in the reversedirection.

A new type of electric iron has beendeveloped. This holds the temperatureconstant at any heat you desire. Anew style of thermostat whichis very rugged, can be adjusted fromthe outside. For ironing light silkwaists the temperature may be set to alow figure and if you are forgetful andleave the iron on one spot too long itwill not heat up and scorch the dress.For ironing heavy sheets or linens thethermostat can be adjusted to give allthe heat which the laundress can use.

Reaching the World's CornersIn the field of radio, developments

have gone forward at a great rate.Broadcasting has been developed, andwith the perfecting of short wave re-peating, the range has been so extendedthat almost every corner of the globecan be reached. The use of carriercurrent telephone systems has provedtheir reliability in dispatching servicefor large power systems. Vacuum tubeshave been built in sizes hitherto un-dreamed.

One year ago, December 31, 1923,radio repeating on short waves re-ceived an International impetus whena New Year's message from KDKAwas picked up in England and repeatedthrough all the stations operated by theBritish Broadcasting Company. Dur-ing the year many variations of theshort wave repeating theme have beencarried out successfullly. On some oc-casions KDKA has supplied the sameprogram to KFKX at Hastings. theseven British Stations, and KGO atSan Francisco simultaneously.

They'll Tell the WorldOn March 7. 1924, the banquet of

the Massachusetts Institute of Tech-nology Alumni was broadcast to theEnglish speaking people of the world.Wire connection was used between thebanquet hall and station WJZ andWGY. whose signals were picked upby station KDKA and relayed to sta-tion KFKX and station KGO, Califor-nia. and was also relayed to the Brit-ish Broadcasting Company, who inturn broadcast it to the British Isles.This was the first time extensive radiointerconnection had been attempted inconnection with radio broadcasting.

On March 14, 1924, station KDKAgave its first concert entirely in Span-ish for the benefit of the Spanishspeaking people of the West Indies,Mexico, Central and South America.The program was relayed by stationKFKX and also by a station in BuenosAires, Argentine. This was so success-ful that several other Spanish pro-grams have been broadcast during theyear.

Talking to McMillanJuly 4th to September 22nd, the Com

pany carried on short wave communi-cations with Captain McMillan's reliefexpedition on the Canadian Govern-ment ship "Arctic." During the sameperiod, constant communication wasalso maintained on short wave lengthwith the Hudson Bay ships "Nascopie"and "Bayeskimo."

At the time of the Wills-Firpo fightat "Boyle's 30 Acres," Hoboken, N. J..the Buenos Aires daily paper, La Na-tion, had an announcer at the ringsidewho broadcast the entire fight, blow byblow, to his paper by the use of sta-

New Powerful Radio TubesUntil recently it has been impossible

to produce large size vacuum tubesthat could be made to oscillate at fre-quencies above 2,000 kilocycles (150meters wave length). As a result ofthe careful study given this problemby Westinghouse engineers, it has beenpossible to develop a water-cooled met-al anode (plate) tube that will suc-cessfully op; -:-_1-r. on frequencies up to6,000 kilocycles (50 meters).

About 30 sets of carrier current tele-phone equipment were placed in ser-vice on the lines of six different powercompanies during the year. By meansof this equipment, different parts ofan interconnected system can be sepa-rated remotely by the main dispatch-er's office. This system which uses themain power wires to carry at the sametime the voice currents, is a great ad-vantage to the central station especial-ly in times of trouble. The high volt-age lines are much more rugged thanthe usual telephone wires and in asevere storm the latter will go downlong before the former. This systemgives the companies the chance to keepcommunication going between substa-tions as long as there are any power

wires at all which are still up. Anothename for this method is "wired wireless," since it uses high radio frequenc3waves along the wires.

WAVING PHOTOGRAPHSContinued from Page 11

fountain pen against a piece of papefastened to an oscillating drum. Ever,time the pull is strong enough the pmmakes a little dot on the paper. Thi

drum is rotated back and forth and advanced a notch each time exactly in stetwith the oscillating film at the sendingend.

Keeping up With the ProcessionOf course, it is of great important

indeed that the two oscillating drumkeep exactly in step. If one were to geahead of the other, it would shift thpicture so that instead of a man's tweyes being put side by side, one mighbe shifted down opposite his mouth.good deal of research work was needsbefore the two drums could be kept e2actly in phase at the two sides of thAtlantic Ocean.

The result of such a series of dotis shown in Fig. 5. President Coolidgwill be recognized as the subject of thipicture. Notice the series of fine dotwhich go to make up the whole. In sonsplaces they are entirely absent, leavinpure white paper. In other spots theare so thick that they make practical)jet black. In most places, however, thelie between these two values and s

give lighter or darker gray. Obseretoo, that the picture has a stippled o

wavy effect. This is quite characteriitic of the transmitted pictures whitare now coming through. This effect icaused by slight irregularities in th

spacing of the mechanism. A verslight shift of a few thousandths of ainch shows up in making a wavy line.

The picture made by the pen anink can be seen by the operators asis being drawn. It is fascinating to sethe pen wiggling back and forth, gradually making a picture. Besides thithe same detector operates a specie

photographic receiver which makesnegative on an ordinary film. Thisdeveloped like any other one and cathen be used to make any number c

photographic prints.

JANUARY 15, 1925 RADIO PROGRESS 15

Fifteen Worthwhile Hook -Ups1-SIMPLE CRYSTAL DETEC-

TORTHE simplest set which it is possible

to make, uses nothing but a coil,crystal, and phones. Its merit is thataside from the phones the entire costcan be limited to less then 50c. Of

course, it does not have a very greatrange, as it is not likely to be verysatisfactory much over six or eight milesaway from a good broadcasting station.

AERIAL

CRZ5TAS.

PHont-5

= GRouNoFig. 1. The Simplest Set

Nor is it at all selective as if therehappen to be two local transmitters in atown, then it will be difficult to tuneout the stronger and pick up theweaker when they are both going atonce. However, if there is only one inyour city, or if several of them dividethe time without conflicting, then thisset gives very clear, smooth tone,- andplenty of volume.

List of Materials(First read article. Page 5)

1 Crystal. $ .151 Tap switch .25

1 Winding form .05

1/8 lb. No. 22 DCC copper wire .15

ExtraAerial and ground complete $1.50Phones 3.00

OptionalJack and phone plug $ .504 Binding posts for aerial, ground

and phones @ 3c .12

Winding the CoilA spider web form made of fibre

about five inches in diameter may beused for the coil, although, if you pre-

fer, a hree inch diameter tube will workjust as well. The spider web coil isconsiderably easier to wind, as it doesnot try to unwrap itself if you accident-ally let go of the end. Wind on sixtyturns of wire, taking a tap off every tenturns at 10, 20, etc. The inside leadruns to the ground and also to one phoneconnection. The outside lead runs to thecrystal detector. Another connection isneeded tying together the other side ofthe crystal and the phones.

The tap switch uses six points al-though a unit with any number morethan this can be employed by omittingthe extra points. Of course, the coilcould be tapped at more places if de-sired, but six is enough to take in theordinary broadcast range. The centerconnection of the tap switch runs to theaerial.

OperationTo operate this set connect aerial and

ground in at the phones whileturning the tap switch. If the broad-casting station is near at hand it willbe picked up on all taps, but some onewill be louder than the others. This isthe proper one to use. If it is at agreater distance, it will perhaps be

heard on only one or two buttons.

2-TWO CIRCUIT CRYSTALSET

This set is considerably more selectivethan the simple crystal set described inhook-up No. 1. It also will receive fromgreater distances. A powerful broad-caster may be heard fifteen or moremiles away. However, the range shouldnot be expected to exceed twenty -miles,even from a 1000 -watt station. Occasion-ally, we hear of this set bringing in sta-tions a couple of hundred miles away,but in such cases it always comes froma near -by powerful tube set, which is re -radiating the distant program.

There are two controls on this set,neither of which is very critical. How-ever, the set is coupled loosely enoughso that it is considerably sharper tun-ing than the single circuit set. Evenwhen two local broadcasters are goingat the same time you will be able totune either one out at will and pick upthe other.

L.Lit of Materials(First read article, Page 5)

1 Tap switch $ 252 Winding forms a 5c .10

1 Crystal. .15

1 23 -Plate .0005 condenser 2.004 lb. No. 22 BCC copper wire .. .25

ExtrasAerial and ground complete $1.50

Phones. 3.00

Fig. 2. A Selective Crystal

OptionalPhone jacks and plug $ .50Binding posts for aerial, ground and

phones at .03

Ordinary varioconpler instead of twocoils. 2.00

ConstructionThe two coils are wound just alike,

except that the first one, or primary,has six taps based every ten turns,while the secondary does not requiretaps. The total number of turns on eachcoil is sixty. The direction of winding(whether right or left hand) makes nodifference. The inside lead of eachcoil runs to the ground. The outsidelead of first or primary coil, runs to oneof the taps of the tap switch just asthe rest of the taps do. The outside endof the secondary coil is connected to thecondenser and also to the crystal.

The two coils are to be separatedabout an inch apart by means of a smallwooden spacer. Depending on the sizeand shape of your aerial it will some-times be found by increasing this dis-tance somewhat, or in some cases reduc-ing it the signals will come in stronger.After once experimenting with thosepoints the final setting of the coils maybe left undisturbed.

16 RADIO PROGRESS

Paths of CurrentThe primary oscillation coming in

from the aerial runs through the lefthand coil direct to ground. It is tunedby adjusting the tap switch to get theright length of wire in the coil. Owingto the high resistance of the ground leadit is unnecessary to try to use any finetuning on the primary. The secondaryis adjusted by the 23 -plate condenser.By this means any local broadcastingstation may be cut out and another onepicked up.

as Pi -ATE

.0005-M Fp

/AERIAL

course, when it is operated correctly, thistrouble does not occur.

Its advantage is that it is simple andeasy to construct, and is quite inexpen-sive. Furthermore, the operation isquite simple, and the range is up to 1500miles on a good night. Every advantagewhich this particular circuit possesses,except a slight one in thei ease of build-ing, is to be had in the two circuit tuner,which is described in the 5th hook-up.The only reason this is given here is be-cause it is in such large use, that it must

GRID RETURNGROUND

ce

Fig. 3. Single Circuit. Popular, but a Squealer

Operation

To operate this set connect up aerialand ground to posts as usual. With thetap switch set at about 40 turns rotateslowly the secondary condenser until astation is heard. Then try the primaryon a different tap and tune again. Theloudest combination is the correct one.It may be necessary occasionally tochange the adjustment of the catwhiskeron the surface of the crystal. This willbe avoided, if one of these units which isalive all over or a fixed crystal is usedinstead of the ordinary one.

3-S I N G L E REGENERATOR-VARIOCOUPLER

This circuit is the one which is usedprobably more than any other, which isto be regretted, since it has one badfault-it is a terrible squealer. Notthat it squeals for the user, as he canstop it by adjustment, but its howls andwhistles are broadcast to everybody

w

0

0

4-131)

Le included, to present anything like acomplete catalogue.

List of Materials(First read Page 5)

1 23 plate (.0005) eondenser....$2.001

1

1

1

1

1

1

2

1

1

22

within a radius of several blocks. Of 1

Tap switch .50

Variocoupler 2.25Grid condenser .00025 .35

Grid leak .25

Socket .35

Rheostat .35

Panel 7x14 1.00

Dials .50

.001 by-pass condenser .15

Binding posts @ 3c.; 1 Ant., 1Gr., 2 "A," 2 "B," 2 phones.

Busbar, etc.

ExtrasAerial and ground $2.00

Tube 4.00Phones 3.00Volt "B" battery 1.75

Dry cell "A" battery .40

JANUARY 15, 1925

Optional1 Jack (1 spring) $ .301 Plug for phones .35

1 Adjustable grid leak .75

1 Cabinet 7x14x7 deep 3.50"A" battery switch .25

Theory of the CircuitsThis is one of the easiest sets in the-

ory. The audio waves come in throughthe aerial and are tuned by the conden-ser C and the tapswitch T. The lattergiVes the coarse adjustments in steps,while the condenser allows the fine tun-ing to pick up the distant station. Thepath of the primary waves is from theaerial through condenser C, stator S,

and tap -switch T, to ground. The sec-ondary circuit oscillates from the fila-ment through grid return, tap -switch T,coil S, and grid condenser to the grid.

The output runs from plate P, throughadjustable rotor R, to the point X, wherethe high or radio frequency dividesthrough by-pass condenser Gb, to the fila-ment and the low or audio frequencytakes the path through the phones and"B" battery to the filament.

ConstructionA good way of laying out this set is

to mount the 23 -plate condenser at theleft; next to this is the tap switch; thevariocoupler knob will appear about inthe 'center of the panel. To the right ofthis is the rheostat, followed by the jackfor the phones. This gives a symmetri-cal appearance.

The connections are shown in Fig. 3.Wire up the filament circuit first. Therheostat goes in the negative line, whichruns from the A minus to the filament.The other filament wire runs to the Aplus and also to ground. When this cir-cuit is done it is well to test it by hook-ing up the "A" battery and noticing ifthe rheostat controls the brightness ofthe filament.

The aerial is connected direct to therotor of the 23 -plate adjustable conden-ser. The stator runs to the top of thestator of the variocoupler and alsothrough the grid condenser and leak tothe grid. The center of the tap switchruns to ground, plus of the "A" battery,and minus of the "B" battery.

The lead from the plate goes to therotor of the variocoupler. If this is theordinary 180 degree unit, it makes nodifference which lead is connected to theplate, but if the 90 degree coupler, which

hi,

JANUARY 15, 1925 RADIO PROGRESS 17

is mounted at an angle is used, then youwill have to find out by trial which is theproper lead to use. When the correctone is found the set will squeal as thetickler is turned on, but if the wrongone, then no squeal can be produced. Theother lead of the rotor runs to the phonejack or binding post. The other side ofthe phones hooks up with the "B" plus.A by-pass condenser is shunted acrossthe phones and "B" battery. This com-pletes the wiring.

Operating the SetTo work this radio turn on the rheo-

stat until the tube comes up to normalbrightness. Then with the tap switchset at about the center, turn up therotor dial until the hissing noise showsthe set is oscillating. It should now im-mediately be turned down again untilthe hisSing just disappears. By doingthis you avoid disturbing your neighborswith your squeal. Now turn the 23 -plate condenser until some station ispicked up. As you turn the condenser,you usually have to readjust the tickler(rotor) to keep it at the point where itdoes not oscillate. It is well to turn onedial with one hand while you adjust thefeedback with the other.

After bringing in the station it is wellto shift the tap switch to a new positionand try the same station again. Thecondenser will have to be turned to alower reading when you increase theturns on the stator to get the same sta-tion. This adjustment of the tap switchshould be continued until you find thebest setting for a given wave length.Once this has been determined the tapswitch should always be placed on thebutton which you find best for that par-ticular wave length and then the exactadjustment made with the condenser.

4-SINGLE REGENERATOR-VARIOMETER

This circuit is similar in operation tothe Single Circuit Regenerator with avariocoupler, as described in Hook-up 3.The principle difference is that the vario-meter is used to control the regenerationinstead of a variocoupler. It has no ad-vantage over the coupler circuit, exceptfor those fans who happen to possess avariometer but no coupler. Control ofregeneration is not as satisfactory withthis set as with Hook-up 3, since to in-crease the feedback it is sometimes nec-

essary to turn the variometer rotor tothe left and sometimes to the right. Thisis because the output must be in reson-ance (tuned the same) with the input inorder to get maximum regeneration. Ifthe variometer dial happens to be tunedto a higher wave length, then it must beturned to the left to increase the feed-back, while if it is too low, then a turnto the right brings it up.

List of Materials(First read Page 5)

This list is exactly like that of Hook-up 3, except that the variocoupler isomitted and the following is added:

1 Variometer $4.001 Spider web form 5 in. diameter .05

/A lb. No. 22 DCC wire .15

ConstructionIn winding the primary coil, sixty

turns of the double cotton covered(DCC) wire is wound on the spider webform. Six taps, one every ten turns, areenough to get satisfactory control, al-though of course, more may be used ifdesired. These taps run to the tapswitch. The hook-up is just the same,except that the plate circuit includes thevariometer instead of the rotor of thecoupler.

OperationThe rules given in Hook-up 3 apply

here except as regards the feedback. Ashas just been described, the amount ofregeneration is controlled by getting thesecondary into resonance with the pri-mary, and this is done sometimes by ro-tating the variometer to the left and atother times to the right.' Your ear isthe guide-you can hear when it startsto squeal or hiss. As before, this condi-tion should be avoided so as not to dis-turb the other radio listeners within afew blocks. Turn the dial away from theposition of hiss about one degree, thenno such trouble will be caused.

5-TWO CIRCUIT REGENERA-TIVE TUNER

This hook-up is one of the best thathave been constructed. It is particularlygood in that the distant stations up to1500 miles on a favorable night, willcome in with considerable volume andclearness and yet the tendency to squealand disturb the neighbors is very muchless than almost any other regenerativesingle tube set. Besides this the selec-

tivity is considerably improved over thesingle circuit hook-ups.

In addition to these advantages, it isa rather easy set to build. Indeed itwould be an advantage for each ownerto re -build his single circuit squealerinto this model-an advantage not onlyfor him but for all his neighbors. Thereason why this set is not so much of aradiator as the others is because thecoupling between primary and secondaryis quite loose, and so only a small pro-

a DAITERY

Fig. 4. Single Circuit-Variometer

portion of the regenerative energy whichcauses the oscillation is fed back fromthe secondary to the primary coil. How-ever, a small part of the energy is trans-ferred in this manner, and for this rea-son the operator should be careful not tomake the set oscillate, as a small amountof disturbance would be caused in spiteof the fact that the coupling is loose.

List of Materials(First read Page 5)

1 23 plate condenser $2.001 Variocoupler 2.25

1 Grid condenser .35

1 Grid leak .25

1 Socket .35

1 Rheostat .35

1 Panel 7x14 1.00

2 Dials .50

1 .001 by-pass condenser ..15Binding posts @ 3c, 1 Ant., 1

Gr., 2 "A, 2 "B," 2 phones.

ExtrasAerial and ground $2.00

1 Tube 4.00Phones 3.00

22 Volt "B" battery 1.75

1 Dry cell "A" battery .40

OptionalSame as in hook-up No. 3, but add:

1 Spider web coil, tapped2 Tap switches

18 RADIO PROGRESS JANUARY 15, 1925

ConstructionThe actual laying out of the panel de-

pends on whether you wish to includethe two tap switches or not. The pri-mary of this hook-up consists of a fewturns. The smaller the number is, themore selective the set, while the greaterthe number up to about fifteen, the morepowerfully the distant stations will comein. Many fans use a 15 -turn primarytapped at five and ten turns. Then thefive -turn coil is marked "S" for selec-tivity, the 15 "P" for power, and the tenturn "M" for medium.

5:115roio

GmovNo

TunNs

Fig. 5. One of the Best

Of course, more than these three tapscan be used if desired, although theyusually will be enough. A switch maybe used to pick out one of these taps, inthat way regulating the selectivity orelse a loop can be made on the primaryout of the wire, and a small spring clipused to make the connection to the loop.If a tap switch is to be used, then it isdesirable to have the first tap at thefirst or second turn, as this will give themaximum in selectivity, although thevolume will not be very great.

Increasing the RangeThe primary, as just described, is non-

adjustable. Some people call it "un-tuned." This is really incorrect, as itis always tuned for some frequency, al-though with so few turns the tuningwould be for a vibration speed of 2000or 3000 k.c. (150 to 100 meters). Sincethis tuning is way outside the broadcast-ing range, the coil appears to be untuned.The selectivity can be still further in-creased, and with it the loudness too, ifanother coil (loading coil) is connectedinto the circuit. This is not shown in

the diagram Fig. 5, so as not to be con-fusing. It is connected between theaerial and the primary coil. The detailswill be explained later.

In case either or both these tapswitches are to be used, they will appearat the left hand side of the panel. Nextto them come the secondary condenserand then the rotor (tickler) of the vario-coupler. At the right are the rheostatand the phone jack or binding posts.

The secondary coil and tickler are thestator and rotor of the variocoupler. Incase you desire to wind these, use fifty

.00/

c))PHONES

F F

/3A1

Single Tubes -2 Circuit

turns of No. 22 on the stator and 25turns $f smaller wire, say No. 24, on thesecondary. If these numbers are notexactly the same as on your coupler, itmakes no difference, as the adjustment ofthe condenser and the tickler takes careof any variations automatically.

On top of the stator at its lower end,wind a couple of turns of good wrap-ping paper, the strip being about an inchwide. The ends should be fastened down,with sealing wax or shellac (not glue,which will absorb moisture). On topof this insulation wind on in either di-rection the primary of No. 22 DCC wire.If you are going to use a tap switch tocontrol the selectivity, then use fifteenturns with three to five taps. If youdo not wish to have the bother of mak-ing an adjustment here, then use fiveturns if you want the best selectivity,or ten turns, if you prefer the greatestvolume. The upper end of this coil, orthe center of the tap switch, if used,goes to the aerial or to the inside end ofthe loading coil.

The Loading CoilTo get the best results as just ex-

plained, a loading coil should be con-nected into the aerial line. This con-sists of sixty turns of No. 22 DCC wire,wound on a spider web form and tappedevery ten turns. This is connected with.the inside end to the primary tap switchand the center of the loading tap switchhooked up to the aerial.

The rest of the hook-up is made asshown in Fig. 5. The "A" battery is con-nected t9.1 the rheostat in the negativeside and7,fhe tube. When this circuit isclone, it should, be tested before goingany further. The output from the plateruns to the rotor of the variocoupler.The right polarity may be found by ex-periment. When the set is working,turning the dial to the higher numbersought to cause a hissing or squeal in thephones. If it does not, then reverse thetwo leads to the stator. The .001 stop-ping condenser is shunted across thephones and "B" battery. The "B" minusis shown connected to the "A" minus,although the "A" plus would be just asgood.

Operating the SetFirst turn on the rheostat and bring

the tube up to normal brightness. Then

with the tap switches adjusted to middleposition, turn up the tickler until thehissing of oscillation is heard in the

phones. Turn it down one or two divi-sions to stop the oscillations. Now ro-tate the condenser until you hear a sta-tion. While making this adjustmentyou will probably need to readjust thetickler to keep the set just at the pointof starting to oscillate. That is all thereis to it. If you have the tap switches,you may now turn the primary to takein 3 'or 5 turns if you want to cut outlocal broadcasting. Then try adjustingthe loading coil (if you use it) at thesame time readjusting the secondary

condenser. When the right value forloading coil is found you will see thatthe music is considerably louder andalso more selective. Once you havefound the best button for the loadingcoil, using a certain condenser setting,you can always work the two pairs to-gether with advantage.

As explained before, this set will notdisturb the neighbors very much, butbe sure not to operate it above the pointwhere it begins to squeal.

JANUARY 15, 1925 RADIO PROGRESS 19

6-THREE-CIRCUIT TUNERThis has proved a very popular hook-

up, as it contains an adjustment forvarying the amount of selectivity andloudness, and does not require any ad-justable condenser at all. Instead, ituses two variometers, one for tuning,one for feedback, and a variocoupler.The tuning is rather sharp, because thevariometer gives the largest amount ofinductance in the grid circuit whichcan be used, which is an advantage.

1 By-pass condenser .001 .151 Panel 7x14 1.003 Dials, @ $ .25 .75

Buss bar, etc.

Extras and OptionalJust the Same as in Hook-up No. 3.

Construction of SetIn laying this equipment out on the

panel it is well to apace the three dialscontrolling the variocoupler and twovariometers so that they are symmetri-

the jack and "B" battery. The by-passcondenser is across the jack and "B"battery, if desired. Another lead, whichis oftentimes advantageous, but has nodirect part in the hook-up, and so is notshown, is a connection from the "A"to ground. This has no effect exceptthat of reducing body capacity. Thiscompletes the hook-up.

The Current PathsThe radio frequency oscillations corn-

Fig. 6. Three -Circuit Tuner Uses No Adjustable Condenser

The range is as good as will be foundwith any single tube set. The princi-ple disadvantage is that the regenera-tion control is had by adjusting the out-put circuit from the plate, so that itis in tune with the input. For thisreason, to get the greatest feedback itis sometimes necessary to drop the wavelength by turning the dial down, andat other times increasing it. That iswhy you can not tell before hand whichway to turn the tickler to get morefeedback. Of course, it is easily foundout by trial.

List of Materials(First Read Page 5)

1 Variocoupler. $2.252 Variometers, @ $3.25 6.501 Tap switch .501 Grid condenser .00025 .351 Grid leak .251 Socket .351 Rheostat. .35

cal. The tap switch may then be putat the left and the rheostat at the rightto balance each other. The tube shouldbe located near the first variometer, soas to have the grid leak short.

The ordinary style of variocouplershould be used with the taps on thestator running to the tap switch. Thecenter of the switch goes to the aerial.The rotor is connected with one lead tothe "A" plus, and the other to the tun-ing variometer. It makes no differencewhich is which of the rotor leads or ofeither variometer. The other lead of thetuning variometer is connected throughthe grid condenser and leak to the grid.

The "A" battery has the plus runningto the filament and the minus to therheostat. The "A" battery filamentswitch may be inserted in either leadif it is desired to use one.

The output from the plate is ledthrough the regeneration variometer to

ing in from the aerial go through thetap switch and stator to ground. Therotor is excited more or less by the mag-netism from the stator. When the twocoils are at right angles, then there ispractically no action and the set is inthe most selective adjustment but thevolume is very small owing to the tinyamount of leakage energy transferredfrom primary to secondary. As therotor is turned in either direction, itbrings the two coils more into line,which increases the coupling. Thismakes the music sound considerablylouder, but at the same time cuts downthe selectivity.

The oscillations generated in the rotorflow between the filament and the tun-ing variometer to the grid. When thevariometer is adjusted so that the rotorand stator help each other, then the in-ductance or electrical weight is heavyand the system oscillates slowly to givea long wave length. When the rotor is

20 RADIO PROGRESS JANUARY 15, 1925

turned in the opposite direction, so thatthe two halves buck or oppose each other,then the inductance is small and thehigh speed vibration gives a short wavelength.

The output from the plate is tuned toresonance by the regeneration vario-meter. The radio frequency waves leav-ing it go through the .001 by-pass con-denser to the "B" battery and filamentwhile the low frequency audio wavestake the path through the jack andphones.

So T

APRI MARY

AERIAL

7-FOUR-CIRCUIT TUNERThis is a simplification of the Cock-

'aday Circuit. When properly built andadjusted it is unusually selective. Therange is good too, as 1500 miles can bepicked up on a good night. It is a littlemore fussy to build than some of theother single tube sets, and will perhapscause more bother in adjustment. Thething that distinguishes it is the wavetrap, which is wound on the same tubeas the secondary and the single turn

E-OnE TURN

PRIMARY

13P -ea. -re

2 3 PLATE

Fig. 7. Four -Circuit

How to OperateAfter bringing the filament up to the

right brightness with the rheostat, turnthe tap switch about to the middle, andthen adjust the rotor so that it is inline either side up with the stator. Thiswill give the loudest signals. Now turnone variometer with one hand and theother with the other, so as to keep theregeneration as great as possible withoutcausing a squeal.

When a station is heard, be sure thatthe set does not oscillate as this hook-up will radiate and tell all your squealsto the nearby listeners.

Now adjust the tap switch to see ifyou can make the station louder. Aftereach shift it is necessary to re -tune withboth variometers. If no local stationis going, that is all that is needed, butif you want to get greater selectivity,then turn the coupler so that the coilsare nearly at right angles and re -tune.

G.

RHEO.

1111 111 11

"A"((FAN

Tuner Has Wave Trap

W

0

primary which is tuned by an adjustableloading coil, located at right angles tothe trap coil.

The arrangement of the plate circuitis also somewhat novel in that the out-put divides-the low frequency flowingthrough the phones and the high fre-quency acting as a feedback through thesecondary to the grid. The amount ofthis action is not adjustable, and thissometimes causes trouble. The gridleak too is not in the ordinary posi-tion. No by-pass condenser is needed.

List of Materials(First Read Page 5)

2 23 -plate condensers @ $2.00 $4.002 3 -inch fibre tubes, @ $ .20 .401 Tap switch .501 Grid condenser .00025 .351 Grid leak .25

1 Socket. .351 Rheostat. . . .35

1 Panel 7x14 1.002 Dials, @ $ .25 .50

lb. No. 22 DCC wire .40

Extra and OptionalJust the Same as in Hook-up No. 3.

Assembling the SetOf course, a combined tuner and load-

ing coil may be bought, but it is prob-ably more fun to wind your own. On a3" diameter tube wind forty turns of No.22 double cotton covered (DCC) wirein either direction.

Leave one-half inch space along thetube and then wind on in the same di-rection sixty turns of the same wire.This is the secondary coil. In the halfinch space one turn of wire constitutesthe primary coil. In the manufacturedcoil this is a turn of bulbar, but thatis merely for looks. Although a singleturn is specified, it is often wise to windon five, bringing out taps at the first,second and fifth turns. A clip can beused to make connections to some oneof the taps or an additional tap switchcan be installed. Using one turn givesit the greatest selectivity while fivegives considerable more volume.

The loading coil is in the primarycircuit and is wound fifty turns on athree-inch tube with taps every six oreight turns. A spider web will do justas well for this position, and it is some-what easier to wind, but it does notharmonize as well in looks. It mustbe placed so that it has no magneticeffect on the other coils. For this rea-son it is usually put at right anglesto the others, right along side. Sinceit is practically impossible to get thisadjusted so as to give no effect at all,on the other coils, it is well to reversethe polarity of the one turn primaryafter the set has been tested. One wayoften gives better results than the other.

This tuner should be mounted at theleft hand end of the panel. The 23 -plate condenser for the trap is the lefthand dial and that of the secondary isat the right. The tap switch, whichcontrols the primary loading coil is atthe extreme left. The rheostat at theright is in symmetry with the tapswitch at the left.

The grid leak is to be connected fromthe grid to the Oats side of the "A"battery. This is necessary, because ifit were hooked up in the usual way(across the grid condenser) it would

JANUARY 15, 1925 RADIO PROGRESS 21

allow full "B" battery voltage to passthrough phones and secondary direct tothe grid. This would stop the opera-tion of the tube, as you will rememberthat the voltage of the grid shouldalways be small.

Theory of CircuitsThe oscillation from the aerial goes

through the primary of a few turns andthen the loading coil to ground. Theforty -turn coil and its condenser actexactly like a wave trap. They pre-vent unwanted stations from beingheard. The secondary is excited fromthe magnetic action of the primary andtuned by the 23 -plate condenser. Theoscillations of the secondary arestrengthened by the feedback actionfrom the plate. The vibrations fromthe secondary do not get back to thefilament directly, but are carried by theleakage capacity, which exists through-out the set.

The output from the plate divides-the radio frequency going to the leftwhere it gives regeneration as alreadynoticed, and the audio frequency to theright to the phones. If a by-pass con-denser had been used around the phonesthen the feedback action of the radiofrequency would have been lost.

OperationFirst adjust the filament to the proper

voltage by turning the rheostat. Thenwith the primary loading coil set toabout the middle, turn both condensersat the same time. Usually they willwork at something like the same read-ing, although this can not be countedon. By adjusting the number of turnson the trap they may be brought tonearly the same readings. As no sepa-rate tickler control is used, there is notany chance of getting such an adjust-ment wrong.

8-HONEYCOMB (SPIDER WEB)REGENERATIVE

This hook-up is quite popular, usingeither honeycomb coils which may bebought or wound (although we do notadvise winding them) or else employingspider web coils, which you can easilywind. Instead of using a dial for ad-justing the amount of tickler action, andalso for changing the coupling betweenprimary and secondary, use is made ofa swinging frame, which allows the coilsto be set at any angle one to anotheras they swing apart.

Since the honeycomb of spider webcoils have lower distributive capacitythan most variocouplers, and also sincethe coupling can be reduced to lowvalues, the set is capable of very sharptuning. The chief disadvantage is thatspecial rigging has to be made for sup-porting the coils, and there is somedifficulty in getting away from bodycapacity, unless the panel is wellshielded.

AERIAL

.0005C

so-, 75T 3s/P" See TocUer

Hook-up 5. The biggest difference isthat instead of tuning the primary witha tap switch, we use a series aerial con-denser, Cp, to reduce the wave lengthfrom the highest value to lower ones.For this reason when the condenser isturned so that the plates are fullymeshed, then no higher wave length canbe picked up except by increasing thelength of the aerial or the number ofturns on the 50 -turn primary.

Fig. 8. Honeycomb or Spiderweb Coils Give Sharp Tuning

List of Materials(First See Page 5)

3 Honeycomb coils, mounted, @$1.50. $4.50

2 23 -plate condensers, @ $2.00. 4.001 Grid condenser .000251 Grid leak1 Socket.1 Rheostat.1 Panel 7x142 Dials, @ 25c1 .001 By-pass condenser1 Set of 8 binding posts

Bulbar, wire, etc.Extras

Same as in Hook-up 3.Optional

1 Jack (one spring) .301 Plug for phones .35

1 Adjustable grid leak .75

1 Cabinet 7x14x7 deep 3.501 "A" battery switch .25

Instead of honeycomb coils.3 Spider forms, @ 5c $ .153A lb. No. 22 DCC wire .40

Theory of the CircuitThe theory and operation of this cir-

cuit is practically the same as that of

.35

.25

.35

.351.00

.50.15.25

When the primary is moved to theleft, away from the secondary, it re-duces the coupling, which improves theselectivity, but cuts down the loudnessof the music. When the right hand or35 -turn tickler is swung away from thesecondary, it reduces the feedback andso cuts down on the volume.

Incoils

Constructionbuilding this set the swingingare arranged on the left, often-

times on the outside of the panel. A

special rigging for holding the coilsmay be bought, but most builders pre-fer to rig up their own method of swing-ing the two outside coils. Tuning ofthe primary is accomplished by con-denser Cp which is in series with theaerial.

An extra lead, running from the "A"-j-, to the ground, although not shown,is oftentimes an advantage in reducingbody capacity. The rest of the circuitis constructed as in Hook-up 5. The

operation of the set is also the sameexcept for the method of swinging thecoils instead of turning them.

22 RADIO PROGRESS JANUARY 15, 1925

9-AUDIO FREQUENCYAMPLIFIER

Any set may have two audio frequencyamplifier steps hooked up to the detec-tor. Furthermore, these amplifiers areexactly the same, no matter whetherconnected to the cheapest crystal setor the most elaborate superheterodyne.A possible exception to this statementmay be taken in the cases where a push -

To DETE C TOR

PLATE

Cs

.001

with one, but even distant stations willbe brought in loud enough to work ahorn. Unless the transformers aregood ones and don't make a noise oftheir own you will not be able to getmuch enjoyment out of listening in ontwo steps with the phones.

List of Materials(First Read Page 5)

1 Good audio transformer $4.00

/sr STEP

Fig. 9. One or Two of These Steps May be Added to Any

pull amplifier is used as the last step,but this is really a combination of twosuch units working together, and thepair do not give any louder amplifica-tion, but only a slight improvement inthe tone of the music.

Any one of the previous hook-ups mayhave one or two sets of audio addedto them in the way which will be de-scribed. In fact, three steps of audioare sometimes used, but the third isvery apt to howl, and in any event theslight outside noises, which come inthrough the detector, are amplified sostrongly that the result is usually un-satisfactory. Instead of putting on threesteps with ordinary transformers, youwill be better pleased to use only twoand be sure that you get non -distortingtransformers.

By adding one step to a detector inany single tube circuit, the range willbe increased slightly-say about twohundred miles-bnt the big gain comesin the loudness. Stations that you hadto strain' your ears to hear before willnow be quite loud in the phones. Lo-cal stations will operate a loud speaker.By adding one more step (two in all)the range will not be any greater than

Detector

1 Socket. .35

1 Jack (two spring) .40

1 Binding post for "B" + 45 .05

Busbar, etc.Extras

"B" Battery 22 volts $1.751 Tube. 4.00

Stopping condenser .001 .15

Optional1 Rheostat. $ .351 "C" battery .50

Extra "B" battery up to 90 voltsLoud speaker $6.00 to $50.00

Theory of the CircuitThe current comes from the plate of

the detector tube and divides. Thehigher, or radio frequency, uses thestopping condenser, Cb to get back to thefilament, while the audio frequency tra-verses the jack and primary of theaudio transformer to the "B" + 22.The secondary of the audio impresses theoscillation on the grid and through the"C" battery (if used) on the filament.The output goes from the plate of thetube through the phones or loud speakerto the "B" 4- 45.

If the phone plug is inserted in thedetector jack, then the audio vibrationswill go through the phones to the "B"

battery instead of the audio transform-er. In case a second step is added, thesame action occurs all over again, thusmultiplying the output a second time.

Building the AmplifierIn adding this unit, the first thing to

do is to find where the phones were con-nected before. This is shown dotted in Fig.9. If these connections were not madeby a jack, which had two or four springs,then a two spring (or four spring) jackmust be substituted. Many listeners donot want to plug in on the detectoralone, as the first step gives so muchbetter results. In such a case the de-tector jack may be omitted entirely, andthe upper end of the primary run directto the connection, which is used to carrythe phones. If it is ever expected toadd a second step of audio, then thephones should be connected through aspring jack inserted in the plate circuitof the first step. Of course, a jack canbe used here anyway to make an easyconnection to the phones.

The next thing to do is to locate by-pass condenser, Cb. Most sets use sucha unit, but a few especially of the oldermake, depend on the capacity of thephone cord itself to supply the capacityneeded to by-pass the radio frequency.Since the phone and its cord is nowtaken out of the detector circuit, it canno longer supply this action. For thatreason it is necessary that such a con-denser be connected across the primaryof the audio transformer (or the jack)in order to get satisfactory detector ac-tion. If you find that such a condenser,with a capacity of .001 or .002 mfd. isalready used in the set, then no changehere is required, but if it is omitted.then it must be inserted as shown in theclotted line.

If a second step of audio is added, itis not necessary to use a second stoppingcondenser. This unit passes only theradio frequency, and no such high speedoscillations appear after the first audiotransformer. That is why in adding thesecond step, no second condenser isneeded.

Omitting RheostatThe tendency of the modern set toward

amplification is seen in the fact that therheostat, as shown in the diagram, is

usually omitted. Just as good resultscan be Obtained when the detector rheo-stat is used to control the amplifier

JANUARY 15, 1925 RADIO PROGRESS 23

filaments as well. For those who wish aseparate control, the diagram may befollowed exactly. Those who do not wishthe extra complication should run thefilament lead (now shown connected tothe rheostat) direct to the correspondingpoint on the detector rheostat. Whenthis is done, observe that turning thelatter makes both tubes brighten at thesame time.

When adding a second step of audio,the same reasoning applies to its control.Since most of the time both steps willbe in use, it seems unnecessary to employa separate switch to cut the last tubeoff. If such action is wanted it can bearranged by using a filament control jack

O 0

.000ar

LEAK

.000C

the music comes through clearer andwith less distortion Either 3 or 41volts of "C" should be used, dependingon the pressure of the "B" battery.

The same "C" should be hooked up toboth steps when a second audio is added.To make this connection run a wirefrom the lower end of the secondary ofthe last transformer direct to the minusterminal of the "C", which will thenhave two connections on it.

Adding a Second StepIf your set already has one audio am-

plifier, or you are going to install one,you may wish to add a second. This canbe done using the same diagram, Fig. 9.Just repeat the same connections over

G "K+ "IV: -

Fig. 10. This is Recommended as One of the Best 3 Tubes-Not Bad Squealer

10-COMPLETE THREE -TUBEREGENERATIVE

Of all the sets which may be built weadvise this one as being the best for anyone who wants to put together his firstthree tube outfit. It is quite selective,has a range of 1500 miles under goodconditions, and is loud enough to worka horn very well indeed up to 1000 miles.

This hook-up is really a combinationof the two-circut single tube set hook-upNo. 5 with a two step amplifier, asshown in Hook-up 9. It is drawn outhere in detail because it is so very popu-lar, that combining both elements in onediagram is an advantage.

in the second step. On the older setsa rheostat was used with each detectortube and so the individual control wasarranged for. If the second step rheo-stat is omitted, the lead should also beconnected to the rheostat of the pre-vious tube.

Using a "C" BatteryIf only 45 volts of "B" battery are

hooked up, then no "C" battery shouldbe used. In such a ease the lower end ofthe secondary runs direct to the "A"minus binding post. Note that this postas shown is not a separate one, but isthe same as is used for the detector.With 67 or 90 volts of "B" there is adouble advantage in using a "C". In thefirst place the life of the "B" battery isdoubled or even tripled, and besides that

again substituting the two (or four)spring jacks as shown at the left, inplace of the phone connection of the pre-vious step as drawn at the right of thefigure. As has already been explained,a separate rheostat may be used, but isnot needed. The same "C" battery doesfor both sets and the same is true of the"B" + 45.

OperationTo operate one or two stages of audit

frequency amplification, the only adjust-ment necessary is that of the rheostatto light the tubes to the proper tempera-ture. Then plug in detector, first or sec -one step jack, and if the tuner has beenalready set to catch the music, you willhear it several times as loud for eachmultiplication by the amplifier.

If a start is made to build the entirecircuit, since it is more ambitious thanthe single tube set, we recommend usinga little better material. For that reasonwe are adjusting the prices to give agood grade of the various parts.

List of Materials(First read Page 5)

1 23 plate condenser $3.001 Spider web coil, tapped .30

1 Variocoupler 3.002 Tap switches @ $1.00 2.001 Grid condenser .351 Adjustable grid leak .75

3 Sockets @ $.50 1.50

1 Rheostat .501 Panel 7x21 2.002 Dials @ $.35 .701 .001 By-pass condenser .15

24 RADIO PROGRESS JANUARY 15, 1925

2 Good audio transformers @ $4.008.00

3 Jacks (two spring) @ 40c.... 1.20Set of Binding posts -Ant, G, A+,

A-, B+45, B+22, B-, C+, C-Busbar, etc.

.45

ExtrasAerial and Ground $3.003 Tubes @ $4.00 12.00Phones . . 5.00Phone plug .4045 Volt "B" battery 4.003 Dry cell "A" batteries @ $.40 1.201 Loud Speaker $6.00 to $50.001 Cabinet 7x21x7 deep 6.00

Optional45 Volt Additional "B" battery $4.001 41/2 -volt "C" battery .50

TheSW ITC

CC

0

4,0

&

3

RNVvtNAPOTEN.

audio frequency amplification the loud-ness was increased quite a lot, but therange was not extended very much.The only way to increase the distancewhich your set will pick up is to in-clude one or more radio frequency tubesahead of the detector. Such a tubeshould add several hundred miles toyour range, but will not increase theloudness to any great extent.

However, it should be explained rightat the start that it is not very easy toadd radio amplifiers to a set alreadybuilt and get much improvement. Mostfellows after putting this addition ontheir set report that it works nearly aswell as before. The reason is thatradio frequency has such a high speed

R.E.

P TRANSR.FS.

LeA

123

T PL

ahead of the detector give just aboutthe same range in miles as a good re-generative set. When it comes to add-ing a step ahead of a detector whichuses a tickler that is something elseagain. That is why you cannot comparethe action of such a unit on a neutro-dyne with its behavior on a regenerativeset.

List of Materials(First Read Page 5)

1 Variocoupler. $3.001 Tap switch 1.001 23 -plate condenser 3.001 R. F. Transformer 2.501 Grid condenser .351 Grid leak .252 Sockets @ 50c 1.00

RIIE0

PHONES

Fig. 11. How to Put a Radio Amplifier Ahead of Detector Tube to Increase Range

Extra rheostat to control amplifiers .50

Theory and OperationThis set works in the same way as

was described for hook-up No. 5..Construction

In laying out the panel, the two tapswitches which control the spider load-ing coil and the primary are at the left.Next comes the rotor dial for adjustingthe tickler, and at its right the .0005mfd. secondary condenser for tuning. Atthe right will be found the rheostat andthe jacks. The method of hooking upthe set is the same as described inHook-ups 5 and 9.

11 -RADIO FREQUENCYAMPLIFIER

Under hook-up No. 9 we explainedthat by adding one or more steps of

of vibration (about 1,000,000 cycles persecond) that the small amount of leak-age capacity which exists in any set isapt to steal so much of the current thatthe loss is greater than the gain fromthe amplification.

Difficulties of R. F.With this in mind it is absolutely

necessary to take all precautions to keepthe leads as short and direct as possible.They should not be run close to eachother nor parallel unless they arespaced at least an inch apart. Eventhen the average builder has greattrouble in adding to the distance he canpick up.

The most popular set using radio fre-quency (R. F.) is the neutrodyne, butthis set does not include regeneration.For that reason the two steps of R. F.

1 Rheostat. . . .501 Panel 7x14 1.002 Dials, @ 35c .701 .001 By-pass condenser .15Set of 7 binding posts .35

Busher, and etc.Extras

Aerial and ground $3.002 Tubes, @ $4.00 8.00Phones. 5.0045 Volt "B" battery 4.003 Dry cell "A" batteries, @ 40c 1.201 Cabinet 7x14x7. 4.00

Optional1 200 -Ohm potentiometer .75

1 .002 Condenser .15

1 23 -plate condenser 3.00

1 Dial . . . .35

1 Phone jack .40

1 Phone plug .40

JANUARY 15, 1925 RADIO PROGRESS 25

ConstructionThis radio amplifier will usually be

added to a three -tube set consisting ofdetector and two audio steps. If thetwo audios have not already been sup-plied then it is better to add them firstbefore using the radio step. The dia-gram Fig. 11 shows only the detectorsince the steps of audio have alreadybeen illustrated in hook-ups 9 and 10.

f, however. only two tubes are to beused, a panel 7x14 is big enough. Inthis ease the variocoupler dial will bein the center with the tap switch on theleft and the tuning condenser at theright. The second condenser Co may beused if you want to get the sharpesttuning, and in that case you should leaveroom for its dial at the right.

The ordinary radio frequency trans-former will not require such a condenser.In looks it is a small device about asbig around as a UV -201A tube, andusually only about two thirds of itsheight.. If you are going to get themaximum of sharpness of tuning out ofthis set so as to he able to pick up dis-tance through loud, local stations, thenyou will do better to use the neutrodynestyle of transformer.

Building Your Own RFIf you wish to build your own trans-

former. get two fibre tubes. one of whichfits fairly closely inside the other, withdiameters of about three inches. Theprimary, which is the inside coil, is madeby winding on fifteen turns of No. 22DCC wire at one end of the tube. Thesecondary, consists of sixty turns of thesame wire, spaced so that the beginningof the winding lies right over that of theprimary underneath. It is customaryto wind these two coils in opposite di-rections. although in many sets it makesno difference. Such a transformer musthave its secondary tuned hy an adjust-able condenser, as shown in Fig. 11. Inease the first style of transformer isused. just omit this condenser.

Notice at the left hand side of thediagram the wire R running dotted tothe potentiometer. This unit is notreally necessary, but may be employed tocontrol the loudness of the set. Also itis an advantage to prevent any unde-sirable oscillations, which might occurand so distort the music. If it is usedwire, R, should be taken off the filamentlead and run to the center of the poten-tiometer. The two end connections

should go to the "A" plus and "A"minus. It makes no difference which iswhich, as the adjustment of the centerarm will take care of the polarity. Thenthe radio frequency oscillations mustthread their way through this resistanceto get to the filament, which reduces thesharpness of tuning to a slight extent.To prevent this loss, it is well to con-nect a .002 condenser from the centerterminal to the "A" plus of the filament.This allows the radio frequency to gothrough the condenser instead of thehigh resistance of the potentiometer.

Theory of the CircuitsThe antenna waves come through the

tap switch and stator to the ground. Itis tuned by adjusting the number ofturns with the switch. The magneticenergy is picked up by the rotor. Byturning it in line with the stator themaximum energy is picked up, whichgives the loudest signals but reduced se-lectivity. The rotor is the secondaryand is tuned by condenser Cg. The po-tentiometer (if used) puts the properbias on the grid. If this is omitted thegrid return should be connected to theminus of the "A" battery rather than tothe minus of the filament.as shown.

The output from the plate excites theprimary of the radio frequency trans-former, and returns to the high pressureside of the "B" battery. Notice that noby-pass condenser is used across thetransformer since owing to the lack ofan iron core this latter unit is able topass; the radio frequency.

The secondary of this transformer(which may be tuned by condenser, Co.as described) passes on the amplifiedoscillations to the filament and throughthe grid condenser to the grid of thedetector tube. The output from the plateexcites the phones in the ordinary man-ner. The phones are by-passed by a.001 condenser to allow the high fre-quency to get hack to the "B" batteryand filament.

OperationThis set is controlled like any other

non -regenerative hook-up. With the tapswitch adjusted for about the wavelength you wish to get and the rotor ofthe coupler in line with the stator (togive loudest signals) turn condenser, Cg,and also Co. (if used) keeping themabout together until a signal is heard.The tap switch may be turned to anotherbutton and the condensers readjusted to

see if the signals can be made anylouder. When the tuning has been foundbest the rotor- should be shifted to giveincreased selectivity if a local stationinterferes.

Connecting the DetectorThe second tube, which is the detector

is hooked up in the regular way. Theoutput is shown going to the phones, butas already explained it is better to usea jack at this point so that one or twosteps of audio amplification can be usedto increase the volume of the programs.Notice that the return from the phonesgoes to the 22 -volt tap of the "B" bat-tery, while the first tube makes use of45 to 90 volts.

The same rheostat is used to adjustthe voltage for the filaments of bothtubes. This is an advantage in reducingcomplication, but if separate control isdesired. the extra rheostat can be con-nected in for the second tube.

12-FOUR-TUBE REGENERA-TIVE SET

Here is a set that will work on a loop.Of course. with such an aerial you cannot expect to get the range which willbe obtained by using an outside aerial.It is a question of size, and the smallloop cannot scoop up as notch energyas a large antenna. Of course, this hook-up may he used with the latter by sub-stituting- the rotor of a variocoupler forthe loop and connecting the statorthrough a tap switch. direct to the aerialand ground.

Although two stages of radio fre-quency are used. the detector is maderegenerative, which still further in-

creases the range. The two tubes of RFahead of the detector prevent this setfront disturbing the neighbors. Theremay be a small amount, of oscillationwhich is carried backward through thecapacity of each tube, but with the twoin series the amount is reduced to sucha low figure that no trouble will be ex-perienced from this cause, even whenthe regeneration variometer is adjustedwrong, so that the detector itself is

forced into oscillation.The grid of the first tube is tuned to

resonance by condenser Cs. The secondand third tubes are not shown in Fig. 12as being tuned, as it is not necessary,provided the ordinary style of radiotransformer is used to couple the tubestogether. If the sharpest tuning of this

26 RADIO PROGRESS JANUARY 15, 1925

set is wished for, then it will be an ad-vantage to substitute RF transformers ofthe neutrodyne class and in that casetwo more variable air condensers will beneeded to tune the grids of tubes II andIII. These are not shown in the hook-up, but it will be understood that theyare connected between the grid and thefilament.

l.00p

_r

1 Tap switch 1.251 Dial . .50If RF transformers are to be tuned,

add2 Variable condensers, .00025, @

$3.50 . $7.002 Dials (a, 50c 1.00

Theory of the CircuitThe loop picks up the broadcasting

F

a

Building the SetThe layout on the panel depends on

whether you are to use tuned RF trans-formers or not. At any rate, you needa dial for condenser Cs and one for thevariometer. The two other condensers, ifused, will require dials. The loudness ofthe set is just as great, and the opera-tion is considerably easier if they are

yAleiorl

"B"+45

Tiv+11

F F

Fig. 12. Two -Step RF Amplifier Has Regenerative Detector. One AF is Added

List of Materials(First see Page 5 )

1 Variable condenser, .00025 $3.501 Paper condenser, .002 .151 Mica Condenser. .001 .401 Grid condenser, .00025 .359 RF transformers @ $2.50 5,001 AF transformer. 3 x 1 4.001 Variometer . 4.001 Adjustable grid leak .751 200 -ohm potentiometer 1.001 Rheostat .604 Sockets C 75c 3.002 Dials @ 50c 1.001 Panel, 7x21 2.50

Set of nine binding posts .50Busbar. etc.

ExtrasLoop $5.00

4 Tubes Et $4.00 16.00Phones . 5.00

45 -Volt "B" battery 4.003 Dry cell "A" batteries a 40c 1.201 Cabinet, 7x21x7 deep 7.00

Optional2 Phone jacks @ 40c $ .801 Phone plug .40If aerial is to be used, omit loop and

add1 Variocoupler $3.00

and after being tuned by condenser Csthe oscillations are impressed on the gridand through condenser Cl on the fila-ment. If an aerial is used instead of theloop, then the primary, which is tunedby a tap switch, runs from aerialthrough the stator to ground. The rotoror secondary then takes the place of theloop and is tuned by condenser Cs asjust explained. The output from theplate of the first tube goes through RF1transformer to the "B"+45 battery. Thesecondary oscillates between the grid oftube II and its filament, through con-denser Cl.

The output of RF amplifier II passes thehigh frequency on through RF2 trans-former to the grid condenser and grid ofdetector III. The plate of the detector istuned by the variometer, which when ad-justed to resonance gives a feedback ac-tion and so gets the extra increase inloudness due to regeneration. The highfrequency passes back to the filamentsthrough condenser C2, but the audiowaves thread the primary of AF trans-former to the "B"+22. The secondaryfrom this unit is hooked up to the audioamplifier IV in the usual way.

omitted. In cities where there is a largeamount of interference perhaps it is bet-ter to use them, as they assist some-what in getting rid of local stations.

The outside aerial, if used, will pickup much greater distances, but will re-quire two more controls -the tap switchto tune the primary and a dial to adjustthe coupling through the angle of therotor. Since this latter will not needto be shifted when it is once set for theposition which gives you the best re-sults, it is not really necessary to mountsuch a dial on the panel.

Using the JacksIn the diagram no phone jacks are il-

lustrated. It will not be required to usethem, as the phones can be connected tothe first step of audio all the time with-out any trouble. It is rare that a de-tector jack would ever be used. How-ever, it can be cut into the plate circuitbetween condenser C2 and the primaryof the AF transformer if wanted. In casea second tube of audio is to be used(not shown here), then run the plate oftube IV to this unit instead of connect-ing direct to the phones. Such a secondstep may be added to advantage by fol-

JANUARY 15, 1925 RADIO PROGRESS

lowing hook-up 9.Notice that a "C" battery connection

is made for the first step of audio. Ifthe "B" pressure is only 45 volts, thenthe "C" battery should be omitted and ashort wire run from binding post C-C-. More than 45 volts of "B" re-quires a "C" battery or 3 to 4y2 volts.

Connecting the PotentiometerThis unit is connected right across

from "A"+ to "A"-, with the centerpost connected so as to put a bias on thegrids of the two RF amplifiers. Thisbias potential reaches the grid of tube Ithrough the loop and grid II throughthe secondary of RF1 transformer.

As remarked when discussing radiofrequency hook-ups, it is quite necessaryto make the grid leads as short and di-rect as you can. The plate connectionsalso should be short and kept some dis-tance away from, the grid. Otherwise aself -oscillation may cause distortion inthe music.

Only a single rheostat is used to con-trol all the tubes. This is in line withmodern practice, but if you prefer a sep-arate rheostat for the detector it maybe cut into the negative side. Noticethat the grid return from the detectormust go to the positive side of the fila-ment.

OperationFirst set the potentiometer to about

the middle, then with the variometerturned up so that the set is just aboutready to squeal, turn the Cs condenseruntil a station is brought in. If thetuned RF condensers are employed itwill be necessary to turn all three oftheir grid control dials at the same time,which is a much harder method of tun-ing. When the station is brought inclearly, the variometer may be used toget more or less feedback. The potentio-meter is adjusted to prevent radio fre-quency oscillations in the first twotubes. It should be held as near thenegative end of the wire as possiblewithout causing any squealing in thephones.

13 -THREE TUBE REFLEXCRYSTAL

Here is a reflex set using a crystalwhich will work on a loop. Of course,more energy is brought in by a largeraerial and we recommend the latterwhere greater distances are to be pickedup. The loop, howbver, because of its

directional effect, is able to tune outeven the most powerful broadcasting sta-tions when it is turned so that the axisof the coil points toward the unwantedstation.

Only two steps of audio are hooked upand so the third tube is used only forRF amplification. If preferred, this latermay also be employed for audio, but isusually not desirable, as three stepsusing good AF transformers give somuch amplification, that the smallestnoises coming in are apt to be amplifiedso much that the music will not be en-joyed through the racket.

Some three tube reflex hook-ups showthe first tube instead of the third, as theone which is used on only frequency.This has the disadvantage that the thirdtube carries the greatest RF load andalso the largest AF currents. In thisway the tube may be overloaded. Withour connection the third tube has thebiggest RF load and the second tube thegreatest AF current. By thus dividingthe energy neither tube becomes over-loaded.

List of Material(First, see Page 5).

1 Variable condenser, 00025 $3.505 Mica condensers, .001 @ 40c 2.001 Condenser, .002 .15

2 RF transformers @ $2.50 5.002 AF transformers @ $4.00 8.001 Crystal detector, complete 1.001 200 -ohm potentiometer 1.00

1 Rheostat .50

3 Sockets @ 75c 2.251 Dial .50

1 Panel, 7x21 2.506 Binding posts .30

Busbar, etc.Extras

Loop 5.003 Tubes @ $4.00 12.00

Phones 5.0045 Volt "B" battery 4.003 Dry cell "A" batteries @ 40e 1.201 Cabinet, 7x21x7 deep. 7.00

OptionalPhone jack and plug .80

If aerial is to be used omit loopand add

1 Variocoupler. 3.001 Tap Switch 1.251 Dial .50

Theory of the SetThis hook-up employs the first two

tubes as amplifier of both radio andaudio frequency waves. The energy from

the broadcasting station is picked upby the loop and tuned by condenser Cs.The oscillations are fed to the grid andthrough condensers Cl and C6 to thefilament of tube 1. The output from theplate, after passing the primary oftransformer RF1, uses by-pass C2 toreach the "B" battery.

The amplified waves reach the grid oftube II from the secondary. The otherend of this winding passes them onthrough C3 and C6 to the filament. Thesame operation again increases the sig-nals through transformer RF2 to tubeIII and the primary of RF 3. The sec-ondary of this latter has its output recti-fied by the crystal detector. After separa-tion by the crystal into radio and audiowaves, the former return by condenserC5 and the latter by transformer AF1.

The secondary of the audio transformeris not shorted by condenser Cl as mightappear from the diagram, since this ca-pacity is too small to conduct the audiowaves. Instead the low speed vibrationsrun through the potentiometer to thefilament and through the loop winding tothe grid of tube I and thus make the in-put to the first audio amplifier. Theoutput from this tube, owing to its lowfrequency, is not affected by the primaryof transformer RF1, nor the capacityC2. It, therefore, threads the primaryof audio transformer AF2 to the "B"45 terminal. The secondary of this trans-former excites the grid of tube II. Theoutput of its plate works the phones orloud speaker in the usual way.

Why the PotentiometerNotice the potentiometer is at the left

hand end. This is used to put the propervoltage or bias on the grids of the threeamplifier tubes. The resistance wire ofthis unit is connected to the "A" - andthe "A" +. The center post carries thevoltage to the different grids by way ofthe secondaries of audio and radio trans-formers. By adjusting this unit to theproper value it allows the set to give themaximum volume without breaking intooscillations. Many hookups show thefirst tube connected in this way but thesecond and third steps have the grid re-turn connected to the "A" -. This is adisadvantage since the proper setting ofbias for one tube is also correct for theothers. By the scheme shown here allthe tubes get the same bias and so areequally efficient.

No grid leak condenser is needed with

28 RADIO PROGRESS JANUARY 15, 1925

this radio since all the tubes act asamplifiers and the dectetor is a crystal.Of course another tube could be substi-tuted for the crystal with a gain in effi-iency. It would then require a grid con-

denser and leak. Since the detector tubeis never reflexed no trouble will be ex-perienced in substituting it for thecrystal.

Building the SetIf the loop is to be used to pick up the

waves, then notice that only a single con-trol, condenser Cs, is used to tune in andadjust for various stations. This is oneof the few sets with a single control

L_ (Joe

Cs00025

appear on the right of the panel. Thecondensers, Cl to C5, should all be ofmica, so as to reduce the losses as far aspossible. Condenser C6 is not really nec-essary, but is used as a by-pass aroundthe potentiometer so that the waves donot have to go through the resistance ofthis unit. A paper condenser will dohere although a mica one would be per-haps a slight improvement.

If an outside aerial is to take theplace of the loop then connect the rotorof this unit just as the loop is nowshown. The stator has one lead eon -

it.Of course the detector must be either

the fixed kind or else you must be surethat the oats whisker is on a sensitivespot. With such a hookup it is con-venlient to use a crystal which is aliveall over. Such a one will bring in themusic no matter where it is set and thendifferent spots can be tried to see whichis the best.

14-THREE-TUBE INVERSEREFLEX

When properly built this set is thenected to ground and the taps running most powerful in this list of hook-ups.

o `234.15

Ca

G f1VILmAiTAN

F F F F

R.F.

C3 Co-

Rota.

eb

-/A F. 1 CR Y5 TA L.

Fig. 13. Three RF Amplifiers, Crystal and Two AF Steps With Loop

which is satisfactory in theory and inpractice. In that case symmetry woulddemand that the control dial should bein the center of the panel. It is prob-ably better to sacrifice the looks slightly,as by such a location it is difficult tohave all the grid leads short. A betterplace at least from the electrical point ofview, is at the left hand side next to thegrid of tube I.

The radio frequency transformers RF1and RF2 should lie between the tubesacross the front of the cabinet. Theaudio transformers can be placed at therear. Potentiometer and rheostat will

through the tap switch to the aerial. It has only three tubes but with themThis gives considerable more volume anddistance but sacrifices the advantage ofthe directional effect which the loop pos-sesses.

Operating the SetIt is easy to work this equipment.

After bringing the filaments up to theproper brightness there is only one con-trol-the variable condenser Cs. Whenyou have picked up a station then tryturning the loop around to point in dif-ferent directions and you will find thatthe station is loudest when the coil ispointing with one edge directly towards

we get two steps of radio frequencyamplification, then a regenerative tubedetector, and this is followed by twosteps of audio amplification. However.as is always the case where you makeone article serve two distinct purposes,there is apt to be considerable moretrouble than if each has only one func-tion to perform.

The particular thing about the in-verse reflex is the order in which theaudio amplification occurs,. Instead ofgoing through tubes I, II, III. I andII. as is customary, it uses the tubes

JANUARY 15, 1925 RADIO PROGRESS 29

in this order, I, II, HI, II, I. Thisreverses the direction through the lasttwo tubes, as you will notice. Theadvantage of this order is that of thetwo amplifier tubes (I and II), thesecond carries considerably heavier loadof RF than the first. This is becausethe first amplifies the input up to four

ael or live times what it originally wasbefore impressing it on tube II. Theordinary method of reflexing puts theoutput from the detector on tube Iagain and amplifies this at audio fre-quency into tube II.

Thus it will be seen that the secondstep gc1.- the big load of audio as well

a

TAP

AERIAL

23131

Cs

List of Materials(First see Page 5)

1 Variometer $4.50

1 Variocoupler. . 3.501 Variable condenser, .00025 3.50

By-pass condensers, .001,40c. 2.00

2 RF transformers, @ $2.50.... 5.002 AF transformers, @ $4.00.... 8.001 Rheostat. .503 Sockets, @ 75c. 2 253 Dials, @ 50c 1.50

1 Grid condenser, .0025 .35

1 Leak. .50

1 Panel, 7x21 2,50

7 Binding posts .35

p

J_Irr

Cq2

RteE0 .91.06 01"46 ) '

CI401

AF2

F F

OI

45-

Ori

O

RF2

the rotor in greater or lesser degree,depending on the angle it hears to theprimary. When in line the least selec-tivity and loudest volume results.The secondary is tuned by CondenserCs. The input to the first tube thenoscillates from the grid through therotor, and condenser Cl to the fila-ment. The output of tube I excitesthe primary of radio frequency trans-former RF1 and through condenser C3returns to the filament.

The secondary of this transformerimpresses the amplified RF on the gridof Tube II and through condenser C4to the filament. This action is re -

Lt A%

Fig. 14. A Most Powerful Set-Two RF Steps, Regenerative Detector, and 2Inverse Reflexed AF Steps

as radio. In this hook-up since theorder of AF is reversed, the second tubegets the output from the detector, andamplifies this to the first. By thismeans the two tubes divide the loadmuch more evenly, as the heavy load ofradio comes on the second, while theaudio frequency load is large on thefirst tube.

There is no particular trouble in ac-complishing this result. Instead offeeding the output from the platethrough the first tube it merely isswitched to the second. The actualpath of the current will be clear fromFig. 14.

Busbar, etc.Extras

Aerial and ground $3.003 Tubes @ $4.00 12.00

Phones. 5.0045 -Volt "B" batteries 4.00Cabinet, 7x21x7 deep 7.00

Optional1 Phone Plug $ .401 2 or 3 jacks, @ 40c1 4I/2 -Volt "C" battery .601 Extra 45 -volt, "B" battery 4.00

Theory of CircuitsThe waves from the aerial run through

the stator or primary to the ground.This coil is tuned by the tap switch.The magnetic energy is transferred to

VAR OM

peated through transformer RF2 to thedetector tube III. The output fromthe plate of the detector is tuned by thevariometer, which thus gives regenera-tion or feedback. After passing thevariometer the RF uses condenser C5as a grid return. The audio frequencyWhich cannot pass such a small con-denser, passes the primary of audio fre-quency transformer AF1 to get to the"B" + 22 terminal of the "B" bat-tery.

The output from this transformergoes direct to the grid of amplifiertube through the secondary of RF1,which does not affect the audio fre-quency. The AF output from tube II,

30 RADIO PROGRESS JANUARY 15, 1925

after threading the primary of RF2,(which does not affect it) passes

through the primary of audio frequencytransformer AF2 to the "B" + 45 post.The secondary of this transformertransfers the audio oscillations to thegrid of tube 1 through the rotor of thecoupler, and through the rheostat tothe filament.

The audio output from tube I, afterpassing RF1 operates the phones andthen goes to the "B" + 45. The audiowaves have not been by-passed by any

which runs from each of the audio sec-ondaries to the "A"-, and connect thesetwo wires together to the minus of the"C" battery. The plus of the "C" bat-tery then will run to "A" minus.

No phone jack is shown after eitherdetector or first step of AF amplifica-tion. If these are desired they can beinserted across the primary of the AFtransformers in the usual way. How-ever, in all good reflex sets the wiringshould be kept down to the absoluteminimum, so we recommend that this

rear,

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Fig. 15. One of the

of the .001 condenser since this value istoo small to allow these slow vibrationsto pass through it. The radio fre-quency, however, is able to use theseunits as short 'circuits around thelarge inductance or weight of the AFtransformer coils.

ConstructionThe layout of this set is quite similar

to Reflex Hook-up 13. The main differ-ence is that two additional dials areneeded, one controlling the coupler, andthe other the variometer. The wiringitself also is similar, but notice thatno crystal detector is needed but a gridcondenser and leak are used on the thirdtube. The 'connection between the tubesis the same as before except that TubeITT is followed by Tube II, as alreadynoted.

No "C" 'battery is shown in the hook-up, but it is an advantage to use onein case the "B" battery runs more than45 volts. To use a "C" remove the lead

Best Neutrodyne Sets

added device be omitted.Operation

The first dial determines the selectiv-ity and loudness. The second is thewave length selector and picks out thestations. The variometer adjuster isfor resonance of the plate circuit, andso adjusts the amount of feedback orregeneration.

15 -5 -TUBE NEUTRODYNEThis set has been regarded as one of

the best for the last two years. It hasthe advantages of sharp tuning (selec-tivity) and also will pick up one thou-sand to 1500 miles. Another good pointis that it will not oscillate and disturbthe surrounding listeners. The stationsonce heard can be logged and picked upagain at the same settings.

The drawbacks are that the five tubesrequire enough energy to light them sothat it is best to use a storage battery.Also three dials must be turned to the

correct setting at once to be able to hearthe distant station. This is sometimesrather difficult and faint signals are aptto be overlooked.

List of Materials(First read Page 5)

3 Variable condensers, .00025 @$3.50 $10.50

3 Neutroformers, @ $3.00 9.00

2 Audio transformers, @ $4.00 8.009 By-pass condensers, @ 40c .80

2 Neutrodyne condensers, @$1.25 2.50

1 Grid condenser, .00025 .35

1 Grid leak .35

2 Rheostats, @ 50c 1.00

5 Sockets, @ 75c 3.75

3 Dials. r 50c 1.50

1 Panel. 7x26 2.75

2 Phone jacks (2 spring) .50

1 Phone jack (Filament con-trol) .90

7 Binding posts .35

1 Filament switch .40

Busbar. etc.Extra,s

Aerial and ground 3.00

5 Tubes, @ $4.00 20.00

Phones 5.0090 -Volt "B" Battery 8.00

6 -Volt. "A" Battery 18.001 Cabinet. 7x26x7 deep 8.00

Optional1 "C" Battery .50

3 Vernier Dials, @ $2.00 6.00

Theory of HookupThe radio waves oscillate from the

antenna through the primary of thefirst neutroformer to ground. The sec-ondary tuned by the first condenser car-ries the input to the grid. The outputfrom the plate operates the primary ofthe second neutroformer. This actionis repeated to the third or detector tubewhich contains the leak and condenser inthe grid circuit. The output goesthrough two audio transformers andamplifiers as explained in hookup 9.

The phone jack is inserted in the out-put of the detector and may be used forsharp tuning. The amplifier jack takesin both steps and when the plug is in-serted the filament control turns on the"A" battery for the last two tubes.

Building This RadioThe layout for the panel usually

follows the arrangement in the same or-der as shown in Fig. 15. The exactdrilling plan for this set was given on

Continued on Page 32.

JANUARY 15, 1925 RADIO PROGRESS 31

Will the Moon Shadow Shut Out Radio?Radio listeners are asked to help in

these experiments.The Bureau of Standards at Washing-

ton have been interested in radio for along time. They have now decided tomeasure the fading and the apparentdirection of radio signals as the moon'sshadow passes over the United States.The eclipse which will occur on themorning of Saturday, January 24, is thefirst total eclipse which northeasternUnited States has seen for a great manyyears. As a matter of fact the zonepasses over an area which is more thick-ly populated than any that has everbeen eclipsed before.

The path of darkness starts at Buf-falo, Rochester, New Haven and Spring-field, and then goes out into the AtlanticOcean. In the path of complete dark-ness there are eleven astronomical ob-servatories. These are all arranging totake photographs of the heavens at thetime.

The general investigation is being or -

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Address Radio Progress. P0. Box 728, 8 Temple Street,Providence, R. I.

ganized by Mr. G. W. Pickard, a promi-nent radio engineer of Boston. TheBureau of Standards is co-operatingwith Mr. Pickard by collecting data fromlaboratories, while the Scientific Ameri-can has undertaken to gather informa-tion from amateurs, in accordance witha special program it has outlined. Sta-tions WGR (940 kc.) at Buffalo, N. Y.;WGY, (790 kc.) at Schenectady; WBZ,(920 kc.) at Springfield, Mass.; andWEAF, (610 kc.) in New York City areto send the signals on which measure-ments are to be made. The first ofthese is in the center of the shadow path,the second and third on its northernedge, and the fourth on its southernedge.

Laboratories having the necessaryequipment are to make measurementson the carrier wave, recording the actualstrength of the wave. It is expectedthat this will vary as the shadow passes,showing effects similar to those observedwith change from day to night. Pos-sible reflections from the shadow walland other changes in direction are alsolooked for. It is expected that theeffects will be most pronounced withshort waves, and perhaps not noticeablewith long waves.

The radio investigation will take inthe effect the darkness has on transmis-sion between various listeners located inpairs. One will be at the north of thedark zone and one at the south and theidea is to see how the transmission be-tween them varies as the dark shadowadvances across the country. The ma-terial to be sent has been prepared al-ready and is known to the receiving sta-tions. They will follow the reading andnotice which words are especially loudor soft.

The list of questions sent out is asfollows:

1. If the sun is not quite eclipsed atyour station there will always be abright edge of the sun visible, or per-haps only a single point. One brightpoint may appear on one edge of the sunbefore the other has entirely disap-peared. At your station was there anytime at which no bright edge of the sunwas visible? Answer YES or NO

2. If the bright edge of the sun en-

tirely disappeared. how many secondselapsed before another bright part ofthe sun became visible? Answerseconds.

3. Was the time set down in the lastquestion merely guessed at or was it ac-tually measured? If measured, how wasthe measurement made?

4. The fringe of light surrounding thesun and called the corona is fully visibleonly if the face of the sun is entirelycovered. At your station was there anytime at which you could see the coronaall around the sun? Answer YES orNO

5. Could you see any stars or planetsat the time when the sun was most com-pletely covered and how many did yousee?

(If convenient draw a little map show-ing the positions in the sky of theeclipsed sun and of the stars and planetsthat you saw.)

6. If you are on a high building or ahill near the edge of the shadow pathyou may be able to see the shadow ad-vancing across the country. If so, whatbuildings or other land -marks were in-side and what were outside the edge ofthe shadow?Landmarks inside the shadow:

Landmarks outside the shadow:

7. It is necessary to locate your posi-tion very accurately, so that the engi-neers who compile the reports will knowjust where to place your observations onthe map. Accordingly, give your posi-tion by means of the nearest street in-tersection (if in a city or town) or bymeans of some easily located buildingsuch as a railroad station, a town hall,or some landmark which can be placedeasily on a map by a person familiarwith the district

If you have a map of your districtpublished in a newspaper or from anyother source, mark a cross on the mapat the position where you stood and sendin the map with your report.

Even if only one of the questions 1 to

32 RADIO PROGRESS JANUARY 15, 1925

5 be answered, question 7 should be care-fully answered.NameAddress

Answers may be sent to "Eclipse," Na-tional Research Council, or the Editor,Scientific American, 233 Broadway, NewYork City.

A WORD A DAY BY RADIOStation WJZ has instituted a pro-

gram novelty of decided value. Dr.Frank H. Vizetelly, managing editor ofFunk and Wagnalls New Standard Dic-tionary, is broadcasting a radio talk un-der the title "Learn a Word a Day."Dr. Vizetelly speaks to the radio au-diences every night for not longer thanone minute, presenting a new wordevery day and explaining its uses. Heis the final authority on the correctnessof over 455,000 words-the largest num-ber of words ever compiled in one dic-tionary-and his "Learn a Word a Day"radio project is an exceptional featureof the W.TZ program,.

"HERCULES" Aerial MastAll steel construction. Com-

plete with galvanized steelguy wires and pulley. Simplediagram shows how to erectquick. 20 feet $10, 40 feet $25,60 feet $45. We pay freight.Install this mast for greaterrange and better results.Write now for literature and

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loon is blown up with hydro-gen and to which is attachedan aluminum alloy wire forthe antenna. Write for litera-ture.

Price all complete, $5.00plus postage. Shipping weight3 lbs. Includes instructions,large hand reel, calcium chlor-

ide drying tube, rubber tubing, stopplesand two extra 30 -inch balloons.

Has been approved for experimentaluse. EVERETT SCANLON, Radio Spec-ialties, Lakewood, Rhode Island.

NEW GENERAL ELECTRICSTATION

Millions heard Denver's new radiovoice KOA, the Rocky Mountain Broad-casting Station of the General ElectricCompany, on its opening recently. Tele-graphic reports began pouring in fromthe four corners of America withinthirty minutes after the opening pro-gram was put on the air. Telegramsand long distance telephone calls nearlyswamped the operators. Reports werereceived from all but three states in theUnited States and more than a dozenpoints in Canada. Those omitted in thefirst telegraphic applause were WestVirginia, Mississippi and Tennessee.

Officials of the Atlanta Journal, atAtlanta, Ga., were among the first tosend congratulations on the successfulopening of KOA, the sister station ofKGO at Oakland, California, and WGYat Schenectady N. Y. "Congratulationsand greetings from the voice of theSouth WSB," the Atlanta wire said.Pine Bluff, Ark., wired that the programwas coming in fine down south. "All

radio fans in Leadville are listeningdown on you to -night from an altitudeof ten thousand two hundred feet," readanother message.

More than four thousand letters andtelegrams and telephone calls werereceived during the next two weeks inresponse to tests conducted preparatoryto the opening of the station. Duringthe test period the call letters of thestation were 3XA. The greatest distancefrom which response was received dur-ing this period was Hawaii, approxi-mately three thousand five hundred milesfrom Denver. The station was pickedup in the Pacific, according to a reportreceived from a sailor, following his ar-rival in Los Angeles.

KOA will be operated on a frequencyof 930 k. c. (323 meters) and the powerrating will be 1,500 watts. Regular pro-grams will be broadcast by the giantplant three nights a week, MondayWednesday and Friday nights. in addi-tion to morning and evening church ser-vices on Sunday.

KINGS AND PAWNS BY RADIOFor five and one half hours a group

of students at Haverford College, Haver -ford, Pa., recently sat before severaltables moving chess men in accordance

with the instructions, shouted at themby a radio operator in the next room.At the same time, another group of stu-dents of Oxford University, England,3,000 miles distant, were making theidentical moves and discussing the samepoints.

The instructions from both teams oneither side of the Atlantic were beingsent back and forth in dots and dashes;the first international chess match byamateur radio was being played. Thegame which started at 7:45 p. an., East-ern Standard Time, was carried on with-out a halt until 12:45 the next morning,at which time the match was adjournedbecause of lengthy consultations by theOxford team.

During the entire period, excellent con-tact was maintained between two sta-tions of the Haverford College RadioClub and the English amateur stationoperated by Gerald Marcuso, honorarysecretary of the Transmitters Section,Radio Society of Great Britain. Allcommunication was on a wavelength of85 meters. Few interruptions were nec-essary despite heavy static and interfer-ence. The moves averaged four anhour, or one every fifteen minutes, whichis normal time for two chess teams play-ing under ordinary circumstances.

FIFTEEN HOOK-UPSContinued from Page 30.

page 10 of the April 15, 1924, issue ofRADIO PROGRESS in "Constructing a Five -

tube Neutrodyne." A method of neu-tralizing was also explained at lengthin this same article. Care must betaken that the spacing and angle of theneutroformer coils are correct or elsethe signals will come through distorted.

OperationAfter adjusting the filaments to the

proper brilliancy, try turning all threedials slowly until a station is picked

up. The readings of the three will benearly alike. Some few sets will haveidentical settings, but this is rare as itis very difficult to make three coils andthree condensers exactly alike allthrough their range. If it is found onedial is consistently one or two degreesahead of the other two then the screwwhich fastens it to the shaft may beloosened and the whole dial turned un-til it lines up with the others.

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...ii .:.::.* ,.. .:..:.. * .:...:.Radio Dealers! ...i:

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4.

Would You Be Deaf For $6.00

If you have a one or two tube set you can add one step of audio amplifica-tion and this will improve the loudness of your set so much that WITHOUT itit will seem as if you were deaf.

It is easy to add one more tube yourself. Our complete kit of audio in-cludes everything you need

When you order

at a cost of $6.00. In it you will find the wellknown Radiclear transformer, socket; rheostat,4 -spring jack, "B" Battery binding post, andwire for the whole job. The directions with itare clear so that you will have no trouble inmaking the connections.

Since the heart of the amplifier is the transfor-mer we use one that does not make music come inlike a tin pan serenade. The ratio in which theloudness is increased should be the same for bothhigh and low notes. Most makes of unit do nothave such regularity. The Radiclear trans-former gives exceptional smoothness in thisrespect. When buying it alone the price is

$3.95 post paid.a complete kit at $6.00 let us know what kind of a tube you

want the socket to fit.

The Taylor Electric Company,1206 Broad Street,Providence, R. I.

Please send me the following by par-cel post. (Mark which one you want.)

Radiclear Audio Transformer @ $3.95Amplifier Kit for tube (a $6.00Audion Crystal @ 25c.Gold Plated Cat whisker @ 15e.D 1 enclose $.... to pay for these.

(These above prices include the postage.)0 Send them to me C. 0. D. I

will pay the above price plus postage.(Indicate which way you wish to pay )

Name

Address

TAYLORELECTRIC CO.

1206 Broad Street

Providence, R. I.