Inductive Neutralization and Tuning Remote Switching of Matching Stubs a T -200 Grid Modulated Transmitter an Improved "Conversion" Type Exciter
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FEBRUARY, 198 30c in U.S.A. and Canada No 22E 1 8 in the United Kingdom; 2 - in Austro asia Inductive Neutralization and Tuning Remote Switching of Matching Stubs A T -200 Grid Modulated Transmitter An Improved "Conversion" Type Exciter www.americanradiohistory.com QRT--- ALL FIVE METER AMATEURS QRV? 0 RADIO MFG. ENGINEERS, www.americanradiohistory.com 1938 will see considerable activity on the 56 -60 megacycle band. The F.C.C. has recently issued its orders and placed definite assignments. Note that it will be imperative to operate within the band. Television broadcasts are on the left, Government assigned frequencies on the right, and we amateurs are i.1 between. The rules have been made; now we must play the game according to the rules! RME as one of the leaders in amateur communication equipment is "placing the first long -range gun" in the interest of five meter operation by introducing the 510X FREQUENCY EXPANDER! WHAT IS THE 510X? -A specially designed unit to be used in conjunction with your present receiver, especially the RME -69, in order to expand the range for real operation on five meters. You must know whether you are in or out of the band! Consequently, the tuning range of the 510X is continuous from 27.8 megacycles to 70 megacycles. (You will note it covers five and ten meter amateur bands.) WHAT DOES THE 510X DO? -Provides an over -all sensitivity of better than one microvolt when used in conjunction with any modern receiver, features excellent stability, com- plete shielding, calibrated dial, finger -tip tuning control mechanism, and incorporates its own power supply. It meets all requirements for five meter operation in a manner never heretofore provided. WHY THE 510X EXPANDER? -With your present superhet as a basic double IF receiver, the 510X Expander gives you an excellent U.H.F. instrument at a nominal cost without having to invest in expensive ultra -high frequency designed supers. RME thus gives to the radio amateur and the five meter enthusiast and experimenter the lowest cost, highest over -all sensitive, calibrated method of working five meters ever offered. The unit will be ready for delivery sometime in February, 1938. Literature is available on request. INC., PEORIA, ILL., U.S.A. 3 www.americanradiohistory.com TELEPHONE 1460 BEVERLY BLVD.,LOS ANGELES, CALIFORNIA YORK 7226 New York Office: Radio, February, 1938. No. 226 12ADIO 500 Fifth Avenue Phone: CHickering 4 -6218 RADIO Is published ten hares yew-is (including enlarged speeiel annual s number) about alw middle of the ,s month preceding its date; August acid Chicago Office: September issuer are omitted. 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Published at 7460 Beverly Boulevard, Los Angeles, Calif. 4 www.americanradiohistory.com February 1938 Number 226 The publishers assume no responsibility for statements made herein by con- tributors and correspondents, nor does publication indicate approval tbereoj. flADIO 'ot tita. asf-te "/lad-la" rviesertts: ARTICLES Fixed -Capacity Final -Charles D. Perrine, Jr., W6CUH - 9 An Improved Type of Volume Indicator-Ray L. Dateley. W6DHG - 12 Improved Conversion Exciter -C. M. W'eagant, II'7GAE - 14 400 -Watt HK -54 Amplifier -Faust R. Gonsett, W6VR - 17 The Foolproof Dynapush Exciter -W. W. Smith, W6BCX - - - 19 Matching Stubs with Remote Switching -B. K. Willoughby, W9NTW -OHK 23 Keying with Grid -Controlled Rectifiers - - 25 The Worm Turns Cold - 28 147 -Ft. Steel Mast ... Only $85 -R. T. Sampson, W6OFU - - 30 An Amateur's Vacuum -Tube Voltmeter -Lloyd W. Root, W9EHD -W9HA 31 Five Bands -Individually Tuned -G. R. Leach, W/8NPJ - - 35 An Economical Phone and C.W. Transmitter -Frank C. Jones, W6AJF 40 Razor -Sharp Phone Selectivity - - - - - 46 Push-Pull 809's Driven by the "Dynapush " -B. A. Ontiveros, IV6FFF 48 A Ham Band Superhet-Raymond P. Adams 50 Let's Whip the Twenty -Meter Rotary-E. H. Conklin, W9FM 56 Band -Switching-Phone and C.W. with RK20's -Dean S. Young, WLMP, W3FZ 59 MISCELLANEOUS FEATURES Frontispiece: Something Different 8 Ham Hints - 34 Free Wheeling "Q" Spacers 24 Pictorial: Photograph -W6NJ1 - 63 Ionosphere Notes - 24 Buyer's Guide - - - 96 Plate Modulation of Beam Tetrodes 27 The Marketplace 97 Index to Advertisers - 98 DEPARTMENTS Dx - - 64 56 Mc. - 72 Yarn of the Month 69 Open Forum 73 Question Box - 70 Calls Heard 74 Postscripts and Announcements 71 New Books 76 THE WORLDWIDE TECHNICAL AUTHORITY OF á AMATEUR, SHORTWAVE, AND EXPERIMENTAL 5RADIO www.americanradiohistory.com Just off the press A three -cent stamp will bring it to you.