Radio broadcast .. (1922-30)

WILLIS KINGSLEY WING Editor KEITH HENNEY . Director of the Laboratory HOWARD E. RHODES . . Technical Editor EDGAR H. FELIX . . . Contributing Editor RADIO BROADCAST PUBLISHED FOR THE RADIO INDUSTRY VOL. XVI. NO. 4 Contents for February, 1930 Review -------- W. K. W. 193 Facts Replace Estimates More Truth in Advertising "Permanent Commission' Flirtations Radio Business New Uses for Radio Mergers in the Radio Industry - - - - Edgar H. Felix The Market for the Battery Set - -T.A.Phillips The March of Radio - - - - An Editorial Interpretation The New Day in Radio Too Much Icing Is Indigestible Educational Broadcasting An Invitation to Mr. Schuette Professionally Speaking ------- - Keith Ilenney Two Needed Developments Regarding Radios in Autos The Inside Story of the Brunswick - - A Page of Pictures The R.C.A. Theremin A Production Testing System (Part II) - J. A. Callanan The Multicoupler Antenna System Ernest V. Amy and J. G. Aceves The 1930 Model Hi-Q Receiver - Curtis W. Hamilton Band-Pass Filter Circuits ----- - E. A. Uehling "Radio Broadcast's" Engineering Review Sheets - - - - Tubes as Amplifiers Simple L x C Measurements The Supreme Diagnometer • Push-Pull A.F. Amplifiers Strays from the Laboratory A Radio Manual Causes of A. C. Hum ------ 'Floyd FausM - J. M. Slinchfield ----- Technical Shorts The Radioln 21 All About Electricity 194 196 198 200 201 202 201 206 210 212 215 217 219 223 Book Reviews ..- 224 Elements of Radio Communica- tion Radio Telegraphy and Telephony Mathematics of Radio The Serviceman's Corner - - Points on Victor Short Cuts to Neutralization International Aspects of Radio Commun icat ion Radio Receiving Tubes An Automatic Switch In the Service Laboratory "Radio Broadcast's" Set Data Sheets ------ 230, The Amrad Model 81 The Fada Models 16, 17, 32 The Sparton ModelSOl News of the Radio Industry ----------- Shall We Buy or Make Parts? - - - - Damson J. Burns In the Radio Marketplace - - Offerings of Manufacturers The Radio Dealer's Directory of Recent Price Changes - - Radio Broadcast Laboratory Information Sheets Howard E. Rhodes 242, 244, 226 232 234 239 240 241 246 No. 319. Apparent Demodulation of a Weak Signal No. 320. Apparent Demodulation of a Weak Signal No. 321. Service Procedure No. 322. Inductance of Coils No. 323. Inductance of Coils No. 324. Hum us Volume Control No. 325. Beat-Frequency Oscil- lators No. 326. Beat-Frequency Oscil- lators No. 328. Fidelity in Modern Sets The contents of this magazine are indexed in The Readers' Guide to Periodical Literature, which is on file at all public libraries among other things Fon THE first time, complete data is presented on the "Multicoupler" antenna system, developed some months ago in New York. The system has been of great interest to engineers because of its simplicity and low cost. Mr. Amy and Mr. Aceves, co-designers of the system, describe it fully on page 206 of this issue. /7T* ANOTHER OF Mr. Uehling's valuable mathematical ^\ articles on theory of receiver design is a part of this issue. Mr. Uehling was formerly a member of the research staff of Fada Radio in New York. Some months ago he returned to the University of Michigan for gradu- ate study in physics. RADIO BROADCAST readers will remember two in- (cresting papers by J. M. Stinchfield of the Cunning- ham engineering department which appeared in our August and October, 1929, issues. The August article discussed "Calculating Detector Output" and the October paper "Grid Leak vs. Bias Detection." Mr. Stinchfield's article in this issue deals with push-pull audio-frequency amplifiers. THE March RADIO BROADCAST will contain con- tributions from H. D. Oakley, of the General Elec- tric engineering department, a paper from the Ward Leonard Laboratory, the third article in Mr. Calla- nan's series on factory production test methods, a description of the ingenious and compact record- changer developed in the Technidyne Corporation lab- oratories, and a number of other interesting articles, in addition to all our regular departmental features. OF ESPECIAL interest is the article from Ward Ixonard which describes for the first time anywhere the " Adaptoron." This is a compact motor-driven unit for the conversion of direct current of any of the com- mon commercial voltages to alternating current. The article descril>es the unit technically and discusses its application. With this unit, which is approximately 80 per cent, efficient, a 32-volt d.c. farm-lighting system will provide 110 volts a.c. to energize a standard a.c. broadcast receiver. The conversion unit will perform the same function on any commercial d.c. supply. This article, we are sure, will be awaited with the greatest interest. Mr. Oakley will describe the signal generator developed by the General Electric Company giving full data on circuit and operation. We shall publish two other articles from Mr. Oakley dealing with ap- plications of the device. TERMS: $4.00 a year; single copies 35 cents; All rights reserved. Copyright, 1930, in the United States, Newfoundland, Great Britain, Canada, and other countries by DOUBLEDAY, DORAN & COMPANY, INC., Garden City, New York MAGAZINES . . . COUNTRY LIFE . . WORLD'S WORK . . THE AMERICAN HOME . . RADIO BROADCAST . . SHORT STORIES . . LE PETIT JOURNAL . . EL Eco . . WEST BOOK SHOPS (Books of all Publishers) . . . NEW YORK: <LoHD & TAYLOR, JAMES McCHEEHY & COMPANY. PENNSYLVANIA TERMINAL, 166 WEST 32m> ST., 848 MADISON AVE., 51 EAST 44™ STREET, 420, 526, and 819 LEXINGTON AVENUE, GRAND CENTRAL TERMINAL, 10 WALL STREET> ATLANTIC CITY: <2807 BOARDWALK> CHICAGO: <75 EAST ADAMS STREET> ST. Louis: <310 N. 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