Radio Broadcast (May 1927-Apr 1928)

JAN -5 i92 8 CI B76328S RADIO BROADCAST JANUARY, 1928 Willis Kingsley Wing, Editor Keith Henney Edgar H. Felix Director of the Laboratory Contributing Editor Vol. Xllf No. 3 CONTENTS Cover Design ' From a Design by Harvey Hopkins Dunn Frontispiece ' In the Laboratory of a Tube Manufacturer 194 Radio Enlists the Helium Atom The March of Radio ' ' Can the Serious Problem of Radio Patents Be Settled? The Prospects of a Patent Pool The Commission Announces a New Policy The Commission Suggests Synchronization Schemes ' Volney G. Mathison An Editorial Interpretation What Readers Say About Broadcasting Conditions Broadcasting Bands Changed Broadcasting Notes News of the Patent Field Among the Manufacturers Push-Pull Amplification — Why? The Phonograph Joins the Radio Set The Screened Grid Tube ■ < ■ ■ What Set Shall I Buy? "Our Readers Suggest " Howard E. Rhodes Keith Henney Edgar H. Felix Why I Installed a Cooley Picture Receiver Suppressing Radio Interference Are Programs Going in the Wrong Direction? The Listeners' Point of View A Vacuum-Tube Voltmeter Radio Folk You Should Know Edgar H. Felix A. T. Lawton (1.) Ralph H. Langley Drawing by Franklyn F. Stratford Some Fine Receivers and Their Chassis "Strays" from the Laboratory How Reliable are Short Waves? Mathematics of the Audio Transformer High-Powered Bunk New Apparatus Concomitants of Good Quality How the "Synchrophase" Seven Was Developed John F. Rider As the Broadcaster Sees It Carl Dreher "Radio Broadcast's" Laboratory Information Sheets No. 153. Standard and Constant-Frequency Stations No. 154. The 112-A and 171-A Type Tubes No. 155. Wave Traps No. 156. Wavelength-Frequency Conversion No. 157. Table for Wavelength-Freemen*.) Conversion No. 158. The Three-Tube Roberts Reflex No. 159. Diagram of Three-tube Roberts Reflex No. 160. Fading Manufacturers Booklets Available "Radio Broadcast's" Directory of Manufactured Receivers ' A Key to Recent Radio Articles ' E. G. Shalhfiauser What Kit Shall I Buy7 195 198 202 206 208 211 213 215 217 John 'Wallace 219 The Laboratory Staff 221 225 226 228 230 232 235 238 244 246 255 257 AMONG OTHER THIHGS. . . IT IS a sad duty to record the death of the Chairman of the Federal Radio Commission, Admiral W. H. G. Bullard, which occurred in Washington on Thanksgiving Day. Admiral Bullard, who served in the United States Navy for thirty-six years, for a very long time was close to the center of radio in almost all of its branches. His loss will be keenly felt, not only by those who knew him as a likable and able individual but especially by the Radio Commission itself. When the Radio Commission went to work on March 15, two of its members had a background of technical radio experience. These two men were Admiral Bullard and Colonel Dillon. Death has removed both. The Commission at this writing now consists of ActingChairman E. O. Sykes, O. H. Caldwell, Sam Pickard, and H. A. Lafount. Not one of these members has a technical radio background which would enable them to better struggle with the complicated problems which confront them. THE reports of international conferences, on whatever subject, usually make rather dull reading for the general public and the Washington Radio Conference has been no exception to this rule. The proceedings may not be exciting, but the results are certainly important. There has been no revision of international agreement since the London conference of 1912, and radio progress has been so rapid since then that the articles of that Convention were hopelessly inadequate to meet present needs. There have been many rocks and shoals in the way of the present conference, which, at this writing, has just wound up its work, but through good management and a praiseworthy desire for general accord, the delegates have succeeded in drawing up a Convention which well meets the needs of radio today. Not the least important decision reached at Washington was that dealing with the international assignment of channels in the frequency spectrum. In that respect, we are glad to note, the future needs of short-wave communication, broadcasting, commercial, and amateur work were provided for. The amateurs had a hard fight, but room has been saved for them — a result of which the broad-minded directors of the American Radio Relay League may well be proud. THE issue of Radio Broadcast before you contains some extremely interesting articles. The story by Howard Rhodes on the problems of push-pull amplification is distinctly helpful and should cast much light on a form of amplification which is again being revived after several years of comparative disuse. . . . Those who are anxious to know what the new screened-grid tube will do will find Keith Henney's article very valuable indeed. As soon as possible, Radio Broadcast will give its readers data on receiving circuits which can be used with the tube; the latter has just been released for general sale. THOSE of our readers who would like to have their names forwarded to the manufacturers of the special apparatus necessary to construct a Rayfoto receiver may send letters to the undersigned, and printed matter containing detailed information will be sent them. . . . The next Radio Broadcast will contain an article describing a new super-heterodyne, entirely operated from a. c, which has much to recommend it, both from the design and appearance point of view. There will also be many other articles of interest. — Willis Kingsley Wing. Doubleday, Page & Co. MAGAZINES Country Life World's Work Garden & Home Builder Radio Broadcast Short Stories Educational Review Le Petit Journal El Eco Frontier Stories West Weekly The American Sketch Doubleday, Page Gr Co. BOOK SHOPS (Books of all Publishers) Lord & Taylor Book Shop Pennsylvania Terminal (2 Shops) New York: <Grand Central Terminal i Wall St. and 526 Lexington Ave I 848 Madison Ave. and 166 West 32ND St. St. Louis: 223 N. 8th St. and 4914 Maryland Ave. Kansas City: 920 Grand Ave. and 206 W. 47TH St. Cleveland: Higbee Co. Springfield, Mass.: Meekins. Packard& Wheat Doubleday, Page & Co. OFFICES Garden City, N. Y. New York: 28^ Madison Avenue Boston: Park Square Building Chicago: Peoples Gas Building Santa Barbara, Cal. London: Wm. Heinemann Ltd. Toronto: Oxford University Press Doubleday, Page Sr Co. OFFICERS F. N. Doubleday, President Nelson Doubleday, Vice-President S. A. Everitt, Vice-President Russell Doubleday, Secretary John J. Hessian, Treasurer Lillian A. Comstock, Asst. Secretary L. J. McNaughton, Asst. Treasurer VOUBLEDAT, 'PAGE & COMPACT, Garden Qity, N.ew Tor\ Copyright, 1927, in the United States, Netf/oundland, Great Britain, Canada, and other countries by Doubleday, Page & Company. All rights reserved. TERMS: $4.00 a year; single copies 35 cents. 192