Radio Broadcast (May 1928-Apr 1929)

© CI B79S274 RADIO BROADCAST SEPTEMBER, 1928 Willis Kingsley Wing, Editor Keith Henney Edgar H. Felix Director of the Laboratory Contributing Editor Vol. XIII. No. 5 Cover Design ' ' From a Design by Harvey Hop\ins Dunn Frontispiece England Tac\les the Multiplex Channel Problem Can We Multiplex Our Radio Channels? Albert F. Murray A "One-Spot" Screen-Grid Super W. H. Hollister The 222 Tube as an R.F. Amplifier ' ' Glenn H. Browning The March of Radio ' ' ' An Editorial Interpretation 244 245 249 252 253 The Laboratories Grapple with Aircraft Radio Guggenheim Fund Shows the Way to 'Frisco At the NEMA Convention Keep Commercialism Out of the Amateur Bands Harrisburg, 111., Needs a 500-Watt Station The Empty Pool Engineers in Quantity Production of Standards Long Waves Needed in Transoceanic Service Here and There A Resistance-Coupled Amplifier and Power Supply ]. George Uzmann 257 "Strays" from the Laboratory Keith Henney 259 Screen-Grid and Automatic Receivers Trailing "Power Leak" Interference More Radio Hoaxes At Last — A Line Voltage Regulator Some Coil Measurements Another Patent Muddle "Radio Broadcast's" Home Study Sheets 261 No. 5. Measuring the Amplification Factor of Tubes Working on 5 Meters ' ' ' As the Broadcaster Sees It ' Broadcast Transmitters Design and Operation of Broadcast Stations No. 6. Vacuum Tube Characteristics Robert S. Kruse 263 Carl Dreher 267 11 (Part 2). Water-Cooled Vacuum Tubes 22. Phonograph Pick-ups Make Your Lighting Lines Safe for A.C. Tubes Kasson Howe 269 "Our Readers Suggest — " ---- 271 A Compact and Inexpensive "Trouble Shooter" Emil Reisman 273 Book Reviews Carl Dreher 274, 280, 3o2 An Adapter for LongWave Reception W. H. Wenstrom 275 "Radio Broadcast's" Service Data Sheets on Manufactured Re 277 ceivers No. 7. Stromberg-Carlson 6^ and 636 Receivers Nos. No. 8. The Marconiphone Model 6r Receiver A Simple Unit for Measuring Impedances F. }. Fox and R. F. Shea A Six-Tube Screen-Grid Receiver ,*•■>■■. McMurdo Silver New Apparatus Useful Information on A[ew Products A Non-Radiating Short-Wave Tuner James Millen What Radio Has Done for Aviation An English Radio Engineer Checking Up on Audio Distortion G. F. Lamp\in Manufacturers' Booklets "F-adio Broadcast's" Laboratory Information Sheets ' ' No. 217. Using a Milliammeter as a Voltmeter No. 218. Servicing Radio Receivers No. 210. Sizes of Tap and Clearance Drills No. 220. The Roberts Four-Tube A.C. Re No. 221. Circuit of the Roberts Four-Tube A.C. Receiver No. 222. Measuring Instruments No. 223. Radio Transmission No. 224. Text Books on Radio "Radio Broadcast's" Directory of Vacuum Tubes Notes on the "Cornet" Receiver ' ; ' W. H. Wenstrom Letters from Readers ' ' The contents of this magazine is indexed in The Readers' Guide to Periodical Literature, which is on file at all public libraries. 279 28l 284 286 288 29O 292 294 300 302 308 AMONG OTHER THINGS. . . FOR a long time, readers of Radio Broadcast have been confused in buying the magazine on the newsstands because the magazine arrives on the newsstands on the 15th of the month and is dated the month following. That is, this issue, which is dated September, is on sale August 15th. In order to avoid confusion, beginning with the October Radio Broadcast each issue will be on sale on the first of the month. Look for your October issue on the first of October. AT NO time since Radio Broadcast first appeared, which was in May, 1922, have so many letters of praise trooped into the editorial office. A great many of our readers are good enough to write us, telling exactly what they like in the magazine, and why. "Strays from the Laboratory," "Radio Broadcast's Home Study Sheets," and the "Service Data Sheets on Manufactured Receivers" are sharing honors at present. The "Home Study Sheets," the newest addition to the magazine, have been prepared because we have felt for a long time that radio readers wanted guidance in making their own home experiments. These "Home Study Sheets" are prepared by Keith Henney, director of the Laboratory. Both the author and the editor will be pleased to hear from readers who have suggestions on how the "Sheets" can be made more valuable to them. IN 1925, when Carl Dreher was induced to begin preparing his department, "As the Broadcaster Sees It," the broadcasting art was very different from what we find it to-day. Since that time, more than 170,000 words dealing with broadcasting — both from the engineering and aesthetic point of view — have appeared under that department heading. The newest development of interest to the engineer and others associated with broadcasting and its problems is the talking movie. Beginning with October, Mr. Dreher's department "As the Broadcaster Sees It," will branch out. In addition to the material on broadcasting, which we are assured is widely useful, Mr. Dreher will treat of talking movies and in later issues of other fields closely related. MANY of our amateur friends have hailed with delight the first article in the series of special short-wave contributions by Robert S. Kruse, formerly technical editor of £JST. In the August Radio Broadcast, Mr. Kruse's first article appeared, dealing with the general aspects of 5-meter transmission. For our October number, Mr. Kruse expects to describe the construction and operation of an efficient and inexpensive batteryoperated transmitter. THE radio service man has found that a few simple instruments will make his task in the field much simpler. Many service men wrote us, praising Mr. Messenger's article in the July issue which described his set tester. On page 273 of this issue, a simpler unit is described which is useful for service men and those who would like to own a compact tester for general home experimental service. WE APOLOGIZE for an error of our draftsman which we allowed to escape us in Fig. 2, page 218, Radio Broadcast for August in the article describing an r.f. stage for any set. The diagram will be correct if the reader removes the short vertical line which — now — short-circuits the A-battery. — Willis Kingsley Wing. DOUBLED AT, DORAK & COMPACT, IA[C., Garden City, Hew Tor\ MAGAZINES Country Life World's Work Garden & Home Builder Radio Broadcast Short Stories Educational Review Le Petit Journal El Eco Frontier Stories West The American Sketch Copyright, BOOK SHOPS (Books of all Publishers) !Lord & Taylor; James McCreery & Company Pennsylvania Terminal and 166 West 32ND St. 848 Madison Ave. and 51 East 44.TH Street 420 and 526 and 819 Lexington Avenue Grand Central Terminal and 38 Wall Street Chicago: 75 East Adams Street St. Louis: 223 N. 8th St. and 4914 Maryland Ave. Kansas City: 920 Grand Ave. and 206 West 47TH St. Cleveland: Higbee Company Springfield, Mass: Meekins, Packard & Wheat OFFICES Garden City, N. Y. New York: 244 Madison Avenue Boston: Park Square Building Chicago: Peoples Gas Building Santa Barbara, Cal. London: Wm. Heinemann, Ltd. OFFICERS F. N. Doubleday, Chairman of th' Board Nelson Doubleday, President George H. Doran, Vice-President S. A. Everitt, Vice-President Russell Doubleday, Secretary John J. Hessian, Treasurer Lillian A. Com stock, Asst't Secretary Toronto: Doubleday, Doran & Gundy, Ltd. L. J. McNaughton, Asst't Treasurer 1928, in the United Slates, ?<ew/ound!and, Great Britain, Canada, and other countries by Doubleday, Doran & Company, Inc. All rights reserved. TERMS: $4.00 a year; single copies 35 cents. 242