Radio Broadcast (May 1928-Apr 1929)

NOV 2 4*28 RADIO BROADCAST DECEMBER. 1928 «Fft Keith Henney Director of the Laboratory Willis Kingsley Wing, Editor Edgar H. Felix Contributing Editor Howard E. Rhodes Technical Editor Vol. XIV. No. 2 CONTENTS Cover Design From a Design by Harvey Hopkins Dunn Frontispiece ' Old Sayvitte Station Returns to Limelight Quartz Crystals R. C. Hitchcoc\ Phonograph-Radio Amplifiers Howard E. Rhodes The March of Radio ' ' ' ' ' An Editorial Interpretation Radio, the Corner Stone of the Amusement Industries Wgy Protests Allocation Plan The 300'Mile Chain Regulation The Fight for Short Wavelengths With the Broadcasting Stations The Progress of Aircraft Radio Radio Abroad The Visual Broadcasting Field News of the Radio Industry The "Skyscraper" Screen-Grid Receiver "Strays" from the Laboratory Clifford Denton Keith Henney 84 85 88 9i 95 97 Accuracy of "Slide-Back" Voltmeters Hum in the "Lab." Circuit Receiver Data on Underground Aerials Type 112 Tubes in First Audio Stage A Test Set for the Radio Service Man The Service Man's Corner As the Broadcaster Sees It B. B. Alcorn oo 101 Carl Dreher 102 Information on Sound Motion Pictures Broadcast Standardization IO4 107 IO9 III 114 Some Experiments with Band-Pass Filters Kendall Clough "Radio Broadcast's" Home Study Sheets No. 11. Resonance in Radio Circuits — Part I No. 12. Resonance in Radio Circuits — Part II Loud Speakers — A Debate Removing Nonsense from Short-Wave Transmission Robert S. Kruse "Our Readers Suggest — " An AC. Screen-Grid Booster Push'Pull with Standard Transformers Work Table Clamp Home-Made Soldering Lug The New A.C. Screen-Grid Browning Drake Receiver Glen H. Browning 115 Book Reviews Howard E. Rhodes 1 16-125 An A.C. Band-Pass Screen-Grid Receiver — The Master "H1-Q29" William E. Barton 117 New HighVoltage Metallic Rectifiers for B-Power Units J. George Uzmann 120 "Radio Broadcast's" Service Data Sheets 121 No. 13. The A.C. -66 Dayton Receiver No. 14. The Fada Models 50, 70, 71 and 72 Problems in Synchronizing Television Receiving Discs Boyd Phelps The "Chronophase" for A.C. Tubes ' ' ' ' Bert E. Smith New Apparatus and Their App lications * Manufacturers' Booklets "Radio Broadcast's" Laboratory Information Sheets 123 126 127 128 130 No. 241. Supplying Power Devices from 220 Volts A.C. No. 242. Resistance-Coupled Amplifiers No. 24J. Resistance-Coupled Amplifiers No. 244. Alternating-Current Ratings No. 245. Power Output No. 246. Power Output Characteristics of Tubes No. 247. Television No. 248. Frequency Characteristics of Television Amplifiers Letters from Readers ShortWave Stations 137 141 The contents of this magazine is indexed in The Readers' Guide to Periodical Literature, which is on file at all public libraries. AMONG OTHER THINGS. WITH this issue, we start the promised department for radio service men. The service man is a most important element in the present radio structure but for some reason or other he has been inarticulate. We know that a great many readers of Radio Broadcast are doing service work, either on whole or part-time and we hope that those who are doing this work will write .us, telling of their problems, how they are being solved, and of topics they would like to see discussed. Incidentally, the head of one of the largest New York organizations specializing in this work, Mr. John S. Dunham, writes: that although he believes service articles are of real value that "the average service man could derive far greater benefit by painstaking, thorough study of Radio Broadcast's Data Sheets from the beginning and the very excellent series of Home Study Sheets, recently inaugurated. From our own experience, we believe that service men generally need to increase their basic knowledge." With this, we agree, but we are certain that the experiences of service men are of deep interest to others working in the field. It certainly goes without saying that no service man can really do his work intelligently unless he has a thorough background in fundamentals. THE application of power amplifiers, microphones, movingcoil loud speakers and similar apparatus for so-called public or group-address work seems to be increasing rapidly. This development is a natural and fortunate one and in our opinion due largely to the increasing appreciation of what good radio apparatus can do. The question which most frequently comes up is not the simple one of how to connect or to operate the gear but what power output is essential for a given service. Radio Broadcast Laboratory Data Sheets Nos. 245 and 246 in this issue discuss this interesting question. EARLY in 1926, Mr. Howard E. Rhodes joined the staff of Radio Broadcast and since that time, his excellent articles have added much to the interest and technical value of our pages. The popular Laboratory Data Sheets are Mr. Rhodes' work. We are pleased to announce that effective November 1st, Mr. Rhodes was appointed Technical Editor of this magazine. THE current issue contains many articles on subjects of great interest to many radio folk. Notable among these are the following: the article on cutting and grinding quartz crystals, the data on underground antennas in "Strays from the Laboratory," the references to sources of information on sound movies, the article on experimental band-pass filters, the discussion of moving-coil and "magnetic" type loud speakers, Mr. Kruse's article on amateur experimenting and finally Boyd Phelps' description of his ingenious work in television synchronizing which is found on page 123. THE January issue will contain the long-promised article on moving-coil speakers and is worth waiting for. Constructional stories on interesting receivers, and power amplifier units are promised as well as more useful data for the experimenter and service man. — Willis Kingsley Wing. DOUBLED AT, DORAH & COMPACT, WP., Garden gxty, Hew Tor\ MAGAZINES Country Life World's Work The American Home Radio Broadcast Short Stories Le Petit Journal El Eco Frontier Stories West The American Sketch BOOK SHOPS {Books of all Publishers) ' Lord & Taylor; James McCreery & Company Pennsylvania Terminal and 166 West 32ND St. New York:^ 848 Madison Ave. and si East 44TH 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. Toronto: Doubleday, Doran & Gundy, Ltd. OFFICERS F. N. Doubleday, Chairman of the Board Nelson Doubleday, President George H. Doran, Vice-President S. A. Everitt, Vice-President Russell Doubleday, Secretary John J. Hessian, Treasurer Lillian A. Comstock, Asst't Secretary L. J. McNaughtoN, Asst't Treasurer Copyright, 1928, in the United States, Newfoundland, Great Britain, Canada, and other countries by Doubleday, Doran & Company, Inc. All rights reserved. TERMS: $4.00 a year; single copiet J? cents. 82