Radio Broadcast (May 1928-Apr 1929)

OCT -5 1928 ©C1B 857 Radio Broadcast OCTOBER, 1928 Keith Henney Director of the Laboratory Willis Kingsley Wing, Editor Edgar H. Felix Contributing Editor Vol. XIII. No. 6 Cover Design From a Design by Harvey Hop\ins Dunn Frontispiece Television — Its Progress To-day A Nme-Tube Screen-Grid Super The March of Radio ' ' The Low-Power Stations Plead Their Case Regulations for Television and Picture Trans Where Radio Progress Begins Howard E. Rhodes Robert Burnham An Editorial Interpretation Here and There The 'Hi-Q 29" — A Receiver with a Band'pass R.F. Amplifier D. K. Oram A Short-Wave Transmitter for 1929 Robert S. Kruse "Strays" from the Laboratory Keith Henney Two Interesting Patents Radio as a Scapegoat A Screen-Grid Mystery Mortality Among the A.C. Tubes Engineers as Salesmen Testing for Soft Tubes Short-Wave Reception The Remler A.F. Amplifying System A TwO'Tube A.C. Screen-Grid Tuner As the Broadcaster Sees It James Millen Carl Dreher Sound Motion Pictures Lord Rayleigh on Sound The Sargent-Rayment Seven Receiver Howard Barclay "Radio Broadcast's" Home Study Sheets Nos. 7 and 8. Alternating Current The 222 Tube as an R.F. Amplifier (Part II) Glenn H. Browning Book Review Carl Dreher Coupling Methods for the R.F. Amplifier Bert E. Smith "Our Readers Suggest A Power Unit Voltage Divider Obtaining Screen-Grid Bias Testing for Soft Tubes Matching Condensers and Coils in Tandem Tuned Circuits An Amplifier Kink Dynamic Speaker Field Supplied from B-Power Unit A Simple Audio Channel Equalizer A.C. Tube to Reduce Microphonics An Antenna Booster for Loop An Output Filter Without a Condenser The "Vivetone 29" Receiver R. F. Goodwin "Radio Broadcast's" Service Data Sheets on Manufactured Receivers , . , , , No. 9. The Bosch Model 28 Receiver No. 10. The Splitdorf "Inherently Electric" Receiver Practical 5-Meter Hints Robert S. Kruse New Apparatus Useful Information on K[ew Products Radio Helps in the Coast Survey ' ' ' D. L. Par\hurst Manufacturers' Booklets "Radio Broadcast's" Laboratory Information Sheets No. 225. Calculating Grid Bias for A. C.Tubes No. 226. Grid Bias Circuits for A.C. Tubes No. 227. The Audio Transformer No. 228. The Dynamic Loud Speaker Photo Broadcasting in England Letters from Readers ' ' ' ' No. 229. The Telephone Transmission Unit No. 230. Filters No. 231. Impedance-Coupled Amplifiers No. 232. The Voltmeter William J. Brittain The contents of this magazine is indexed in The Readers1 Guide to Periodical Literature, which is on file at all public libraries. 330 331 334 337 34i 344 347 349 352 354 357 359 360 361 364 366 369 37i 372 < 374 376 378 384 386 AMONG OTHER THINGS. . . READERS who did not see our announcement in this space last month with respect to the change in our publication date and who failed to see our October issue when they expected may be somewhat confused. Effective with this number, Radio Broadcast is on sale at all good newsstands on the first of the month. That is easy enough to remember. THE issue before you now contains an unusually wide range of material, and in the descriptions of receivers offered the constructor in kit form for the present season, is especially complete. Our November issue promises a story on present trends in radio progress, a description of a new audio amplifier system, two articles on television, the first of a series of practical articles on radio service for men actually facing the music, and a variety of constructional articles. These are in addition to our popular departments which will run as usual. A FEW of our readers who carefully classify the contents of each issue feel that each article should be classified according to the Dewey decimal system when published. At one time our excellent British contemporary, Experimental Wireless,, classified their articles this way, but has since discontinued the practice. Radio Broadcast is quite willing to serve its readers, but we feel that this classification would appeal to all too few. The editor would be glad to hear from those who favor the scheme — and from those who prefer the status quo. AND here we group many miscellaneous matters; read them, but remember, you were warned! . . . The complete set of " R. B. Lab. Data Sheets " in book form — No. 1-190 — is now available at $1 per copy from the Circulation Department of this company. . . . We shall soon start a special department, along lines similar to "Our Readers Suggest — " to be made up of practical contributions from radio service men and professional set builders. Quite a few interesting contributions are already in the office and readers who desire to submit any ideas that seems to them worth while passing on are invited to do so. The same general rules hold for these contributions as for the "Readers Suggest" department. . . . How many readers are interested in the problems of series-filament connection for a.c. operation? We should like to hear from readers who have done some work along this line, or from those who would like an article devoted to the subject. ... In the past few weeks, our mail has contained a number of simple questions about radio which we are thinking of answering in a short article composed simply of the questions and their answers. We invite the submission of short and particularly troublesome questions which readers would like to see treated in this way. ... A radio house in Sao Paulo, Brazil, informs us that they are expanding and desire exclusive American agencies for radio apparatus in Brazil. Manufacturers who wish to get in touch with this house may write the editor. . . . Our request in the August "Strays" for methods of testing for hard and soft tubes has brought two answers. One may be found in this number on page 348, in the "Strays" department, and the other on page 364 in the department "Our Readers Suggest — " TWO of the writers in this issue who have investigated the use of the screen-grid tube with various kinds of coils, arrive at conclusions which are different — but most interesting. The stories concerned are by Bert Smith and Glenn Browning. — Willis Kingsley Wing. VOUBLEDAT, VORAN & COMPANY, INC., Garden Qity, New York MAGAZINES Country Life World's Work The American Home Radio Broadcast Short Stories Educational Review 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 i 66 West 32ND St. New York:-^ 848 Madison Ave. and 51 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. OFFICERS F. N. Doubleday, Chairman 0/ the Boar 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 Toronto: Doubleday, Doran & Gundy, Ltd. L. J. McNaughton, Asst't Treasurer Copyright, 1928, in the United States, "Newfoundland, Great Britain, Canada, and other countries by Dou TERMS: $4.00 a year; single copies 35 cents. , Doran & Company, Inc. All rights reserved. 328