Radio Broadcast - 1927, May - 61 Pages, 4.9 MB ... - VacuumTubeEra

60 RADIO BROADCAST ADVERTISERMire's WoUSThatisAlmiisiEARNBIGMONEY*RADIOGet into the great new BIG Pay IndustryRadio. If yqu'ie earning a penny less than$50 a week, clip coupon now.Send for 64-page FREEBOOK. Be a Radio Expert,and draw down bigmoney for this easy, fascinatingwork. Positionseverywhere. Need for RadioExperts in every community.Short hours. BIGPAY. Free Book givesall the facts.Learn Quickly andEasily at HomeSkilled Radio Engineers willshow you how to qualify, quicklyand easily at home, for Radio'sfine job*. We train you completelyand thoroughly. Hundredsof N. R. I. trained menare today down holding1 goodbig jobs fn the Radio field. Hundredsofopportunitiesnow awaitingthe trained man. FREEEMPLOYMENT SERVICE.Many other big features. Getthe facts-CLIP COUPON."My charges forconsultation $2.50per hour. All successdue to you.''R. W. Blackhill,BrooklynRadio a goldmine yourcourse worththousands."A. R. Herke,WinnipegGet This FREE BOOK!Send coupon below forFREE BOOK "Rich Rewardsin Radio." Readfor yourself. No previousexperience needed. Commonschooling enough.WRITE NOW.Materials for building up-to-date receiving srts and toconstruct 50 well-known Radio circuits included to helpyou learn. An UNEQUALLED OFFER. Other specialfeatures now being offered, so Act Quick!NATIONAL RADIO INSTITUTEDept. E-94. Washington, D. C.MAIL COUPONNational Radio Institute,Dept. E-94, Washington, D. C.Without obligating me in any way, pleasesend me your free book, "Rich Rewards inRadio." also complete information on yourpractical, home study Radio course.NameAddressTown. .StateA KEY TO RECENTRADIO ARTICLESBy E. G. SHALKHAUSERTHISis the nineteenth installmentof referencesto articles which have appeared recently in variousradio periodicals. Each separate referenceshould he cut out and pasted on 4" x 6" cards forfiling, or pasted in a scrap book either alphabeticallyor numerically. An outline of the DeweyDecimal System (employed here) appeared lastin the January RADIO BROADCAST.Rsso. BROADCASTING.BROADCASTINGPopular Radio. Jan., 1927. Pp. Il-ff. Who Pays for,"Who Pays the Broadcaster?" O. E. Dunlap. Jr.The problem of supporting radio broadcast programs,either through actual contributions by the listening public,or through indirect channels, such as advertising, and thuscreating good will and deriving publicity, is discussed. Alist of sponsors of various program featurfes, and the stationsbroadcasting, is tabulated, showing what is beingdone to-day in furnishing entertainment. A chart is alsoappended stating the toll charges of the various stations forgiven periods of time on the air.Ri4i.2. .. RESONANCE. .RESONANCE,Popular Radio. Jan., 1927, Pp. 3i-ff..Tuning."What Happens When You Tune Your Set," Sir OliverLodge.A simple treatise on the conversion of radio waves intoelectrical impulses in the tuning circuits of the radio setand its analogy to mechanical or sound resonance is givenin this second of a series of articles. The function of the detectortube is clearly outlined.R62o.o8. INSTALLATIONS.INSTALLATIONS,Bureau of Standards Handbook No. 9. Safety Rules."Safety Rules for Radio Installations."The material contained herein is a reprint of Part 5 ofthe National Electrical Safety Code, dealing with properradio installations as approved by the American EngineeringStandards Committee.ROQO. HISTORY.HISTORYRadio Service Bulletin. Dec. 31, 1926., Pp. 24-32."Important Events in Radio-Peaks in the Waves ofWireless Progress."A brief outline of the important happenings in the historyof radio, opposite the year in which these events occurred,is given. Starting with the year 1827, when the principleof magnetism was first discovered, and leading downthrough the year 1926, the progress made in radio is presented.R$50. BROADCASTING;BROADCASTING,Radio Service Bulletin. Dec., 31, 1926.Pp. 9-21. List of Stations."Broadcasting Stations, Alphabetically by Call Signals."A list of broadcasting stations, giving call signals, locationof station, owner of station, power, wavelength, andfrequency, is presented. The list is complete up to December31, 1926. This publication may be procured fromthe Superintendent of Documents, Government PrintingOffice, Washington, District of Columbia, at five cents percopy.R330. ELECTRON TUBES. ELECTRON TUBES,Radio. Jan., 1027, Pp. 2O-ff. 4 Element."The Shieldea Grid Vacuum Tube," E. E. Turner, Jr.By placinga second grid between the plate and the controlgrid of a vacuum tube. Doctor Hull, of the GeneralElectric Company, has succeeded in reducing inter-electrodecapacity between the elements of the tube. This secondgrid is said to act as an electrostatic shield when positivelycharged. It is composed of a number of flat circular discs,or rings, 3 mm. wide and spaced 3 mm. apart. The characteristicsof the tube are discussed.R344.5 ALTERNATING CURRENT SUPPLY.Radio. Jan., 1927. Pp. 23-24.SOCKET-POWERDEVICE,A Battery."A Home-Built A Battery Eliminator," G. M. Best.Constructional data concerning a 2-ampere A batteryeliminator employing a transformer, chokes, two tungar 2-ampere bulbs, and electrolytic condensers or rheostats,are presented.R382. INDUCTORS. INDUCTORS,Radio. Jan., 1927. Pp. 26-27. Chart."A Reversible Inductance Chart," A. C. Kulmann.A very comprehensible and useful inductance chart forsingle-layer solenoids, giving either the inductance of a coilor the coil size required for a given inductance, is shown.The range in inductance is from 4 to 20,000 microhenries.The use of the chart is illustrated.Ri34.8. REFLEX ACTION. REFLEXRadio. Jan., 1927. Pp. 290*. ACTION."More About the New Inverse Duplex," D. Grimes.In this second of a series of articles on the new InverseDuplex System, complete data on the construction of theseparate coils, data on wiring and assembly, and eliminationof trouble that might occur, are given.R343. ELECTRON-TUBE RECEIVING SETS. RECEIVER,Ra" .tadio. ' Jan., 1927. Pp. 3off. Infradyne."How and Why the Infradyne Works," R. B. Thorpe.The writer discusses theoretically the operation of thenew infradyne receiving circuit, analyzing the action takingplace within the various parts of the circuit. Various diagramsand graphs are shown, in order to explain clearlythe arrangement employed.R344-3. TRANSMITTING SETS.TRANSMITTERS,Proc. I. R." E.Jan., 1927. Pp. 9-36. Crystal-Controlled.Piezo-EIectnc Crystal-Controlled Transmitters," A.Crpssley.A discussion of piezo-electric crystals and the early historyof the development of the art are given.The development of crystal-controlled vacuum-lubeoscillators by the Naval Research Laboratory is outlined,and various means of amplifying the output of a crystalcontrolledoscillator are cited, the best method being described.This method consists of balancing or neutralizingthe various stages of amplification and also observing properprecautions for reducing grid circuit losses by using highvalues of biasing voltage.A complete high-power low-frequency crystal-controlledtransmitter is described, and a schematic wiring diagramof the circuits employed in this transmitter is shown. Aschematic wiring diagram, and illustrations of one type oflow-power high-frequency transmitter, complete the subjectmatter covered in this paper.R344. ELECTRON-TUBE GENERATORS. ELECTRON-TUBEProc. I. R. E. Jan., 1927. Pp. 37-39. GENERATOR."Simultaneous Production of a Fundamental and aHarmonic in a Tube Generator," H. J. Walls.A method whereby a single generator tube may be usedto transmit two frequencies simultaneously, thus eliminatingthe necessityof using two separate tubes, is described.In addition to the fundamental, some harmonic is amplifiedin a separate oscillating circuit. A broadcasting station maythus send put the same modulated energy on two frequenciesusing but one transmitter.Rii3.i. FADING. FADING.Proc. I. R. E. Jan., 1927. Pp. 41-47.Recorder lor,"An Automatic Fading Recorder, T. A. Smith and G.Rodwin.A device for automatically recording signal intensitiesis described, with the method employed to amplify the signalsufficiently to operate a commercial type graphic meter,Sample fading records of various transmissions are alsopresented.R33i. CONSTRUCTION; EVACUATION ELECTRON TUBES,OF TUBES.Proc. I. R. E. Jan., 1927. Pp. 40-55. Alkali" Vapor.Behavior of Alkali Vapor Detector Tubes," H. A. Brownand C. T. Knipp.The comparative efficiency of gas-filled tubes now onthe market, and certain potassium sodium alloy tubes, isdescribed. It is shown how the operation of gas-filled tubesdepends on the temperature of the gas and the tube walls.It is also shown how these K Na tubes compare with the2OI-A and the 200 type tubes, and that the K Na tubesare ideal for durability, true tone reproduction, and noncriticaladjustment of plate and filament voltage.International Short-WaveTestCROM April i8th to joth, short-wave testson yooo-kc. (43 meters) will be conductedfrom WAQ-2 XAI, the Westinghouse experimentalstation at Newark, New Jersey. The schedule is:8 to 8 :3O P. M. (Eastern Standard Time) " A BC de2 XAI" sent automatically on a crystal-controlledtransmitter. From 8:30 to 9, amateurs will beworked and other tests made. The manager ofthe station, E. Gundrum, Westinghouse Electric& Manufacturing Company, Plane and OrangeStreets, Newark, New Jersey, welcomes reportson audibility, fading, and keying, from listenersthroughout the world. Reports should be forwardedeither to RADIO BROADCAST or directlyto the station.TECHNICAL INFORMATION INQUIRYBLANKTechnical Service,RADIO BROADCAST LABORATORY,Garden City, New York.GENTLEMEN:Please give me fullestinformation on theattached questions.I enclose a stampedaddressed envelope.C] I am a subscriber to RADIO BROADCAST, Iand therefore will receive this information (free of charge.HH I am not a subscriber and enclose $1 to jcover cost of the answer.NAMEADDRESS .. . .R. B. M.