Radio Broadcast (May 1927-Apr 1928)

RADIO BROADCAST ADVERTISER 255 1 10. Receiver Construction — Circuit diagram and constructional information for building a five-tube set using restricted field coils. Bodine Electric Co.mVany. in. Storage Battery Care — Booklet describing the care and operation of the storage battery in the home. Marko Storage Battery Company. 112. Heavy-Duty Resistors. Circuit calculations and data on receiving and transmitting resistances for a variety of uses, circuits for popular power supply circuits, d.c. resistors for battery charging use. Ward Leonard Electric Company. i 13. Cone Loud Speakers — Technical and practical information on electro-dynamic and permanent magnet type cone loud speakers. The Magnavox Company. 114. Tube Adapters — Concise information concerning simplified methods of including various power tubes in existing receivers. Alden Manufacturing Company. 115. What Set Shall 1 Build? — Descriptive matter, with illustrations, of fourteen popular re-eivers for the home constructor. Herbert H. Frost. Incorporated 104. Oscillation Control with the "Phasatrol" — Circuit diagrams, details for connection in circuit, and specific operating suggestions for using the "Phasatrol" as a balancing device to control oscillation. Electrad, Incorporated. A KEY TO RECENT By E. G. SHALKHAUSER THIS is the twenty-fifth installment of references to articles which have appeared recently in various radio periodicals. Each separate reference should he cut out and pasted on 4" x6" cards for filing, or pasted in a scrap book either alphabetically or numerically. An outline of the Dewey Decimal System (employed here) appeared last in the January Radio Broadcast. R402. Short-Wave Systems. Short Waves. QST. Aug., 1927. Pp. 9-14. 1-Meter "The |-Meter Band Officially Opened," B. Phelps and R. S. kruse. Detailed information on f-meter transmitting and receiving sets is presented. It is stated that tubes having the XL filaments have a very short life at these frequencies, best results being obtained from the old UV-202 tubes. The antenna system, and the methods used in determining the length of the wave transmitted, are shown. The field tests indicate the manner in which signals decrease in strength and show the location of dead spots. R132. 1. Amplifying Action: Inductive Amplifiers, Coupling. Audio QST. Aug., 1927. Pp. 15-20. " Better Audio Amplification for Short-Wave Receivers," L. W. Hatry. The writer shows the practical use of more than one audio stage of amplification for short-wave receivers. In order to insure more uniform volume from headphones, whether listening to foreign or domestic stations, a switching or a shunt resistance system is described. The type of audio transformer to be used depends greatly upon the type of reception desired, a scheme being shown whereby an amplifier may be made either peaked or flat by using a tuned rejector circuit. Transmitter, Short-Wave Crystal. R346. Radio Telephone Sets (Electron-Tube). QST. Aug., 1927. Pp. 21-24. "Cuban 6 XJ," F. H. Jones and H. P. Westman. The construction and the tuning of a first-class phone station operated on 20 meters, are outlined. A crystal, having a natural period of 159.6 meters, controls the transmitted frequency. The set consists of an oscillator and three amplifiers. Instead of using the Heising constantcurrent method of modulation, the series method of plate modulation is employed with good results. A circuit diagram and a list of parts are shown. R213. Harmonic Methods. Harmonics, QST. Aug., 1927. Pp. 34-35. Determination of. "The Identification of Radio-Frequency Harmonics," J. E. Waters. A method of determining and identifying radio-frequency harmonics when making measurements of radio-frequency ■oscillations is outlined. Use is made of a standard wavemeter, an oscillator, and a receiver. Ri 13. Transmission Phenomena. Transmission, QST. Aug., 1927. Pp. 36-42. Short-Wave. "Short-Wave Radio Transmission and Its Practical Uses," C. W. Rice. (Continued.) The variation of signal strength with distance is discussed, taking into consideration the effect of multiple reflection. In order to choose the proper wavelength to use for distant transmission in summer daylight, a theoretical chart is prepared, showing probable performance of different waves. Conclusions drawn point to the following: Below 10 meters distant communication is impossible; the plane of polarization in the sky wave is no determining factor for energy flux density and for ray paths; different waves give best results between two given points; low-angle radiation is best for long-distance work. R281. 71. Quartz. Quartz. Radio Broadcast. Sept., 1927. Pp. 271-273. " Piezo-Electric Crystals," M. T. Dow. The writer explains the use of quartz crystal oscillators in the calibration of frequency meters. How to distinguish between the harmonics that are heard when two oscillators are in operation, is fully outlined. Photographs and circuit diagrams illustrate the points in question. HEATER TYPE TUBE No i "A" Batteries "A" Battery Eliminators Special Sockets Noise Hum your set up-to-date Leading radio engineers approve and endorse the Sovereign Heater Type A-C Tube. They know that A-C Tubes give results that can be obtained in no other manner. Think — with A-C Tubes all you ever will have to do is press a button — switch on your set just as you switch on an electric light. There's no bother with "A" batteries or "A" battery elimina' tors, or battery chargers, no noise, no microphonics — nothing but pure, round, undistorted tones. Bring your set up-to-date. If your dealer cannot supply you with Sovereign A-C Tubes for standard sockets, write us. Special treatise with diagrams free. Write Sovereign Electric & Mfg. Company 127 No. Sangamon St. Chicago, Illinois Set Builders and Amateur Transmitters — Here are your Instruments! D. C. and A. C. Panel Types in flush style cases — 1Models 506, and 517, 2"; and Models 301 and 476, 3|" sizes. A complete line of Voltmeters, Ammeters and Milliammeters, as well as Thermo-Couple types, all uniform in appearance. Nothing on the market can compare with them in quality of workmanship and electrical features. It has required years to redesign the famous Weston Standards down to these small sizes and offer them at such low prices for such high quality. Improve upon your old sets when building the new. Write for Circular J — the new booklet which completely covers the Weston Radio Line. WESTON ELECTRICAL INSTRUMENT CORPORATION 179 Weston Ave. Newark, N. J. WESTON RADIO INSTRUMENTS