Radio broadcast .. (1922-30)

710 RADIO BROADCAST ADVERTISER PARTS THE S C RECEIVER In this new, single control, all-wave, 4-tube receiver, designed by eight eminent, engineering staffs, SM PARTS were used wherever possible. Their unquestionable excellence and dependability made SM Parts the logical selection for this advanced receiver. That is why in almost every successful receiver design of past and present seasons you will find SM Products — depended upon, and dependable. THE "SIX" Type 600 KIT Includes all parts necessary $53.00 Type 610 KIT Essentials only, including 3 condensers, 3 inductances and 3 inductance sockets $27.75 Type 316 Condenser, .00035 Mfd. for single or gang control. Brass plates, die cast frame. Price, $5.75. SM THORDARSON RAYTHEON B-ELIMINATOR The SM Type 650 Kit includes Thordarson Transformer, Choke, Tube Condensers, genuine Ratheon Tube, Bradleyohms and all necessary parts $34 This Eliminator will deliver from 20 to 200 volts at three different adjustable voltages with maximum current of 50 milliamperes — • more than enough for the largest receiver. Send for Assembly Instructions by McMurdo Silver lOc SEE SM PARTS AT YOUR DEALERS OR SEND FOR CIRCULARS Silver-Marshall, Inc* 103 S. Wabash Ave., Chicago Type 801 Universal Vernier Dial, Ratio 14.5:1. Fits any standard condenser right or left, 180 or 360° movement. Price, $2.50. Interchangeable Coils for any wavelength. Standard Sizes. $2.50. Type 515 Coil Socket, $1.00. Type 340 Compensating Condenser, .000025 Mfd. with knob, $1.50. Type 510 AllBakelite Socket for UX Tubes, 50c. Why not subscribe to Radio Broadcast? By the year only $4.00; or two years, $6.00, saving $2.40. Send direct to Doubleday, Page & Company, Garden City, New York. Ifammarlund ^ P FIE C /S / O A/ PRODUCTS Write for Descriptive Literature HAMMARLUND MANUFACTURING CO. 424-438 West 33rd Street New York City A KEY TO RECENT RADIO ARTICLES By E. G. SHAULKHAUSER THIS is the sixth installment of references to articles which have appeared recently in various radio periodicals. Each separate reference should be cut out and pasted on cards for filing, or pasted in a scrap book either alphabetically or numerically. An outline of the Dewey Decimal System (employed here) appeared in the November and January RADIO BROADCAST, and will be reprinted in an early number. Rii3.4. IONI7AT10N; HEAVISIDE LAYER HEAVISIDE Popular Radio. Jan. 1926, pp. 61-63. LAYER. "Up and Down Movement of the Heaviside Layer." Dr E.E. Free. A short outline covering the research in high frequencies carried on at the Naval Research Laboratory by Dr. A. H. Taylor and Dr. E. O. Hulburt, is reported. Most of the phenomena observed are explained on the basis of the Heaviside Layer movements. Skipped distances and fading apparently depend upon the height of this Jayer and its position during day and night. R38z. INDUCTORS. INDUCTION Popular Radio. Jan. 1926, pp. 80 83. COILS. "Some Methods for Determining the Distributed Capacity of Coils," H. S. Knowles. A discussion covering several methods which may be used in measuring the distributed capacity of coils, is presented. Mathematics and graphs are used in giving the information. R38z. INDUCTORS. INDUCTION RADIO BROADCAST. Feb. 1926, pp. 436-438 COILS. "Design of Radio Inductances," W. W. Harper. Inductances, whose efficiency is high, must be designed to have a low high frequency resistance compared to inductance, twenty-five or more microhenries per ohm being considered a good coil in the opinion of the writer. Such a coil results in sharp tuning when combined with good condensers, although pick-up action of coils and crowding of apparatus in sets may make tuning broad. The standards of coil design are given as follows: (i) Low resistance over the broadcast frequency spectrum combined with as high a value of inductance as is permissible under the circuit conditions: (2) Effective confinement of electrostatic and electromagnetic field: (3) Consistent mechanical and electrical characteristics: (4) Small physical dimensions so as to permit compact construction. Experiments and tests have shown that spacewound solenoids are best for radio frequency purposes. With proper copper shielding and grooved space winding, the new so-called Metaloid coil was designed and built. Its L/R value (5320/9.5, equal to 33, as given in the data. R343. ELECTRON TUBE RECEIVING SETS. RECEIVERS, RADIO BROADCAST. Feb. 1926, pp. 430-444 Crimes Reflex "How to Build a Grimes Inverse Duplex," F. J. Fox. Constructional details of a four-tube Grimes Inverse Duplex receiver are given. The set is considered very sensitive and selective, and is easily built by the home constructor. Photographs, circuit diagrams, details of coil construction, panel layout, and method of locating audio, radio, or overload howl, which might be found in the completed re ceiver, give the necessary information desired when building such a receiver. R8oo (621.353) BATTERIES, PRIMARY. BATTERIES, RADIO BROADCAST. Feb. 1926, pp. 452-455. Life of B. "How Long Will My B Batteries Last?", G. C. Furness. A discussion on the life of B batteries in all sets from one to eight tubes or more, leads the author to the conclusion that the life of B batteries depends entirely upon current drain and size of cells in the battery. Charts and figures are presented, verified experimentally, showing how a definite time limit of six, eight, or twelve months can be set on the average life of B batteries when these are chosen properly for the receiver in question. Rl3l. Characteristic Curves; General Properties. VACUUM TUBES. RADIO BROADCAST. Feb. 1926, pp. 456-461. Characteristics. " How to Use Vacuum Tubes," Keith Henney. In this article, the elementary principles of vacuum tubes and their characteristics are discussed, a clear meaning of such terms as amplification constant, mutual conductance, plate impedance, of tube characteristics in general, etc; being included. Data covering a great many makes and varieties of tubes are presented. Circuit diagrams show how this information was obtained. The proper use of C batteries and correct amount of fi'ament current, are essential in good tube operation, according to the author. R62o.o68. TESTING. TESTS OF RADIO BROADCAST. Feb. 1926, pp. 462-464 BROADCASTING "The 1926 International Radio Broadcasting Tests, " W. K. Wing. An outline of the plans and the transmitting schedule for the 1926 International Radio Broadcasting Tests are given. Many foreign stations |ent their full cooperation and support to the success of this undertaking sponsored by RADIO BROADCAST. Raio. FREQUENCY; WAVELENGTH. FREQUENCY TO RADIO BROADCAST. Feb 1926, pp 471-472 WAVELENGTH. "Taking the Complexity Out of Wavelength-Frequency Conversion," H. S. Davis. A simple full-page frequency-wavelength conversion chart is presented together with information on how to use it. The author emphasizes the fact that the term frequency and not wavelength is the proper term to use, and gives definite reasons. Tested and approved by RADIO BROADCAST