Radio Broadcast (May 1929-Apr 1930)

THE RADIO DEALER'S NOTE BOOK— NO. 3 TESTING INSTRUMENTS Free — Complete Information* ACCURATE summaries of useful information are constantly of value to those radio folk who deal with the public. This sheet, one of many on various subjects to follow, sets down collected imformation on testing instruments. The dealer or serviceman can remove this part of the page for his notebook or he can have it photostated. Good instruments are essential if receivers are to be serviced properly. In this connection, the table below lists the offerings of a few of the prominent instrument manufacturers. A dealer or serviceman ordinarily can make use of two instruments; one instrument is useful for checking the performance of all types of a.c. and d.c. receiving tubes and rectifiers and the other, a set-tester, for checking the performance of a receiver. Whether a simple or a complicated set-tester is purchased depends upon one's personal preference. Some servicemen prefer the simplest possible instru ment. The idea back of this is that if the set'only re Suires a slight repair, it can be done on the job, but considerable work must be done on the set, it is best to take it back to the shop where complete facilities for testing and repairing receivers are available. Other servicemen, however, prefer to complete the job on the spot and to such servicemen a very complete instrument of tests is probably essential. In any event, whether or not you have a settester and tube-checker, data on all the available instruments should be in the hands of dealers and servicemen. A. N. Golsmith, vice-president and chief broadcast engineer of the Radio Corporation of America. "Experimental work on such subjects as fading, picture quality, and other phases of television problems is being carried on by w2xbs." Dr. Goldsmith continued by saying that this will in due course evolve in a service to the public on a basis similar to sound broadcast, and of like high quality. The Supreme Instruments Corporation, of Greenwood, Mississippi, manufactures a test set, model 400a, capable of making a very large number of tests on tubes and receivers. The device contains several special devices among which are a modulated oscillator which can be used in aligning the various tuning condensers in a single-control set and it also contains apparatus for rejuvenating tubes. The instrument is equipped with Weston meters, and sells for $124.65 list. It can be purchased on the time-payment plan. The down payment is $38.50 to be followed by ten monthly payments of §10.00 each. This company also makes a smaller service instrument, the model 99a, which lists for $97.65. If purchased on the deferred-payment plan, the down payment is $28.50 followed by eight monthly payments of $10.00 each. The J. E. Jenkins and S. E. Adair Company, of Chicago, are manufacturers of high-grade, audio-frequency apparatus such as audio-frequency transformers, gain controls, mixing controls, etc. The type gl-35 gain or volume control consists of nichrome-wire resistor units and the total resistance of the device is 350,000 ohms. The various steps give a logarithmic increase in resistance, each step giving a gain of about 3 db. The Utah Radio Products Company has announced an automatic remote-control tuning device for radio receivers. The remotecontrol device, by means of which the radio set is operated from a distance, contains two knobs, one a station selector and the other a volume control. The control is small enough to hold in the palm of one's hand. The control box is connected by wires to an electric motor which is fastened to the radio receiver. The control box functions to turn on the set, tune it, and turn it off when the dial on the control box is turned to the "off" position. Dynamic Loud Speakers in various models are manufactured by Wright-DeCoster, Inc., St. Paul, Minn. The models 105 and 106 are designed for operation from a storage battery, the models 107 and 108 have self-contained rectifiers, and the models 105x and 106x should be supplied with current from the filter circuit. The latter two models normally require a current of about 100 milhamperes. A model 107 loud speaker has been in use in the Laboratory for some time and comparatively it has much less hum than many other a.c-operated dynamic loud speakers which we have tested. Its frequency response range is excellent. RCA Licenses First Tube Company THE Raytheon Manufacturing Company has been granted a license to manufacture vacuum tubes under the patents of the Radio Corporation, it was announced by RCA on March 26. "The license signed by the Radio Corporation and the Raytheon Manufacturing Company is a decided step toward stabilization in the radio tube industry," said L. K. Marshall, president of Raytheon. "Raytheon," continued Mr. Marshall, "through extensive laboratory research, pioneered in the developments that have resulted in electric power sets and made valuable contributions in producing effective tubes for use in B-power units. Recent Raytheon improvements are *As a service lo readers, the Editors have arranged thai dealers may obtain complete information on all the devices listed in the table by writing to the Service Department of Radio Broadcast and asking for data on testing instruments. All requests must be written on a business letterhead or a card must be enclosed lo identify Ike writer a.s a dealer or serviceman. Manufacturer Device Type No. Price MlLLIAMMETER Voltmeter Remarks Jefferson Electric Co. Tube Rejuvenator 175 180 $ 4.50 6.00 For 50 to 133 cycles 100 120 volts a.c. For 25 to 40 cycles Hoyt Electrical Instrument Co. AC-DC Set Tester Tube Tester A.C. Attachment D. C. Set Tester 600 400 101 300 65.00 22.50 15.00 48.75 0-30,120 0-10, 50 0-25, 100 0-12, 120, 600 d.c. 0-3, 9, 150 0— 3[ 9 a.c. and d.c. 0-3, 9 a.c. and d.c. 0-10, 500 d.c. A complete set tester Tests all types of a.c. and d.c. tubes A device for use with d.c tube testers to make possible the testing of a.c. tubes For testing d.c. sets only Jewell Electrical Instrument Co. Tube Tester A.C. D.C. Set Tester Test Panel 210 199 580 65.00 97.50 212.00 0-100 and special scale 0-15, 150 0-15, 150 A.C. line voltage indicator 0-7 . 5, 75, 300, 600 d.c, 0-4, 8, 16, 160 a.c. 0-7.5, 75, 150, 300, 750 d.c, 0-4, 8, 16, 150, 750 0-4! 8 a.c. A tester for all types of tubes, including double-plate rectifiers A complete instrument for testing all types of sets A special test panel for use in the shop. Contains special meter to measure condensers capacity up to 15 mfd. Tube Checker 150 38.00 0-15 Tests all types of a.c. tubes Sterling Manufacturing Co. Tube Tester Tube Tester Tube Checker Set and Tube Tester R-510 R-520 r-514 R-522 35.00 37.50 13.50 67.50 0-15, 100 0-15, 110 0-10, 100 0-15 a.c. 0-15 a.c 0-150 a.c. 0-3, 15 a.c. 0-10, 125, 500 d.c. Checks performance of all types of a.c. and d.c. tubes. For 115 volts, 60 cycles a.c. Same as r-510 except for 25 cycles a.c. Special meters indicate short and low emissions in all types of a.c. and d.c tubes Tests all a.c. and d.c. sets; also a.c. and d.c. tubes, including screen-grid type. Binding posts for separate use of meters. Supreme Instruments Corp. Set Tester Set Tester 400-A 99-a 124.65 97.65 0-125 0-2 J ampere 0-10, 100, 600 d. c, 0-3, 15, 150 a.c. An a.c. and d.c. set tester complete with full sets of tools. Contains a modulated oscillator, tube rejuvinator, etc. A set tester lacking a few of the features of the larger model 400-1A Weston Electrical I nstrument Corp. Set Tester Tube Checker 537 533 100.00 67.50 0-30, 150 0-20, 80 0-4, 8, 150 a.c. 0-8, 60, 120, 300, 600 d.c A.C. line voltage indicator A complete a.c. -d.c radio set tester For use by dealers in checking tubes at time of sale Hickok Electrical Instrument Co. Set Tester ac-4600 $135. 0-20,200 0.-300, 600 d.c. 0-7.5 d.c. 0-3.3, 15 150 a.c. A complete set tester Generul Radio Co. Test Oscillator 320 A modulated oscillator for receiver testing • may, 1929 page 46 •