Radio Broadcast (May 1928-Apr 1929)

~z_ RADIO BROADCAST 7 licensed receivers, prices, and number and type of tubes employed. Among the licensed sets listed, the following companies not themselves holding an R.C.A. license are shown to supply sets: Brunswick Phonograph Co., Buckingham Radio Corp., Bush & Lane Piano Co., S. Freshman. Graybar Electric Co., National Carbon Co., Sonora Phonograph Co., and Victor Talking Machine Co. THE SPRING MEETING of the National Electrical Manufacturers Association will be held at the Homestead, Hot Springs, Va., May 20-25, 1929. A CLEVELAND BRANCH of the Thordarson Manufacturing Co., has been opened at 520 Citizens Bldg., with C. M. Hendricks in charge. THE MANUFACTURING activities of the Chas. Freshman Co. and the FreedEisemann Radio Corp., will be combined in a new factory to be located in Clifton, N. J., 12 miles from New York, according to a recent announcement of C. A. Earl, head of the two concerns. THE KELLOGG SWITCHBOARD AND SUPPLY CO., of Chicago is now licensed under the patents of the Badio Corporation to make receivers. The license was granted as of January 1, 1929. A complete list of BCA set licensees will appear in a subsequent issue of this magazine. THE BREMER-TULLY MANFACTURING CO., has just received a receiver license under the Hazletine and LaTour patents. THE NEW RECEIVER manufacturing plant of the Temple-Sleeper Corp., is located at 5253 West 65th Street, Chicago. A. Marchev is president of the new company. THE FACTORY OF Colin B. Kennedy, Inc., is being moved from Highland, 111., to South Bend, Ind. It is said that the Kennedy company has merged with the Studebaker Co., of South Bend and plans to market sets through mail order channels. THE EBEBT FURNITURE CO, Red Lion, Pa., is now offering a line of highquality cabinets at popular prices. A. Irving Witz and M. J. Polikoff have been appointed national sales agents. Mr. Witz was formerly eastern representative for Bremer-Tully and the Webster Co., of Chicago, and the Fidelity Radio Corp., of Salt Lake City. He is now also vice president and sales manager of the Argon Tube Corporation, Newark N. J. PRICE reductions on ten types of R.C.A. tubes were announced on February 15th by the Radio Corporation of America. Radiotron ux-226 is reduced to §2.00, uy-227 to 83.00, xjx-280 to $3.50. ux-281 to $7.25, TO-112A to S2.50, ux-250 to $11.00, ux-199 to $2.00,ux-17lAto $2.50, tjx-200a to $3.50, and ux-201a to $1.40. Technical Notes VARIABLE condensers of all types for use in the manufacture of receivers are made by the Precise Products, Inc. Single or gang condensers can be obtained with maximum capacities of 0.0005, 0.00035, or 0.00025 mfd. Relative to the accuracy of these condensers, the following data was received from A. deFord, sales manager. "We hold the accuracy of our condenser to within three mmfd. plus or minus over the entire range. All of our production condensers are calibrated in five different positions using the resonance method. The tolerance we have specified above is closer than some manufacturers demand. "We are building group condensers with as many as 5 to a gang, and the returns on these condensers have been less than one half of one per cent." PRODUCTION TESTS ON Durham Metallized Resistors have been made more severe to make certain that the units have an ample safety factor, According to a recent release from the International Resistance Company, all Durham Metallized Resistors are "flash" tested for five minutes at a load of twice the normal rating of the unit. The Radio Dealer's Note Book — No. 2 Voltage-Control Devices \ CCURATE summaries of useful information are constantly of value to those radio -iV. folk who deal with the public. This sheet, one of many such on various subjects to follow, sets down collected information on voltage-control devices. The dealer or serviceman can remove this part of the page for his notebook or he can have it photostated in any number of copies. A.C. line voltages throughout the country are set. Whether a fixed or variable resistor is used denot constant. When an a.c. set is installed the dealer pends upon various factors. Most radio owners are must make whatever adjustments are necessary to not particularly interested in the mechanics of the permit the set to operate at maximum efficiency at set and don't want to be bothered by having to adthe particular value of voltage at the socket to just a line voltage control device from time to time, which the set is connected. For this reason a fixed resistance of the proper value This adjustment may be accomplished readily should be used whenever possible. This is quite with those sets supplied with several taps on the satisfactory where the voltmeter test of the line power transformer. In such a case the proper pro voltage shows the supply to be high but uniform, cedure is to make measurements with an a.c. volt If the test shows that the voltage varies over wide meter to determine the maximum voltage at the limits, sometimes being high, sometimes normal light socket. The tap on the transformer is then and at other times quite low, it is best to install one adjusted for operation at this voltage. of the devices containing a variable resistance so All receivers are not supplied with taps on the that the amount of line-voltage compensation can power transformer and in other cases it may be be adjusted as necessary by the owner of the set. found that the taps available do not in some in The second thing to do if the line voltage is found stances permit a wide enough adjustment; for ex to undergo wide variations is to write a good stiff ample, a set might have taps to permit operation complaint to the power company, on line voltages up to 115 volts but by test it may Space limitations do not permit us to go into debe found that the line voltage is at times as high as tail regarding how to determine what size resistance 125 volts. In such a case it is necessary to install to use under different conditions but fortunately some device to reduce the line voltage to 115 volts. the various companies manufacturing these devices A complete list of the adjustable line voltage con can supply excellent charts showing just what retrol devices made for this purpose is given in the sistance to use. This information should be in the table below. hands of all dealers and servicemen. A note to These devices which are either fixed or variable Radio Broadcast written on your business stationresistors are generally mounted in some convenient ery will bring to you complete data on all the devices manner so that they may be connected readily be listed in the following table, tween the light socket and the power lead from the Mfgr. Type No. Price Characteristics Remarks Fixed Resistor Variable Resistor Ohms Wattage Ohms Wattage Aerovox 997 1.50 3 to 75 60 Central Radio Laboratories Control Box 3.00 Mounted in a metal box with socket and input power lead Clarostat Mfg. Co. Power Clarostat 3.50 0-10 25 to 500 40 40 DeJur-Amsco Corp. Voltage Regulator No. 360 12.50 Mounted in a metal box with socket, input lead, and a.c. voltmeter to permit accurate adjustment to 110 volts Insuline Corp. of America Resistovolt Light-Duty Resistovolt Heavy-Duty 1.75 125 250 Thermatrol Mfg. Co. Voltage Control 1.75 30 75 Consists of small device to plug into light socket. Four adjustments for voltages from 110 to 125 volts Ward Leonard Mfg. Co. 507-63 507-59 507-83 507-96 507-39 507-41 507-43 507-44 507-45 507-97 :,o7 507-99 507-100 507-101 5.50 5.50 5.50 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.5 3.5 5.0 7.0 10 12.5 15.0 22 31 45 62 60 60 60 60 60 60 60 60 60 60 60 50 20 12.5 60 60 60 V\ hich size resistor is used depends upon the line voltage and the current drawn by the set. A complete chart is available indicating what resistor to use. Wirt Company No. 211 No. 211-b 2.25 3.25 65 150 Mounted in a convenient unit to plug into the light socket X-L Radio Labs. X-L Link 5.75 Mounted in a metal box with socket and input power lead april, 1929 page 407 6 4