Radio broadcast .. (1922-30)

.RADIO BROADCAST. detect either radio or audio signals and noises. Used for checking reception and locating noises. 6. Jewell No. 117 test kit. and tool kit. This is standard except for connection to connect grid and plate of tube together, to note total emission. 7. (Above) No. 199 Analyser. Pratt maintains (with considerable logic) that he "has always had best suc- cess in testing and adjusting sets in the location and under the conditions in which they are to be operated." Data on Eveready sets: GEORGE W. BROWN, radio service manager, Motor Supply Company, Boston, Massachusetts, distributors of Eveready, sends along this con- centrated service data: " I am submitting a few troubles and their solutions as I have found them in the 1929 Eveready Set. In many instances they will apply to receivers in general. power tube or tubes. If they are cool, there is no plate voltage on them, or a very low voltage. This would naturally suggest a blown filter condenser as the first pos- sibility. In order to check this, place the hand on the rectifier tube. If the tube is very hot, the condenser is blown, or the wiring is shorted. Shorted elements in any of the tubes will cause trouble, and may be located readily by tapping the tubes and listening for the tell-tale crack- COMPLAINT SOLUTION No C Bias—Bad 327 tube. Open volume control or resistor. Cathode lead off. Noisy Set—Set screws on vario- meter loose. Shields loose. No plate voltage—Connection broken at terminal strip in box. Plate lead off. Oscillation—Shields on r.f. coils loose. Detector shield loose. Bad tube. Antenna Compensator has no effect— Antenna too long. If over 20 feet should be connected to the long antenna binding post. Volume control has no effect—Bad 327 tube. Dynamic loud speaker does not work (Table model)—Open output trans- former. "The Eveready table model loud speaker will not work on the Console model set and visa versa. The table model set has a 1-1 ratio output transformer, and the table model loud speaker has a 25-1 ratio transformer but the console loud speaker is not equipped with a output transformer. Some dealers have returned loud speakers because they did not know this." Testing receivers without equipment: A few pithy oscillations come from A. H. GOUD, of South Portland, Maine: " Much has been written about servicing equipment of all kinds, and every service- man desires to acquire all the apparatus possible, to make his work easier and more accurate. "However, emergencies do arise, and sometimes the serviceman finds himself empty handed, confronted by a balky set, with nothing but gray matter to guide him. There are quite a few tests that may be made with no equipment at all. At least, if the real trouble is not found on the spot, these preliminary tests are very helpful. "Suppose the serviceman is asked to diagnose the trouble in an electric set. He may follow the procedure described below: " If the set is dead: Turn on the current and wait about two minutes. Feel of the Fig. 1 — The d.c. screen-grid tester adapter. George IT'. Broirn in the service laboratory of the Motor Supply Company, Boston, Mass. The Radio Broadcast a.c. tube tester and mod- ulated oscillator are among the prominent pieces of equipment, in this laboratory. ling noise. If the rectifier tube is cooler than usual, an open circuit in the B-supply circuit is indicated. "If the tone quality is poor, and upon feeling of the power tubes, they are found to be very hot, there is no C-bias voltage. "Continuing with the tests on the dead set, place the hand on the detector tube, or touch the grid leak. A hum indicates that the detector and audio system is ok. Now try tapping the antenna wire on its binding post. If the audio system is ok., and this tapping does not produce clicks in the loud speaker, the trouble is localized in the radio-frequency system. If clicks are heard, the trouble is probably due to loss of pickup caused by weak tubes, condensers out of resonance, open grid suppressor, or bad joints. "When an analyzer is at hand, these tests are often convenient before it is used." Number of servicemen in average shop: A recent survey made by the National Radio Institute, at Washington, D. C., showed that the average radio dealer in the United' States employs four service- men. The survey also indicates that 17 per cent, of the dealers contract for their service and repair work to be handled by outside service organizations. New radio service school: John F. Rider, radio writer and well-known service consultant, has opened a service school at 1991 Broadway, New York City. Mr. Rider is teaching radio servicing both to attending and correspondence classes. The course is divided into two grades, an elementary course of five months and an advanced course for two months. Electrifying Old Sets '•'In reference to the modernizing of older types of battery-operated sets referred to in the August issue, we have done a large amount of this work and feel that we are qualified to give a little information on the subject, as all the sets we have powerized to date have given excellent results. " Practically all work of this type has come to us through new set prospects who have been interested in the lower- priced a.c. sets and who are the owners of high-grade battery sets, such as Zenith, Stromberg, Federal, etc. These prospects are attracted to the lower-priced sets by the convenience of a.c. operation; other- wise we usually find them satisfied with their present equipment. "To offer the owner of a $400.00 Strom- berg-Carlson set a $40.00 allowance on, for example, a Radiola No. 44 results in his leaving your place of business in a huff; yet that is about as high as a dealer can go on a set of the type of the R. C. A. No. 44. "We usually suggest to the owners of these sets that they let us make an a.c. set out their present job. We explain that their set can be made as convenient as the current models and they usually take us up. If their pre- sent set is equipped with a B- power supply the cost to the cus- tomer will be $40.00 for a six-tube set, and correspondingly higher as the number of tubes increase. If a B-supply unit is not used in the present installation, the cost to the customer will be from $60.00 up, depending on the num- ber of tubes. '' For this work we use the equip- ment of the Radio Receptor Cor- poration and the type apparatus usually required is the Powerizer Jr. A and C or the Powerizer Jr. A, B, and C. On the first type the list and cost prices are as follows: Powerizer A and C Adapters Tubes Harness Miscellaneous Labor Total Profit LIST $12.00 3.00 12.00 5.00 2.00 6.00 $40.00 *17.60 COST $ 7.20 1.80 7.20 3.00 1.20 2.00 $22.40 "On sets using the Powerizer A, B, and C the list and cost prices are as follows: Powerizer A, B, Adapters Tubes Harness Miscellaneous Labor Total Profit and C LIST $35.00 3.00 15.00 5.00 2.00 0.00 $60.00 $23.00 COST $21.00 1.30 9.00 3.00 1.20 2.00 $37.00 "In many cases this price can be re- duced by making our own harness and some sets require no additional volume control or reneutralization which fur- ther reduces our cost. Wherever practi- cable we solder the adapters to the ori- ginal socket prongs. We also short the original 1 A- and C-battery leads, as the powerizer is equipped with a variable C- bias resistor and this we balance to the B- supply used. "We limit our efforts in this field to the better grade of sets and discourage the making of this change in the lower priced units. Our record in this field to date is 96 Stromberg Carlsons, 7 Kolsters, 8 Zeniths, 4 Bosch, and 2 Atwater Rents, a total in all of 117 sets. No changes were made or found necessary in the audio channels of these sets." B. B. ALCORN, Kew Radio Electric Inc., Kew Gardens. L. I. 0 C Screen-Grid Tester Adapter Fig. 2 — The' a.c. screen-grid tester adapter. • NOVEMBER 1929 39