Radio today (Sept 1935-Dec 1936)

SERVICE NOTES (From -page 54) turer built his set. For this reason it is essential that the serviceman be sure that he is using the correct beat. There are two simple ways to tell whether the set is aligned to the high or low beat. See accompanying diagram. If a signal is produced in the set when the dial reading is increased by an amount equal to twice the i-f. frequency, the oscillator in the act is working at a frequency lower (low YOU'RE IN LUCK if you Have ALL 4 ^HE DEALER or Service-* man who carries the ARCTURUS Line is lucky. He doesn't have to pass up sales! For he has the FOUR different classes of tubes the public demands today: 1. GLASS. 2. "G". 3. CORONET— "the Perfected Met al Tube." 4. The NEW CORONET for modernizing old glass-tube sets Only in ARCTURUS is this FOUR-WAY LINE available. Thousands of dealers and servicemen are cashing in on this FOUR -FOLD profit builder. 1936 is a good tube year. Make the most of it. For full details of the 4-way Areturus line write: ARCTURUS RADIO TUBE CO., Newark. N. J. GLASS— "G" CORONET— THE PERFECTED METAL RADIO TUBES Smusk ao PRICES/' Triumph Condenser Bridge Analyzer First Quality — latest design — 9 built in Standards — 50 mint (I. to 20 nifd. 50 ohms to 2 megohms. 50 microhenries to 20 millihenries. All direct readings. Visual leakage indicator tests leakages up to 1,000 megohms and just LOOK AT THE SMASHING OFFER! Was $20.00, NOW 1HMPB' Triumph Preheator and Continuity Tester For all filament voltages ; directly calibrated ; 14 sockets for all type of tubes. Tests pilot lights — Special Continuity Circuits with visual indicator. Saves over 75% of tube testing time and DRASTICALLY REDUCED. Was $14.95, NOW $495 TRIUMPH MANUFACTURING COMPANY HIGH BEAT LOW BEAT fb fd FSG F0 F0 FSG 450 450 10000 10450 9.550 10000 NORMAL OPERATION fD |Fo |fsg |FSG |Fo |FD b 0 450 450 450 9.100 9.550 10.000 P0.000 10.450 10900 IMAGE OPERATION FD ■ DIAL (FREQUENCY Fo ■ SET OSC. FREQUENCY FSG ' SIGNAL GENERATOR FREQUENCY 4017 W. LAKE STREET CHICAGO, ILLINOIS Chart showing frequency of dial, signal generator, and set oscillator for normal and image operation. beat) than the detector. This is the usual mode of operation. If the dial setting has to be decreased by an amount equal to twice the i-f. frequency to tune in the image, the oscillator is higher than the detector in frequency. (High beat). During these tests it will probably be necessary to increase the output of the oscillator since the signal frequency circuits are out of tune. A simple way to remember the frequency relationship is : high image — low oscillator (usual) low image — high oscillator (unusual) when the set is retuned for the image — not the test oscillator. Two settings of oscillator trimmer The second method of finding the beat is by adjustment of the oscillator pamllel trimmer condenser. On the highest bands it will be found that there are two settings of the trimmer condenser which will give a peak. The setting with the greatest capacity — trimmer springs close together — is the low frequency peak, while the peak requiring less capacity is the high frequency one. When aligning a set, a check should always be made to make sure that the proper beat is being employed — this means that the manufacturer's service data must be consulted. However, in about 95 per cent of the sets the oscillator works at the high beatfrequency higher than that of the detector and r-f. circuits. If data is not available and in doubt as to whether or not the proper oscillator beat is being used, set the oscillator at various frequencies within the tuning range of that particular band and tune the set to reson(To page 60) 56 Radio Today