Radio age (Jan-Dec 1926)

RADIO AGE for February, 1926 The Magazine of the How 55 53 Sources of Radio Interference (Continued from page 34) be taken in making this test to avoid the danger of confusing the interference which originates from different sources, which may appear similar in the receiver. The most satisfactory way of making this test is for one observer to listen to the interference received on two radio receivers at different points at the same time by means of a telephone system. To carry out this test an assistant at the distant Radio receiver should place his head phone (or preferably his loud speaker) near the transmitter of the telephone in order that the observer at the other receiver may listen at the same time to the interference heard on his own receiver at his right ear, while listening to the interference heard at the distant radio receiver by means of the telephone to his left ear. This test should be continued for a sufficient length of time to observe a number of variations in the nature of the interference. In cases where it is not convenient to use the telephone system for this test, the two observers at distant Radio receivers may keep an accurate log of the interference, but in this case they should first synchronize their watches and record any characteristic change in 'the interference heard, noting the time accurately to within a few seconds. Fourth Test: To determine if any suspected source actually causes Radio interference. In carrying out this test either of the two systems referred to in test No. 3 is suitable. Great accuracy is required in these tests for it has been found that many misleading reports have been received from observers who were not sufficiently accurate in their observations. For instance, interference has been reported to be associated with the switching on of the street lights in cases where the interference actually was produced by another circuit which was switched on every evening about dusk. If the observers in this case had noted the time very accurately, the source of the interference could have been located much more readily. Fifth Test: To determine where the interference radiates from, by means of a portable Radio receiver. In cases where a portable receiver is available the source of interference may be very often traced by this means. RADIO AGE ANNUAL FOR 1924— AT SPECIAL PRICE! Clip the coupon and send It with 50 cents, and the RADIO AGE ANNUAL FOR 1924 will be sent you by return mail. RADIO AGE, 500 N. Dearborn St., Chicago. Enclosed is 50 cents, for which send me the RADIO AGE ANNUAL for 1924. Name City (2-26) Jot down the call letters in the handy slots — right on the dial itself — and there is your permanent record of station settings. Instant Response searching dial action for the model set The designers of the Radio Age Model HX set wanted responsive, supremely accurate tuning, to meet today's conditions. They realized how inadequate old type dials are, to cope with 1926 broadcast congestion. As an essential feature of theModel set, therefore, you find MAR-CO dials. For these are the newday tuning controls that experts everywhere advise. Nickel-plated, $2.50 Gold-plated $3.00 They respond to your slightest touch with no suggestion of backlash. By splitting a single degree into hair's breadth divisions, they get stations you now pass over. Until you put MAR -CO dials on the set you're building, or on your present set, you'll never realize what a difference a dial can make! Martin Copeland Company, Providence, R. I. W&M. The 1926 model tuning control Tell them you read it in Radio Age