Radio today (Jan-Dec 1938)

"TUNE UP" RADIOS FOR SUMMER Eliminate interference, replace antennas and tubes < ANTENNA ANTENNA — -/ ;y M 7 . HOUSE C HOUSE B ~ 3 ll 2] | HOUSE A || IISB1B C How man-made interference is transmitted from nearby dwelling, through power lines and through antenna interaction. * IN more than one hundred broadcasts over nationwide networks of NBC, CBS and Mutual, 0. H. Caldwell, editor of Radio Today, has given practical advice to radio listeners on getting their sets in best condition to receive the great program offerings on the air. The following is an extract from one of these coast-tocoast broadcasts, and may be quoted by radio men as newspaper text or on the air, in any way that will benefit radio reception. * # * To determine whether the noise arises inside the radio set or comes in on the antenna, the simplest test, of course, is to disconnect the antenna while the radio set is still turned on. If the noise continues with little change, with the antenna disconnected, the trouble is somewhere in the set. Tubes may be at fault. This may be tested out by trying new tubes in place of the old ones, one by one, to see if the noise disappears. If, however, the interference is found to come into the set only when the antenna is connected to the set, the position and condition of the antenna should be looked into. No better than antenna Do not be satisfied with a short indoor antenna if you want good, clear interference-free reception. Instead use an outdoor antenna and see that your antenna is up as high as possible, where it has a chance to pick up a strong "signal" from the broadcasting station, while at the same time picking up a minimum of interference and man-made static from the wires and appliances in the house. If a short antenna is merely run around the picture molding of the room (as is so often most convenient to do), such an antenna may bring in sufficient volume, but it also brings in considerable interference induced from the network of electrical wires in the house, electrical appliances, etc. So that at times the amount of "radio noise" picked up by the antenna, and heard in the set, may be very disturbing. Such interference may be reduced or eliminated at its source by applying condensers or choke-coils at the offending appliances. To do this work, an experienced radio serviceman should be called in. In, on the other hand, the antenna is mounted high above the house or runs off from the house, high above the ground, the antenna will get a minimum of noise and a maximum of broadcasting. The intensity of the noise will then be so far below that of the broadcast signal, that the noise will not be noticeable. So in this way, by means of a high antenna, one usually puts an end to interference from local electrical causes in the house, and at the same time brings in clearer, louder signals from the broadcast station, greatly improving the quality of reception. The wire leading down from such a high antenna to the radio set may pass right through the interference area of the electric wiring and electrical appliances. To avoid this the new scientific twisted-pair lead-in may be used. This shields the antenna from interference which would otherwise reach the antenna wire and be carried into the set. Many good antennas are on the market which improve reception on both the broadcast channels and short-waves. Abofe all else the answer to clear, interference-free reception is an adequate antenna, installed as high as possible and far away from the house wiring and appliances. Methods of installing condensers and chokes to cut out interference. 16 Radio Today