RADIO BROADCASTS

Wairarapa Times-Age, 6 March 1939, Page 6

RADIO BROADCASTS

ESSENTIALS FOR GOOD RECEPTION. ADVICE FROM INSPECTORS. Complaints radio interference, which are dealt with by the Radio Inspection Branch of the Post Office have been traced in about 25 per cent of the cases to faults in the listeners’ own equipment, and from the official experience in dealing with these troubles some useful information can be made public. It is satisfactory to find that the average modern radio receiver gives excellent service and that New Zea-land-made sets are as good in this respect as those which are imported. However, complaints come in by the thousand every year and they have to be carefully investigated by the Post Office experts who, while they trace the bulk of the troubles to outside causes, find a substantial number in the apparatus under the listeners’ control. Powerful modern radio receivers are so efficient that the need fbr a good aerial is frequently discounted, although in the opinion of the best technical advisers there is nothing so essential to high quality reproduction as a good aerial even in the best of radio receivers. Enormous amplification can be obtained and this enables weak radio signals to be reproduced in the loud speaker at the necessary volume. But if a good aerial and an equally efficient earthing system have not been provided, the high amplification necessary not only increases radio signal strength but amplifies in even greater proportion the local noises due. to electrical interference from high' tension mains, tramways or electrical appli-\ ances. An efficient aerial and earth system increases thee radio signals but does not correspondingly amplify the local noises. The attitude of a.listener who buys- an expensive receiver but avoids the very modest expenditure for a good earth and aerial connection is much the same as that of a motorist who, after providing himself with a luxury car, neglects to purchase good petrol and lubricating oil. Though the modern radio receiver is well finished and highly reliable, it will not go on indefinitely without attention. There comes a time when the sensitivity of its receiving valves becomes reduced. The usual reaction ot the' listener is to increase the amplification, which gives extra strength to the annoying interference with programme reception. There is some danger involved in leaving inefficient valves in the receiver, since undue strain on working parts may result in the burning out of coils and resistances. When trouble is experienced the first advice of the radio inspector is to test the values of a set and also make sure that the aerial-earth system is in good,condition. Faults frequently discovered in earth systems are unsoldered joints, breaks inside rubber insulation, contact with spouting, stay-wires, etc., etc. The listener valuing good reception with first-class tone —and he can be assured that the tone of most broadcasts is of high quality—should also make sure that the earth connec l tion to his set is not merely a wire coiled around a pipe with dirt and verdigris preventing a good electrical contact. There is one interesting case on record of a listener who, having absorbed the advice regarding the necessity of a good earth, led a wire from his set into an earth-filled flowerpot on the window-sill. The conditions mentioned above can be tested by the radio licensee without reference to the inspectors; and in many countries, including the Australian Commonwealth, a listener making a complaint of poor reception is required to give an assurance that he has provided an efficient outdoor aerial and earth system. He is informed that if reception continues poor after these precautions have been taken the cause of the complaint will then be investigated. All competent authorities overseas and in the Dominion declare that a fairly general idea that “the larger the aerial the greater the noise” is quite fallacious. Height in an aerial gives the advantage of removing the connecting wire from the vicinity of] noise-producing electrical equipment' 1 on the ground level, and where the down lead is to pass through a field, of interference, such as on a building having lifts, the down lead can be shielded against interference and excellent results achieved despite these adverse conditions. Radio inspectors are always willing to give advice to listeners on this subject.