RADIO NOTES

Rotorua Morning Post, Volume 2, Issue 393, 30 November 1932, Page 6

RADIO NOTES

"Kathode")

(By

Conditions during the past week were very erratic The YA stations all had periods of fading and distortion though 3YA was consistently good from 9 pm on. On two oecasions the Australian stations came over after 1 p.m. with good volume, but a heavy hackground of static and local interference did not malcing listening a pleasure. A very noticeable hum is present on 2YA's transmission when the _announcers microphone is switched into circuit. The better the. low frequency response of the receiver, the more noticeable is this defect. 3YA evidently continues to use the old style turn-table for gramophone records. The varying sp'eed of this device detracts from the value of recorded programmes. Distortion is still part of lZR's programmes though not as had as of yoi'eThere is no doubt that even_ with the increased power of transmitters, and the improvement in design of receivers, interference is still the greatest question facing country listeners. There is no douht that a good_ deal of man made static can and will he eliminated, but the fact remains that if local listeners are forced to reach out for programmes, noise must be picked up and become part of that programme. A great deal of the hackground heard in Rotorua is due to natural causes such as static, but in most cases, part of it is due to inductive interference. In one case the remedy is beyond human control — in the othm*, a remedy can be

found in the receivers themselves such as looso connections, noisy valves, worn out batteries and poorly constructed aerial and earth systems. Where interference is caused by electrical apparatus, the remedy is obvious, but the question arises "Who is going to pay?" And there the matter stops. In some cases considerable sums of money would be required to instal filters and shields and until a law to rprohibit the use of noise producing apparatus is brought into i'orce, the listener has no remedy, unless he is prepared to foot the bill. It might be argued that the Broadcasting Board should find the necessary £.s.d. but to cover New Zealand, a huge sum of money would be necessary and the programmes would suffer in consequence. The Electrical Federation has taken a wise move in asking that all future apparatus imported into this country be interference free and in this way the interference problem will gradually find a remedy. Some listeners expeet an Immediate cure but there is little doubt that improvements must come slowly. Let us examine radio in the merchant marino, perhaps the finest jrganised body of radio engineers and . echnicians in the world. When the •m spark transmitters became obsol- . te, and valve transmitters took their idace, some sections of the service lound it nec.-ssary to continue with .he obsolete equipment, even though it caused considerable interference :ver wide areas. To have forced the use of up-to-date sets would have imposed undue hardship, therefore a period of time was given and to-day, the spark has praetically gone out of existence. If memory serves "Kathode" right, the last of the spark transmitters are due to be scrapped this year. After that the use of such i-.pparatus will be illegal. Along those !u;es, listeners may expect improvements. In the meantime every avenue whereby interference may be lesmust be explored and no doubt a considerable reduction in noise level will result. Less than 7000 watts of radio energy is used to transmit programmes over this country. The following are only a -few of the leading Ameriean stations. — • KDKA, 50.000 watts; KFI, 50,000 watts; KGO, 7,500 watts; KMOX, 50,000 watts; KOA, 12,500 watts; KOB 20.000 watts; KRLD, 10,000 watts; KSTP, 10,000 watts; KTHS, 10,000 vvatts; KWKH, 10,000 watts; IvYW, 10,000 watts; WABC, 50,000 watts; WGY, 50,000 watts; WTIC, 50,000 watts; WTAM, 50,000 watts; WOR, 50,000 watts; WOAI, 50,000 watts; , WGN, 25,000 wTatts; WFAA, 50,000 watts, WENR, 50,000 watts; WEAF, 50,000 watts; WCAU, 50,000 watts; WJZ, 30,000 watts; WJJD, 20,000 watts; WBZ, 15,000 watts.

Any one of the above transmitters radiate more energy than all of the New Zealand stations together. Exneriments with types of earths often lead to surprising results and are often worth while. To the best of "Kathode's" knowledge, the fan type ground has not been tried in Rotorua and no doubt, this type of eai'th would prove remarkably efficient. Bare copper wires of fairly heavy gauge and twenty five to one hundred feet in length are burried a few inches below the surface of the soil and as nearly directly under the aerial as possible. The wires may be buried by making a cut several inches deep in the sod with a sharp spade and pressing the wire into it. The earth should be then tramped back into place. The grass should soon grow over the cut and in the case of a lawn, this would not be marred in any way. Broadeasting stations using the Marconi type if aerial use this type of ground and find it the most efficient. Transmitters have found that system capable of good radiation, invariably lend themselves to excellent reception. Servicing of radio receivers is beccming a specialised job and is more than a trade — it is a profession. When traeing faults in a set, cut and try methods are no longer permissible. Not only should the service man krow what he is doing but why he is doing it, and the probable results he should expect. For instance if a resistor has blown in a set he should know the position and use of the device in the circuit and should be able to calculate the value of a replacement. The carrier of 3YA frequently carries a fair amount of A.C. hum. The same may be said of 2YA.