INTERFERENCE TO RADIO

Timaru Herald, Volume CXLI, Issue 20340, 12 February 1936, Page 4

INTERFERENCE TO RADIO

REPORT TO POWER BOARD WORK TO BE DONE | At yesterday’s meeting of the South j Canterbury Power Board, the General | Committee reported having received a : letter from the Postmaster-General in connection with a deputation that I waited on the previous Postmasteri General in connection with radio ini terference in the Geraldine district. The Committee recommended that after considering the report from the engineer, that it be a recommendation to the Board that the necessary alterations be done as soon as possible, the Board to co-operate in every way with the Department, the terminal poles at Temuka to be done first. The committee also considered that the Radio Broadcasting Board should meet some of this expense which would not be necessary if there was no radio. The engineer (Mr G. W. Morrison), in his report stated that the Minister’s letter referred to many things that interfere with radio reception, but the main interference was from: (a) Copper binders on insulation H.T. conduc- | tors; (b) difference of potential on I metal work of 11,000 volt 10 inch disc insulators; (c) old pattern street lamp in Geraldine and Temuka; (d) H.T. fuses with grounded metal work; (e) other minor interference is dealt with by the local staffs as it arises. “The total number of insulators carrying H.T. insulated conductors is just over 2400, this, together with some 200 cradle crossing, makes a total of 6000 I binders to be dealt with. “(b) The most expensive insulators that could be purchased at the time, and are located at points of termination and isolation. These insulators do not interfere with radio on account of leakage, but these do give off a crackling noise due to a difference of potential across the metal connection between the insulation and crossarm. This varies from time to time in accordance with vibration. “(c) These particular type of street lamps in Geraldine and Temuka arc a harbour of refuge for insects such as | spiders, etc., which eventually cause I arcing inside—the only cure is to clean I them out from time to time—they are much too good to be scrapped and are I cleaned out periodically. i “(d) The removal of the ground I connections would eliminate the i trouble, but on the coast line, salt is I deposited on the contacts and causes arcing. They are dealt with when the radio inspector advises us. “The whole staff have at all times co-operated with the Radio Depart-

ment in eliminatnig interference, but only where the matter comes under the heading of maintenance. Such matters as (a) (b) and (c) would still give very many years of useful service, but it appears to me that the advent of radio, necessitates these useful units being replaced. “The main interference as before stated is disc insulators and copper binders, and to replace these, the estimated cost will be as follows: — £ (a) The capital cost of units uggested to be scrapped .... 650 Cost of kidney replacements 472 (b) Estimated cost of installing anti-interference binders .. .. 200 (c) Capital cost of units suggested to be scrapped 520 Captal cost of replacement .. 550 Total cost to eliminate main interference 2392 “On the 3rd Inst., I visited Temuka and various points of the district, and together with the telegraph engineer and radio inspector, made a close inspection of the main interference, particularly at the 11,000 vole terminal poles in Temuka Borough. At these poles there was considerable interference which the Radio Department put down to leakage and other causes. The ground wires were disconnected and the noise continued as before; this proved that the interference was not from leakage. Further tests located the interference to the metal connections between the 11,000 volt 10 inch disc insulators and the crossarm. There are 18 of these insulators on two poles adjacent to Temuka substation, which the Radio Department would like us to replace. The estimated cost of new insulators erected and fitted £22/10/- and the zapital value of those replaced, £3O/12/-, total £53/2/-.

Closer Co-operation “It is not a question of insufficient staff to attend to the ordinary run of maintenance, but there are many occasions during meter reading in the Temuka district when it is impossible to assist the Radio Department in eliminating interference. Last winter, I promised the Department that we would deal with interference in so far as heavy expenditure was not involved —this was done when possible to open the lines; over 50 H.T. fuses were overhauled and several hundred copper binders replaced by marline; the latter with the result that most of the marline binders have severed and have been replaced with copper. My experience with marline is that if exposed to the weather in tension its life is only 8 to 9 months. “With a view to closer co-operation, I have arranged with the local telegraph engineer that instead of the radio inspector dealing direct with the district staffs, all interferences are to be reported to me in writing, when, if heavy expenditure Is necessary to eliminate same, the matter will be placed before the Board for consideration. If, however, interferences are in the ordinary run of maintenance, I will instruct the staff concerned, to cooperate with the Radio Department on a fixed date, to have same eliminated. “The local radio inspector realises the difficulty in opening lines at all hours of the day, but at the same time I also know that interferences under the run of maintenance, will in due course interfere with continuity of supply, and are being dealt with when possible to open the lines. “The important matters however for the board to consider are (a) and (b). To effect the change in (a) will necessitate 90 man hours and that for (b) 500. In the Temuka district, nothing can be done till the milking season ends in April.”