IMPROVING RECEPTION ON WEST COAST

New Zealand Listener, Volume 17, Issue 436, 31 October 1947, Page 7

IMPROVING RECEPTION ON WEST COAST

New Transmitter for 3ZR Greymouth

HOUGH Greymouth is only 100 miles or so in a direct line from Christchurch, the high Southern Alps _ intervene. And for this reason, reception in the West Coast district from Christchurch broadcasting stations is poor. To give the western part of the South Island a satisfactory radio service, a separate station is necessary. For some years, 3ZR, a small station of about 100 watts output has operated at Greymouth, and now that new technical »equipment is becoming available, it is intended to replace the existing

transmitter with one of 10 kilowatts, and to enlarge the studio accommodation, It is hoped that this new station will be on the air by the middle of 1948. The West Coast district, with the main population extending from Hokitika to West‘port, and a large proportion of it along the Grey River up to Reefton, is difficult to serve from the technical point of view because of hilly country and heavy bush. The populated area between Brunner,and Reefton, for example, is in the valley through which

the Grey Kiver runs After careful examination of many factors the NZBS has decided to locate the new transmitter near the mouth of the Taramakau River, not far from Kumara Junction. This location will give a transmission path up the Grey Valley, with a minimum of obstruction from the ranges. The site, being less than a mile from the sea coast, will also be in the most suitable position to serve listeners along the coastline. Difficulties of Laciition Very little choice was offered by way of sites in the area decided on, but eventually one was selected near the main road. At one time it was covered with thick bush, much of which has been removed; but it is still a mass of stumps and fallen trees which are being cleared away for the aerial and ground systerns of the transmitter. As in all cases when modern broadcasting sites are selected, tests are made with mobile testing equipment and fieldstrength receiving gear. In this case the transmitter was set up on the actual site chosen, and field-strength observations, which were made in the main centres of population, confirmed the location as the most syitable for radio coverage. Though tne transmitter will be eight miles from Greymouth, a strong signal will be received there owing to the power of 10 kilowatts. It would be undesirable to place a transmitter of such power in Greymouth itself, for it would tend to interfere with the reception of other stations. As the NZBS was unable to obtain authority to erect a new transmitter building, it bought surplus buildings

from the War Assets Realisation Board and a contract was let fer dismantling, transport, and re-erection at Kumara Junction. This timber will be used to house the transmitter and for another building for temporary staff quarters. Saving Costs A vertical mast radiator, 400 feet high, will be used with the transmitter. It will be of angle-section steel in triangular lattice formation and held up by insulated cables. The mast itself will be insulated from the ground and will act as a radiator without aerial wires. To save expense the mast will be "sectionalised" at about two-thirds

of its height, which means that the top third will be insulated from the rest, with a spécial tuning-coil between the two sections. This type of construction is being used because it gives the effect of another 100 feet or so in actual height, yet avoids the costs which rise rapidly with the height of construction. Beneath the mast there will be an elaborate system of about 120 earth wires, extending out from the base of the mast for 150 yards all round. Buried from six to twelve inches under the surface, they will form an earth-mat. Both the transmitter and the mast were ordered from Australia early this year, and the construction of the transmitter is well on the way. Modern technical equipment for the studios in Greymouth has also been ordered and this will give better facilities for the use and development of local talent.