Radio-Telephone Equipment Being Produced in N.Z.

Waikato Independent, Volume XLV, Issue 6235, 6 May 1949, Page 7

Radio-Telephone Equipment Being Produced in N.Z.

I Radio-Telephone equipment, one of the most modern developments now coming into general usage in the Dominion, is already being produced by New Zealand radio engineers. Overcoming many difficulties, they have succeeded in building sets which compare favourably with overseas models, and which, they say, are cheaper. ~ One firm, Communications (N.Z.), Ltd., staffed mostly by returned servicemen, has been established for some time. A young Christchurch returned serviceman, Mr A. M. Tait, tackled the big job of production more or less on his own, and has succeeded in making efficient radio-telephone equipment. Both Communications (N.Z.), Ltd., and Mr Tait showed in ' tests that their equipment provided a perfect link between a travelling motor vehicle and a central office. In the firm's test, conversations between people in a car on the bridge over the Cam River at Kaiapoi and others iit a van at the Sign of the Takahe were loud and clear. Mr Tait set out about twelve months ago to develop a set built to Post and Telegraph Department specifications. With limited capital and many major problems to overcome he achieved his purpose through sheer tenacity. War' Experience Invaluable Mr Tait had to depend mainly on his own knowledge, and the experience he gained during World War 11. was' invaluable. Before the war he was a radio engineer. He joined the Air Force in 1940, and went to England in 1941. He was there for six years alnd did considerable experimental work, mostly on radar. When he tackled the radio-telephone project Mr Tait first of all built a rough prototype. Three big questions which he had always to bear in mind from a commercial point of view were how much he could build a set for, how much current it would consume (having in mind that it would have to run off a car battery), and also how much space the set would take up. It was about two o'clock on a morning last December when he first got the set working. After convincing a curious policeman that he was not a saboteur or enemy agent, he was able to talk from his car in Latimer Square to the workshop in Cashel Street. The range was very limited and the reception was poor, but a foundation had been established. Worked Hard and Late. Mr Tait concentrated on improving the *set. He worked round the clock six days a week, and was still hard at it as late as three o'clock in the morning. He struck dozens of snags. Still he persevered until today he has eliminated all the major troubles. The efficient range of the radiotelephone equipment about Christchurch will be increased when the Post and Telegraph Department builds a base station at Cashmere. The very, high frequency signals of such equipment are audible only over a slightly greater distance than the line of sight, and the advantages of having a station high up are obvious. Use of the very high frequency eliminates the interference encountered at times in broadcasting. The mobile units can be operated alongside heavy machinery or behind a moving tram with no loss of efficiency at all. Ignition Noises Noticeable. The only source of interference to which the sets are prone is ignition noises from passing motor vehicles. However, the use of silencers discriminate against these noises and allow the signals to get through clearly. Usually the only background to a conversation is a slight hiss which develops from the valves and the atmosphere. The use of very high frequency also prevents others from listening in to a conversation. Through the use of the new postwar miniature valves and components, the New Zealand manufacturers have succeeded in putting the complete set, including both the transmitter and the receiver ,into a space little bigger than an ordinary car radio. The set can be placed comfortably in the luggage boot of a taxi or doctor's car, for example. The hand-piece and the loudspeaker are attached to the dashboard. The police and the Fire Brigade are already using radio-telephone equipment in Christchurch, and it is expected that taxis and big carrier firms will instal it on a big scale before long.