Aeroplane Radio

Radio Record, Volume III, Issue 37, 28 March 1930, Page 8

Aeroplane Radio

N.Z. E nterprise AN interesting and unique experiment took place’at the Auckland Aero Club’s base on Wednesday morning last, when, as far as is known, the first short-wave transmission in New Zealand from a ’plane in flight was made. With the object of testing out a portable transmitter-receiver for the use of Captain Hewitt on his proposed Dunedin to Auckland non-stop flight, Messrs. Abel, Smeeton, Ltd., in conjunction with the Aero Club officials and the P. and T. Department, carried out a test transmission using a three-valve transmitter with an input of 3 watts, operating on a wavelength of 36 metres. The set, which was designed and built by Mr. J. H. Trenwith (ZLIFX) is housed in a box 8} inches x 15 5-8 inches x 10 inches, outside measurement, and includes transmitter and receiver, batteries, valves, phones, key and aerial equipment, weighs just 19Ib. It can be used fo1 either Morse or telephony transmission and receiving, a very ingenious switching arrangement giving "Key," "Off," "Mike," and receiver connections. IN actual test, using an aerial and ecounterpoise strung from the wing tips to the tail of the ’plane, Mr. Trenwith, using the call sign ZKAAR, connected ZLW on good readable strength. Unfortunately just as the ‘plane left the ground one of the two parallel audio valves went out, reducing the output to only .8 watt. As a result of this test it can now be definitely stated that it is possible for Captain Hewitt to keep in touch with the ground throughout the whole of his flight. To show the efficiency of this small set, it has only to be realised that this test gave a range of 1330 miles per watt of output-no mean achievement. The altitude of the "plane varied up to 5400ft. Mr, Trenwith, prior to this test and transmitting from his station ZLIFX, has been successful in working Christchurch on more than one occasion, and is continuing his experiments with the object of attaining even greater efiiciency.