WIRELESS.

Star (Christchurch), Volume XLIV, Issue 600, 2 November 1932, Page 4

WIRELESS.

:jProgress in Ultra Short Wave Work. ■ FOR LIMITED RANGE. (By "AERIAL ’.) ■•During the past three months the engineers of Amalgamated Wireless h4ve been carrying out a series of experiments on the ultra short wavelength of 7 metres, and, although a power •of only 10 to 15 watts is used in the aerial, ■vfcry satisfactory results have been obtained, reception being effected in many of the suburbs of Sydney, and in ohe instance at Springwood on the Blue Jsbuntains, about 30 miles air line from SJrdney. The transmitter is located at Wireless House, the vertical aerial being attached to the flagpole bn the roof. Bke radio-frequency energy is conveyed to the aerial by means of two feeder wires. The frequency of the carrier wave is maintained constant by means of a crystal oscillating on a wavelength of 112 metres. This frequency is multiplied by means of frequency doublers until the desired wavelength is reached, namely, 7 metres. The object of the teats is to determine the usefulness of ultra sfiort wavelengths for giving a broadcast Servlet over a restricted area, without causing any-appreciable Interference outside a comparatively limited rqbge. If this proves -possible, a number of local broadcasting services could be carried out oh a* common wavelength without mutual interference, a development of great importance and. utility. Zl » K K

W. Watson, secretary of the local of the DX Club, writes: “We have pleasure iir announcing -that the trelley buses will all be fitted with fleers in about three weeks’ time. The liMer chokes are designed to .eliminate per cent of the interference (with radio- reception). We also wish to acknowledge the courteous' hearing gty-en us by the Tramway Board. It is evident that the board »s out to help us whenever possible. We are still alive tqj the Interference problem, much machinery being in action not apparent teethe casual observer; reports on interference, therefore. are still being accepted for investigation.” information obtained from the board i»- to the effect that: If experiments that are now being carried out prove successful, thte Tramway Board intends tor? fit filter chokes on trolley buses in Cnfistchurch to eliminate most of the Interference with radio sets.