RADIO NOTES

Rotorua Morning Post, Volume 2, Issue 387, 23 November 1932, Page 6

RADIO NOTES

"Kathode.")

FADING TROUBLE success claimed for latest method of control static not ireduced

(Notes by

The past week has not been a good one for reception. Fading, distortion and local interference has marred reception of the YA stations, whil'e trans-Tasman reception has been almost impossible. Several "B" class stations have been coming in with good volume, the strongest being 1ZR Auckland, though this station is not worth listening to on account of bad distortion. Summer eonditions are now very much with us, and many lisbeners, failing to locate overseas stations before 10 p.m., have blamed their receivers. A number have gone to the expense of purch'asing new valves, only to find that the Australian and foreign stations remain elusive until late in the evening or have disappeared altogether. These eonditions have advanced upon us rapidly, therefore until autumn approaches, reception of foreign stations west of New Zealand before 10 or 11 p.m. may be counted as freak reception. On the othei* hand stations east of the 180th meridian will arrive strongly later on in the summer. December, January and February are the best months for locating Oanadian and American stations, though KFI has faded out in the meantime. Listeners may wonder why reception east of the ,180th improves during the summer while stations west of it, become weak and disappear altogether. The explanation is simple. Winter eonditions now prevail in America, and the transmitters there are op'erating under winter eonditions. Less sunlight and longer hours of darkness combine to aid the penetrating or carrying power of radio energy. West of New Zealand the transmitters are operating in daylight, long after darkness has fallen here, and the strong summer sun ionises the heviside layer making it an extremely poor reflector of radio energy. Therefore, reception of Australian stations may even be impossible before ten p.m. with a super-sensitive receiver. "Kathode" has not heard an Australian programme for over a month though the receiver he uses is capable of logging dozens of American stations. Fading and Static Much has been done to overcome fading and the most modern receivers incorporate an automatic volume control. "Kathode" has heard two up-to-date models demonstrated by local dealers and both certainly justify avery claim made by the manufacturers. Fading of 2YA was almost eliminated, though fading associated with distortion did not make for quality. Providing distortion remains at a low value the automatic volume control makes it unnecessary to touch the receiver after a station has been tuned in. Contrary to certain claims made, the A.V.C. does not eliminate static or even reduce it to any extent, as static modulates the carrier, and the control does not function on modulation percentage. The automatic volume control functions on the actual carrier strength and not on the amount of modulation placed upon it. If such was the case, soft passages in music would be brought up loud and loud passages would be weakened, which of course would ruin the light and shade, so necessary in music. Noise in receivers must not always be associated with power lines and current supply systems. During the week "Kathode" located two causes of mysterious clicking noises in his receiver. One turned out to be caused by a clothes line swinging in the wind and rubbing on a second line just beneath. The other was located in the aerial itself. A broken strand in the lead in wire made intermittent contact when the wire was moved. One of the local amateurs devised a novel and effective means of audio coupling and high hopes were held until investigation revealed the fact that Clough, in America, had already 'patented the system. Exceptionally fine quality is obtainable from the coupling and probably the receiver using it, in Rotorua, is the only one in the Dominion making use of the Clough system with pertode valves in push-pull. Interesting Tests The Radio Emergency Corps held its final field day last Sunday. Stations were active all over the Dominion and interesting tests were carried out. The local section were on duty at 10 a.m. and continued with the tests until axter mid-day when the p'ower went off. The^ local station was then in touch with Gisborne, but owing to failure in power supply, was forced off the air. The portable set could have been used to complete the contact but owing to lack of funds, the local operators have not been able to purchase sufficient batteries for long distance work. The British Empire short wavte bioadeasting transmitters are now being tested and owners of short wave sets should listen for them between 20 and 30 ^ metres each evening. The probable time will be between seven and eleven p.m., New Zealand summer time. . Short wave adaptors are not expensive and unless a snperhetrodyne circuit is required, a home made adaptor will prove successful. No extra pnwer suPPly is required as the instruments use the usual supply 0f the broadcast receiver. A little patience is required to tuna a short wave set, but with short experience even a child mav operate them.