RADIO NOTES

Rotorua Morning Post, Volume 2, Issue 375, 9 November 1932, Page 7

RADIO NOTES

"Kathode.")

NEWS AND HINTS GOOD RESULTS FROM NEW AMERICAN STATION. INTERFERENCE PREVALENT.

(Notes b*y

Reception during the last_week has been very erratic. At the beginning of the period all stations were weak, but ,a few ;dp.ys later, exceptional i strength was obtainable from local and distant transmitters. Particularly good reception was experienced- during th'e week-end, though 2YA distorted occasionally. KSL, the new 50 kilowatt transmitter in Salt Lake City, Utah, has been : coming in with wonderful strength. The writer has heard this station at good volume, when using a short indoor antenna, though KFI was not audible. On an outdoor aerial, volume was too great, and cverloading took place when the control s were advanced to full. Several American stations have permission to use high power and before long KDKA, the pioneer broadcaster of the world, will use an •experimental power of 400 kilowatts. Even though the output rating will he about seven times stronger than KSL or KFI, itfdoes not follow that KRKA will arrive mueh stronger than either of the lower powered transmitters, though the high'er power will gives a greater degree of degendability. t European stations continue to be heard on the broadcast band. One listener reports reception of FPTT Paris at fair volume. -If rop'e halyards are soaked in boiled linseed oil before being put up, there will be practically no shrinkage and the life of the rope will he ; lengthened. i j Interference is becoming a real | problem in Rotorua and reception in some localities is almost impossihle. One listener in Whaka Road suffers a continuous harrage both day and night, rendering an expensive receiver almost useless. It is hoped that steps 1 will be taken as soon as possible to remedy the trouble.

The opening of new high-powered stations in Japan and American, nd the establishing of a host of "B" class stations in i.sew Zealand and Australia has caused a bad type of hetrodyne interference to appear on most of the YA stations. This whistle or hetrodyne is heard when the difference between the two carriers comes yithin the audio range. , As an, example, if one carrier is operating on one million cycles and another on one million five hundred cycles, the difference is five hundred cycles, which is well within the audible range. When one valve in a push-pull stage of a receiver or ampliffer has become defective, both tubes should he replaced. To work effieiently valves in push-pull must be matched. In drilling aluminium or other soft metal the jagged edges can he removed neatly by inserting th'e point of a knife blade in the hole and rotating the hlade round the edge. In this way the metal is not exposed to digs or scratches as in filing or hammering the edges. The flickering of the dial light in an a.c. receiver should not be tolerated, as it is the cause of much noise and apparent interference. The b'ght is usually taken from the same power supply as the valve filaments, therefore flickering will have an influence in the valve circuits. In most cases it is caused hy a loose hulb and" the remedy is obvious. If the hulb is not loose', try a new oue and examine the eircuit wiring. * Motor-boating is a common fault in both a.c. and battery operated receivers. This defect can generally he cured by reaucing the deteetor voltage, though it may be necessary to redesign the audio end of the set. A persistent ringing sound in a receiver may be caused by a badly microphonic deteetor valve. The hest remedy is to try a new tube', though padding round the old one may cure the trouble. The licens'e figures are again on the increase, over 85,000 now being issued. It is interesting to note that though Auckland has a greater population, Wellington leads in the number of receiving- licenses held, the numbers being Auckland, 23,728; Wellington, 34,701.