RADIO NOTES

Rotorua Morning Post, Volume 2, Issue 380, 15 November 1932, Page 7

RADIO NOTES

"Kathode.")

NEWS AND HINTS CHELMSFOLR REBROADCAST RECEIVED WELL IN ROTORUA. SHORT WAVE IMPROVES.

(Notes by

The last week has been an excellent one for reception, the YA stations heing above average strength for this time of the year. Using a short, low aerial, the writer has found it necessary to keep the volume control well back for cdmfortable reception of 2YA and 3YA. The "B" class stations have also heen coming in strongly, the hest of them being 2ZJ Gisborne and 2ZW Wellington. IaR Auckland is usually strong, but bad distortion, hoth day and night, has been very noticeable from this transhiitter. European stations continue being heard in Rotorua, one listener reporting excellent reception of several continental programmes. The relay hy 2YA of G5SW Chelmsford, England, was remarkably successful and though fading was evident, very little of the proceedings was missed. "Kathode" tuned G5SK direct, hu rapid fading ruined reception. A iii_ Ii powered transmitter has alnu::'. F completed in Budapest, and when the station goes on the air, keen local enthusiasts should have no difficulty in logging a new Enropean. It is a deplorable fact that many types of British receivers are totally unsuitable for local conditions. The Post and Telegraph Department have rejecteu several types oi English sets as definite creators of interference. Short wave reception is improving rapidly, the broadcast hy W2XAF Schenetdy, New York, of the recent elections in America heing clearly received in Rotorua from 3 p.m. The local amateurs also report improved conditions on their bands. Owners of short wave receivers should listen on the 80 metre hand between 5 and 10 p.m., when many American and Hawaiian amateurs are on the air. Several of them have been heard at good volume during the p>ast week and many interesting conversations have been intercepted. Short wave receivers frequently work hetter without the conventional earth. This applies particularly to battery sets when being used helow 80 metres. The usual type of a.c. receiver must he earthed to work efficiently, and to comply with the regulations all parts liahle to hecome "alive" must be efficiently grounded. In the case of battery receivers, the capacity to earth of the batteries and components usually supply sufficient ground, though body capacity may he troublesome on ultra high frequencies. It is important, to seeure the best results and longest life from valves, to see that the filaments are run at their rated voltage. If too high a voltage is used, the filaments will burn out long before their time, and, on the other hand, if the tubes are run below their rated filament voltage, slow paralysis of the filament will take place. Many enthusiastic listeners send report cards to stations heard, but in many cases no replies are received. The following appeared in QST: — Fundamental — ^ Roses are red, Violets are hlue, Send me a card, And I will you. Second Harmonic — Roses are red, Berries are black, Sent ninety cards, Got fourteen back. Third Harmonic — Roses are red, Asters are pink, Send cards agais? I don't think The servicing of modern a.c. radio receivers is becoming more and more specialised. The tinkerer who "once owned a crystal set" is no longer qualified o do the job. Instability in the radio freqeney stages of a receiver is frequently difficult to locate. A milliameter in the plate circuit of the high frequency tube will he the hest guide. If the amplfier oscillates, or if there is intercoupling hetween the stages, the meter will dip as the controls are varied over the tuning range, and the effect of any adjustments can be followed accurately. "Kathode" ran into a curious trouhle with a battery type receiver the other day. The slamming of a window or door would cause the set to do one of two things. Either it would go dead altogether, or reception would be improved considerably. Every point in the set was 'examined and vigorously pulled, but everything seemed OK in that direction. The trouble was finally located in a solder-lug terminal. The lug had been bent over the wire and pinehed with a pair of pliers. Solder was then applied, but did not actually reach the wire. Corrosion under the lug eventually led to a high resistance point. Evidently a good jar moved the wire slightly and altered the contact. A fuse should always be used in a battery receiver. One listener in the Rotorua district has had a set three months, and to date has blown three sets of valves. ZL1BN Rotorua eontinues to receive reports fro mforeign stations though he has not heen on the air for some months. He would appreeiate it very much if the fellow usipg his call would uae crystal control and work Africa so that he will be able to qualify for "worked all continents."

It is often noticed that speakers, especially those of the dynamic type, tend to blast on certain notes. It is usually not caused by any defect in the speaker, but hy the presence of some loose objeet whose natural frequency corresponds with the musical note. A loose valve shield, bolt or screw, stray needles on the metal chassis, or a stray lead resting lighton some metal objeet will usually be found to he the cause.