WIRELESS NOTES

Nelson Evening Mail, Volume LXVI, 13 February 1932, Page 4

WIRELESS NOTES

A Mistaken Idea There still lingers in the. minds of some amateurs the idea that if you plug into your set a valve having a greater magnification factor than the one previously used the signal strength is bound to increase. As a matter of fact, the strength may remain, or it may well decrease. It is necessary to consider the impedance of the valves, as well as their magnification factors. Of two valves having equal impedances and one having a greater magnification factor than the other, it is possible to say that a difference in the strength of distant stations will be noticed. The reason is that flic amplification of the set is greater with the better valve in circuit. But even this must not he carried too far, for supposing the valves under discussion arc of tlio screen-grid typo, it is possible that by using the valve with the greater magnification factor the set is made unstable. In low-frequency circuits, however, it can he predicted pretty closely what will happen when the valves having known characteristics are used. In high-frequency circuits it is not possible to say what will happen, as the characteristics of the coils and the circuit generally are important factors. Some screen-grid valves are better shielded than others with the result that pure amplication effects arc masked by various reactions. A Good “Radio Voice”

It is a privilege to go into the living rooms of listeners —that is the attitude that should lie adopted by speakers before then, microphone. Radio, to tlio man with a message, is a most effective weapon if the messenger has. something listeners consider worth hearing and lie says it in a tone that carries conviction.

Tile great trouble with the majority of radio speakers is that they use too many polysyllabic words and involved compound sentences. They arc not speakers —they are lecturers, orators, readers of the written word. Others seem to “talk down” to their audiences, or to give that impression. There is no need to “get down” to one’s audience; it is rarely the audience is loss intelligent than the speaker! The quality of the voice on the air means much. The microphone magnifies the bad qualities in a voice rather than the good ones. Voices that have warmth, sincerity and force are rare. Listeners recognise them instantly. Reading a speech properly is far from being a universal art. Few radio speakers —except an occasional regular announcer —have acquired it. Nothing is quite so monotonous to hear as the “parroting” of a speech that might readily lend itself otherwise, to the aims originally intended. Such “parroting” is a direct reflection on the intelligence of the listener. Only those who have respect for the listener will succeed as radio speakers.

Few Knobs on Sets Now Early wireless sets, like early motor cars, were fearsome contraptions to work owing to the huge number of controls that were needed to operate them satisfactorily. I have just been looking at a photograph of a set of mine built in 1923 which contained five valves and had no less than seventeen knobs, each of which really did something (writes “Detector”). Compare this with my present long-distance receiver which, though it has seven valves, is controlled by two knobs only. One of these docs the timing, the other regulates the volume. There arc absolutely no others. And the volume control is so arranged that when you turn it to the minimum position a littlo projecting arm automatically switches off the filaments. In a year or two at the outside the knobs may be reduced from two to only one. Experts are working now upon methods of making the set automatically regulate its own volume. The results so° far obtained are very encouraging, though means have still to be found of making a device sufficiently simple and sufficiently foolproof for general use. What happens is this. The owner of the set decides upon the volume that ia most pleasing to him and most suitable for the rooms in which reception takes place. Having tuned in, say 2ZK, to the volume he adjusts a small indicator which never needs to be touched again. Every station within the powers of the Bet then comes in with exactly the same volume. Should the transmission be rather weak the . automatic volume control increases the magnification until the desired loud-speaker strength is reached. If, on the other hand, it is very powerful, the magnification ia reduced automatically, so as to keep the volume to the desired level. The wireless set of to-day with its usual tuning knob, volume control knob, wave-change switch and filament switch seems simple enough, but it may be regarded in a few years’ time as a surprisingly complicated device.. Simplicity of operation, though, is apt ,to entail cither a loss in general efficiency or a considerable increase m cost, for clearing the panel of knobs means as a rule using more complicated and more expensive components within the set.

Useless Detail Under the new regime a feature noted has been the condensation of the opening and closing announcements. K is a moot point whether the blue pencil might also be employed on the market reports, which merely reiterate what lias been stated in previously-read cables. There is big scope for a vast improvement in broadcast news sei - vices. Much useless detail comes over the air. It has to be borne m mind that information in its most suitable form for reading silently is not always most effective when spoken over the air. With the naturally slower pace

of the latter, sentence condensation is frequently advisable. Powerful Radiation One of the loadin'; British radio firms lias produced a short-wave transmitter capable' of propagating waves which will severely burn anyone standing near the aerial. It is reported that the radiation is so powerful that a coil of wire of a certain length, held near the transmitter, emits a long flame at both ends. This effect is due to both the extremely short-wavelength used —5 metres —and the high power of 20 k.w. “Request Item Wanted” An Auckland station received a ’phone call from a listener during the transmission of what was supposed, to be a popular programme. “Would you put over a request number?” inquired the voice at the other end. “Well, we are not allowed to give request numbers,” was the reply. “Go on. Be a sport. We want this one very much,” came the appeal. “Oh. all right, then, replied the announcer. “Thanks ever so much. Play us ‘God Save the King* will you please,” hit back the voice from afar, and up went the receiver. At the other end stood an announcer with a receiver in his hand, his tongue between his teeth, and a far away look in his eyes.