Dealing with Distorted Reception

Radio Record, Volume I, Issue 40, 20 April 1928, Page 12

Dealing with Distorted Reception

SEVERAL CAUSES AND THEIR CURE

s Mo ISLENERS who reside at m| cousiderable distance from anv main broadcast station may be inclined to think Ai that those at closer quaromar ters have little to complain of, aud that "everything in the garden is lovely." Such a view is to some extent a mistake. Certainly here in Wellington we have the evening, session on six nights a week, wninterrupted hy howling of any description. ‘hat co

is something to be thankful for. But midnight is a popular time for city people to retire, and the time after 10, p.m. may be filled in with reception of Australian stations. It is at this time that everybody in New Zealand is on somewhat of an equality with regard to conditions, the isolated set owners having, if anything, the best of it, for the howling valves in populated centres detract greatly from the pleasure of listening until, one by one, a sufficient number of oscillators has retired to bed, leaving reception more or less unmarred. ‘hen there is the ‘silent night"-anything but silent with regard to oscillators, but it affords the writer a spleudid opportunity of studying the interference problem. In many suburbs of Wellington reception of musical programmes from distant New Zealand stations on the silent night is useless from an entertainment point of view, so in order that oscillators may indulge in their mnocturnal wrist exercise, others are debarred from receiving programmes that would otherwise be available. It is quite evident that a set requiring continuous movement of the dials is not getting any reception that is of any value, except as "something instead of nothing" to the operator.

| MOREOVER, it is quite evident to | the experienced listener studying interference from howling, that a set requiring a heroic struggle with the dials for perhaps a quarter of an hour cannot be one of ally magnitude, as the owner of a four or five valve set will be able to tune in any New Zealand station in half a minute or less, and that without howling--if he knows how, and uses only ordinary care, even if the set is not a neutralised one. Iverything appears to point to the one and two-valve sets being the creators of a large proportion of the disturbance in the ether. But it must not be thought from this that the writer wishes to discourage the use of small scts-far from it, for beginners must learn. But everybody would like to have such beginners as careful of other people’s rights as they would have to be when learning to drive a motot-car. But there are large sets, too, that do their share of interfering, frequently in ignorance, for often a listener who knows nothing about radio will have a set installed, aud is informed that it "cannot possibly annoy the neighbours,’? when otherwise is actually the case.

It is not always the constant moving of dials that is the miost annoying. There is the set owner that tunes-in a station and leaves the set oscillating, with the result that his neighbours receive that station to the accompatiment of a continuous whistle, which is, to say the least, extremely irritating. The wet finger test on the aerial terminal will give an indication of such oscillation by the two clicks-one whet the finger touches the terminal, the other when it is taken off. DISTORTION FROM INTERFERENCE Now the purpose of this article is to emphasise the great amount of © distortion caused by interference from oscillating aud radiating sets. Wheu listening to distant stations aud getting full yolume on the loudspeaker, the writer has frequently experienced the effect of one violently-interfering set practically "wiping out" reception for a few moments. Then there is the cumulative effect of a certain amount of radiation from a number of sets all receiving a distant station-the joint effect is a general weakening of volume, at bad periods reducing it to such’ .«n extent as to be worthless for entertainment, But this is not all. DISTORTION PRODUCED IN THE SET. N° matter what good quality recep- ° tion a receiver is capable of giving, quality is impossible where there is much interference. An oscillating valve communicates a reflection of its mutilated and distorted signals to other receivers close at hand, and though its influence may be only slight, quality is affected. But suppose we have a

receiver that, under best conditions, is not capable of producing quality with the volume it is expected-to give. With outside distortion added to such reception, the result may be anything but pleasing. A listener naturally likes to think he has made a good bargain when purchasing his set-and quite likely he has. But the stumbling-block in radio reception is the thirst for volume-the desire for signals to ‘‘roar in." Certainly a receiver that brings in the music with tremendous volume will give good and pleasing quality if it is toned down to a reasonable strength, but it is necessary that this should be done. Raspy or gritty tone is to be avoided ‘at all times-it is bad for the nerves. A smooth, mellow tone is soothing and restful. TRACKING UP CAUSES OF DISTORTION. DURING the past few years the writer has been up against this problem of good reproduction, contivually making improvements to produce (Continued on Page 13.)

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