Am I Howling?

Radio Record, Volume I, Issue 34, 9 March 1928, Page 4

Am I Howling?

THE UP-COUNTRY NOVICE

— STATES HIS DIFFICULTIES THE CASE DIAGNOSED.

(By

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AW radio enthusiasts sympathise with the up-country novice listener whose remoteness from the centres of settlement renders his plight most trying when he encounters trouble with his receiving set. ‘to make matters worse, his frequent unfamiliarity with even the elementary technicalities of radio prevent his supplying a lucid explanation of his troubles, and necessary data regarding valves, battery, voltage, etc., when he applies to a city radio writer for assistance. This renders the feat of diagnosing the trouble in the up-country novice’s set a most difficult matter for the radio writer, and adds to his labours enormously. ‘This is not intended as a reproach to up-coun-try correspondents, but it may stimulate them to endeavour to supply fuller particulars regarding their equipment, such as make and type of valves, hattery potential, age and type of batteries, character of aeria] and earth, make and type of loudspeaker, make and trade number of receiving set, etc. Upcountry correspondents will realise the difficulty that would confront a medical practitioner if he were called upon to diagnose the ailments of patients by correspondents, even if they gave the fullest particulars as to the symptoms. It is certain that even the most skilled ‘and experienced doctor would not commit himself to a diagnosis in the majoritv of such cases. The position is somewhat akin in radio, for a receiving set can develop ‘sickness’? from various and widely different causes, just as a pain in a natient’s body may he due to different diseases. " The Case Stated. HE following letter from ‘'R.J.M." (Urenui) has been handed to me for consideration. The writer of it may be classed a type of listener whose isolation places him at a great disadvantage, so that he merits whatever assistance can be rendered. Ss "We have a five-valve -- set, and are much annoyed by a horrible distortion in reception (at times), which I can only describe as ‘nasal.’ Frequently, too, squeals and whistles continue for some minutes. In answer to a disparaging remark re ‘howlers,’ I have been told that ‘perhaps your set annoys the others.’ Now there has never been the least suggestion of ‘squeal’ or ‘whistle’ when tuning in on this set. Is it possible for any- set to develop ‘howls’ after a few minutes or a few hours’ perfect reception? Qur set was bought second-hand, and we do not know from whom it was procured in the first place. The only knowledge that we have was learnt from Cassel’s_ *Simple Valve Sets,’ and from newspapers, but nowhere can I find a suggestion that a set can ‘howl’ without the knowledge of the ‘tuner-in.’ "Qur experience of 2¥A is ‘no fading, but rather low yolume in the afternoons,’ and ‘plenty of volume but much fading’ in the convert session. We invited quite a few friends to hear the Maori Pageant--25 all told ‘listened in’? on our set. ‘he nearest sels are about four miles on either side of us. "Sinee writing the foregoing I have found, in the ‘Radio Record’ of Vebruary 17, two items re oscillation, which is, I believe, ‘howling.’ Firstly, that a set builds up a ‘howl? from the loudspeaker, and, secondly, a simple test for oscillation. Now, this seems to verify the gentleman’s assertion that our set can annoy others. But, in such a case, would the ‘howling’ or distortion, as deseribéd, cease immediately on ‘tuning in’? to some other station? Now, Jast Monday we could not enjoy the concerts ‘from: either 2YA\ or 3YA, but from 2bI, got a good lecture on Hawaiian "music and later the concert came in quite equal to anything- we hear in New Zealand... Also we. frequently Jiave to-‘tune out’ from JYA which. is. gencrally our best reception, It .is YA. from which we get that, ‘nasal’ — distortion. We cannot get 4QG at all distinct, it scems, to have a distortion similar to a noise that can be evolved on, oar set by wrong adjustment in the, speaker. We are rather anxious tc ascertain the truth abont the ‘howling’ as we ‘tune in’ every day Sometimes, as during the Tasman figlit, and the Maori pageant on the Tuesdes night, we have have had our set ‘tuned in? from the afternoon session, openit at 3 p.m. te the finale,’ and have heard 2B, close done and BEC rebroadcast from 21,0, so if we are annoying anvone, we are doing it thoroughly." "T have kept this letter open io give you the result of the ‘simple test’ of which I zeid. This test was applied on ‘tuning in’? to TVA last evening, and again when a ‘howl developed, and there was a total absence of anv ‘click’? or sound of any kind. While I am writing T may say that we sometimes get a lot of intermittent buzzine. I think it is Morse, Some other sounds we located as looze connections. ‘These particular noises were very bad last Monday night. and we tried every connection around the set, but failed to locate any noise from them. However, on ‘tunning in’ to 2B, the noises ceased," FORM." has supplied the name of his set, but it is quite unknown to us. ~-Ed.] Possible Catises Discussed. ROM the above it will seem at first . glance that "R.J.M." has contradicted himself in the first portion of his letter, He says, ‘I’requently, too, saneals and whistles continue for some minutcs."* Further on, he writes, ‘Now

there has never been the lease suggestion of ‘squeal’ or ‘whistle’ when tuning in on this set."? Statements of such a seemingly completely conflicting nature may, however, bear a different construction. Possibly ‘‘R.J.M.’? means to conyey that while actually tuning in, there are no squeals or whistles, but after he has tuned in they commence. His troubles appear to be :- (1) A "Nasal" distortion at times from some of the New Zealand stations, but no such distortion from 2BL, Sydney. (2) Squeals and whistles which continue for some minutes. (3) Howls, which develop after a few minutes or a few hours’ perfect reception. (4) Intermittent buzzing. Detailed Consideration. Let us examine his complaint about "nasal" distortion. At the outset it is quite possible that this distortion is due to the action of some neighbouring listeners . (even four miles away), tuning their sets so that they are slightly oscillating. ‘"‘R.J.M." admits that at times he gets perfect reception from 2YA, Wellington. On

such occasions it IS possibie that iS neighbours are either avoiding oscillation, or that they are listening to another station, or, further, not listeningin at all. Then, again, there are certain areas in Taranaki (where he resides), which ate subject to intermittent distortion, due to some natural, obscure cause, such as absorption by sub-terranean mineral belts or intervening high land absorption of radio waves from north or south, but not from the open sea space westward. Other Points. Poe squeals and whistles (2) are possibly the "howling’’ valves of ! neighbours. ‘They may also be due to | excessive use of reaction in ‘R.J.M.’s" own set. Ife does not state his set is regenerative, as he evidently does not know. A corroded "B’ battery connection | will sometimes cause squeals, as also | ! | | , will too much or too little ‘B’ battery potential on his detector valve, the type and make of which he docs not mention, , The howl referred to (3) may be anything from the howling of a neighhour's valyvé to ai howl = develuped on the audio side of his sct--not on the acrial side or radio frequeney side of his detector valve. It is quite evident that his set was not oceasioning interferencé "with other listeners, when he "applied the test by tapping Iris aerial terminal with a moistened finger, and heard no cli¢k in his loudspeaker. The audio howl may be due to various causes, among which ‘are inter-action between the audio-transformers through being badly placed in relation to each other, an acoustical effect on the detector valve through the loudspeaker being plaecd too near the set or pointed towards it, or, even through the use of-an ¢xtra long twisted-flex londspeaker cord. dnoping in the Dark, ] TAGNOSING -this trouble at a-dis-tance is "like ‘groping © in the dark. Run-down, or exhausted, ‘B’’ batteri¢s caused a howl in a loudspeaker which the writer was called upon to examine recently. If a 45-yvolt 9 drv

-_ "BRB battery is down to, say, about 36 volts it should be thrown away. To prevent the how! due to the length of the loudspeaker cord a fixed condenser of, say, .002 mfd should be soldered across the loudspeaker cord close up to the receiving set. To prevent the londspeaker causing the detector valve to howl through acoustical effect, the loudspeaker should be moved away and pointed away from the set, or a tubber sheath, such as a section of an old bicycle rubber tube, should be fitted over the valve itself. (PHE intermittent buzzing (4) seems to be ship ‘‘spark’’ transmission, which is drowned out when 2BL, is tuned in. "R.J.M." need not be perturbed by the blurring of 40G, Brisbane. For several months past reception, in New Zealand, of that station has been badly distorted. One could go on, almost by the page, suggesting possible causes of "R.J.M.’s" difficulties, but I have mentioned the most probable. On the other hand, a personal testing of the set would most likely reveal the position in a couple of minutes.