RADIATION

Radio Record, Volume I, Issue 13, 14 October 1927, Page 5

RADIATION

ADVICK FROM MR. BILLING. A talk by Mr. Preston B. Billing, delivered through Station 2YA, upon radiation covered the following points of inferest to listeners. "It is unnecessary to explain what is meant by the term radi-ation-we have all experienced its effects from time to time, much to our disgust. You have often listened to a fine broadcast item and been enjoying it when all of a sudden Mr. Squealer attives and completely mars the remainder of that item and very often the whole of the items for the evening from that particular station Nor does he confine his attentions to the one station, he seems to be like some of our American listeners endeavouring to log AS matiy stations in a single evenitig as. @ possibly can. You know the game or have read it-he totals up the avgregate mileage of the stations heard and as lony as his mileage for the evening exceeds that of his nearest competitor fre declares himself the w'nner. Tt is small wonder with operators such as this in our midst that we can hear anything decently at all. "These howls or squeals which are heard from your loudspeaker are cansed through nearby radiating receivers. It is hard to lav down a speciiie distance over which one can heat this form of interference, but it docs run into miles and that with very simple apparatus can give us quite a deal of atiriovarice. "This radiation is occasioned by cerfain types of circuits in receiving scts and also hy improperly handled receiyers and those which haye been imperfectly neutralised. "Y would suggest first of all that receivers of the Armstrong type (that is the three coil, double and sinvle circuits) be discarded. Possibly the parts could he used in an improved and imore ip to date set, preferably with one ot fmore stages of neutralised hieh frequency amplification on the Huazeltine Principle. "If it is not possible for one to do Chis a cheaper wavy would be to convert €. to a Browning-Drake or else add a stage of high frequency on the lines Suggested. In any case it is nothing short of criminal for parents to allow their children to operate a receiver of he type mentioned (Armstrong). Peraps there is a young boy in the family who is heing encouraged to do his own constructing and operating, there is nothing wrong with this provided the pareut or perhaps a helper who really understands radio can assist by seeine that the right type of circuits are feing used, and who will also see at the neutralising process if the receiver is of the neutralised type, is cortectly carried out. ‘This adjustment should he made at a time when as little interference as possible will be caused to listeners. "The neutralising process is a fairly Gomplicated one for one who is inexperienced, and I am not going to take up your time with a technical talk as to how it is done. Instead I am going to explain: as simply as possible how you = — —

can tell if your receiver is radiating or not. If you have a friend who lives close handy you could arrange to carry out a test on these lines. Arrange to listen on the same wave-length with both receivers at a predetermined time, each man operating his receiver to get the most out of it, and notice if any whistles are picked up at a certain spot on one or the other of the sets. It would be better if one set were set to a wavelength such as Christchurch, for instance, both listeners then retiring to the home of the other listener, to proceed to fish about on this wave-length and notice if any whistles are picked up, use headphories and listen very in- [ tently, if no sounds are heard it is safe

to presume that the receivers are reasonably free from any tendency to oscillate. "You can also ascertain by touching the aerial wire with your finger. If the receiver is radiating there will be a noticeable plop when the finger both touches ami leaves the aerial wire. There is of course a difference between signal interruption and the foregoing test. Do not mistake one for the other. I trust you will let inv remarks sink in. Te concerns you and the other fellow as well. Do make an honest endeavour to keep this nuisance down. With the advent of more receivers there is the nossibility of still more trouble being experienced. The cost of converting that old set to a modern one is not big and will give the builder or owner a good deal better entertainment and in addition he will be blessed by all his: neighbours." (Loud applause from all. sufferers).