QUESTIONS AND ANSWERS

Radio Record, Volume X, Issue 3, 24 July 1936, Page 48

QUESTIONS AND ANSWERS

"STATION 94K/A" (Invercargill): Is there a one-valve or two-valve A.C. receiver which could be adapted to put in a portable case? A.: In the July, 1985, "Radio Times" we described an "A.C. Twin" which could be adapted for this use. Copies of this issue are available at 1/1 posted. ‘K J.D." (Te Kuiti): My TRF. has * developed a fault, in that the volume drops with the volume control on full and gives the maximum with the volume controlled a shade back from full. A.: This fault may be due to the volume control itself, as some, when worn a bit, have a higher resistance at the low resistance end than they should. A clean here with petrol will often fix things, otherwise a new control is indicat-

ed. But withthe other question you ask, about the hum and heating of the transformer, there seems to .be more than this, You should check all resistances for value, both when cold and when hot, and also all condensers. It almost seems that a bypass condenser, most likely on a Screen, has open-cireuited. It is difficult to advise definitely without seeing and hearing the teceiver itself. 2. There is a closed circuit jack in the detector cathode circuit. Is that for pick-up connection? A.: Yes, the jack is evidently there for that purpose, st A &8CHIb" (Nelson): My aerial runs over the roof for about one-quarter of its length. Is this a disadvantage? A.: If the aerial is near the roof and the roof is iron, then it is a disadvantage. 2. How should an aerial be erected to obtain the best results? A,: The aerial] should be clear of allobjects as far as possible and as high as it is eonvenient-tg put it; height at the expense of length. About 100 feet of wire altogether, from the aerial terminal to the far end. of the aerial, is about the average, and if the aerial is supported on Lil poles then the far end should be the igher. "COMMANDER EIGHT" = (Sydenham): Thanks for your letter giving us the results you have had with our sets. . The trouble you are having seems to be in that instability that you term "slight." A common cause of whistles and broad tuning is instability in either an R.P. stage or IF. stage, and the only cure is to track the point where the instability comes in. It may take some time.to do this, but the set will not be of much use till you get the set stable. Check your bypassing and see that there is no coupling between wires under the chagsis, et. » We sympathise with you this time!

BecAUSE "most of the complaints made to the police about noisy, wheezy, ill-regulated radio sets refer to very old apparatus,’ Austrian radiv . manufacturers recently destroyed. . about a thousand. old receivers. The idea began in Denmark. ‘The radio firms give sets not more than two years old in exchange for the old ones, ‘at a nominal price or none at all, and when fifty or a hundred old sets have . been assembled, a few strong men with { sledge hammers are let loose on them in the presence of the firms’ direc- io tors, ‘

Information Coupon (To be used with ali requests fu: information.) Name Of Set ..sscceiscccsseseecerers, Model Sovccsecesteontecescosecsceete Name , Vneeedvesccscsececeseceracess Address TOS eererereseceeneevestuses "REPRO SHOOT PROSE Teer ECE ET ESSOOaH EE Ees SOPH OHOARH COTES COOH EAesesEeeeseaeors Nom de plume SP eoeaeevesseeseeseses Please Note:-- © 1) Be specifie and brief. We do not design circuits foindividual requirements, (3) Limit three questions unles 1/- is enclosed. (4) Postal ueries .imit 8 ques tions, Suclose stamped and addressel envelope and 1/- fee