Questions and Answers

Radio Record, 4 September 1936, Page 48

Questions and Answers

"AS" (Spreydon): You do not give any particulars of the condenser; but we assume that it is 0.0005 mfd. per section. If this is so, approximately 182 turns. of 80 enamel S.W.G. wire on your formers would do for the secondary. The primaries can be up to 40 turns each of the same gauge. but the maximum you ean use will depend on the extent of the shielding and by-passing, as the set will oscillate if the primaries are too large for the amount of by-passing. These turns will do to start with and can be subtracted from depending on the operation when finished. If the coils you have already are a set by a good manufacturer, be sure that you are not blaming them unnecessarily and that you have not got ‘ong leads which upset their performance. UZZLED" (Lower Hutt): An aerial would make all the d‘fference in your reception both on broadcast and shortwave ‘bands. The reverberation you mention may disappear when the aerial is used, but if not, havea serviceman look at the speaker, as it may, have a little grit in the air gap or the coil may not be. quite central. "I 12° (Punakaiki) : The receiver that you have is very like the ‘"Duodyne One" which was. described in the 1936 "Radio Constructor’s Guide." except that the transformer in your set is replaced by what is known as ‘resistancecapacity coupling between the detector portion and the audio portion. The trouble that yon are having could be due to the transformer breaking down in insulation or its wires heing eorroded: We suggest that you have the set overhauled by a serviceman, and further suggest that if the transformer is faulty it "would be quite satisfactory for him to change the cirenit to that of the "Duodyne One," as this set has given very good results. ‘Ty: MLL." (Auckland): It is quite a good idea to put the R.F. stages of the "De Luxe Shortwave Six" ahead of the detector and audio of the "Trans-Pacific Four" if one has that already built up but the method of promoting regeneration in the first R.F,. stage should definitely be retained. The actual arrangement of the components should follow the layont of the "Shortwave Six," and should be followed very closely, at least up to and including the detector. if the full benefit ‘of the cireuit and design is to be obtained. Keen the 6F7 nearer the 42 in your proposed Iayout and keep all leads short. OUBLE DOUBLET" (Thames) : The trouble that. sou are having ~ with th's serial is certainly not the usual thing The switch seems to be reversed for ‘one’ thing. Not’ knowing any details of the particular aerial that you are usiag, we cannot form any idea of the eanse. It may’he a faulty one. and awe suggest that von refer’ yvonr. trorble to the dealers from whom it. was-bought, -V.C." (Clyde): Yes,..it- is feasible to add AVC to vour receiver and the valve that chonld he sed world be either 5H or 9PR7.. Ann'v the AVC voltages to the RF and TR. steeeg, Cir cnits. sre given in the "Radin Times" and the "Radia Conctrnetar’s Guide" fer this nortion. and thev apply to » efther T.RLE. or superhets alike.