Useful All-wave Set

Radio Record, Volume II, Issue 44, 17 May 1929, Page 26

Useful All-wave Set

. No having noticed reports of reception of 7LO, Nairobi, in the shortwave notes during the last few weeks, it might be of interest to know that 7LO is coming in here at good strength in the mornings, closing down 6.30 a.m., on 31 metres. I do #ot now bother with stations I cannot get on the speaker, as I am too busy to sit with the phones on, and my morning programmes up to 7 a.m. are provided. by. PGJ,; 58W, 8L0O, and TLD. My set is an all-wave type, built specially for low-wave, but giving good reception on long-wave. It is all aluminium, 1-16in. thick, no wood being used, and measures 24in. long, 12in. wide, and 8in. high, and as audio portion (2 stages) take up 6in. only of the length, it will be seen that detector and.screengrid stages are roomy. All coils are 3in. diameter, shortwave ones being 16g. tinned copper, space wound, and broadcast coils 28g. d.s.e., all ticklers being 2 7-8in. diameter, and fitting inside their coils on 2 pins, allowing of movement if required. All coils wound on air. Formica stages, lin. above base, carry the coils (and valves), which plug into flush valve sockets, arranged in the stages. Variable coupling provided for aerial coils. Variable grid-leak .1 to 7 meg., with potentiometer, 400 ohms, right alongside detector valve, both of these being operated with long +in. ebonite rods. All stages well-shielded,. variable condensers,’ .001, special low-wave rheostats on detector and screen-grid filaments, first quality valves and transformers, H.T. battery is 144 volts, home-made, as is the set. Output fitter as per "Radio Record." Regarding this latter I had an ‘experience. I cut over 100 pieces of tin, varnished them, and hung them on a line to dry. Unfortunately the varnish did not dry quickly, and next day I found I had caught about 100 flies and moths. Their legs dé not seem to affect the reception, though. 4MF condenser is used with this. 2MEF condenser across first audio, HT tapping, 1MF condenser across each of detector, and screen-grid tappings. The formica panel, carrying jacks, ete., is across end of set on outside of audio stage, and fixed condensers, output fitter, ete., are all confined in this stage. Ne earth is used on shortwave. The HT battery gives very good results, in spite of the fact that it is home-made, and lasts about four weeks on a charge. It is in two blocks of 72 volts each, about the size of a handbag (small), and fitted with a handle. There is a valve base fit ted to each, and two bases of valves have all the H.T. flex leads fitted, so that the work of connecting up HT takes about two seconds. I must now state my appreciation of your excellent paper, to which I owe practically all I have learnt about wire. jess, since I byilt my first crystal set about one year and eight months ago. I must not forget to mention that hand capacity is absolutely unknown, and once tuned set need not be touched. I must add, that when "Megohm" notified his intention of leaving, I thought your paper would hold no further interest, and must congratulate you on obtaining the services of his worthy successor, "Pentode."

W. T.

WEBB

(Devonport:)