TWO-VALVE PORTABLE IN LONDON
TAYLOR, B.Sc., M.I.R.E.
A small portable two-valve set was used in London in connection with a number of experiments. The set consisted of a detector-valve, followed by a resistance coupled low-frequency amplifier. Complete with phones and batteries, it weighed about 91b. Within ten miles of 2LO moderate loud-speaker volume was got. The first test was in a train on a six-mile trip. Here there was more than phone strength, and quite clear transmission was got, free from all microphonic noise and distortion. Slight fading was experienced in tunnels, with a larger drop in signal strength in the long tunnel at the terminus. The results were good enough to indicate the possibility of its use on short train journeys. The next trip was on a bus, where good reception was got above the roar and bustle of the traffic. In a steel tube-station 50ft below the surface, the best that could be got was a carrier wave, but no recognisable signals as might be expected. In a steel building, reception was good in the basement 30ft below the surface, but on going up the lift the signals died away until on the roof, where they were about the same strength as at ground level.
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https://paperspast.natlib.govt.nz/newspapers/SUNAK19280314.2.111.4
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Sun (Auckland), Volume I, Issue 303, 14 March 1928, Page 14
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207TWO-VALVE PORTABLE IN LONDON Sun (Auckland), Volume I, Issue 303, 14 March 1928, Page 14
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