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At last, Heaviside's theory of a conductive layer in the upper atmosphere was experimentally verified. Amplifying work done in the previous year, Appleton wrote an article showing how, by a method of distinguishing between waves travelling horizontally and those arriving in a downward direction, he had concluded the height of the layer of ionised air at night was 50-100km.
The introduction of the screened-grid valve in 1927 (S625) enabled higher RF gains to be achieved with stability
The first public transatlantic telephone service was opened and we conducted a campaign for Empire broadcasting on short waves.
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