Stone Vintage Radio Museum - Antique Radios, Wireless, Crystal Sets, Tubes, and Valves

Captain Henry Round was one of the leading consultants of Marconi's Wireless Telegraph Company. He specialized in the design of valves (tubes) and radios that used them. Round's early tubes were designed for performance, not for the mass market. They were handmade until 1919. The Round Valves were introduced in 1911. They were partly-ionised gas filled. At the tip of the valve is a piece of asbestos that contains gas adsorbed within it. The operator would heat the asbestos (for example, by holding a match under it) which would allow the asbestos to release some of the gas it was holding and replenish the gas needed in the valve for optimal operation.. When the valve was cold it slowly reabsorbs some of the gas again.

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