FREQUENCIES


Home


Wireless (pre-1920) Radios


Marconi Wireless (pre-1920) Sets


Tubes & Valves


Crystal Set Radios


Antique Radios (1920s)


Antique Radios (1930-1960s)


Antique Radio Advertising


Radio Speakers & Microphones


Articles on Antique Radio I Have Written


Wanted Radios


Tubes for sale


Tube Amplifiers


Defeating Depression book by Howard Stone


Interview of Howard Stone on Tube Talk Classic Radio Show


Early Books and Literature on Radio, Tubes, & Electricity


Contact Me


Round Valve
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.

Unless otherwise noted, all materials contained on this web site are copyright protected. Materials may be downloaded and/or reprinted for personal use only. Permission to reprint or electronically reproduce any document or graphic in whole or in part for any non-personal or commercial use is expressly prohibited unless prior written consent is obtained from the respective copyright holder(s).

Copyright 2003-2004 Howard Stone PhD.
stonevintageradio@gmail.com