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Marconi Radio Valve Type Q, by Ediswan, London, c. 1918
Inventory Number: 74162
Number of documents: 2
Document Type: Miscellaneous Note
Document Heading: Manufacturer Details - Ediswan
Text:
Ediswan, the trade name of the Edison and Swan United Electric Light Company Limited, made this valve for Marconi's Wireless Telegraph Co. Ltd. Joseph Swan, a Briton, and Thomas Edison, the famous American inventor jointly founded the company, as a result of the major court battle they fought over who was the original inventor of the electric light bulb. The company produced all the Marconi valves up to 1919, manufactured at them at their factory in Ponders End, North London.
Some Ediswan valves were marked 'Royal Ediswan' up to 1923.
Document Type: Miscellaneous Note
Document Heading: Marconi Radio Valve Type Q
Text:
The Q valve was probably the first 'hard' (i.e. high vacuum) wireless receiving valve to be designed and manfactured in Britain. Designed by Captain H. J. Round as a general purpose receiving valve for the Marconi Company, its features included small size, well-spaced electrodes and complete enclosure of the filament by the grid assembly.
Type Q valves were produced by Ediswan in their Ponders End factory in North London, from their initial production in 1916 until 1919, when production was changed to the newly-founded Marconi-Osram Valve Co. Ltd. The M-OV, as it was later known, was a joint Marconi-GEC valve-manufacturing company. Captain Round's initial version of the Type Q in 1915/16 was an excellent valve for professional use but had two important problems in relation to military and Merchant Navy purposes. First, it was a high impedance valve and therefore required additional HT batteries, not easily or readily available at sea. Secondly, it was a high-gain valve and required skilful use for HF amplification. These problems were fixed in the later Type R model.
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