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Mullard Radio Valve Type EF37A, by Mullard, England, Mid 20th Century
Inventory Number: 69132
Number of documents: 3
Document Type: Miscellaneous Note
Document Heading: Historical Background - British Radio Valve Manufacturers' Association (BVA)
Text:
The British Radio Valve Manufacturers' Association (BVA) was established in July 1926 and was a registered trade union. It had been preceded by the Valve Manufacturers' Association, which had established a 'Memorandum of Sales Plan'. This agreement, which was signed by the seven major British valve manufacturers, secured a uniform practice in the sale of radio valves for broadcasting purposes in the UK. Practical examples included similar discounts and sales conditions, and were considered a form of restrictive practice. This association continued into the 1950s.
Document Type: Miscellaneous Note
Document Heading: Historical Background
Text:
Valves of this type were used in the original Colossus, the world's first large electronic valve programmable logic calculator, first built by the British in 1943. Ten of these were built before the end of WW2 and used at Bletchley Park to decrypt German codes including the most complicated German code, Lorenz.
Document Type: Miscellaneous Note
Document Heading: Technical Details
Text:
Mullard designated the EF37A as high gain, high impenance pentode for use in AF pre-amplifier stages. The electrode system was of anti-microphonic construction, and the specially designed heater reduced hum to negligible proportions. High quality amplifiers used the EF37A for many decades with the EF86 as its successor.
Data sheets also gave parameters for use as a triode.
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