| This reminded me of the story of the EF50 valve and 'PYE IF strip', so I've added a submission: https://news.ycombinator.com/item?id=25735404 'The history of a pioneering tube that was developed by Philips Research and that was, next to the magnetron, “The most important tube from World War II” - Ronald Dekker' One of the problems Bowen was facing was that while early 1939 all components of the Airborn Radar seemed to have fallen in place, he still had only one receiver which up to that moment no supplier had been able to duplicate. But then quite unexpected his old professor comes up with a golden tip: "Quite by chance in april or May of 1939, I heard some encouraging news from Edward Appleton, my old professor at King’s Colledge and now Jacksonian Professor of Physics at Cambridge. He told me that the Pye Radio Compagny, still hoping that there would be a television industry in Britain, had set up a production line for 45 Mc/s TRF chassis and had actually made a trial run. I went hot-foot to Cambridge to see B.J. Edwards, the Technical Director of Pye Radio, and was rewarded with a remarkable sight – he had scores [!] of TRF chassis just the type we were looking for. These used a new valve with an octal [sic] base, which had not yet appeared on the market. It was the EF50, a valve which was destined to play almost as important a part in Radar war as the magnetron itself." Bowen took a few samples of the Pye chassis back to Bawdsey and quickly verified that it was significantly better than their old EMI chassis; it was also smaller and lighter. Touch and his men quickly put a 200 MHz mixer (at that time still based on an acorn tube, but later replaced by an EF54) in front of it and the receive problem was as good as solved.
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