The EF50 the tube that helped to win the War

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  The radio valve factory of Philips in Eindhoven was the scene of unusual tension and activity in the evening of the 9th of May 1940. The Germans had been building up an enormous armed force near
The EF50 the tube that helped to win the War - schematic

the Dutch-German border, and the people in Holland realized that it was only a matter of time before the Germans would invade their country. This threat was in itself enough to give the nice spring evening an almost unreal and un-earthy atmosphere. On top of that, for the past two months the factory had been working frantically to produce an enormous amount of radio valve components for an unknown customer with an unknown application. Duplicates of special machines to make these components had been hurriedly put together and all these components and machines were now loaded into a truck that that same evening left for the Dutch coast with England as destination. When the truck left the gate of the Philips plant nobody knew that hours later, at 5:30 the Germans would indeed invade Holland. Certainly nobody of those workers, who as the sun set waved the truck good-by, could have imagined that that truck was actually carrying components which were vital to their liberation five years later! As by miracle the truck made it to England although the ferry which carried it was bombarded by German airplanes. These dramatic events marked the start of the life of a radio tube that, not only would play an important role in the outcome of the upcoming war, but that also would be the mother of all modern all-glass radio tubes. The EF50 RF penthode constitutes a landmark in the history of the radio tube. Before the EF50, all radio tubes...

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