[petesoper]

Eimac, founded before WW2 but now some division of some corp, is the gold standard for amateur radio amplifier tubes and is still used by governments. They developed technical advantages while making a lot of radar tubes during the war and amateurs scooped up the surplus and later became regular customers and then commercial suppliers like Collins designed them in. They were part of Varian for a while and make modern very high power klystrons among other things.