‘QQE’ RF power double tetrodes (ca. 1950)

Happy with the good response I got to two previous Retronics stories about little known valves like the Dekatron and E1T, I decided to dig out some more ‘rare glass’. The principle of the push-pull power output stage is well known for its application in audio amplifiers using valves like the EL34 (6CA7), 6L6 or EL84 (6BQW5) to mention just three. And it works for RF too using golden oldies like the 807 beam tetrode which will happily work up to 30 MHz or so.