Output pentode / Endpentode
As in the UK high-gm output pentodes were launched yet in 1933, this new genre of tubes came to continental Europe as the AL3 appeared in late 1935, with a round cathode and a gm of 9 against 2,5 mA/V of earlier types as a new standard in Europe which remained until the end. Early 1936 appeared the almost equal AL4, with the better profile cathode.Telefunken sold it also in two beam-power-tetrode versions.
