Sensibly equivalent¶ to:
The EF22 is an early example of an all glass construction amplifier pentode. The metal spigot holder is located on the glass base by a shaped pillar for one of the pins, and then held in place by a metal sleeve. The pins themselves are of short hardened type.
The pentode is described as of variable mu. That is that the characteristic curve is such that different amplifications are possible by varying the grid bias point. Mullard describe the EF22 as primarily intended for use in DC/AC mains operated equipment in the role of RF or IF amplifier.
The mesh screen obscures most of the internal details but the anode can be made out as two vertical plates with the rest of the circumference left open apart from a securing strap.
The wide glass tube envelope is 27 mm in diameter and, excluding the B8B base pins, is 61 mm tall.
References: Datasheet & 1040.
Absolute Maximum Operating Conditions¶
Updated September 28, 2018. shape:wide.glass.tube construction:all.glass type:pentode age:1940.1950 base:b8b heater:6.3v pins:8 pin:1.h pin:2.a pin:3.g2 pin:4.g3.s pin:5.- pin:6.g1 pin:7.k pin:8.h