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 wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 62 mm tall.

 
Pin Connections

B8B	1	2	3	4	5	6	7	8
	g3	s	g2	g1	a	k	h	h

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.2	250	100	-2.5	6	1.7	1.2M	2.0

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 30 March 2008 {find valves by name}