The HL2 is a dull emitter battery triode. It was designed as a detector in broadcast receivers, in the early 1930s.

We know from the envelope that this was made in England, and this version of the valve has an external metalising for enhanced screening.

The balloon envelope is 40 mm in diameter and, excluding the B4 base pins, is 82 mm tall.

 
Pin Connections

B4	1	2	3	4
	a	g1	f	f

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	2.0	0.1	150	-3	1.8	18,000	1.5

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 12 June 2007 {find valves by name}