The HL2K amplifier triode has a directly heated 2.0 Volt filament and an anode voltage of 150 Volts. This indicates a valve for battery HT operation and a 2.0 Volt accumulator for the filaments. This was almost certainly a valve for broadcast radio reception.

The valve has a vertical box anode suggesting 1930s origin. The filament is a thin wire single inverted 'V'. The grid is hidden by the anode but the supporting rods can be seen protruding through the mica supports.

The wide glass tube envelope is 25 mm in diameter and, excluding the B4 base pins, is 64 mm tall.

 
Pin Connections

B4	1	2	3	4
	a	g	f	f

 
Absolute Maximum Operating Conditions

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

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This exhibit was last updated on 29 July 2006