The VR21 is a battery triode as supplied to the Royal Air Force. The R indicates a receiving valve.

The directly heated filament is designed to be run from a 2 volt accumulator, and takes the form of a fine wire supported as a double inverted V. The filament is kept under tension when hot by two coiled springs seen at the top of the node assembly.

The balloon envelope is 42 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	0.1	120	-6	7.5	7000	1.6

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This exhibit was last updated on 07 October 2006