The PM12A is a most interesting valve, one of the early oxide valves from Mullard. As a contrast see the earlier PM12A with the gold paint masking the blackening caused by the azide process.

The anode consists of two small plates on a saddle of stout wire and connected to the top cap. The control grid has almost the same area as the anode plates and is threaded by a single inverted V of filament. The screen grid and suppressor grids are larger than the control grid / anode for maximum electrostatic isolation.

The classic envelope is 42 mm in diameter and, excluding the B4 base pins, is 110 mm tall.

 
Pin Connections

B4	1	2	3	4	tc
	g2	g1	f	f	a

 
Absolute Maximum Operating Conditions

Tetrode	Vh	Ah	Va	Vs	Vg	mAa	ra	gm
	2.0	0.18	135	75	-0	2.0	330,000	1.5

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This exhibit was last updated on 21 July 2005