The PM2HL is an amplifier triode. The electrode Voltages mark it out as a battery valve. The original PM (Philips Mullard) series of valves were oxide cathodes produced by the Azide process.

The top of the metalised envelope carries the Mullard identification. In other versions of this popular valve the lettering appears on the side and the envelope takes on balloon form.

The classic envelope is 34 mm in diameter and, excluding the B4 base pins, is 80 mm tall.

References: Datasheet & ¹⁰⁴³. Type PM2HL was first introduced^¶ in 1938.

 
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	135	-1.5	2.2	21,500	1.4

Thanks to Andy Cowley for supplying the above PDF datasheet

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