The Mullard EL84 is the definitive expression of this design. This exhibit is a run-of-the-mill unbranded EL84.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 70 mm tall.

References: Datasheet, ³⁰⁰² & ¹⁰⁴⁰. Type EL84 was first introduced^¶ in 1953.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	ic	g1	k,g3	h	h	ic	a	ic	g2

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm	Pout	Pdiss
	6.3	0.76	250	250	-7.3	48	5.5	6.7	2.2	12W

Thanks to Frank Philipse for supplying the above PDF datasheet

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