The 3Q4 miniature dry battery pentode was designed for radio receiver use. The output of 0.27 Watt maximum would only drive a small efficient loudspeaker, not hi-fi.

The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 45 mm tall.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	f-	a	g1	g2	fct,g3	a	f+

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm	Pout	D
	1.4	0.1	90	90	-4.5	9.5	2.1	100,000	2.15	0.27	7%

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 02 July 2007 {find valves by name}