The 3S4 is an audio output pentode valve designed for battery portable broadcast radio receivers. The output power is very small so either a high efficiency loud speaker would be used or headphones.

The thin glass tube envelope is 18 mm in diameter and excluding the B7G base pins it is 43 mm tall.

 
Pin Connections

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

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm	Pout	D
	1.4	0.1	90	67.5	-7	7.4	1.4	0.1M	1.58	0.27	12%

Thanks to Frank Philipse for supplying the above datasheet

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