The 14S7 is a triode heptode frequency changer. The American valves with designations starting with 14 were designed for operation on nominal 12 Volt vehicle supplies. Brimar do not give the operating frequency in their short form catalogue. The 7S7 has identical operating characteristics but with a standard 6.3 Volt heater.

The wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 54 mm tall.

 
Pin Connections

B8B	1	2	3	4	5	6	7	8
	h	a(h)	a(t)	g1(t),g3	g2,g4	g1	k,s	h

 
Absolute Maximum Operating Conditions

Heptode	Vh	Ah	Va	Vs	Vg	mAa	gm
	12.6	0.15	250	100	-2	1.8	0.53

Triode	Va
	150

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 12 June 2007 {find valves by name}