The 7S7 triode heptode was designed for frequency changer use in radio receivers. The 7S7 was also made for mobile use with 12 Volt vehicle batteries for the heater, in this case the valve was called the 14S7.

The coating on the inside of the envelope obscures the details of the valve's construction.

The wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 55 mm tall.

 
Pin Connections

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

 
Absolute Maximum Operating Conditions

Heptode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	100	-2	1.8	3.0	1.25M	0.525

Triode	Va	mAa
	150	5.0

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 05 July 2007 {find valves by name}