The 6SQ7 is a double diode triode sharing a common cathode, probably designed in the mid to late 1930s specifically for superhet receiver use. The diodes would act as signal detector and AGC detectors, while the triode would be the first stage audio voltage amplifier.

The thin metal tube envelope is 25 mm in diameter and excluding the IO base pins the valve is 50 mm long.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	m	g	k	a(d2)	a(d1)	a	h	h

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	6.3	0.3	250	-2	0.9	91K	1.1

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 04 June 2007 {find valves by name}