The 7H7 is a variable μ amplifier pentode. It is a high impedance device with a medium mutual conductance. Variable μ devices are primarily designed for IF and RF amplifiers in radio receivers. The anode current is quite high and with the large electrodes, this suggests that the device may have been designed for low noise input stages of HF communications receivers.

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	g2	g3	s	g1	k	h

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	150	-2.4	10	3.2	0.8M	4.2

Thanks to Frank Philipse for supplying the above datasheet

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