Mullard designate the EF37A as a high gain, high impenance, pentode for use in AF pre-amplifier stages. The electrode system is of anti-microphonic construction, and the specially designed heater reduces hum to negligible proportions.

High quality amplifiers have used the EF37A for many decades. The EF86 was its successor.

The data sheets also give parameters for use as a triode.

See also 6J7 almost the same valve in operation.

The classic envelope is 29 mm in diameter and, excluding the IO base pins, is 85 mm tall.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	m	h	a	g2	g3	nc	h	k

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.2	250	100	-2	3	0.8	2.5M	1.8

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 06 September 2008 {find valves by name}