The EF72 subminiature wire ended pentode dates from 1950. The multiple connections to the cathode suggest that the valve was to operate at a reasonably high frequency, easily into the HF range. It is a high impedance device with moderate gain, this probably indicates use with a tuned anode load. The most likely use is as an IF amplifier at 10.7 MHz.

Mullard instruction: direct soldered connections to the leads must be made at least 5 mm from the seal and any bending of the valve leads must be at least 1.5 mm from the seal. The maximum bulb temperature should be about 100 C, a mounting clip will assist.

The thin glass tube envelope is 9 mm in diameter and, excluding the B8D base pins, is 36 mm tall.

 
Pin Connections

B8D	1	2	3	4	5	6	7	8
	g1	k,g3	h	k,g3	a	h	g2	k,g3

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.15	100	100	-1.4	7	2.2	0.25M	5

This exhibit was last updated on 02 December 2007