This X31 is a metallised triode hexode frequency changer from the 1930s.

The X31 designation was later re-used for a miniature valve. in this exhibit the printing has all but been lost from the metallising and it was difficult to identify it without strong light and a glass.

The classic envelope is 42 mm in diameter and, excluding the B7 base pins, is 117 mm tall.

 
Pin Connections

B7	1	2	3	4	5	6	tc
	a(t)	g1(t),g3	g2,g4	h	h	m,k 7_a	g1

 
Absolute Maximum Operating Conditions

Hexode	Vh	Ah	Va	Vs	Vg	gm
	13.0	0.3	250	80	-1.5	0.55

Triode	Va
	150

This exhibit was last updated on 12 March 2006