The UCH81 is a triode heptode frequency changer for use in AC/DC mains equipment. The heater is designed for use on 100 mA heater chains. This valve would be most likely found in domestic broadcast radio receivers.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 57 mm tall.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	g2,g4	g1	k,g5,s	h	h	a	g3	a(t)	g(t)

 
Absolute Maximum Operating Conditions

Heptode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	19.0	0.1	200	120	-2.6	3.7	8.1	1.0M	0.78

Triode	Va	mAa
	100	13.5

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 12 June 2007 {find valves by name}