The AF3 is a variable-mu RF pentode. Operation under AGC control would have been in RF or IF amplifier service in superhet receivers.

This AF3 from Valvo has a bright external gold metallic paint finish. The Ct8 base was much more popular in continental Europe than in the UK. The colour and the base suggest a 1930s design.

The classic envelope is 41 mm in diameter and, excluding the Ct8 base pins, is 103 mm tall.

 
Pin Connections

Ct8	1	2	3	4	5	6	7	8	tc
	m	h	h	k	g3	-	g2	-	g1

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	4.0	0.65	250	100	-3	8.0	2.6	1.2M	1.8

Thanks to Frank Philipse for supplying the above datasheet

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