The 7AF7 is a double triode. On an octal base the equivalent type would be a 6SN7.

The reverse side of the envelope carries the makers plea to replace with a similar valve.

The B8B Loctal base is effectively an all glass development of the IO base. The shaped spigot allows for a sprung base to hold the valve in place.

The triode is formed in a small diameter cavity formed by the stitched anode.

The valve type is etched onto the dome of the bulb.

The wide glass tube envelope is 29 mm in diameter, and excluding the B8B base pins is 57 mm tall.

References: Datasheet & ³⁰⁰². Type 7AF7 was first introduced^¶ in 1945.

 
Pin Connections

B8B	1	2	3	4	5	6	7	8
	h	k(1)	a(1)	g1(1)	g1(2)	a(2)	k(2)	h

 
Absolute Maximum Operating Conditions^¶

Triode	Vh	Ah	Va	Vg	mAa	ra	gm	μ
	6.3	0.3	300	-10	9.5	7,600	2.1	16

Thanks to Frank Philipse for supplying the above PDF datasheet