The UAF41 is an early all glass valve introduced in 1948 together with the EAF42 and consists of a single diode and a variable μ RF amplifier pentode in a single envelope.

The valve is screened and the envelope has the moulded glass pip for pin registration in the metal skirt of the base. The first B8A valves had metal skirts fitted with built in locating pips and spigots to guide the valve into its base.

By the early 1950s the B8A valves were being phased out in favour of B9A and B7G based valves.

The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 52 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type UAF42 was first introduced^¶ in 1948.

 
Pin Connections

B8A	1	2	3	4	5	6	7	8
	h	a	a(d)	g3	g2	g1	k,s	h

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	12.6	0.1	200	85	-2.0	5.0	1.5	1.0M	2.0

Thanks to Frank Philipse for supplying the above PDF datasheet