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UAF42

Sensibly equivalent to:
12S7 WD142
See also:
Mullard EAF42 & UAF42 Advert - New valves from Mullard - The EF91 and the Blue Band
    
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The UAF42 is an early all glass valve introduced in 1948 together with the EAF41 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.
Like the EF91 the inside of the glass is coated to reduce the release of gas during the life of the valve.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 53 mm tall.
References: Data-sheet & 1040. Type UAF42 was first introduced in 1948. See also 1948 adverts.

 

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.
Updated July 10, 2020.
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