The UAF42 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 single signal diode can be seen above the screening cylinder.
The suppressor grid can be seen within the outer screen. The anode is just two small plates either side of the central assembly.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 52 mm tall.
References: Data-sheet & 1040. Type UAF42 was first introduced in 1948. See also1948 adverts.
