The W2 was a dull emitter replacement for the bright emitter type P2. The Cossor Wuncell range was introduced in late 1924 and were the first oxide coated filament valves to be designed in the UK after WW1.
Like the P1 and P2 the design featured a self-sprung bow shaped filament, the grid was a series of hoops held in a support ribbon and the anode was a parabolic hood. The early bright emitter had metal shells to the bases but later types such as P1 had composition bases like the Wuncell range.
The box is fitted with two terminals so the the filament can be checked without breaking the packaging seal.
The side vier of the electrodes reveals three vertical supports. Left to right they are filament, grid and anode. The red paint on the envelope denoted the RF valves.
The reverse side of the anode showing the attachment of the supports.
The pins are simple split pin construction with the leads soldered to the top of the pins. The formation of the composition base is indicative of Cossor production of this date.
The grid construction is visible as a series of hoops.
The wide glass tube envelope is 28 mm in diameter, and excluding the B4 base pins is 75 mm tall.
References: 1003 & 1004. Type W2 was first introduced in 1924.