The WR1 from Cossor dates from 1924 and is a dull emitter triode with a built-in filament resistance of 8 Ohms. The filament is oxide-coated.
Cossor had introduced dull emitter replacements for their earlier valves in the form of the W1 and W2. This valve was made to ease the transition from the six volt filament supply for bright emitter sets to the two volt LT supply for the dull emitter valves. The advertising literature stated that when all the bright emitters had been replaced, the screw could be moved and the set immediately operated on the more economical two Volt accumulators.
The Tin Hat anode, the resistance wire is under the tape and the shorting screw is on the side.
The base cap with moulded A and G as well as 2 and 6 Volts. The pins are of the simple split-pin type.
Here the focus is on the wires emerging from the underside of the pinch. Out of focus on the base are the filament voltages.
A makers code ZC883.
With the microscope the grid loops are visible together with the fine wire that ties the tops together to stop movement.
The grid loops are held to the support cradle by bending over lugs formed on the top.
The wide glass tube envelope is 29 mm in diameter and, excluding the B4 base pins, is 82 mm tall.
Reference: 1003. Type WR1 was first introduced in 1924. See also1924 adverts.
