Sensibly equivalent¶ to:
The W31 is a variable-μ RF pentode on a B7 base and designed for use on a 300 mA series heater chain in universal (AC and DC) mains sets.
The W31 is pin compatible with the Catkin W30 but has a higher specification.
This valve was covered in grey metallic paint that has detached in significant areas. Under the paint the valve was etched with the Type designation. The data-sheet shows the metal paint, our other glass W31 has no paint at all.
Only a small section of the glass can be seen through. The bright metal seen within is probably the anode connection.
The classic envelope is 44 mm in diameter, and excluding the B7 base pins is 120 mm tall.
References: Data-sheet, 1040 & 1043. Type W31 was first introduced in 1935. See also 1935 adverts.
Absolute Maximum Operating Conditions¶
Updated August 29, 2018.