Sensibly equivalent¶ to:
The Z90 produced by M-OV is another manufacturers implementation of the EF50. The design was used by many devices used by the UK government and subject to a CV specification and many valve makers produced valves to the specification. Government procurement could not rely on a sole supplier.
Post war the EF50 design was used in television receiver designs for the restarted television service, thus commercial production was valuable for the valve makers.
The screening can has helical scratches and this suggests that the valve has been used with a screw locking base as developed by the RAF. See EF50 for a picture of the base.
The plain aluminium can carries the Osram logo of M-OV on the reverse.
The wide metal tube envelope is 33 mm in diameter and, excluding the B9A base pins, is 59 mm tall.
References: Datasheet & 1043.
Absolute Maximum Operating Conditions¶
Updated December03, 2012. shape:wide.glass.tube construction:all.glass type:pentode age:1930.1940 base:b9g heater:6.3v pins:9 pin:1.h pin:2.g2 pin:3.a pin:4.g3 pin:5.s pin:6.k pin:7.g1 pin:8.s pin:9.h