Sensibly equivalent¶ to:
The EH90 is an indirectly heated heptode mixer from the 1950's. In the early 1960's Mullard designed circuits for the EH90 so it could act as an FM demodulator for 6 MHz inter-carrier sound.
This exhibit from Mullard features the later yellow paint to mark the envelope. See Mullard for why the yellow paint was used.
See EH90 for full details.
The side view of the anode shows the wire grids.
The thin glass tube envelope is 17 mm in diameter, and excluding the B7G base pins is 46 mm tall.
References: Datasheet & 1040. Type EH90 was first introduced in 1954.
Absolute Maximum Operating Conditions¶
Updated September 07, 2016. shape:thin.glass.tube construction:all.glass type:heptode age:1950.1960 base:b7g heater:6.3v pins:7 pin:1.g1 pin:2.k.g5 pin:3.h pin:4.h pin:5.a pin:6.g2.g4 pin:7.g3