Sensibly equivalent¶ to:
The DK91 is a miniature B7G dry battery heptode, it was designed for frequency changer use in battery portable radio receivers for medium and long wave. The valve was designed for self oscillating service.
The top mica with the single strand oxide coated filament in the centre. The tensioning spring support is on the right and it is also the final suppressor grid support.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 45 mm tall.
References: Datasheet & 1040. Type DK91 was first introduced in 1946.
Absolute Maximum Operating Conditions¶
Updated September 25, 2019. shape:thin.glass.tube construction:all.glass type:heptode age:1940.1950 base:b7g heater:1.4v pins:7 pin:1.f- pin:2.a pin:3.g4.g4 pin:4.g1 pin:5.f- pin:6.g3 pin:7.f+