Sensibly equivalent¶ to:
The Mullard DK1 is a dry battery heptode frequency changer. The oscillator section would run with 90 Volts on the anode and draw 1.2 mA.
In this exhibit we have a glass envelope with external gold coloured zinc loaded metalising, our other DK1 has a clear glass envelope.
Thanks to Stef Niewiadomski for sending in the picture and base connections.
The wide glass tube envelope is 30 mm in diameter, and excluding the Ct8 base pins is 90 mm tall.
References: 1043 & 1040. Type DK1 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated August 04, 2013. shape:wide.glass.tube construction:pinch type:heptode age:1930.1940 base:ct8 heater:1.4v pins:8 pin:1.m pin:2.f pin:3.f pin:4.- pin:5.g2 pin:6.g1 pin:7.g3.g5 pin:8.a pin:tc.g4