The DEH612 is labelled as a Marconi valve. It is a dull emitter triode for general purpose applications.
The valve has lettering etched into the glass. Also present is the BBC stamp that contains the words 'Entirely British Made' and this dates this valve to between September 1924 and 1927.
See also DEH612 for a slightly later version.
The balloon envelope is 56 mm in diameter, and excluding the B4 base pins is 93 mm tall.
Reference: 1043. Type DEH612 was first introduced in 1927.
Absolute Maximum Operating Conditions¶
Updated April 11, 2013. shape:balloon construction:pinch type:triode age:1920.1930 base:b4 heater:6.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f