The DE2HF is a dull emitter triode dating from 1925. It was designed for RF amplification. The valves from M-OV of this period used carbonized thoriated tungsten filaments. The carbonizing reduced the effects of any residual gasses in poisoning the thoriated filament.
The BBC logo is present on this valve illustrating the fact that this valve is an original 1920s valve and not a later replacement.
The balloon envelope is 32 mm in diameter and, excluding the B4 base pins, is 73 mm tall.
References: 4051 & 1003 Type DE2HF was first introduced in 1925.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated January 24, 2011.