Sensibly equivalent¶ to:
The HL2 is a dull emitter battery triode. It was designed as a detector in broadcast receivers, in the early 1930s.
We know from the envelope that this was made in England, and this version of the valve has an external metalising for enhanced screening. HL2 is a plain glass version.
The balloon envelope is 40 mm in diameter and, excluding the B4 base pins, is 82 mm tall.
References: Datasheet & 1040 Type HL2 was first introduced in 1931.
Absolute Maximum Operating Conditions¶
Updated January 15, 2018. shape:balloon construction:pinch type:triode age:1930.1940 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f