Sensibly equivalent¶ to:
The HL2 is a general purpose triode but the Mazda advert for this metalised valve suggests that it is well suited for use as a leaky grid detector of first audio voltage amplifier.
The reference number.
The balloon envelope is 42 mm in diameter, and excluding the B4 base pins is 85 mm tall.
References: Datasheet, 1040 & 1043. Type HL2 was first introduced in 1931.
Absolute Maximum Operating Conditions¶
Updated May 18, 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