The SD2 is a 2 volt battery triode designed for use as a detector or first stage audio amplifier.
The identification on the envelope carries the makers logo and brief details of operating characteristics. The attached datasheet is taken from the Triotron 1931 booklet.
The balloon envelope is 48 mm in diameter, and excluding the B4 base pins is 87 mm tall.
References: Datasheet & 1043. Type SD2 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated August 11, 2017. shape:balloon construction:pinch type:triode age:1920.1930 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f