The AC2/HL screened triode was introduced by Mazda in 1932.
As the metalising has fallen off in places it has been possible to photograph the internal structure. Apart from the clearly visible indirectly heated flat cathode, the fine control grid is just seen. The glass pinch is labelled AC2/HLJ.
The metalised balloon envelope is 43 mm in diameter and, excluding the B5 base pins, is 90 mm tall.
References: Datasheet, 1043, 3002 & 1040. Type AC2/HL was first introduced in 1931.
Absolute Maximum Operating Conditions¶
Updated February 07, 2013. shape:balloon construction:pinch type:triode age:1930.1940 base:b5 heater:4.0v pins:5 pin:1.a pin:2.g1 pin:3.h pin:4.h pin:5.k