Sensibly equivalent¶ to:
The 12SG7 is a 12.6 Volt version of the 6SG7 semi-vari mu pentode. The pins are compatible and the ratings are the same.
The envelope is also marked with the American Government code of VT-209.
The 12SG7 is a variable μ design with a medium gain. It was obsolete by the early 1960s.
The thin metal tube envelope is 25 mm diameter, and excluding the IO base pins, is 50 mm tall.
References: Data-sheet, 1040 & 1043. Type 12SG7 was first introduced in 1940.
Absolute Maximum Operating Conditions¶
Updated November 28, 2013. shape:thin.metal.tube construction:glass.disc type:pentode age:1930.1940 base:io heater:12.6v pins:8 pin:1.m pin:2.h pin:3.k pin:4.g1 pin:5.k pin:6.g2 pin:7.h pin:8.a