Sensibly equivalent¶ to:
The 12SJ7 is a high gain amplifier pentode and is the 12.6 Volt heater version of the 6SJ7. This Tungsram valve is of American manufacture.
The S in the Type designation tells us that it is a single ended valve ie no top cap. The 12J7GT shows a glass tubular version with the control grid taken to the top cap for good isolation between anode and grid circuits.
Design use is as a Class A amplifier, so good for audio with its excellent linear characteristic curve.
The thin metal tube envelope is 25 mm in diameter and, excluding the IO base pins, is 50 mm tall.
References: Data-sheet, 1040 & 1043. Type 12SJ7 was first introduced in 1939.
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.g3 pin:4.g1 pin:5.k pin:6.g2 pin:7.h pin:8.a