Sensibly equivalent¶ to:
The 12SR7 is a double diode triode sharing a common cathode. It was designed for superhet receiver use where the diodes would act as signal detector and AGC detector and the triode would be the first stage audio amplifier.
The 12SR7 differs only in heater voltage from the 6SR7. Compared to the pin compatible 6SQ7 this valve would exhibit lower gain in the triode stage.
The can also carries the Brimar logo.
The thin metal tube envelope is 25 mm in diameter and, excluding the IO base pins, is 52 mm tall.
References: Data-sheet, 1040 & 1043. Type 12SR7 was first introduced in 1940.
Absolute Maximum Operating Conditions¶
Updated February 28, 2013. shape:thin.metal.tube construction:glass.disc type:double.diode.triode age:1930.1940 base:io heater:6.3v pins:8 pin:1.m pin:2.g1 pin:3.k pin:4.a(d2) pin:5.a(d1) pin:6.a pin:7.h pin:8.h