The Brimar 6Q7GT is a commercial double diode triode designed for receiver audio use.
The diodes would be for signal and AGC rectification and the triode would act as AGC amplifier or first audio amplifier. This is a miniature glass tubular version of this valve, we also have the older version with the classic glass envelope.
The triode is at the top with the diodes below. It is difficult to see if the box around the diodes is acting as one of the diode anodes or as a screen. At least one of the diode anodes is formed by the vertical rods within the diode box.
The wide glass envelope has a maximum diameter of 29 mm and a length excluding the IO base pins of 72 mm.
References: Datasheet, 1040 & 1043. Type 6Q7GT was first introduced in 1936.
Absolute Maximum Operating Conditions¶
Updated January 20, 2016. shape:wide.glass.tube construction:pinch type:double.diode.triode age:1930.1940 base:io heater:6.3v pins:8 pin:1.m pin:2.h pin:3.a pin:4.a(d2) pin:5.a(d1) pin:6.nc pin:7.h pin:8.k pin:tc.g1