The 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 construction of this Ferranti valve matches that of the American Tung-Sol 6Q7GT and the etched octagon on the glass together with the printed Ferranti suggests an American made valve re-badged by the UK company..
The Ferranti logo is printed on the envelope. The triode sits above the pair of diode anodes. The blackening of the triode anode enhances heat dissipation by radiation.
The wide glass envelope has a maximum diameter of 29 mm and a length excluding the IO base pins of 69 mm.
References: Data-sheet, 1040 & 1043. Type 6Q7GT was first introduced in 1936.
Absolute Maximum Operating Conditions¶
Updated December20, 2018. 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