The 6Q7G is a double diode triode and was 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.
The reverse of the internally carbonised envelope carries a makers code.
The triode control grid is connected to the top cap and the triode section sits at the top of the envelope the diodes will be below and are not visible.
The classic envelope is 38 mm in diameter and, excluding the IO base pins, is 97 mm tall.
References: Data-sheet, Data, 1040 & 1043. Type 6Q7G was first introduced in 1936. See also1936 adverts.
