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. The box around the diodes is a screen. The diode anodes are formed by vertical rods within the box.
The diode screen is connected to the cathode tube by the wire on the lower right.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 72 mm tall.
References: Data-sheet, 1040 & 1043. Type 6Q7GT was first introduced in 1936. See also1936 adverts.