The 6Q7 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 the original metal version of this valve.
American made and a production number.
The envelope carries the RCA Victor, RCA and His Masters Voice logos.
Fitting a top cap to a metal valve was not easy.
The octal base of the 6Q7. The four skirt pinches hold the plastic base and the spigot hides the evacuation stem that attaches to the centre of the hard glass disc that the connecting wires pass through.
The thin metal tube envelope is 25 mm in diameter, and excluding the IO base pins is 62 mm tall.
References: Datasheet, 1040 & 1043. Type 6Q7 was first introduced in 1936.