This exhibit carries the Cunningham name as well as Radiotron and the ultimate owner RCA.
The 85 triode valve would be used in radio reception equipment. The diodes are for signal use and probably would be for AGC and AM signal detection. The triode would act as AGC amplifier or first audio amplifier, probably the latter.
The same characteristics and heater but with an IO base are found in 6V7G. The same characteristics but with a 2.5 V heater are found in Type 55.
The cathode tube runs vertically through both parts of the valve. The lower screening box connected to the cathode, contains the two diode anodes, each anode is just a vertical rod. The upper black anode is formed with a cylindrical cavity that houses the cathode and grid.
The base showing that Cunningham was taken over by RCA.
The triode and push fit top mica.
The classic envelope is 38 mm in diameter and, excluding the UX6 base pins, is 97 mm tall.
References: Data-sheet, 1040 & 1043. Type 85 was first introduced in 1936. See also1936 adverts.