Sensibly equivalent¶ to:
The 6C31 is a triode heptode mixer with an external metal paint coating. The connection to the coating (Zinc paint) is made via the wire wrapped around the base of the envelope. The equivalent ECH33 was replaced by the ECH35 a year after introduction and was pin compatible.
The triode would run with 80 Volts on the anode and consuming 5 mA and would deliver 9 Volts pk-pk local oscillator injection to the heptode mixer.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 90 mm tall.
References: 1040 & 1043. Type 6C31 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated April 15, 2013.