The 7C6 is a double diode triode, and no specific design use is quoted. Normally such a valve would be used as signal and AGC detector plus first audio amplifier stage in broadcast receivers. This valve is unusual in that the anode impedance is high, maybe this valve was to be used for video demodulation and amplification.
The design dates to the late 1930's in America and the UK versions are post-war. Here the Type designation in an octagon suggests that it was made in America and overprinted with the Brimar identification.
This clearly states that it was Made in England.
The triode is mounted above the screened diode anodes.
The wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 56 mm tall.
References: Data-sheet, 1040 & 3002. Type 7C6 was first introduced in 1938. See also1938 adverts.
