The 6AJ7/6AC7 American metal pentode was designed for high gain amplification. Since it has a sharp cut-off it is unsuitable for domestic radios with AVC. The intended application is as an IF or video amplifier for wide-band receivers, e.g. radars. Bearing in mind that the RCA design of metal valves was pinch-less and had very short lead-outs well shielded from each other by the metal envelope, Type 6AC7 can be thought of as the American answer to the EF50. It consumed 50% more heater power but provided 50% more mutual conductance as a result. It was used in enormous numbers in American WWII equipments. Presumably the accessible suppressor grid might be used to 'gate' the signal output if required.
The overprint carries the date May 1960 - probably when it was last tested.
The stylised Marconi name and Made in Canada.
The thin metal tube envelope is 25 mm in diameter and excluding the IO base pins, is 51 mm tall.
