Valve Gallery - Frequency Converters (2)

Valves: AC/TP, AC/TH1, EK2, 2A7.

Shown above is a Mazda AC/TP frequency converter.  This valve uses the much less common B9 base, and was in particularly short supply during WW II. It is a triode/pentode with 4v heater approx 125mm height. Shown above is a Mazda AC/TH1 frequency converter utilising a B7 base.  It is a triode/heptode with 4v heater, approx 123mm height.

Shown above is a Mullard EK2 frequency converter, with P type base, also known as CT8 base.  It is an octode with 6.3v heater.  Approx 92mm high.  It must be the lack of pins that makes focusing of side-contact valves tricky! Shown above is a Am-Brit 2A7 frequency converter.  This uses a UX7 base which was commonly used in the USA during the 1930s. Using a 2.5v heater it is a heptode of about 128mm height.

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