Output pentode introduced by Marconi-Osram in 1929. The 4 pin base carried the filament, plate and control grid connections; the screen connection was a side terminal. This was done so that the valve could be used in place of a triode by simply plugging it in and connecting the side terminal to the plate supply. 4 volt directly heated cathode. Used as a Class A power output amplifier.

Physical Description

Internal structure of an output pentode with its bulb removed which has suffered some damage. Mounted on an American style 4 pin (UX) base with a side terminal.

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