P1 triode. Made by Cossor. Circa 1923.
Bright emitter triode for use as a low frequency amplifier or detector. 4 V directly heated cathode.
Filament voltage is 4.0 volt at 1.0 amp. Electrodes arranged as an arch, the anode taking the form of a covering hood. Exhausting nipple at apex. Used as low detector and low frequency amplifier. Plate voltage was 20 to 80 volts. Amplification factor is 6.6. Introduced 1922 in time for the opening of the B.B.C.
This valve cost 15 shillings in England in 1923.
Manufacturer: A. C. Cossor Ltd. Highbury Grove, London, UK.

The structure of the valve is consistent with type P1 but with no inscriptions it cannot be confirmed.

Physical Description

Cylindrical bulb (sectioned) with top exhaust tip on 4 pin European style base with metal shell.

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