Summary

General purpose high vacuum ("hard") triode developed during World War 1, based on the French TM valve. Manufacturer: Edison Swan Electric Co. Ltd. For Marconi's Wireless Telegraph Co. Ltd.

4 Volt directly heated cathode. Anode voltage 100 V.

Physical Description

Spherical bulb, with evacuation tip, mounted on with 4 pin European style base with metal shell. Bulb internally discoloured.

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