Summary

Triode, used with small public address amplifiers. Manufactured by: Western Electric (USA). Released in 1922. Originally intended for use in the Western Electric 7A amplifier and originally only licensed for this use. In 1926, the grid shape was changed from a ladder type to a flattened spiral type.
5.5 to 6 volt directly heated cathode.

Physical Description

Spherical bulb with top tip, 4 pin metal UV style base.

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