Summary

Triode, known as the 'half-ampere L tube', used in telephone repeaters. Manufactured by Western Electric (USA). Introduced in 1927. The 101 or 'L Tube' family were produced for a very long time. The ST bulb on this one suggests that it was made in the late 1930s or 1940s.

0.5 amp directly heated cathode. 4 Volt filament drawing 0.5 amp (hence its name).

Physical Description

Shouldered glass bulb, 4 pin bakelite UV style base.

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