Summary

Used as a Class A audio amplifier in telephone repeater equipment and manufactured by S. T. C., Sydney, Australia.
It has a 2 volt directly heated cathode.

Introduced in about 1927 used until the early 1950s

This valve is equivalent to the ST&C (England) type 4020A but was made in STC's Sydney factory as indicated by the SY prefix. It would have been produced for use in STC manufactured telephone repeater equipment. They were designed to have a life of at least 10,000 hours.
It has a Defence Department stamp.

Physical Description

Four pin American UV style base.

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