KEY AND LAMP UNIT - SA 4219
This is a two line Secretarial unit for providing intercom facilities on two shared exchange lines or P.A.B.X. Extensions.

Used by BP (Moorfields) and introduced circa 1966.

This was a three key unit (1000 type keys) with three supervisory lamps.

Circuit diagram - SA/SAW4219.

Specification - S874.
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Last revised: August 11, 2025
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