Special fire telephone used in exchange buildings This is the later model called the Mk 4

Fire emergency phone for use in CB and Automatic exchanges.

The Mk 4 version consisted of a Telephone No. 232 mounted on a Bellset which in turn is mounted on a wooden box that houses batteries and a hand generator. The hand generator is locked by means of a releasable bar.

The Mark 4 was introduced in 1938.

Circuit diagram - N181.

Adjustment of Magneto bells

Telephone No 81 (Mark 4)

Looking down into the unit with the lid open


Pictured below is the Telephone No. 103
It has an big generator which needs an enlarged cover


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Last revised: December 18, 2018