PYRAMID WITH BELLSET
explains how to mount a BPO 100 or 200 Pyramid style telephone onto a Bakelite Bellset.
To start with the Bellset must have the special two threaded screws. These
came as standard on early Bellsets, but were replaced by ordinary single
threaded screws later on.
The correct screws are shown to the right and have slotted heads with a thread down the centre. The inner top and outer bottom threads are 2BA, whilst the centre threaded section is 0BA..
The special screws should be removed from the Bellset cover and then offered directly into the screw fixing holes of the Bellset chassis, from the rear. The screws should be screwed past the two threaded sections until they are right against the Bellset and are free to turn. The picture below shows a rear view of the Bellset with the two screws in place.
Generally the Bellset was fixed to the wall, so there were not a lot of
phones with Bellsets attached to phones in circulation.
Last revised: January 10, 2016