Cabinet work of well-seasoned walnut.
Fitted with self-replacement device attached to the ringing key and switch hook. Outward conversation finished, replacing receiver or handset on switch hook or cradle automatically disconnects radial switch from instrument speaking circuit.
Only necessary to move radial switch when making outward call; calls received and answered whatever position of radial switch. Contact with more than one line at a time cannot be made. Receiver, or handset, should be removed from switch hook before making an outward call.
Switch contacts and line terminals fitted at back of instrument, well protected from dust and rough handling.
To facilitate wiring wall instrument provided with hinged fixing batten. Inductive cross-talk reduced to a minimum.
Pirelli-General anti-inductive intercommunication telephone cables, Class No. 992 braided, and No. 993 lead covered are recommended for use with these instruments. Two central batteries, one each for ringing and speaking, each comprising three No. 1 Carsak cells, L 4885, are all that are required, local batteries being dispensed with.
These instruments are suitable for working in conjunction with the Sterling "Primax" systems.
Instruments fitted with induction coil, and arranged for ordinary local or central battery circuits, can be obtained for extension to existing installations at extra charge.
Wall type telephone, comprising radial switch, K 7670 carbon granule transmitter, K 7631 “Watch” pattern electro-magnetic receiver, auto-reset ringing key, automatic switch hook, impedance coil and 25 ohm bell on tail piece. External metal parts oxidised copper bronze.
Cost in 1932 and 1935 for the 21 line model was £4.0.0
Found in the 1932 and 1935 Catalogues
Last revised: November 20, 2010