|AUTOMATIC OR C.B. INTERMEDIATE AND EXTENSION
The Intermediate and Extension system allows two stations to share one public exchange line. The two also have full intercommunication over a single pair of wires using hand generators for signalling. This 'external working' system is most economical when the telephones are in separate buildings some distance apart. The alternative 'internal working' system usually more convenient when the two instruments are in the same building, employs push button battery ringing over an extra pair of wires.
These telephones, which supersede the considerably larger N 1046 or N 1049 types, are fully tropical and have p.v.c. insulated conductors. They are for use on lines of up to 1,000 ohms loop resistance. Similar 600 ohm loop sets can be supplied.
The stock instruments are black with black nylon braided straight cords. Alternatively, ivory sets with ivory cords or black sets with 'grebe' (silver grey) cords can be supplied:-
The intermediate telephone has four interacting push button keys to connect:
Calls from the extension operate a buzzer in the telephone. Calls from the exchange operate a bell in a moulded wall case connected to the instrument by a cord and containing screw connections for cable termination.
Exchange-to-extension conversation can be made secret or non-secret from the intermediate by appropriate terminal strappings.
The intermediate telephone contains a relay which operates a 6-volt lamp to act as an 'engaged' signal during exchange-to-extension conversations. A domed plastic lens in the telephone case increases the luminosity and angle of vision of the lamp signal.
A battery of 6-9 volts is required at the intermediate point for extension-to-intermediate conversation. The battery should be ordered separately.
The extension telephone is an ordinary auto or C.B. set designed to accommodate the generator and containing a buzzer instead of a bell.
Both telephones have lift-off cases to allow easy access to the components mounted on the base plate.
Note - Dimensions and weights of intermediate telephones include the external bell set.
Supplied in black only.
Taken from the Ericsson Catalogue No. 55
Last revised: October 02, 2019