GEC No. 4300 Series
C.B. PRIVATE BRANCH EXCHANGES
Switchboards of this series can he supplied in any size, suitable for either large or small installations. The standard type illustrated and listed below is designed for use where the number of extension lines does not exceed sixty and not more than ten junctions are required.
Indicators serving the exchange lines are of the hand restored type, the corresponding jacks being mounted above the extension jacks. In the extension line circuits, totally enclosed self-restoring disc indicators are employed. Supervisory signals, mounted on the keyboard, are provided in the answering and calling sides of each cord circuit and are arranged to give negative supervision.
The equipment also includes a manual ringing circuit with ring-hack facilities, a cord test jack, and a night alarm circuit with key for disconnecting the bell when necessary. By means of night switching keys, fitted in the face of the switchboard, the exchange lines may be left plugged through to any selected extensions when the operator is not on duty.
The operator's telephone consists of a head receiver and breastplate transmitter, complete with cords and a standard four-way concentric plug.
Switchboard No. 4370 is suitable for use where the public exchange is of the manual C.B. type, No. 4371 being fully equipped for working to an automatic exchange. While in the former a dial and dialling keys are not provided, the necessary wiring for these is included in order to facilitate conversion if and when automatic switching is adopted in the public system.
Current for operating the switchboard may be supplied from the public exchange battery or from a local battery of not less than 16 volts.
Cat. No. 4370 is shown pictured above.
Taken from the GEC Telephones and Switchboards (Manual and Automatic) Catalogue No. 11 (Circa 1936)
Last revised: July 30, 2012