N 539A shown pictured to the right.
These boards are designed for small factories, offices, etc., requiring a telecommunication system of 6 to 20 lines. Simple to operate and occupying very little space, they may be placed on a table or shelf or, if necessary, fitted with wall battens.
The casework of hardwood has a hinged front and is matt polished.
Connections are made by means of lever keys. Broad lines in different colours extending right across the rows of keys indicate clearly the connections made and thereby minimise operating errors.
Drop type hand-restored indicators, N4816F, are used for the extension lines and also act for clearing purposes.
An "alnico" generator, night bell and key are fitted and a hook switch for disconnecting the microphone battery.
The operator's Bakelite hand-set is plugged into a jack in the board and the circuit is arranged for direct connection to each line.
An acoustic shock absorbing device is incorporated in the operator's circuit.
Taken from the Ericsson Telephone Catalogue issue no. 49
Last revised: October 12, 2019