PRIVATE AUTOMATIC TELEPHONE EXCHANGES
This compact and completely self-contained telephone exchange
provides secret automatic communication facilities for up to ten extensions. It
is ideally suitable for small organisations, or as a separate auxiliary to the
main telephone system in a large organisation. The single wall-mounting unit,
finished in steel furniture green, incorporates all the automatic-switching
equipment and an all-mains power unit.
The exchange has the following features:-
Automatic connexion between extensions.
Two-wire lines to each extension.
One connecting link.
Executive right-of-way for one extension.
Operates from single-phase mains supply 50.60c/s, 100-110
or 200-250 volts.
Dial tone and ringing tone returned to a caller.
Extensions numbered from 0 to 9.
The exchange is suitable for operation in either tropical or
Any extension user is connected to any other extension by dialling a single
digit. When the connecting link is free, an extension hears dialling tone on
lifting his receiver, and ringing tone when the wanted extension is being
called. If there is no tone when an extension lifts his receiver, the connecting
link is engaged.
One extension connected to the exchange can have an executive
right-of-way facility. This extension instrument is fitted with a pushbutton,
and to break-in to an established connexion the extension user presses the
pushbutton. If neither of the answering parties is the one required, they are
requested to replace their handsets ; the executive then dials the required
number. In this way the head of a small organisation, or the leader of a group
in a larger organisation, can talk to any member of his organisation at all
LINES AND TELEPHONES
Each telephone can be connected to the exchange unit by any insulated twin
conductor having a loop resistance of less than 300 ohms and a line leak greater
than 130 000 ohms. This latter condition means that bare open-wire lines should
- not be used with this exchange. An extension with executive right-of-way
facility must be connected to the exchange by two insulated twin conductors.
Recommended telephones for this exchange are the 'New Gecophone' described in
Catalogue Leaflet STL16 and the "G.E.C. 1000" Telephone and the G.E.C. Muraphone
"K" described in Catalogue Leaflet STL13. When the executive right-of-way
facility is required, the executive telephone must be fitted with a pushbutton.
The ringing current is derived from the mains at 50 or 60c/s, compared with the
normal telephone exchange ringing current of 25c/s, therefore slight adjustment
of the bell is required to give the most satisfactory ring.
The connexions to extension lines are by screw-type terminals,
and the only tool required to install the exchange is a screwdriver.
Each exchange is fitted with 10ft of 3-core flex to connect to
the mains supply.
This compact, neat, inexpensive telephone exchange is easy to
install, and available for quick delivery.
G.E.C. 15 LINE P.A.X.
||12 x 24 x 8
||30.8 x 61 x 19.3
Taken from Catalogue Leaflet No. PXL6A
GEC article on the PX1211