GEC PAX 50 EXTENSIBLE

50-line extensible
private automatic exchange

The exchange is built up from self-contained 50 line extension-switching units.  An exchange can consist initially of a single switching unit and extended later up to an economic maximum of 400 extensions.  When more than two of these units are required, group-selector units are included to ensure full interconnection between the switching units.  Two types of group selector are offered: the first uses uniselectors (limited expansion) and is recommended where it is known that the capacity will not exceed 200 lines; the second (full expansion) uses 2-motion selectors and is used when the capacity may exceed 200 lines.

PX3650 Front view		PX3650 Rear view		PX7404

STANDARD FEATURES
Capacity
50 extension lines extensible to an economic maximum of 400 lines, in multiples of 50 lines.

Connect circuits
Each 50 line switching unit provides for up to six simultaneous conversations.

Numbering scheme
Ultimate capacity not more than 100 lines - in the range 00 to 99.
Ultimate capacity more than 100 lines - 3 figure numbers.

Executive's priority
Selected executives can break into an existing conversation: either the executive operates a pushbutton on the telephone* when he hears engaged tone, or the break in can be effected automatically.

OPTIONAL FEATURES
Tie lines*
Tie line facilities are available to suit individual requirements.

Conference*
Up to 10 designated extensions can be connected together via a special circuit.

Fire alarm*
Various procedures are available to suit individual requirements and local fire regulations.

Staff location*
Staff absent from their offices may be called by dialling a special locating number followed by a personal code, to operate lamps or bells.

Secretary service*
A secretarial switching telephone enables secretaries to filter calls to an executive.

Public exchange lines*
Public-exchange service can be provided after the addition of a special attendant's cabinet.

GENERAL
Mode of operation
Fully automatic using 2-motion selectors, uniselectors and relays.  All conversations secret from each other.

Tones and ringing
Electronic tone generators provide dial tone, ring tone and current, and busy tone.

Signalling
Required dial pulse characteristics: 7 to 14 i.p.s., 2:1 break to make ratio.

Alarms
Audible indication of blown fuse; visual indication of failure to replace receiver (PG condition).

Power Unit*
AC power unit for use on 100 line exchanges, or less: input 100 to 120v 60Hz single phase or 200 to 250v 50Hz single phase; output, 50v d.c. 10A.
or
Battery: 50v 32AH (up to 100 lines) with float charger, output 50v DC 3A; 50v 48AH (up to 200 lines) with float charger, output 50v DC 5A. Float charger input as for AC power unit.  Above 200 lines, individual recommendations are made.

Line loop resistance
Not to exceed 900 ohms.

Construction
Wired-in and plug-in equipment mounted on a steel framework and contained in steel cabinets (painted dark green) with lift-off dust-proof covers front and rear.

Dimensions and weight

*To be specified when ordering

1969

Last revised: 18 November, 2000