plessey2.gif (5108 bytes)PLESSEY TELEPHONE
No's N2060, N2063, N2064, N2067, N2069, N2070, N2080, N2083 & N 2090


Press button Telephones
DC & MF

n2060b.jpg (16018 bytes)These BPO approved DC and MF (multi-frequency) press button telephones are structurally similar to the BPO type 746 telephone but incorporate a press button Keyset instead of the conventional rotary dial for speed, convenience and reliability in the setting up of calls.

Both types are available as table and wall-mounted instruments and are suitable for working into fast switching systems that employ either DC (ITT code C) or MF (CCITT-recommended 1/4 + 1/4 VF) signalling.

Main Design Features

Modular, robust construction

High-speed signalling

n2070b.jpg (10331 bytes)Precise press button action

Easily visible Keyset characters

Non-adjust Keyset-spring gaps and tensions

Printed-circuit boards with miniature components

Automatic line regulator

Stain-resistant, high-impact moulding

Integral recessed carrying handle

Optional press button for operator recall, shared service etc.

Standard or tropical finish.

Cover and Escutcheon
The cover and escutcheon plate are colour fast ABS copolymer mouldings of high-impact strength and high-gloss finish.

The cover incorporates a recessed carrying handle, and a dummy button that is easily replaced by a press button when shared-service or operator-recall facilities are required.

The escutcheon plate is held to the cover by four metal clips that allow limited lateral movement to ensure correct cover-to-baseplate relationship when the cover is replaced. Provision is made on the escutcheon for a label under a clear plastic window to display the subscriber's number and/or supplementary information as required.

DC version with case removed MF version showing the oscillator in the foreground

Keyset
The Keyset comprises press buttons, printed-circuit board with associated high-quality miniature components and buttons laid out to CCITT recommendations.

The digits 1 to 0 are arranged in a 3 - 3 - 3 - 1 pattern and read from left to right. Two other buttons, generally used for extra facilities and marked ) * and # are situated either side of the 0 button, forming a 3 - 4 format.

The 'break-through' characteristic of the press buttons eliminates any false contact operation, and therefore false signals.

The concave-faced white buttons have black, permanent, inset-moulded characters and are push fitted on to the key stems. Button markings can be provided to most specifications. DC telephones with a 10 button Keyset format (3 x 3 x 3 + 1 ) are available for orders of sufficient quantity.

Oscillator (MF only)
n2060y.jpg (17208 bytes)The printed-circuit oscillator board is fitted to the rear verticals of the cradle switch and powered from the exchange battery.

It comprises high-quality components, ensuring stability of output under the most adverse conditions of ambient temperature, humidity and exchange-battery voltage.

Handset
The handset is a lightweight, one-piece moulding with screw-fitted mouthpiece and earpiece. The cord is bayonet clamped and the transmitter and receiver inserts are connected by screw terminals for good connection.

Cords
The cord conductors for both desk and handset cords are copper-tinsel with PVC insulation and spade terminals. The outer sheath is of flexible PVC. The handset cord is the coiled extensible type. Grommets, fitted to both ends of the cords, lock into entry holes of the terminal block and main instrument and act as strainers.

Baseplate
The baseplate is moulded in toughened polystyrene and rests on four chloroprene non-stain feet to prevent the instrument from sliding. All interior parts of the instrument, cradle switch bracket, ringer and gongs, Keyset assembly and printed-wiring board are mounted on the baseplate.

Printed-wiring Board
A printed wiring board accommodates all speech circuit components except the transducers, and terminates all incoming and outgoing connections. The cradle micro switch has a low operating pressure and requires no maintenance. The regulator maintains constant speech levels irrespective of line lengths. Unregulated instruments can be supplied for large-quantity orders.

Terminal Block
This is for termination of the table version and comprises a two-piece copolymer moulding that can be secured to any flat surface.

Simplified Maintenance
The cover is easily removed on the release of a single screw at the base of the telephone.

The cradle switch can be locked by a manually operated latch to allow incoming calls to be signalled during instrument inspection.

All cord conductors are spade terminated to provide easy connection to the instrument wiring board and terminal block.

Ringer, bell gongs, Keyset, oscillator board and printed wiring board are readily accessible and easily replaced.

Robust construction and reliable components ensure trouble-free operation over long periods.

Colour Range
Standard colours are black, ivory and two-tone grey, but demands for special colours (red, blue, yellow and two-tone green) can be met for instruments ordered in sufficient quantity. In two-tone colours, the handset, cords and terminal block are in the darker tone.

Dimensions and Weights

Style   Height ins.   Width ins.   Depth ins.   Weight lbs.
Table telephone 4.5   9.3   8.9   5
Wall telephone   8.5   9.3   5.5   5

Telephone Types

Instrument Style   Code No.   Description Keyset format   Type of signalling   BPO Type
Table   N2060A   PB standard 3x3+1   DC   -
Table   N2060B   PB standard 3x4   DC   3A-2
Table, Blue N2060B5 PB standard 3x4 DC SA4252
Table, Grey N2060B6 PB standard 3x4 DC SA4252
Table N2063B PB two lamps (sim 740) DC
Table Yellow N2063B4 PB two lamps (sim 740) DC 2/SA4252
Table N2064B PB two lamps (sim 740)
Table N2064B1 - B7 B two lamps (sim 740) 2/SA4252
Table N2067A PB one lamp (sim 740) 3x3+1 LD
Table N2069B PB 2 lamp (sim 740) 3x4 DC
Table Yellow N2069B4 PB 2 lamp (sim 740) 3x4 DC 4/SA4252
Wall Grey N2070B6 PB standard 3x4 DC 3/SA4252
Wall   N2070B   PB standard 3x4   DC 3B-2
Table   N2080B PB standard 3x4   MF   4A
Table N2080B6 & B13 PB standard 3x4 MF SA4258
Table N2083B PB (sim 740) 3x4 MF
Wall   N2090B   PB two lamps (sim 740) 3x4   MF 4B

Abridged specification
Cover, Escutcheon, Handset and Terminal Block

ABS high-impact plastic.

Baseplate
Toughened polystyrene.

Colours
Standard: black, ivory and two-tone grey.
Special orders: red, blue, yellow and two-tone green.

Cords
PVC insulated copper-tinsel conductors in a PVC sheath.
Spade terminations.
Handset cord: coiled, extensible from 10 in (254 mm) to 6 ft (1 82gmm).
Desk cord. 6 ft (1 829mm) standard. Other lengths available.

Cradle switch
Microswitch BPO type 20A.

Keyset
'Break-through' action press button type with non-adjust phosphor-bronze springsets that are gold-silver plated at the contact area.

Oscillator (MF only)
Single transistor printed-circuit oscillator board providing stable multi-frequency oscillations for 1/4 + 1/4 VF signalling.

Button Characters
Black, permanent, and inset on white background to most specifications.

Handset Transducers
Receiver: BPO type 4T (rocking-armature type).
Transmitter: BPO type 16 (carbon-granule type).

Regulator
Transmission and reception zero-line sensitivity attenuated by 5dB.
Attenuation decreases with line length to 0db at 400 ohms.

Ringer
Unicoil type. N9268
Resistance: 1kohms
Impedance at 25Hz: 3kohms.
Impedance at 1 kHz. 10kohms.
Ringing frequency: 15-30Hz.

Bell Gongs
Double gong: harmonising tones.

Introduced around 1970.

Click here for a blueprint (290k)

PUBLICATION No.7621, 10/75

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Last revised: November 22, 2007