PLESSEY TELEPHONE
No's N1340, N1341, N1900 & N1901

AUTO or C.B. GENERAL SERVICE
ETELPHONE

N1341		N1900

The "Etelphone" is a perfectly proportioned instrument moulded in the most modern plastic material combining rich, permanent surface lustre with robust strength. It is designed for highest quality transmission on lines of up to 1,000 ohms loop resistance and is available in black, new ivory, lacquer red, concord blue, topaz yellow, two-tone green and two-tone green.

Compared with earlier designs it has the following advantages:-

1. The risk of incorrect dialling is reduced by increased visibility of the dial numbers, which are external to the finger-plate. The numbers are in bold characters on the underside of the transparent plastic ring and cannot be defaced.
2. The handset is lighter, more comfortable to use, and specially shaped to rest in the hand in the position of maximum efficiency.
3. No apparatus is attached to the case; it is mounted on the strong composition plastic base-a most convenient arrangement for maintenance.
4. A single push-button key for Operator Recall, Shared Service, etc., can be easily fitted to a non-button instrument at any time.
5. Dial connecting wires are included in C.B. sets to simplify conversion to auto.
6. A key-operated dial lock switch can be fitted to the auto set to prevent unauthorised calls being made.
7. An automatic regulator unit can be fitted in the telephone to ensure high quality transmission irrespective of line resistance variation.

The telephone has full tropical finish. Connecting wires are insulated with p.v.c. which is moisture-proof and not susceptible to fungoid growth or insect attack. Coils are impregnated, metal parts specially finished and ringer perforations screened.

Two-tone sets have the case in one colour and the handset, number ring, and push key when fitted, in another. The dial dummy of the C.B. set and the key dummy for either set are coloured to match the case.

Instruments normally have a carrying handle under the handset.

Cords are of the p.v.c. insulated type and are normally coloured to match the handset, the desk cord being straight and the handset cord coiled. Similar cords in grebe grey, or nylon braided all straight cords in grebe grey can be supplied.

See also General Purpose Telephone

Introduced in 1959 and supplied worldwide.

Weight approx 3 lbs 11oz.

N1900 in Green	N1900 in Ivory	N1900 in Red

Taken from the Ericsson Catalogue No. 55

The Etelphone range combines high performance with attractive appearance and wide application. It includes the basic instrument designed in conjunction with the British Post Office and caters for the following requirements:-

1. Auto, c.b., or magneto working.
2. Conversion from c.b. to auto working.
3. Conversion from auto to c.b. working.
4. Conversion from magneto to auto or c.b. working.
5. Conversion from table to wall mounting and vice versa.
6. Line performance regulation.
7. Press button for additional switching or signalling functions.
8. Tropical finish with components specially finished and treated to withstand extreme climatic conditions.
9. Amplified handset for users with impaired hearing.
10. Ringer volume control.
11. Unauthorised call restriction by a key-operated dial lock.

All versions are similar in external design and available in a range of pleasing light-fast colours: black, ivory, concord blue, topaz yellow, lacquer red, two-tone green and two-tone grey. The instrument case and handset mouldings are of ABS copolymer, a high-impact material impervious to cosmetics, inks, oils and most chemicals. Table telephones are complete with a moulded desk connecting block in matching colour and both table and wall instruments feature a convenient off-hook position for the handset.

The transmission circuit ensures maximum frequency response and line sensitivity over exchange lines with loop resistances up to 1000 ohms. It employs a conventional hybrid transformer with a fixed balanced network and includes the following standard components:-
Ringer with coils wound to any specified resistance. The latest ceramic magnet material is used in conjunction with a pressed-iron frame to obtain high, stable performance with simplicity. A simple wire biasing-spring can be fitted to eliminate bell tinkle when the instrument is used on party lines.
Induction coil with high anti-sidetone properties.
Transducers of sealed capsule type.
Contact springs tipped with precious metal contacts to ensure maximum contact reliability.
Internal conductors are insulated with p.v.c., a material fully resistant to moisture, attack by insects and fungoid growth. Desk and handset connecting cords are additionally protected by p.v.c. sleeving. External conductors terminate on screw terminals on the instrument terminal field.

The dimensions are common to all versions of the Etelphone, being 11 in. x 9.25in. x 5.5in. (279 x 235 x 140mm); the weight varies between 3 and 4.6lb (1.3 and 2.1 kg).

The N1900 Series
Etelphone:
Auto or c.b.
This, the basic Etelphone, is suitable for use as a main or extension instrument. The dial (BPO type 21) is adjusted to transmit 10 pps with 2 :1 break/make pulse ratio. The dial number ring is fitted externally and bears standard numbering, i.e. 1 to 0. Alternatively, dials can be supplied with adjustments and numbering to suit customer requirements.

Line regulation (when required) is provided by a plug-in automatic performance regulator which limits sensitivity over short lines without affecting performance over long lines. If regulation is not required, the regulator can be inverted in the socket on the telephone base to form an unregulated telephone.
The internal wiring is point-to-point with soldered connections.

The N1901 Series
Etelphone:
Auto or c.b.
Produced to the same specification as the N1900 type this version is equipped with a press button for additional switching and signalling functions, e.g. shared service or operator recall. The button is positioned immediately in front of the handset cradle and operates a microswitch secured to the main instrument bracket.

The button, which is coloured to match the telephone and inscribed with the appropriate legend, may be locking or non-locking according to application.

Also in the Plessey Telecommunications Publication No. 7099 (1/69)

Front and Rear Views

Side View

Last revised: October 24, 2006