GEC
ST3100 and ST3200

GEC MAGNETO TELEPHONE
TABLE TYPE
Catalogue Nos. ST3100 series (Standard) and ST3200 series (Tropical)

Application
A table telephone of modern design, for use with all types of magneto switchboards.

Construction
The moulded Bakelite case, identical in shape with the latest British Post Office model, combines a robust design with a pleasing simplicity of line.

The ringing generator, embodying the latest Alnico magnet, is of sturdy and compact design, giving high output for small bulk. For very long multi-party lines a higher-output generator is available.

The handset is the well-known moulded Bakelite Gecophone pattern, with inset-type transmitter and receiver.

The flexible handset cord will give exceedingly long service; the conductors are made from tinsel that withstands 200,000 reciprocations without breaking.

All components, except the dry cells, are mounted on a main assembly plate, which can be withdrawn from the case very easily as a complete unit.

The cradle-switch has been specially designed to eliminate any likelihood of sticking plungers. Twin contacts give maximum reliability.

The four - way Bakelite terminal strip connecting line wires and battery leads to the telephone cord, has moulded separators between terminal plates to maintain long leakage paths. There are separate entrances for the line and battery leads and the cord.

Performance
The transmitter and receiver are British Post Office standards and the high-efficiency speech circuit gives maximum volume with excellent frequency response and sidetone suppression.

Tropical Pattern
G.E.C. telephones for service in tropical climates incorporate several special features which are the result of long experience:-

• Ventilation holes in top and bottom of the case allow air to circulate freely through the case to minimise condensation (see the ST3221 above).
• All apertures are covered with fine wire gauze to prevent ingress of insects or foreign matter.
• Metal parts are specially finished and all wiring is specially treated to resist the effects of high humidity and salt-laden atmospheres.
• Flexible cord conductors are V.I.R. covered and braided overall and have rubber protection at the points of entry to the mouldings. Since textile bindings are not in contact with conductors, moisture absorption cannot cause leakage.
• All coils are specially treated to render them impervious to damp, heat and sudden changes in temperature.
• The cradle-switch springset has large insulators to ensure long leakage paths between springs.

Colours
The standard colour is Black but enquiries are also invited for the telephone in Ivory, Jade Green or Chinese Red, with cords finished to match.

Batteries and Battery Boxes
Magnet dry cells (made by the G.E.C.) are particularly suitable for service with this telephone. There are active and inert types suitable for service in either tropical or temperate climates.

Battery boxes to hold two dry cells can also be provided.

Extension Bell
A magneto extension bell in the G.E.C. Cat. No. BE 1100 series (Standard) or BE 1200 series (Tropical) is recommended for use with this telephone, to provide calling signals at a distant point, indoors or out, or to augment calling signals in very noisy surroundings.

Dimensions
Length - 7.25" (18.4 cm)
Width - 9" (22.9 cm)
Height - 6" (15.2cm )
Weight - 7.5 lbs. (3.4 kgs)

Enquiries and Orders
Please state on all enquiries and orders:

• Finish - whether standard or tropical
• Colour required.
• If batteries are to be supplied and whether they are to be active or inert.
• For component parts, please refer to item by name and quote catalogue number of complete instrument ; for example, "Handset cord for Telephone Cat. No. ST3101".

Taken from the GEC Catalogue Leaflet No. STL.5

It is also possible that GEC used the Ericsson N2120H base and added their own handset.  Click here for the Ericsson N2120H

The ST prefix model numbers were introduced in 1948.

The diagram numbers are all prefixed with KS.

GEC MAGNETO TELEPHONES
TABLE AND WALL MODELS

APPLICATION
Table and wall telephones of compact and modern design, for use with magneto switchboards and suitable for service in either temperate or tropical climates.

CONSTRUCTION
The moulded plastic cases, of distinctive and pleasing designs, combine robustness with simplicity of line. The case of the wall model is hinged to a metal base plate.

The table model has all components mounted on a metal base plate which can be easily withdrawn from the case as a complete unit.

The wall model has all components mounted on a self-contained unit which can be easily withdrawn from the case. For maintenance purposes the case, with the components unit attached, may be removed from the hinges.

The ringing generator, embodying the latest type magnet, is of sturdy and compact design, giving high output for small bulk. For multi-party lines, a generator with a higher output is available.

Provision is made for a capacitor to be included either in the receiver or bell circuits.

The handset is fitted with an inset-type transmitter.

The handset cord will give exceedingly long service: the use of tinsel conductors ensures freedom from breakage.

The cradle-switch has been specially designed to eliminate any likelihood of sticking plungers. Twin contacts give maximum reliability.

Table model telephones are provided with a four-way plastic terminal strip for connecting the line wires and battery leads to the telephone cord. The strip has moulded separators between terminal plates to maintain long leakage paths. There are separate entrances for the line and battery leads and the cord.

To ensure satisfactory service in tropical climates, the telephone incorporates various special features which are the result of long experience:-

• Ventilation holes in the case allow air to circulate freely through the case to minimise internal condensation.

• All apertures are covered with fine wire gauze to prevent ingress of insects and foreign matter.

• Metal parts are specially finished and all wiring is specially made to resist the effects of high humidity and salt-laden atmospheres.

• All coils are specially treated to render them impervious to damp, heat and sudden changes in temperature.

• Flexible cord conductors are V.I.R. or P.V.C. covered and braided overall, and have rubber protection at the points of entry into the mouldings. Since textile bindings are not in contact with conductors, moisture absorption cannot cause leakage.

PERFORMANCE
The transmitter and receiver are British Post Office standards, and the highly efficient speech circuit gives maximum volume with uniform frequency response and excellent sidetone suppression.

COLOUR
The instruments are black in colour.

BATTERIES
G.E.C. dry cells are particularly suitable for this telephone, and are suitable for service in either temperate or tropical climates.

EXTENSION BELL
To provide calling signals at a distant point, indoors or out, or to augment calling signals in very noisy surroundings, a magneto bell of the G.E.C. Cat. No. BE1100 series (Standard) or BE1200 series (Tropical) is recommended for use with this telephone.

BATTERIES
Suitable batteries for use with these telephones are listed below. Two are required for each instrument.
G.E.C. Long Life Dry Cell Catalogue Number Standard & Tropical BA4955.

ENQUIRIES AND ORDERS
Please state on all enquiries and orders: Catalogue Number of the instrument required and whether batteries are to be supplied.
For component parts, please refer to the item by name and quote the catalogue number of the complete instrument.

DIMENSIONS
Table Model
Length 7.25 ins. (18.4 cms.)
Width 9.25 ins. (23.49 cms.)
Height 6.75 ins. (17.19 cms.)
Weight 7.25 lb. ( 3.28 kgs.)

Wall Model
Length 5.5 ins. (13.97 cms.)
Width 8.5 ins. (21.59 cms.)
Height 9.25 ins. (23.49 cms.)
Weight 8 lb. ( 3.63 kgs.)

Taken from the GEC Catalogue Leaflet No. STL.5

The GEC pictures of the ST3131 have an Ericsson circuit diagram inside them which infers that GEC may have bought these sets in.  See Ericsson N2204

PICTURES OF THE GEC ST3121, ST3122 & ST3131
 

ST3121 - Early model
 

ST 3122 Early Model
 

ST3121 - Later model
 

ST3121 - later model with chassis removed from case

Later version of ST3231 identified by the chrome escutcheon plate around the ringer handle

ST3231 with case open
This is the tropicalised version - identified by mesh over the sound holes in the base plate
 

ST3231 open wide with components unit removed showing the clean layout

Last revised: August 04, 2022