GEC C.B. TELEPHONE
Catalogue Nos. ST3300 series (Standard) and ST3400 series (Tropical)
A table telephone of modern design, for use on all manually-operated central
The corresponding telephone for automatic systems is described in
The moulded Bakelite case, identical in shape with the latest British Post
Office model, combines a robust design with a pleasing simplicity of line. This
instrument is the same as the automatic telephone, except that a dial dummy
replaces the dial, and its conversion to suit automatic systems is a simple
All components are mounted on a main assembly plate, which can be withdrawn
from the case very easily as a complete unit.
The cradle - switch mechanism has been specially designed to eliminate any
likelihood of sticking plungers. Twin contacts give maximum reliability.
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.
The four - way Bakelite terminal strip, connecting the incoming line wires to
the telephone cord, has moulded separators between terminal plates to maintain
long leakage paths. There are separate entrances for the line wires and the
The transmitter and receiver are British Post Office standards, and the
high-efficiency speech circuit gives maximum volume with uniform frequency
response and excellent sidetone suppression.
G.E.C. telephones for service in tropical climates incorporate various
special features, which are the result of long experience (See picture below):-
- A shunt is connected across the transmitter to minimise the minute
arcing that tends to occur at the granules and electrodes as the cradle
switch operates ; the accelerated tendency towards frying often shown by
transmitters in the tropics is thereby offset. The effect of any increase in
transmitter resistance upon line circuit conditions is also minimised by the
shunt. The loss in volume efficiency is very small and is partly cancelled
by reduction of sidetone, the nett result being a difference of only 1 db.
Should the conditions of use render the protection unnecessary and require
the very maximum of volume efficiency, then the shunt may be disconnected by
the simple transfer of one wire from one terminal to another.
- Ventilation holes in top and bottom of the case allow air to circulate
freely through the case to minimise condensation.
- All apertures are covered with fine wire gauze to prevent the ingress of
- Metal parts are specially finished, and all wiring is specially treated,
to resist the effects of high humidity and salt-laden atmospheres.
- Cradle-switch springs have large insulators to ensure long leakage
- Flexible cord conductors are V.I.R. covered and braided overall. Since
textile bindings at the ends are not in contact with the conductors,
moisture absorption cannot cause leakage. Rubber fittings give mechanical
protection at the points of entry to the mouldings.
- All coils are specially treated to render them impervious to damp, heat
and sudden changes in temperature.
The standard colour is Black but enquiries are invited for the telephone in
Ivory, Jade Green or Chinese Red, with cords finished to match.
A magneto extension bell in the G.E.C. Cat. No. BE1100 series (Standard) or
BE1200 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.
C.B. to Automatic
The conversion of this telephone for working on automatic systems is a
After removal of the case, the dial-dummy is replaced by a dial, and a dial
cord is connected between the dial and a terminal strip on the base.
Length - 7.25" (18.4 cm)
Width - 9" (22.9 cm)
Height - 6" (15.2cm )
Weight - 5 lbs. 3 ozs. (2.38 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
- For component parts, please refer to item by name and quote catalogue
number of complete instrument ; for example, "Handset cord for Telephone
Cat. No. ST3301".
Taken from the GEC Catalogue Leaflet No. STL.5
||300 TYPE - TROPICALISED
The ST prefix model numbers were introduced in 1946.
diagram numbers are all prefixed with KS.
ST3403 in Black (Note the vents about the dial dummy - this
ST3403 with chassis removed. This is a later model
with the "non-stick" switch hook plungers
ST3301 Standard CB telephone