Automatic Metal-clad Telephone
Flush or bulkhead mounting type
The Pye TMC automatic metal clad telephone has been designed for
installation as either a flush mounted or bulkhead unit.
constructed case and deck are manufactured from sheet steel. The deck which
is hinged along the bottom edge, is retained by a single captive screw, it
can therefore, be swung open for maintenance purposes. The finish is hammer
tone grey stoved enamel.
Standard '1746' telephone components are used throughout. The handset and
its cord are black and held firmly in place by a retaining device. The
robust nature of this instrument makes it particularly useful for industrial
and shipboard use.
A version can be supplied with recall/earth/priority button.
Height - 158 mm
Width - 310 mm
Depth - 110 mm
Weight - 3.5 Kg
Pye TMC Stock No S538270 or S538271 (with recall/earth/priority button)
The case and deck is fabricated from sheet steel and finished in hammer tone
grey stoved enamel. The hinged deck can be swung open for maintenance
purposes. The handset is retained on the deck by a plastics covered
clip ensuring retention under severe conditions of vibration.
The complete construction is very robust and suitable for use in arduous
PVC - covered cadmium-tinsel-conductor cords. Held in position by
grommets which relieve conductors of any stresses. Handset cord,
coiled: 250 mm uncoiled 1.7 m.
Articulated-trigger type with self-compensating action. Projects
through self-centering ring on case. Characters printed black on
silver background beneath clear plastics finger plate.
Speed: 10 pps nominal.
Interdigit pause: 240 ms min
Break-to-make ratio: 2:1
Overall Transmission Characteristics
Carbon granule replaceable capsule type. The change in sensitivity
over the input range 3-30 dynes per sq. cm. is less than 5db at a given
frequency in the range 300-3400 Hz.
Rocking armature, replaceable capsule type. The receiver has a mean
sensitivity of +46 2dB relative to 1 dyne per sq. cm. per mW of available
power when tested with an artificial ear.
An automatic regulator is fitted to limit speech-signal amplitudes on lines
shorter than 400 ohms: introduces virtually no attenuation on longer lines.
Double coil, d.c. resistance 1000 ohm; impedance 2000 ohm at 25 Hz, 20 K
ohms at 1000 Hz. Accepts ringing currents of between 16 and 30 Hz.
Bells, double gong, harmonizing tones. Extension bell can be connected if
Suitable for use in all temperate climates. Tropical instruments available
Taken from Publicity Leaflet T108/3/74 (dated 1974)