Telephone, hand, c

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Telephone, Hand, C
Instruction in Army Telegraphy and Telephony Volume I - Instruments, 1914 - Chapter 11 Figure 9 (detail).jpg
Telephone, Hand, C, Mark II
Telephone, Hand, C Mark I is of Ericsson's Telephone design, and is generally similar to A Mark I. It is used with Telephone sets, Portable, C Mark I, and is equipped with Cord, telephone, C. The mouthpiece is of rubber to avoid damage from rough usage. The chief point of difference lies in the switch, which has an additional contact, for the purpose of short-circuiting receiver and secondary of induction coil when at rest. The conductors are therefore, two for receiver, one for transmitter, and one for switch. Care must be taken in joining up this instrument to get the conductors on the right terminals of the telephone.[1]

Telephone, Hand, C Mark II is intended for use with Telephone sets, Portable, C Mark II and Vibrator, telegraph, Mark I. It is made of aluminium, the handle consisting of a tube covered with leather, which is prevented from pressing the switch when shrunk with wet by an ebonite collar. The ends of the tube are closed by screw plugs, and the collars carrying the microphone and receiver cases can be removed by taking out a screw. The receiver is wound with •003-inch wire to a resistance of 120 ohms, and the microphone is of the capsule type. The mouth-piece is a leather hood, and is hinged to lie flat along the handle. The cord used is Cord, telephone, C Mark II, which terminates in hook-shaped contacts, labelled Ml, M2, Rl, R2. When used with Telephone set, Portable, C Mark II, M2 is spare.

The Mark III Telephone, Hand, C, differs from Mark II as follows : —

(a) A fibre push fitted outside the leather cover over the pressel switch,
(b) A fibre ear-piece fitted to the receiver in place of the pattern in Mark II.
(c) A metal deflector fitted to transmitter as in Telephone, Hand, D Mark I, in place of the present leather one.

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References

  1. Description from Instruction in Army Telegraphy and Telephony Volume I - Instruments, 1914