Telephone Sets F High Power

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Telephone Set F High Power No. 1 Mk II
Working Instructions Telephone Sets F High Power No. 1 Mark II, 1944 - Figure 1.jpg
Weight 25 lb
Length 12.5"
Width 11"
Height 6.5"

The Telephone Set F High Power is a portable instrument for army communication on ranges greater than those obtainable with Telephone Set F Mk I. Its most common functions are at the end of direct long range extensions to a magneto switchboard, or a magneto calling equipment on a Common Battery (C.B.) switchboard, and on point to point circuts over which speech is not possible with ordinary telephones. The set comprises a modified Telephone Set F, and a valve amplifier. A handset P.O. type 184C which incorporates a pressel switch replaces the handset normal employed with the Telephone Set F.[1]

It provides the follow facilities:

Calls by magneto generator
Calls by buzzer
Responds by bell to magneto generator calling
Responds by aural indication to buzzer calling
Speech communication, using an over-over method

The amplifier incorporated in the set is unidirectional, the direction of amplification being controlled by the pressel switch on the handset which must be depressed while sending speech or buzzer signal and released while receiving, if the amplifier is switched on. hence no reception is possible while the telephone set is in a condition to send so that an "over-over" method of communication must be adopted. With the amplifier switched off, the set may be operated as a normal telephone F and the pressel switch need not be used.

The range of the Telephone Set F H.P is approximately three times that of a normal telephone, if high power telephones are provided at both ends of the circuit.

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  1. Working Instructions Telephone Sets F High Power No. 1 Mark II, 1944