Figure 5-2.--Single-gang sound-powered telephone jackbox.

Most large combatant ships have several sound-

powered telephone switchboards installed in different

centrally located and protected control stations. Each

switchboard facilitates and controls several

sound-powered telephone circuits.

Switchbox Circuit

A s w i t c h b o x c i r c u i t originates from a

sound-powered switchbox. Figure 5-4 is an illustration

of a type A-17A sound-powered telephone switchbox.

Each telephone station jackbox in the circuit connects

to a line cutout switch in the switchbox. The line cutout

switch either connects or disconnects an individual

telephone station jackbox from its circuit. There are also

tie lines and tie switches installed to allow paralleling

with circuits in other switchboxes or switchboards.

Switchboxes contain either 10 or 20 switches and

Figure 5-2.--Single-gang sound-powered telephone jackbox.

function primarily as small action cutout (ACO)

switchboards. Switchboxes are normally located at the

section from the sound-powered telephone switchboard.

station having operational control over the circuit or

Each telephone station jackbox (fig. 5-2) in the circuit

circuits concerned. Usually, there is only one circuit in

is connected to a switchjack on the switchboard. The

a switchbox.

switchjack (fig. 5-3) is a combination line cutout switch

and telephone jack. The line cutout switch portion of the

switchjack either connects or disconnects a telephone

String Circuit

station jackbox from its circuit. The jack portion of the

switchjack either parallels the telephone station

A string circuit consists of a series of telephone

associated with a particular switchjack to another circuit

station jackboxes connected in parallel to a common

or parallels two entire circuits. This method of

line. There are no line cutout switches provided for

paralleling is accomplished by a patching cord. A

cutting out individual stations. However, some string

patching cord is a short length of portable cord having

circuits are connected to communication consoles,

a jackplug at each end. The lines and tie switches are also

selector switches, and plotter transfer switchboards.

installed to allow paralleling with circuits on other

These will be discussed later in this chapter.

switchboards or switchboxes.

Figure 5-4---Sound-powered telephone switchbox.

Figure 5-3.--A switchjack.

5-4