Vf and E&M Panels

TM 11-5895-1012-10

lead when a signal is received from the ringdown

trunk circuit. It also receives signals over an E-lead

from a signaling circuit and transmits 20 Hz signals to

a ringdown trunk circuit. This equipment can be ar-

ranged to operate with signaling frequencies other

than 20 Hz when required.

d. E&M Signal-Lead Extension Circuits (DX1 and

DX2). These signal-lead extensions units are designed

to interconnect two signaling and supervision circuits

when the metallic resistance between users exceeds

patch panel has four cable connectors mounted on the

operational limits. They are also used to interconnect

rear of the panel. As shown in figure F0-2, C1 and C3

an E&M signaling circuit to a distant trunk circuit

are used to bring the transmit and receive circuit leads

which uses single frequency signaling. E&M signal-

into the panel. C2 and C4 are known as the normal-

lead extension circuits are usually required where the

through connectors. The normal-through wiring which

connecting facility (cable) resistance exceeds 25 ohms

connects the line side to the equipment side of the

(50 ohm loop). These circuits, which have been coded

panel is routed through these connectors. Thus

DX1 and DX2, are always used in pairs (a DX1 being

is provided to the normal-through connections for fu-

connected to the trunk relay circuit and DX2 being

ture uses, such as automation of the Technical Control

Facility.

connected to a single frequency signaling unit). They

may be used in any combination, DX1 at one end of the

b. 6-Wire Primary Voice Frequency Patch Panel

circuit and DX2 at the other, or with like units at each

(E&M Signaling). The 6-wire Primary Patch Panel is

end of the circuit. This equipment usually functions

over metallic circuits with loop resistance up to 5000

ohms.

e. Pulse Link Repeater. The pulse-link repeater cir-

cuit connects two signaling circuits, using E&M leads,

panel between them. The E&M patch panel provides

signaling jack appearances for the 12 channels above,

by converting an incoming E-lead potential to an out-

as well as the 12 channels below it. A front view of an

going M-lead potential in both directions of transmis-

sion. This equipment does not connect to or affect the

E&M signaling patch panel is shown in figure 2-15B

and the interconnection diagram in figure 2-16. The

talking it is connected in the signaling path only.

odd numbered jacks serve the E&M signaling leads of

2-35. Vf and E&M Panels

the vf above it while the even numbered jacks serve

the E&M signaling leads of the vf panel below it. The

A voice frequency jackfield is designed as an area in

top row of jacks is electrically toward the line, and the

the Technical Control Facility where voice frequency

second row of jacks is toward the Technical Control

circuits and their associated signal and control leads

Facility equipment. As with other patch panels, the

can be patched, monitored and tested. A patch panel is

normal&rough connections between the line and

a signal unit in the jackfield. There are four types of

equipment sides of the panel (row 1 and row 2) are

voice frequency patch panels in the TCF; the Equal

brought out to a normal&rough connector for future

bevel., the 4-wire, the 6-wire primary, and the 2-wire

use.

primary patch panels. Each panel serves a different

c. 2-Wire Primary Voice Frequency Patch Panel.

function as described in paragraph 2-17.

This panel is similar to the 6-wire vf patch panel in

a. Equal Level and 4-Wire Primary Patch Panels

that it has four rows of jacks for line side, equipment

(fig. 2-15A) Each Equal Level and 4-wire primary

side, and monitoring operations. Since it is a 2-wire

patch panel contains 12 channels. Each channel occu-

panel, it can hold 24 channels. Refer to figure 2-17 for

pies a paired jackset (a jack& consists of 4 jacks ar-

the interconnection diagram of a 2-wire patch panel.

ranged vertically) of the panel as shown in figures

2-15 and F0-2. The receive circuit occupies the left

2-36. Dc Patch Panels

jackset (odd numbered jacks) in each paired jackset,

a. Primary Dc Patch Panel.

and the transmit circuit occupies the right jackset

(1) Panel Description (fig. 2-15). The primary dc

(even numbered jacks) of each paired jackset; there-

patch panel is that equipment within the Technical

fore, the jacks are alternately labeled REC and

oni-

TRANS. The top row of jacks are labeled LINE and are

the

electrically toward the line or away from the Technical

2-38