CHAPTER 4. FUNCTIONING OF EQUIPMENT

TM 11-5830-255-14

CHAPTER 4

4-1. Introduction

4-2. Intercom System Functional Block

Diagram Description

(fig. 4-1)

Figure 4-1. Control and remote intercom system

functional block diagram.

switch S21 is held at TALK, it connects the coil

of relay K1 to 48V dc causing relay K1 to

operate, switching the loudspeaker (LS1) ter-

minals to the input of microphone preamplifier

TLC-503 (AMPL-2) the audio output of which

is applied through a fixed 30 dB attenuator pad

4-3. Central Intercom Unit Circuit Analysis

comprised of resistors R3, R4, and R6 to the

(fig. F0-2)

input of talk power amplifier TLC-409 (AMPL-

3). The output of this amplifier is applied through

closed contacts 3 and 4 of relay K1, contacts

A and B of the channel in use (S1 through S20)

to the VF line connections for that channel on

jack J1 or J2, supplying audio to the associated

remote station. Amplifier AMPL-3 is used to

provide capability to drive all 20 remote lines

if used simultaneously, and is nominally adjust-

ed for a -6 dBm output across 10-ohm load

resistor R2.

e. Aural and Visual Alarm and Control Cir-

cuits. When RING pushbutton S22 in depressed,

alarm DS21 sounds at the central intercom unit

4-1