Orderwire Assembly 1A13 Circuit Functioning

TM 11-5820-695-35

circuits.

In figure 538.1, the voltage filtering

components are L3,1 L4, and capacitors C6 through

Capacitor C1 charges with negative polarity on the side

C10.

connected to the base of Q1. On negative-going input

signal transitions, the negative charge on C1 speeds up

switching time of Q1.

2-50. Orderwire Assembly 1A13 Circuit Functioning

Output Circuit. The cable direct current

Orderwire assembly 1A13 provides party line

path is shown in figure 5-29 which illustrates the

communication on a single orderwire channel by

complete current path through digital data modem 1A12.

amplifying and interconnecting signals between Handset

Diodes CR8 through CR15 provide protection against

H-156/U, remote phone, the radio equipment, and the

breakdown voltages in excess of 1300 volts. The cable

through orderwire. The internal orderwire connections

current is set for a nominal 38 milliamperes. The cable

are such that sidetone is only provided for Handset H-

simulation networks are 1/4-mile line sections which can

1656/U. The orderwire assembly also provides central

be patched on-line for proper termination of the cable.

alarm monitoring circuits, an input to a speaker monitor,

These are selected to provide a 1-mile cable section for

inband signaling at 1.6 kHz, a 1.1 kHz test tone, and

the remote cable repeater. Capacitor C4 provides

orderwire fault detection circuits. Five daughter board

signal ground for pcm.

assemblies 1A13A1 through 1A13A5 plug into orderwire

chassis 1A13A7 to provide the functions mentioned

Traffic Detector. The traffic detector circuit

above. The interconnections between the five daughter

board assemblies and chassis mounted components of

consists of transistor stages Q2 through Q4. The traffic

the orderwire assembly are shown in figure 5-39.

signal from cable output amplifier Q1 is applied to traffic

Paragraphs 2-51 through 2-55 describe each board in

detector amplifier Q2, Q3 through transformer T1. The

reference designation order (1A13A1, 1A13A2, etc).

output of Q3 controls transistor switch Q4 in the traffic

The descriptions are at the circuit level and are based

detector circuit and also transistor switch Q5 in the

on the schematic diagram of the associated board.

indicator circuit. When a traffic signal is detected Q4

and Q5 are turned on. With Q4 and Q5 turned on, the

ONOR output is low and DS1 is on (normal condition).

2-51. Daughter Board No. 1 Assembly 1A13A1

When a traffic signal is not detected, Q4 and Q5 are

Circuit Functioning (fig. 5-40)

turned off. With Q4 and Q5 turned off, the ONOR

output is high and DS1 is off (alarm condition). Positive

Daughter board No. 1 assembly 1A13A1 provides the

pulses at the secondary (pins 5 and 6) of transformer T1

orderwire fault detection circuits. The circuits consist of

are applied through current limiting resistor R26 to the

a 4.02 kHz oscillator circuit, monitor circuit, MODULE

base of Q2. Q2 turns on and develops a negative-going

TEST selector switch, and TEST TONE switch. The

voltage pulse across collector load impedance R27, R28

MODULE TEST selector switch (1A13A1S1) connects a

and R29. Part of this signal is connected to t-he base of

test input signal (4.02 kHz or ground) to the orderwire

Q3, which then develops a positive-going voltage pulse

circuit under test. The output of the orderwire circuit

across collector impedance R34. The positive-going

under test is connected through the MODULE TEST

output signal of Q3 is coupled through current limiting

selector switch to the monitor circuit. The TEST TONE

R32 and R33 into the bases of Q4 and Q6. Q4 and Q5

switch (1A13A1S3) is used to control the 1.1 kHz

turn on and signals ONOR and 1RP-FAIL are logic zero.

oscillator circuit on daughter board No. 2 assembly

Lamps DS1 is lighted. Diodes CR3, CR4, CR6 and CR7

1A13A2. When depressed, the TEST TONE switch

are connected from base to emitter at their respective

turns on the 1.1 kHz oscillator and the 1.1, kHz test tone

transistors. They protect the base emitter junction

signal is routed to the orderwire circuits. The following

against excessive reverse voltage. Resistors R31 and

subparagraphs describe the 4.02 kHz oscillator and

R35 speed up turn off time of Q4 and Q5. Resistor R36

monitor circuits on daughter board No. 1 assembly

keeps lamp DS1 warm during off time. CR5 and R30

1A13A2.

limit current (to external relay 1A12A12A2TB1K1) for

logic one (Q4 off).

4.02 kHz Oscillator Circuit. The 4.02 kHz

oscillator circuit generates a test signal for amplifier

Voltage Filtering Components. In figure 5-

circuits on daughter board assembles

38, voltage filtering components L1, L5, L6, L7, C2, C3,

and C14 through C19 limit the coupling of switching

transients and other stray signals to the power supply

2-88

Change 1