Alarm-Monitor 1A5 Block Diagram Description

TM 11-5820-695-35

(2) The traffic monitor signal is supplied by

lamp DS1 assembly off, causing failure lamp DS1 to be

radio transmitter modulator 1A8 through attenuator

extinguished. When the sawtooth signal is not present

assembly 1A3. The traffic monitor signal is applied

or its amplitude drops to a low level, the ac detector

directly to operational amplifier (integrated circuit) AR1.

biases the transistor in failure lamp DS1 assembly on,

The operational amplifier output is detected and applied

causing failure lamp DS1 to light red (alarm condition).

to the traffic meter through a potentiometer and to

Pressing the TEST button on electrical frequency

Schmitt trigger circuit Q5, Q6 through dc emitter

synthesizer 1A14 front panel applies 5 vdc to the failure

follower Q1. If the traffic monitor signal exceeds a

lamp transistor causing the lamp to light red.

predetermined level, the dc voltage developed by the

detector CR1 and CR2 will cause Q5 to turn on, causing

(4) Voltage regulator Q02 provides 20 vdc to

Q6 to turn off and Q7 to turn on. With Q7 turned on, a

operate transistor circuits Q3 through Q6 and Q8

low impedance path to ground is provided for the normal

through Q13.

traffic indicator lamp, and the TRAF indicator lights

green. Since Q6 is turned off, a high impedance path to

2-14.

Alarm-Monitor

1A5

Block

Diagram

ground is provided for the alarm traffic indicator lamp

Description (fig. 5-14)

causing the indicator lamp (red) to remain off. When

the traffic monitor signal falls below the predetermined

Alarm monitor 1A5 receives monitor

voltage, the dc voltage applied to the base of Q5 is not

signals (traffic monitor, forward rf power monitor,

sufficient to keep Q5 conducting. With Q5 turned off,

reflected rf power monitor, and synthesizer monitor

Q6 turns on and Q7 turns off. For this condition, a high

signals) and controls the associated alarm indicators on

impedance path to ground is applied to the normal

transmitter meter panel assembly 1A15A8. Depending

traffic indicator lamp and a low impedance path to

upon the signal level received, the associated indicator

ground is applied to the alarm traffic indicator lamp.

lights either green (normal indication) or red (alarm

Consequently, the TRAF indication changes from green

indication). The alarm monitor also contains a summary

to red. Also with Q7 turned off, the Q7 output dc

alarm circuit which is enabled when any one of the

voltage is high, enabling the OR gate which causes Q23

alarm conditions occur. The traffic monitor signal

to turn on. With Q23 turned on, a transmitter summary

indicates the signal level input to radio transmitter

alarm indication is provided.

modulator 1A8. The forward rf power monitor and

reflected rf power monitor signals indicate the power

(3) The synthesizer monitor signal is derived

levels at the output of the T-1054/GRC-144. The

from electrical frequency synthesizer 1A14. The signal

synthesizer monitor signal is received directly from

(dc level) is applied directly to Schmitt trigger Q14, Q15.

electrical frequency synthesizer 1A14 and indicates if

Circuit operation is identical to that described above for

the signals from variable 2 frequency divider 1A14A5

the traffic monitor circuit. If the synthesizer monitor

and standard radio frequency oscillator 1A14A7 are

signal exceeds the predetermined dc level, the SYNTH

phase locked. An identical alarm monitor 2A12 is used

LOCK indicator lights green (normal indication). If the

in the R-1467/GRC-144; however, the jumper

synthesizer monitor signal is below the predetermined

connections on the associated plate assembly

level, the SYNTH LOCK indicator lights red (alarm

connectors are different for each assembly. Alarm

condition) and, in addition, the summary alarm circuit is

monitor 2A1,2 is described in paragraph 2-24.

enabled.

The following description is based on the

(4) The forward rf power monitor signal is a

circuits shown in figure 5-14.

detected dc voltage supplied by directional coupler

1DC1. The dc signal is applied to operational amplifier

(1) The TRAF, RF POWER, REFL RF

(integrated circuit) AR3 and the meter selector switch on

POWER, and SYNTH LOCK indicators on the meter

meter panel assembly 1A15A8 through an attenuator.

panel assembly 1A16A8 are controlled by Schmitt

The output of AR3 is applied directly to Schmitt trigger

trigger circuits in alarm monitor 1A5. The Schmitt

Q11, Q12. The operation of the Schmitt trigger is

trigger circuits cause the associated indicators to light

Identical to that described above for the traffic monitor

green (normal indication) or red (alarm condition). The

circuit. If the rf power monitor signal exceeds the

input signals to the alarm monitor control the operation

predetermined dc level, the RF

of the associated Schmitt trigger circuits.

2-41