Discriminator Alinement

TM 11-5820-549-50-1

d. Adjust T4, T6 and T6, in sequence, for

maximum voltage at TP2. Repeat the adjustments until

no further improvement is obtained.

3-6. Discriminator Alinement

If misalinement is indicated during troubleshooting (para

2-5), the discriminator should be alined as follows:

a. Connect the equipment as shown in figure 3-3.

b. Set the PP-3514/U for 3.2 volts.

c. Adjust the TS-585A/U for an impedance of 150

ohms

d. Adjust unmodulated frequency of AN/ URM-103

to channel frequency of AN/PRR-9 (XE-9) at 50

microvolts and fine-tune AN/ URM-103 frequency to

produce an indication of 455 kHz 500 Hz on AN/USM-

207.

e. Tune T8 for 0 volts on TS-352B/U.

f. Without changing frequency of AN/URM103, set

modulation at 1 kHz at 8 kHz deviation.

g. Adjust receiver control R7 for 3.5 milliwatt

indication on TS-585A/U.

h. Adjust T7 for minimum distortion indication on

TS-723A/U.

Figure 3-3. AN/PRR-9(XE-9) discriminator

3-7. Local Oscillator Alinement

alinement, test setup.

The local oscillator of the AN/PRR-9(XE-9) is normally

alined on the ID-1189(XE-2)/PR.

An alternate

b. Set the PP-3514/U for 2.6 volts. The lower-

procedure using test equipment is described below.

than-normal voltage will assure satisfactory oscillator

a. Connect the equipment as shown in figure 3-4.

operation under field conditions.

c. Install the desired crystal Y1 in the receiver and

set the receiver for squelched operation.

d. Adjust C15 fully clockwise.

e. Slowly adjust C15 counterclockwise until an

upward indication on the AN/URM-145 meter 100 mv

scale is observed.

Continue to adjust C15

counterclockwise until maximum indication is observed

on the AN/URM-145. The maximum indication should

be about one-quarter turn counterclockwise from the

point of initial upward deflection of the meter. A final

meter reading of 40 to 50 millivolts is typical.

3-8. Squelch Sensitivity Adjustment

The squelch sensitivity is normally adjusted with the ID-

1189(XE-2)/PR.

An alternate procedure using test

equipment is described below.

a. Connect the equipment as shown in figure 3-5.

b. Set the AN/URM-103 to the receiver channel

frequency with 50 microvolt output, and external

Figure 3-2. AN/PRR-9(XE-9) 10.7 MHz i.f. alinement,

modulation.

test setup.

3-3