Crystal Oscillator Alignment.

TM 11-5820-509-35

trace and observe that the waveform amplitude is not

(10) Repeat step (4) with switch S1 on the

less 3.3 volts peak-to-peak and the frequency counter

front of the test fixture at 6. Verify that the output

indicates 1.0 MHz.

frequency is 694,000.00 1.0 Hz. If not, adjust

capacitor C125 (fig. 3-100) on the top of the module to

(20) Repeat step (4) except rotate switch S2

obtain this reading.

one complete revolution clockwise to a reading of 9.0.

(11) Repeat step (4) with switch S1 on the

(21) Adjust capacitor C72 (fig. 3-103) for

front of the test fixture at 7. Verify that the output

minimum 100-kHz modulation on the oscilloscope trace

frequency is 693,000.00 1.0 Hz. If not, adjust

and observe that the waveform amplitude is not less

capacitor C127 (fig. 3-100) on the top of the module to

than 3.3 volts peak-to-peak and the frequency counter

obtain this reading.

indicates 0.9 MHz.

(12) Repeat step (4) with switch S1 on the

e. Crystal Oscillator Alignment.

front of the test fixture at 8. Verify that the output

(1) Set switches S1 and S2 on the front panel

frequency is 692,000.00 1.0 Hz. If not, adjust

of the test fixture to O and OO respectively.

capacitor C129 (fig. 3-100) on the top of the module to

(2) Attach clips to the leads of a 0.01

obtain this reading.

microfarad capacitor and install it from the outer case of

(3) Repeat step (4) with switch S1 on the

variable capacitor C131 (fig. 3-100) to chassis ground

front of the test fixture at 9 Verify that the output

(module drive end plate).

frequency is 691,000.00 1.0 Hz. If not, adjust

(3) Place the frequency counter input probe

capacitor C131 (fig.. 3-100) on the top of the module to

at the base of transistor Q21 (common junction of C100,

obtain this reading.

C101, R111, and R112 on fig. 3-59) and verify that

(14) On the test fixture, return switch S1 to 0.

oscillator Q21 output frequency is 3,707,000.00 1.0

Rotate switch S1 to 1.0 and verify that the output

Hz. If not, adjust capacitor C133 (fig. 3-101) on the

frequency is 690,000.00 + 1.0 Hz.

If not adjust

bottom of the module to obtain this reading.

capacitor C135 (fig. 3-101) on the bottom of the module

(4) Remove the 0.01 microfarad capacitor

to obtain this reading.

installed in step (2) and connect the oscilloscope vertical

(15) Repeat step (14) except place switch S2

input and the frequency counter to jack J1 (fig. 3-100).

on the front of the test fixture to 2.0 and verify that the

Verify that the output frequency is 700,000.00 1.0 Hz.

output frequency is 680,000.00 1.0 Hz. If not, adjust

If not, adjust capacitor C113 (fig. 3-101) on the bottom

capacitor C137 (fig. 3-101) on the bottom of the module

of the module to obtain this reading.

to obtain this reading.

(5) Repeat step (4) with switch S1 on the

(16) Repeat step (14) except place switch S2

front of the test fixture at 1. Verify that the output

on the front of the test fixture to 3.0 and verify that the

frequency is 699,000.00 1.0 Hz. If not, adjust

output frequency is 670,000.00 1.0 Hz. If not, adjust

capacitor C115 (fig. 3-101) on the bottom of the module

capacitor C139 (fig. 3-101) on the bottom of the module

to obtain this reading.

(6) Repeat step (4) with switch S1 on the

(17) Repeat step (14) except place switch S2

front of the test fixture at 2. Verify that the output

on the front of the test fixture to 4.0 and verify that the

frequency is 698,000.00 1.0 Hz. If not, adjust

output frequency is 660,000.00 1.0 Hz. If not, adjust

capacitor C117 (fig. 3-101) on the bottom of the module

capacitor C141 /fig. 3-101) on the bottom of the module

to obtain this reading.

(7) Repeat step (4) with switch S1 on the

(18) Repeat step (14) except place switch S2

front of the test fixture at 3. Verify that the output

on the front of the test fixture to 5.0 and verify that the

frequency is 697,000.00 1.0 Hz. If not, adjust

output frequency is 650,000.00 1.0 Hz. If not, adjust

capacitor C119 (fig. 3-101) on the bottom of the module

capacitor C143 (fig. 3-100) on the top of the module to

to obtain this reading.

obtain this reading

(81 Repeat step (4) with switch S1 on the front of the

(19) Repeat step (14) except place switch S2

test fixture at 4. Verify that the output frequency is

on the front of the test fixture to 6.0 and verify that the

696,000.00 1.0 Hz. If not, adjust capacitor C121 (fig.

output frequency is 640,000.00 1.0 Hz. If not, adjust

3-101) on the bottom of the module to obtain this

capacitor C145 (fig. 3-100) on the top of the module to

reading.

obtain this reading.

(9) Repeat step (4) with switch S1 on the

(20) Repeat step (14) except place switch S2

front of the test fixture at 5. Verify that the output

on the front of the test fixture to 7.0 and verify that the

frequency is 695,000.00 1.0 Hz. If not, adjust

output frequency is 630,000.00 1.0

capacitor C123 (fig. 3-100) on the top of the module to

obtain this reading.

6-33