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w<j-o 110-13/ r r.
n r
n c o c i v L a
MAINTENANCE
4.3.6
4.3.6.1
ADJUSTMENT/ALIGNMENT PROCEDURES
General
The following Adjustment and Alignment Procedures should not be
performed on a routine basis, but instead, should be used as aids in troubleshooting
and post-repair testing. Before alignment is attempted, the technician should first
perform the relevant procedures to determine which module needs alignment.
4.3.6.2
Synthesizer Alignment
4.3.6.2.1
1st LO Synthesizer, A5A1, (791630) Alignment
The only alignment for the 1st LO Synthesizer is the 1st LO VCO
(A5A1A1). The VCO is a very sensitive circuit should only be adjusted when a definite
alignment is needed.
1.
2.
3.
4.
5.
Mount
the
1st
and 3rd LO on
an
extender
card and
remove the VCO front plate to gain access to alignment
components.
Connect a Digital Voltmeter to module pin Bl.
Refer to Table 4-38.
Tune receiver to the middle of band
0.
Adjust the components indicated until the voltage at
Bl is within stated limits as the receiver is tuned
throughout the range of band 0.
The voltage at Bl
should be verified with the VCO front plate in place.
Repeat step 3 for bands 1 through 7.
1st LO frequency band can be verified by connecting a
counter at test point A5A1A1-P2.
Table 4-38. VCO Alignment Parameters
VCO BAND
1ST LO FREQ
PIN Bl
VOLTAGE(DC) COMPONENT
0
(0-3.99)
42.91-46.90
-8.5
to
6.0
C6*, LI
1
(4-7.99)
46.91-50.90
-7.5
to
4.1
L2
2
(8-11.99)
50.91-54.90
-7.2
to
2.8
L3
3 (12-15.99)
54.91-58.90
-5.3
to
3.9
L2, L3
4 (16-19.99)
58.91-62.90
-6.6
to
2.7
L4
5 (20-23.99)
62.91-66.90
-6.0
to
2.2
L4, L2
6 (24-27.99)
66.91-70.90
-6.2
to
0.4
L3, L4
7 (28-29.99)
70.91-72.90
-5.7
to
-3.0
L4, L3, L2
4-59
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