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Page Title:
Figure 65. Module A13, parts location. |
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|  nector on the mother board. Insert A13
procedure given in (8) above dif-
into the module extender. Apply a 10-
fers from that indicated in (5) above
by more than 2 db, proceed to the
millivolt rf signal of the frequency in-
alignment procedures in c below.
dicated in the chart in (1) below and
(10) If the indications obtained in the
measure the voltages across the parts
indicated. Compare them with the normal
procedure given in (5) and (8) above
are normal, testing of A13 is com-
signal levels listed. Press switch S3 for
pleted.
these measurements.
c. Faulty Parts Isolation. Insert the
Note: Measure all voltages to ground.
module extender (fig. 27) into the A13 con-
(1) Signal voltage chart.
to 53.400 mc, as indicated by the
(2) After the replacement of a faulty
AN/USM-26.
part, repeat the procedures given
(12) Set the receiver-transmitter tun-
in a and b above.
ing knobs for 30.90 mc. Record the
d. 53-Mc Filter Alignment.
the level at A12J2 as indicated by
(1) Remove module A15.
the 411A.
(2) Set the receiver-transmitter tun-
(13) If the levels recorded in (10) and
ing knobs for 30.50 mc.
(12) are not equal, 2 db, repeat
(3) Connect the 411A across the AN/
the procedures given in (8) through
URM-48 output.
(12) above while adjusting T1.
(4) Adjust the AN/URM-48 frequency
to 53.000 mc, as indicated by the
AN/USM-26, and the level to 20
millivolts, as indicated by 411A.
(5) Disconnect the 411A from the AN/
URM-48 and connect it between
A12J2 and chassis ground.
(6) Adjust L1, T2, and T3 for a peak
indication on the 411A. A typical
indication is about 100 millivolts.
(7) Disconnect the 411A from A12J2
and connect it across the AN/URM-
48 output.
(8) Adjust the AN/URM-48 frequency
to 52.500, as indicated by the AN/
USM-26, and set the level to 20
millivolts, as indicated by the
411A.
(9) Disconnect the 411A from the AN/
URM-48 and connect it between
A12J2 and chassis ground.
(10) Set the receiver-transmitter tun-
ing knobs for 30.00 mc. Record the
level at A12J2 as indicated by the
411A.
(11) Adjust the AN/URM-48 frequency
Figure 65. Module A13, parts location.
129
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