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|  above is the 60-db bandwidth and
(3) Adjust the output of the AN/URM-
should not exceed 100 kc.
48 until the voltage indicated on the
(19) If the 60-db bandwidth is not as de-
411A is 100 millivolts. Record the
scribed, proceed to e below.
AN/URM-48 setting, which should
d. Alignment Procedure.
be about 20 microvolt.
(1) Repeat the procedures given in a (1)
(4) Increase the AN/URM-48 output 6
through (9) above.
db above that noted in (3) above.
(2) Set the VOLUME control on the re-
(5) I n c r e a s e the AN/URM-48 fre-
ceiver-transmitter fully counter-
quency until the voltage indicated
clockwise.
by the 411A is 100 millivolts.
(3) Adjust the AN/URM-48 output volt-
(6) Connect the AN/URM-48 to the AN/
age to 2.5 microvolt between pins
USM-26. Record the frequency in-
C and D of J9.
dicated by the AN/USM-26.
(4) Tune T1 and T2 for a maximum in-
(7) Adjust the AN/URM-48 frequency
dication on the ME-30A/U.
to 11.500 mc and the level to that
(5) Adjust the VOLUME control on the
noted in (4) above between pins C
receiver-transmitter to produce
and D of J9.
not more than 1 volt of audio signal
(8) Decrease the AN/URM-48 fre-
as indicated by the ME-26 B/U
quency until the voltage indicated
(connected between A25J4 and
by the 411A is 100 millivolts.
ground) .
(9) Connect the AN/URM-48 to the AN/
(6) Connect the TS-723A/U between
US M-26. Record the frequency in-
A25J4 and chassis ground.
dicated by the AN/USM-26.
(lo) The difference between the fre-
(7) Tune L4 and T2 for a minimum
1,000-cycle distortion as indicated
quencies noted in (6) and (9) above
by the TS-723A/U.
is the 6-db bandwidth and should not
be less than 32 kc.
(8) Repeat the procedures given in (4)
through (7) above until the audio
(11) If the 6-db bandwidth is not as de-
output, indicated by the ME-20A/U,
scribed above, proceed to e below.
(12) Adjust the frequency of the AN/
cannot be increased by tuning.
(9) Replace A5.
URM-48 to 11.500 mc and the out-
e. Faulty Parts Isolation.
put voltage to 60 db above the level
(1) Remove A5.
noted in (3) above across pins C and
(2) With the AN/URM-48 set to 11.50
D of J9.
(13) I n c r e a s e the AN/URM-48 fre-
mc, adjust the output level at J9,
pins C and D, as indicated in the
quency until the voltage indicated
chart in (a) below.
by the 411A is 100 millivolts.
(3) Measure the voltages at the points
(14) Connect the AN/URM-48 to the AN/
listed in the charts in (a) and (b)
USM-26. Record the frequency in-
below. Compare them with the nor-
dicated by the AN/USM-26.
mal signal and dc voltage listed.
(15) Adjust the AN/URM-48 frequency
to 11.500 mc and the output volt-
Note: Measure all voltages tO ground.
age to 60 db above the level noted
(a) Signal voltage chart.
in (3) above across pins C and D of
J9.
(16) D e c r e a s e the AN/URM-48 fre-
quency until the voltage indicated
by the 411A is 100 millivolts.
(17) Connect the AN/URM-48 to the AN/
USM-26. Record the frequency in-
dicated by the AN/USM-26.
(18) The difference between the fre-
quencies noted in (14) and (17)
139
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