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Page Title:
Alignment of Rf and Power Amplifier Subunit |
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|  (2) Connect the AN/URM-43A to the
Caution: Do not bend the tabs
ANT. jack on the front panel. Set
beyond 30 from parallel to the
the AN/URM-43A to the 60-watt
stator plates. Bending beyond this
range.
point produces little change in ca-
(3) Set the ME-26/U to the 3-volt .ac
pacitance and will weaken the tab.
range and connect rf probe to the
(9) Connect the dc probe of the ME-
junction of R114 and J113 (fig. 72).
26/U to test point J104 (fig. 68).
d. Procedure.
(10) Key the transmitter as in (3) above.
(1) Turn trimmer capacitors C215,
(11) O p e r a t e the MANUAL FRE-
C221, C227, and C233 (fig. 55)
QUENCY TENS control from 29
counterclockwise to their stops
through 22 and, at each position,
(minimum capacity).
bend the tab that is half-meshed
(2) Set the MANUAL FREQUENCY
with the stator for a maximum volt-
TENS control to 39.
age indication on the ME-26/U.
(3) Key the transmitter by connecting
Start with Z208, and then tune Z206,
a lead between the RADIO CONT
Z204, and Z202. The voltage at J104
LINE and the CONT LINE RETURN
should vary from -1 to -3 volts.
terminals on the audio test box.
(12) Unkey the transmitter by removing
(4) Turn C215, C221, C227, and C233
the lead in (3) above.
clockwise to the first voltage peak
Caution: To prevent damage to
indicated on the ME-26/U.
V104, V105, and V106, do not op-
(5) Unkey the transmitter by removing
erate the rf unit as a transmitter
the lead in procedure (3) above.
for longer than 3 minutes at one
(6) Set the ME-26/U to -3 volts dc
time when the rf amplifiers are
range and connect the dc probe to
misaligned.
test point J106 (fig. 68).
(7) Make slight adjustments on C233,
C227, C221, and C215 to obtain
maximum voltage on the ME-26/U.
Subunit
This voltage is approximately 1.8
to 2.75 volts.
a. Test Equipment and Tools Required.
(8) Track the frequency tripler-am-
(1) Multimeter ME-26/U.
plifier section of the uhf injection
(2) Radio Frequency Wattmeter AN/
URM-43A.
system over the upper half of the
(3) Alignment tool.
radio set frequency range (399.9
(4) Tuning wand.
to 309.9 mc) by bending the tabs
on the main tuning capacitor rotors
b. Test Setup.
(1) Perform the alignment test setup
of Z208, Z206, Z204, and Z202 (fig.
54). For example, when the radio
(2) Set the AN/URM-43A to the 60-
set is tuned to 399.9 mc, the tabs
watt range and connect it to the
with black tips will behalf-meshed
ANT. jack on the front panel.
with the stators on Z208, Z206,
c. Procedure.
Z204, and Z202. DO not adjust any
(1) Set the MANUAL FREQUENCY
other tabs at this frequency. Tune
for maximum voltage on the ME-
controls to 399.9 mc.
(2) Check the mechanical synchroni-
26/U. Operate the MANUAL FRE-
zation of Z101, Z103, Z105, Z106,
QUENCY TENS control from 39 to
and Z108 (fig. 68); the small tab on
30 and, at each position, bend only
the rotor should be in full-mesh
the tabs that are half-meshed with
the stators. Start with Z208; then
with the stator, and the tab (black
tip) opposite should be in half-
tune Z206, Z204, and Z202. The
mesh. On the Z107 (fig. 68), the
chart in b above shows the tab fre-
first rotor tab leading edge on both
quencies and tab color code.
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