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|  (25) Track Z103 and Z101 (fig. 68) by
half-meshed tabs on each side for
bending the tabs on the rotors of
a maximum voltage indication on
the main tuning capacitors for a
the ME-26/U. Refer to the tab
maximum voltage at the ME -26/U.
color chart in paragraph 136 b.
Start at 399.9 mc and decrease the
(22) Set the ME-26/U to the -3 volts
the frequency in 10-mc steps to
dc range and connect the dc probe
229.9 mc; then decrease the fre-
to test point J106 (fig. 68).
quency to 225.0 mc. Refer to the
(23) Track Z105 by bending the tabs on
chart in paragraph 136b.
the rotor of the main tuning ca-
Note. When the tank circuits are com-
pacitor (part of Z105) (fig. 68) for
pletely misaligned, it may be impossible to
a maximum voltage on the ME -26/
track each tank circuit individually from
U. Start at 399.9 mc and decrease
399.9 mc to 225.0 mc because of lack of
the frequency in 10-mc steps to
excitation. If this happens, bend the tabs
229.9 mc; then decrease the fre-
on the appropriate tanks at each frequency.
quency to 225.0 mc. Refer to the
For example, at 389.9 mc, bend the tabs on
chart in paragraph 136b.
Z108, Z106, Z105, Z103, and Z101; then
bend the tabs on Z107. Start with 375.0
(24) Set the ME-26/U to the -1 volt
mc and decrease the MANUAL FREQUEN-
dc range and connect the dc probe to
CY control in 20-mc steps to 235 mc; then
test point J105 (fig. 68).
decrease to 225 mc.
Section IV. ADJUSTMENTS
between the audio test box termi-
nals labeled AF INPUT and AF IN-
a. Test Equipment Required.
PUT RETURN (10-pin audio con-
(1) Audio Oscillator TS-382/U.
nector terminals C and E).
(2) Oscilloscope AN/USM-50.
(6) Connect the TS-382/U between the
(3) Radio Frequency Wattmeter AN/
audio test box terminals labeled
URM-43A.
AF INPUT and AF INPUT RE-
(4) Multimeter ME-26/U.
TURN.
(5) Electronic Voltmeter ME-30B/U.
(7) Turn control R831 (fig. 76) fully
(6) Audio test box.
counterclockwise (zero resist-
ance.)
b. Test Setup.
(8) Set NOR BB switch S801 (rear of
(1) Perform alignment test setup (para
main frame, fig. 48) to NOR.
c. Procedure.
(2) Connect the AN/URM-43A to the
(1) Key the transmitter by connecting
ANT. jack on the front panel.
a lead between the RADIO CONT
Warning: Be extremely careful
LINE and the CONT LINE RETURN
when making the following connec-
terminals on the audio test box.
tions because +300 volts dc is pre-
(2) Set the TS-382/U audio output to
sent at test point J803.
1,000 cps and adjust it to produce
a 0.1-volt ac indication on the ME-
(3) Connect the AN/USM-50 to test
30B/U.
point J803 (fig. 76).
(3) Adjust control R843 (fig. 76) until
(4) Set the ME-26/U to 300 volts ac.
clipping of the sine wave is barely
Connect the ac probe to test point
perceptible on the oscilloscope.
J803. Ground the other ME-26/U
The ME-26/U indication should be
test lead.
approximately 150 volts ac or
(5) Set the ME-30B/U to the 0.3-volt
more.
ac scale and connect the test leads
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