Section III. ALINEMENT AND ADJUSTMENT PROCEDURES
used, allow a warmup period for this equipment as
73. Test Equipment Required for Alinement
prescribed in the appropriate manual.
a. Rf Frequency Meter. The output frequencies to
be measured are in the range of 50 to 400 megacycles.
b. Be careful when altering coil forms during the
Alternate use of Frequency Meters TS-174/U and TS-
alinement procedures. In most cases, only a slight
175/U, or equivalents, will provide full range coverage.
change in coil form is required to bring that particular
stage into correct alinement. Use a tuning wand (copper
check and adjust the dc voltage ( + 200 volts). It may
at one end, iron at the other) to predetermine the extent
also be necessary to measure reactor L2 primary current
and direction of coil forming required.
(approx. 10 milliamperes (ma)). Multimeter TS-352/U,
c. Conduct the test in a shielded inclosure. If a
or equivalent, will perform both functions.
shielded room is not available, make the alinement in an
area free from stray rf and electrical disturbances.
or equivalent, is used in completing the rf distortion test
d. To assure stable functioning of all test
setup.
equipment used, maintain a regulated line voltage to the
d. Audio-Frequency Meter. Frequency Meter FR-
test area.
67/U, or equivalent, is required for accurately measuring
e. Follow the alinement procedures in sequence.
the audio-oscillator operating frequencies of 1,000 cps,
1,600 cps, and 20,000 cps.
75. Adjusting Regulated Supply
e. Audio Distortion Indicator. Distortion measure-
Adjustment of the dc voltage (200 volts) is
ment at the audio oscillator is required in alinement
required before any other alinement is started.
procedures. Use Spectrum Analyzer TS-723/U, or
a. Turn the POW'ER switch to ON.
equivalent.
f. Rf Distortion Indicator. A reliable low-distortion
between ground and the junction of resistors R94 and
fm receiver, in conjunction with Spectrum Analyzer TS-
R95.
723/U, will serve to indicate rf distortion within Signal
c. Adjust potentiometer R105 (+200 adjust) for a
Generator SG-3/U.
meter reading of 200 volts.
g. Coil Alinement Tool. Tuning wand S/N 6 R
38490, or equivalent, must be used in predetermining
coil forming, when adjusting the stationary rf coils.
76. Adjusting Rf Oscillator
h. Rf Deviation Indicator. The rf deviation must be
The rf oscillator supplies the base frequency for
measured during the alinement procedures.
Use
all output ranges of the signal generator. Therefore, it is
Panoramic Indicator IP-173/U, or equivalent.
important to use an accurate frequency measuring
i. Rf Output Level Indicator. Barretter bridge
device when adjusting the rf oscillator. Be sure that the
model 209-B, or equivalent, is used as a standard for
instrument has had a 1/2-hour warmup period before
measuring and adjusting output level.
beginning these adjustments.
a. Connect the R. F. OUTPUT jack to the
74. Alinement Procedures
external frequency meter. Use Frequency Meters TS-
174/U and TS-175/U or their equivalents.
is repaired or altered, an alinement check is required. If
b. Set the MODULATION selector to the OFF
a circuit is found to need alinement, follow the
position.
procedures described in the following paragraphs.
c. Place the FREQ. RANGE-MC selector in the
Before starting, remove the outer covers from the signal
50-100 mc position.
generator. Refer to figure 39 for alinement points.
d. Rotate the TUNING knob to indicate 50
Allow 1/2 hour for instrument warmup before making
megacycles on the FREQ. IN MIEGACYCLES scale.
any adjustments. When additional test equipment is
e. Increase the OUTPUT control knob for a
reading at the external frequency meter, which
59
