MAINTENANCE
PERFORMANCE TESTS
The UUT settings in this procedure are
chosen
to provide a strong confidence of the
modulation performance
of
the
UUT throughout its range. However, performance also
may be checked at other instrument settings if desired.
The FM deviation accuracy depends
upon software correction data stored in the VCO
Calibration EPROM
that
is derived from the measured
data
of
the
particular VCO
assembly installed in
the Generator.
TEST EQUIPMENT
Modulation Analyzer
Distortion
Analyzer
Frequency Counter
Low-Frequency Synthesized Signal Generator
(LFSSG)
DVM
PROCEDURE
1. Internal Modulation Oscillator
Frequency Test
a. Connect
the
UUT
RF
OUTPUT to the Modulation Analyzer
input,
b. Connect the
Modulation Analyzer
modulation
output to the Frequency
Counter input.
c.
Program the Modulation Analyzer to
measure
AM depth in a 0.05-kHz to
15-kHz bandwidth.
d.
Program
the UUT to [RCL]
[9][8].
Program
the
UUT for
90%
INT AM at a
1-kHz rate and a level of +1 dBm.
e. Verify that the Counter
reads
between
970
and
1030
kHz.
f.
Program
that the UUT to a modulation
frequency of 400 Hz.
g.
Verify the
Counter
reads between 388 Hz and
412 Hz.
2. Internal AM Accuracy Test
a. Measure the mean AM
depth, (+PEAK plus
-PEAK)/2, with the
Modulation Analyzer.
b. Verify that the mean AM
depth is between
84.4% and 95.6%.
c. Program the
UUT to a modulation
frequency of 1 kHz.
d.
Verify
that the mean AM depth
is between
84.4%
and
95.6%.
3. AM
Accuracy
and Distortion
Test
a. Connect the
output
of the LFSSG to the
UUT MOD INPUT and the DVM
(use a BNC T connector).
b. Program
the UUT for a frequency
of0.4 MHz, 1 d Bm level,
and
EXT AM at
30%
AM depth.
4A-13
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