Model
8901B
Adjustments
Adjustment
14
AM
CALIBRATOR
0
Service
Sheet
30
Description
The Modulation Analyzer
is
set
to
read
%AM
as
computed from internal measurements. The AM
depth
is
adjusted for
33.33%.
The AM
is
then demodulated and the symmetry
is
adjusted
as
the signal
is
measured with the peak+ and peak- detectors.
NOTE
This
calibration adjustment
is
not critical. Built-in safeguards minimize
the possibility
of
erroneous calibration.
If
conditions exist that are out
of
calibration, the Modulation Analyzer displays an error message.
Procedure
1.
Connect CALIBRATION AMPM OUTPUT
to
INPUT. (The CALIBRATION
AMPM
OUT-
PUT
can be connected either
to
a
sensor module or directly
to
the Modulation Analyzer’s
INPUT.)
2.
Key in
13.0
SPCL. This sets the instrument
to
display the
AM
computed from internal
measurements.
3.
Adjust A50R45
(“A”
LVL) for a display
of
33.330
to
33.336%.
4. Key in 49.5 SPCL. This Connects the internal voltmeter
to
measure the output le&l from the
AM
calibrator. The display should read between
1.8
and
2.2.
5.
Key in
13.2
SPCL then
5.1
SPCL. This sets the instrument
to
display the demodulated AM from
the calibrator and sets the peak detector time constant
to
slow.
6.
Alternately set the DETECTOR
to
PEAK+ and PEAK- and note the display for each setting.
Adjust A50R39 (SYMM) until the readings are the same for both detectors within
*0.015%.
Adjustment 14
5-23
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