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Operation
Model 8902A
BLOCK DIAGRAM
I
7
AM DEMODULATOR-
IALC LOOP1
TO AUDIO DETECTORS
VOLTMETER
AND DISPLAY
8888888888]
IF Lt~vc~l12fi~autrerncn~
Block Diagranr
COMMENTS
Acceptable
IF
Level Display.
An IF level display between 99.9% and 100.1% is considered acceptable for all measurements.
Input/Output Status.
When
IF LEVEL is
selected, the output at
MODULATION OUTPUT/AUDIO INPUT
continues
to
outpiit the demodulated signal corresponding t o the last modulation measurement selected as
indicated by the
MODULATION OUTPUT
annunciator. If the IF level
is
not IOOYo, the calibration
of the output is directly affected for AM and degraded for FM and QM if the IF level is very low.
Relative Measurements.
If
IF level is to be displayed relative to a reference level, enter the ratio reference using the RATIO
key. (Refer to Rario on page 3-245.)
IF
Levels Less Than 100%.
Error
03
(input circuits underdriven) is generated whenever the IF level is less than 1009'0 unless the
ALC loop is open, Override this Error Message using Special Function 8 . (Refer to Error lI.lcwagc>
Disahlc Control on page 3-267.)
3-1 10
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