Model 8901B Performance
Tests
10. Connect the audio analyzer’s input
to
the Modulation Analyzer’s MODULATION OUTPUT/
AUDIO INPUT. (See Figure 4-1.) Set the audio analyzer
to
measure the distortion on the
20
kHz
signal at the MODULATION OUTPUT/AUDIO INPUT with
80
kHz
of low-pass filtering
(on the audio analyzer). The distortion should be
0.3%
or
less (-50
dB
or
less).
AM Distortion
at
20
kHz
Rate; 50% AM
0.3%
11.
Increase the audio analyzer’s oscillator level until the Modulation Analyzer reads 95%
AM.
Measure the distortion. The distortion should be
0.6%
or less
(-44
dB
or less).
AM Distortion
at
20
kHz
Rate; 95% AM
0.6%
12.
Set the audio analyzer’s oscillator frequency
to
20
Hz.
Readjust the level,
if
necessary, for a
Modulation Analyzer display of 95% AM. Measure the distortion. The distortion should be
0.6%
or less.
AM Distortion at
20
Hz
Rate;
95% AM:
0.6%
13.
Decrease the audio analyzer’s oscillator level until the Modulation Analyzer reads 50%
AM.
Measure the distortion. The distortion should be
0.3%
or less.
AM Distortion at
20
Hz
Rate;
50% AM
0.3%
AM
Flatness
14. Set the audio synthesizer
to
1
kHz
at
+1
dBm. Connect its output
to
the audio input of the
AM/FM
test
source. (See Figure 4-1.) Fine adjust the audio synthesizer level for a Modulation
Analyzer display
of
80%
AM.
NOTE
Flatness
of
the audio synthesizer
is
critical
for
this test.
If
the audio
synthesizer has leveling capabilio, switch it on.
15. On the Modulation Analyzer, press
AVG.
Set RATIO on (with LOG/LIN
set
for
a
linear display).
Set the audio synthesizer frequency
as
listed in the
following
table. For each setting, note the
Modulation Analyzer’s display. The difference in readings between any
two
frequencies should be
less than
0.8%
REL.
NOTE
f0.3%
of
reading
is
equivalent to a difference
of
0.6%
between any pair
of
readings.
fl
digit at a nominal reading
of
80.0
is
about
f0.176
of
the
reading in the
RATIO
mode
or
f0.2%
for
any pair
of
readings. The total
limit
is
then
0.8%.
Audio Synthesizer Displayed AM
Frequency (Hz)
(%
REL)
1
1
000
10
000
150
90
I
I
I
AM Flatness (Maximum Difference):
0.8%
REL
Performance Test
1
4-5
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