HP 8901B Operation And Calibration Manual page 345

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% A M
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
H z
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 i s 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