HP 8901B Operation And Calibration Manual page 417

Adjustments Model 8901B
3. On the Modulation Analyzer, press
AM.
Set H P FILTER
to
50 Hz, LP FILTER
to
3 kHz, and
DETECTOR
to
AVG. Adjust A6C8
(IF
FLATNESS) for a minimum display (but less than 0.2%).
4. Disconnect the signal generator and connect the remaining equipment as shown in Figure 5-7.
5.
Set the audio analyzer's oscillator
to
10
kHz
at 4V. On the AM/FM test source, set the test mode
to
FM.
6. On the Modulation Analyzer, press FREQ. T h e the AM/FM test source's carrier frequency to
approximately 12.5 MHz.
7. On the Modulation Analyzer, key in 3.1 SPCL to set the
IF to
455
kHz,
press FM, and set LP
FILTER
to
>20 kHz and DETECTOR
to
PEAK+.
8. Adjust the audio analyzer's oscillator level for a Modulation Analyzer display of 10 kHz peak
deviation.
9. Set the distortion analyzer (in the audio analyzer) to measure the distortion on the 10 kHz
signal at the MODULATION OUTPUT/AUDIO INPUT with 30
kHz
of low-pass filtering on
the distortion analyzer.
10. Adjust A17Lll (FM DISTN 455 KHZ
IF)
for minimum distortion but less than 0.1% (less than
11. On the Modulation Analyzer, set LP FILTER
to
3 kHz.
12. Set the audio analyzer's oscillator frequency to 1 kHz and level for 5
kHz
peak deviation on the
13. On the Modulation Analyzer, press AM. Adjust A17L8 (INC AM 455 KHZ
IF)
for a minimum
-60
dB).
Modulation Analyzer.
display (but less than
0.2%).
NOTE
The specification for incidental AM requires that 0.5 times the residual
AM be subtracted out. The residual AM can be measured by momentarily
disconnecting the audio input to the AM/FM test source and noting the
displayed AM on the Modulation Analyzer. Subtracting 0.5 times the
displayed AM from the AM measured in step 14 gives the actual incidental
AM.
14. If a signilkant adjustment was made in either step 10 or step 13, repeat steps 5 through 14.
5-26 Adjustment 16