Keysight N9038A, Руководство по обслуживанию

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250 Keysight N9038A MXE Service Guide
RF Downconverter Section
RF Downconverter Section Troubleshooting
11. Tune the instrument to 6 GHz with a span of 0 Hz by pressing FREQ , 6 GHz
and SPAN , Zero Span .
Passband Insertion Loss
The insertion loss of the A12 YTF Preselector assembly at this frequency, with
the current filter tuning, can now be determined by calculating the difference
of what is read from the spectrum analyzer display and the -10 dBm signal
level being output by the signal generator (be sure to also account for the test
cable loss as well, which can be significant at the frequencies that this
assembly operates at).
The passband insertion loss of the A12 YTF Preselector itself should not be
greater than 10 dB, when properly tuned.
If the passband insertion loss is greater than expected, the cause for this will
need to be determined. It could be due to a greater loss than normal, distorted
passband filter shape, or incorrect passband centering.
Passband Filter Shape
12. Set the amplitude scale per division setting on the spectrum analyzer to
3 dB.
13. Turn on trace 2 of the spectrum analyzer and set it to use the Maxhold
function.
14. Slowly vary the frequency of the signal generator between 5.95 GHz and
6.05 GHz until the spectrum analyzer display looks like that of Figure
6-16 .
Figure 6-16 A12 YTF Preselector Passband Filter Shape