Keysight N5221A Service Manual page 320

General Purpose Maintenance Procedures PNA Series Microwave Network Analyzers
Error Terms N5221A/22A
Isolation (Crosstalk) (E and E )
XF XR
Isolation, or crosstalk, is the uncorrected forward and reverse isolation error terms that represent leakage
between the test ports and the signal paths. The isolation error terms are characterized by measuring
transmission (S , S ) with loads attached to both ports during the measurement calibration.isolation
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errors affect transmission measurements primarily where the measured signal level is very low.
The measurements most affected by isolation error terms are DUTs with large insertion loss. Since these
terms are low in magnitude, they are usually noisy (not very repeatable).
Typical Cause of Failure A loose cable connection or leakage between components in the test set are the
most likely cause of isolation problems.
After verifying the cable and its connections, suspect the analyzer switch splitter, step attenuator, coupler,
or receivers, and associated cabling.
To troubleshoot, refer to "Checking the Receiver Group" on page 4-38 or to "Checking the Signal Separation
Group" on page 4-34.
8-12 Service Guide N5222-90001