Keysight Technologies N5247B, Service Manual

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8-10 Keysight N5247B Service Guide
General Purpose Maintenance Procedures
Error Terms
8-
The measurements most affected by load match errors are all transmission
measurements, and reflection measurements of a low insertion loss two-port
device, such as an airline.
Typical Cause of Failure
The calibration kit load or a bad “thru” cable is the most common cause of
load match specification failure.
If the load and cable performance are independently verified, then suspect the
analyzer test port coupler, step attenuator, or the test receiver at the bad
port.
To troubleshoot, refer to
“Checking the Receiver Group” on page 4-52 or to
“Checking the Signal Separation Group” on page 4-47 .
Isolation (Crosstalk) (E
XF
and E
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
21
, S
12
)
with loads attached to both ports during the measurement calibration.isolation
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 4-52 or to
“Checking the Signal Separation Group” on page 4-47 .