Keysight Technologies 11644A K, User'S And Service Manual

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X, P, and K 11644A 1-5
General Information
Preventive Maintenance
Preventive Maintenance
The best techniques for maintaining the integrity of the devices in the kit include:
• routine visual inspection
• routine cleaning
• proper gaging
• proper connection techniques
All of these are described in
Chapter 4 . Failure to detect and remove dirt or metallic particles on a mating
plane surface can degrade repeatability and accuracy and can damage any device mated to it. Improper
connections resulting from poor connection techniques, can also damage these devices.
When to Calibrate
A network analyzer calibration remains valid as long as the changes in the systematic error are
insignificant. This means that changes to the uncorrected leakages (directivity and isolation), mismatches
(source match and load match), and frequency response of the system are small (<10%) relative to
accuracy specifications.
Change in the environment (especially temperature) between calibration and measurement is the major
cause in calibration accuracy degradation. The major effect is a change in the physical length of external
and internal cables. Other important causes are dirty and damaged test port connectors and calibration
standards. If the connectors become dirty or damaged, measurement repeatability and accuracy is affected.
Fortunately, it is relatively easy to evaluate the general validity of the calibration. To test repeatability,
remeasure one of the calibration standards. If you can not obtain repeatable measurements from your
calibration standards, maintenance needs to be performed on the test port connectors, cables and
calibration standards. Also, maintain at least one sample of the device under test or some known device as
your reference device. A verification kit may be used for this purpose. After calibration, measure the
reference device and note its responses. Periodically remeasure the device and note any changes in its
corrected response which can be attributed to the test system. With experience you will be able to see
changes in the reference responses that indicate a need to perform the measurement calibration again.