Keysight Technologies 85032B User's And Service Manual

85032B/E 1-7General InformationWhen to CalibrateWhen to CalibrateA network analyzer calibration remains valid as long as the changes in the systematic error areinsignificant. 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 toaccuracy specifications.Change in the environment (especially temperature) between calibration and measurement is the majorcause in calibration accuracy degradation. The major effect is a change in the physical length of externaland internal cables. Other important causes are dirty and damaged test port connectors and calibrationstandards. 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 yourcalibration standards, maintenance needs to be performed on the test port connectors, cables andcalibration standards. Also, maintain at least one sample of the device under test or some known device asyour reference device. A verification kit may be used for this purpose. After calibration, measure thereference device and note its responses. Periodically remeasure the device and note any changes in itscorrected response which can be attributed to the test system. With experience you will be able to seechanges in the reference responses that indicate a need to perform the measurement calibration again.