By running a few checks, you can identify if the analyzer is at fault. Before calling Keysight Technologies or returning the instrument for service, please make the following checks.
A problem can often be solved by repeating the procedure you were following when the problem occurred. Before calling Keysight Technologies or returning the instrument for service, please make the following checks:
Is there power at the power socket? Is the instrument plugged in?
Is the instrument turned on? Check to see if the front panel line switch and at least one of the LED rings around the test ports glows green. This indicates the power supply is on.
If you are experiencing difficulty with the front-panel keypad or peripherals, the USB bus may be overloaded. Remove the USB devices, restart the VNA, and reconnect the USB devices. See Power-up.
If other equipment, cables, and connectors are being used with the instrument, make sure they are connected properly and operating correctly.
Review the procedure for the measurement being performed when the problem appeared. Are all the settings correct?
If the instrument is not functioning as expected, return the unit to a known state by pressing the Preset key.
Is the measurement being performed, and the results that are expected, within the specifications and capabilities of the instrument?
If the problem is thought to be due to firmware, check to see if the instrument has the latest firmware before starting the troubleshooting procedure.
Check that the measurement calibration is valid. See Accurate Measurement Calibrations for more information.
If you print the error terms at set intervals (weekly, monthly, and so forth), you can compare current error terms to these records. A stable, repeatable system should generate repeatable error terms over long time intervals, for example, six months. If a subtle failure or mild performance problem is suspected, the magnitude of the error terms should be compared against values generated previously with the same instrument and calibration kit. See the procedure for monitoring error terms.
A long-term trend often reflects drift, connector and cable wear, or gradual degradation, indicating the need for further investigation and preventative maintenance. Yet, the system may still conform to specifications. The cure is often as simple as cleaning and gaging connectors or inspecting cables.
A sudden shift in error terms reflects a sudden shift in systematic errors, and may indicate the need for further troubleshooting.
Consider the following while troubleshooting:
All parts of the system, including cables and calibration devices, can contribute to systematic errors and impact the error terms.
Connectors must be clean and gauged, and within specification for error term analysis to be meaningful. See the Chapter 2 in the VNA Service Guide for information on cleaning and gaging connectors.
Avoid unnecessary bending and flexing of the cables following measurement calibration, thus minimizing cable instability errors.
Use good connection techniques during the measurement calibration. The connector interface must be repeatable. See the VNA Service Guide for information on connection techniques.
It is often worthwhile to perform the procedure twice (using two distinct measurement calibrations) to establish the degree of repeatability. If the results do not seem repeatable, check all connectors and cables.
Use error-term analysis to troubleshoot minor, subtle performance problems. See Chapter 3, "Troubleshooting," in the VNA Service Guide if a blatant failure or gross measurement error is evident.
Some VNAs create automatic log of data for troubleshooting purpose. The log file stores data related to the total power ON time, number of times of power ON, results of power ON test and so on. For security reasons, if this data needs to be deleted, then SERVice:LOGGing:CLEar command can be used to clear the log recorded by the instrument.