Review the General Troubleshooting recommendations before proceeding with this section.
This troubleshooting procedure assumes the PNA successfully passed the Power Level Accuracy (Source Power Accuracy) Performance Test. A failure in this test is often due to drift in the source linearity performance. To reset the coefficients which control this performance, perform the Source Calibration Adjustment.
Prior to running this test, two settings must be set to avoid error messages and possible test failure:
Meas: Mathematical offset for source attenuation
This setting must be set to ON. To verify the setting, follow the steps below:
If it was necessary to change the setting, return the PNA to its previous state after the test is completed.
Report when receiver is overloaded
This setting must be set to OFF. To verify the setting, follow the steps below:
If it was necessary to change the setting, return the PNA to its previous state after the test is completed.
You should not see a source unlevelled error reported on the PNA display during this test. If this error occurs and the test fails, first fix the source unlevelled problem. If phaselock lost errors appear on the PNA display during the test, it is usually best to perform a Receiver Calibration Adjustment. The linearity of the PNA receiver is the standard against which the source linearity is checked.
If the test fails on either Port 2 or Port 4 (or both) at lower power on the first test frequency, set up S22 and S44 (for 4-port) measurements. Also set the channel as CW sweep with frequency as 1 GHz, and let the unit run a few minutes before starting this test.
If failures continue, replace the source. Refer to the appropriate PNA service guide for replacement procedures.