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Troubleshooting CalPod Opcheck Failures


Instructions for using the CalPod Operational Check are contained in the built-in PNA help in the CalPod section.  Link to online version of CalPod PNA help.

The CalPod Operational Check exercises both the CalPod controller and individual CalPod modules.

This web page covers additional user information for CalPod Operational Check usage and troubleshooting.


Additional User Information for CalPod Operational Check

The results file is saved as calpodopchklog.txt.  The file is located in c:\Program Files\Agilent\Network Analyzer\Service.  Text lines marked with '===>>>' indicate a failure.

The attenuation inserted between the PNA port and the CalPod module prior to the Recorrection step may be up to 10 dB.  Six dB or less is recommended.


Troubleshooting CalPod Opcheck Failures

If you have multiple CalPod modules connected to your controller, make sure the correct module is connected to the PNA during the OpCheck.

Failures for Load Match, Thru Loss, or States may be caused by a poor calibration.  Repeat paying special attention to the calibration process.  Make sure appropriate calibration standards are used.

Calibration accuracy is less important than cable stability.  Adapters added after calibration typically are not significant.

A failure during the Recorrection Test is likely caused by an unstable cable.  Try the following:

- Skip inserting the attenuation prior to the Recorrection step (click Cancel at the prompt), if Recorrection passes, this indicates the problem is most likely cable stability.

- Test the cable for satisfactory stability (see process below).

- Allow 30 seconds of settling time whenever the cable is moved or changed.

- Torque all RF connections carefully to maximize connection repeatability.

- The measurement traces displayed on the PNA following the last step in the OpCheck are the recorrection measurement results.  Move the OpCheck window down to view these traces.

If the Ecal is not detected, perform a normal PNA calibration using the Ecal to make sure the Ecal is functioning properly.

If the temperature check fails, the temperature sensing circuit in the CalPod module has likely failed.  The absolute value of the temperature is not critical to the CalPod module operation.

Make sure that cables and adapters of appropriate frequency range are used.  This is particularly important for 40 GHz modules.

Make sure you are using the appropriate cal standards, click on Connector label for cal kit info.

How to test cable for stability:

(Using a very stable cable is the most critical requirement for getting accurate results.)

  • Connect the cable between two ports of a NA.
  • Set the frequency range to cover the range of the CalPod modules under test.
  • Set up a thru measurement on the cable.
  • Normalize the measurement to produce a flat trace at 0 dB.
  • Move the cable to stress various sections, disconnect and reconnect one end of the cable.
  • Allow the cable to mechanically settle into a steady position.  Wait for the trace to stabilize.
  • The trace should be within the limits indicated below -

Below 20 GHz:  +/-0.05 dB         20 to 33 GHz:  +/-0.1 dB        33 to 40 GHz: +/-0.2 dB


Last Updated: March 6, 2012

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