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What does Error Code 27 on the 8970B Noise Figure Analyzer indicate?

The Keysight 8970B/71B/71C Noise Figure Measurement Operating Manual specifies the error code as: “Overflow while calibrating”.

This error is generated when excessive loss exists between the noise source and the noise figure analyzer´s input during calibration. This condition could exist due to several conditions as outlined below:

  1. High insertion loss in the calibration path due to external high loss devices such as an: isolator, attenuator, cable, etc
  2. Noise source not attached to the analyzer’s input
  3. A failed noise source
  4. Improper switching of the noise source +28V dc control voltage
  5. Other service failures

If excessive insertion loss is the culprit, remove the path loss from the calibration path, utilize Special Function 34.x, "Loss Compensation", to account for the pre and/or post DUT insertion loss, and re-calibrate directly between the noise source and analyzer input. Another alternative is to implement Special Function 32.x, and force the Calibration, Input Gain Selection, to a specific mode or range.

If a service failure is suspect, the following manuals may be of assistance in troubleshooting the 8970B analyzer.

Operating Manuals

  • 8970B /8971B /8971C Operating Manual (08970-90118 - see link)
  • Option H18 Operating Guide Special Supplement (08970-90042 – see link)

Service Manuals

  • 8970B Service Manual. For Standard instrument only. (08970-90054)
  • 8970B Option 020 Service Manual Supplement (08970-90115 - see link)
  • 8971C Service Manual (08971-90011)

Manuals that are listed without a link indicate an electronic version of the manual is not available. Visit Keysight "Find-a-Part" to arrange for purchase of these manuals.