Testing the precision cables on the Polar CITS900
Application Note AP196 

Testing the precision cables on the Polar CITS900

After extensive use the flexible cables used with the CITS900 will deteriorate and this will ultimately affect measurements made. This application note is intended to help owners of the CITS900 to check on the condition of the flexible test cables and decide when to replace.

Equipment required

  • CITS900
  • MQX448 SMA barrel connector
  • “Cable test” test file (click to download)


Connect the CITS900, turn on and wait for the instrument to warm up and come into calibration.

Load the “Cable test” file and open it. The test file should set up the CITS test parameters as shown in the diagram below.

CITS Cable test file parameters

Choose a channel on the CITS on which to run the tests. Ideally, this will be a channel on which the original cable is attached and in good condition.

Edit the test file to run on this channel.

Connect the barrel connector to the cable on the test channel.

MQX448 SMA barrel connector

Connect the cable under test to the barrel connector.

Run the test. The resulting waveform should be similar to that shown below.

If the test trace enters the red shaded areas — indicating that the impedance of the cable has changed by more than ±5% at some point — then replace the cable with a new Polar supplied cable, Polar Part No. WMA360.

Important: Use only the precision cables supplied by Polar Instruments; the CITS is calibrated using the supplied Polar cables. Use of any other cables will invalidate the calibration of the CITS900.