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pna-x swept IMDX vs IMDX measurement issue

Question asked by rok on May 16, 2011
Latest reply on May 18, 2011 by Dr_joel

I am using the Swept IMDX measurement to measure C/3IM for a downconverter. My IM3Hi at the midpoint is about -64.42dB, while the IM3Lo is about -59.95. But when I create a conventional C/3IM measurement using the IMDX channel to focus on the center point of the band, I am getting the IM3Lo at -59.7, but my IM3Hi is about -60.744, which is 3.676 dB off, which is quite significant. I first used the calibration that I did for the swept IMDX channel and applied it to the IMDX channel. Later, I did a separate IMDX channel calibration, but I am getting roughly the same results. I am using firmware A.09.33.05. I tried using A.09.33.07 since it mentioned that it fixed several IMD/IMDX issues in the release notes, but the PNA-X application would crash whenever it  tried to trigger a IMDX channel. I read somewhere on the forum of other folks having some issues with the A.09.33.07 as well, but I am not sure if it is related to this issue or not. Any help would be greatly appreciated.