EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: ralphrmartin on October 27, 2020, 10:35:08 am
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I'm trying to use the approach suggested here
http://www.hhft.de/index.php?page=competences&subpage=calibration (http://www.hhft.de/index.php?page=competences&subpage=calibration)
for a low-budget custom calibration kit for a Rigol RSA3000 series VNA.
However, I have a problem: the approach says to set (ignoring Open and Thru which are not a problem)
Match / Load (female): Offset Length: 0 mm
Short (female): Offset Length: 1.96 mm
but unless I am missing something, on the RSA3000, it does not seem possible to set an offset length for Load - it seems that whatever value you put in for Short is also used for Load, with no chance to set it differently.
Any helpful observations welcomed. Thanks.
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It isn't necessary to set a location for the 50 Ohm Termination. The Open and Short Positions set the Reference point for the Measurements. Your measurement will be at the actual Reference Position determined by where the Short/Open were set. You normally use an Open and Short that are each at the exact same distance, and the 50 Ohm Termination should have a very high Return Loss (preferably at least -45 dB). These are the basic reasons why the VNA Calibration Kits are so expensive.
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Thanks Ted, you are quite right. The user interface is a bit dicky, but the device works as expected, with zero offset for load, as I confirmed in a chat with Rigol's engineers.