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Thread: E5071C Calibration Issue


Permlink Replies: 2 - Pages: 1 - Last Post: Apr 23, 2012 6:40 PM Last Post By: gk
gk

Posts: 5
Registered: 04/17/12
E5071C Calibration Issue
Posted: Apr 17, 2012 10:02 AM
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Hi so I have a e5071c network analyzer and have an ecal module kit. I have many saved states and use the ecal for them. However it seems now that if I change states and/or cables the calibration becomes bad and I see way to many ripples on the s11 curve(mainly use above 5GHz) therefore having to do the cal again. Is this common or is the ecal module bad or vna need to be calibrated?

Thanks,

G
odanzy

Posts: 1,543
Registered: 11/16/05
Re: E5071C Calibration Issue
Posted: Apr 17, 2012 9:22 PM   in response to: gk in response to: gk
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Changing cables after a calibration can definitely cause mismatch issues. There are other variables (such as environmental - temperature and humidity and physical - cable flexure) that can effect the length of time that a calibration is valid. I personally, also think that the default 70 kHz IFBW that the ENA uses is too wide and usually drop it down to or below 3 kHz. You would also want to be careful with an additional adapters that are added to the system after calibration (or removed after calibration) as they can cause the mismatch conditions to change which will affect the calibration.

You might consider posting a couple screenshots of what you are seeing as well as what is changing in the setup.
gk

Posts: 5
Registered: 04/17/12
Re: E5071C Calibration Issue
Posted: Apr 23, 2012 6:40 PM   in response to: odanzy in response to: odanzy
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I wasn't very clear in my original post, here is a little better/further explanation. I do a 2port ecal calibration on the frequency range 4.9GHz to 5.9GHz and then save the state for example in state 1. The s11 looks fine and the calibration seems to work until I either change the state and go back to state 1,or change a cable and then go back to the same cable I calibrated on then the calibration seems to be off. The cables are 3ft in length FYI. This used to not happen before. The calibration can last for hours or days. It seems to be less frequent when I do a manual calibration than when I use the ecal. I will try to get some pictures uploaded soon. Trying to determine if its the ecal or VNA.

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