Products > Test Equipment
Kirkby calibration kit alternatives?
G0HZU:
Try clamping the cable ends so they can't move during the calibration.
Here's a 6dB attenuator measured using the crappiest SMA cables I have here. These are used/salvaged cables that cost less than £1 each on ebay and they are old but made with decent quality SMA elbow connectors. But the cable is regular skinny low cost cable.
See below for the attenuator response to 6GHz and how feeble these old cables are. But I still got a good result with a bit of care wrt not moving the cables during the full 2 port SOLT calibration.
hendorog:
--- Quote from: G0HZU on March 12, 2018, 01:39:44 am ---...during the full 2 port SOLT calibration...
--- End quote ---
--- Quote from: TheSteve on March 12, 2018, 12:23:28 am ---...Simply normalized the system...
--- End quote ---
I think the difference is ^^^
G0HZU:
The poor plots were blamed on poor phase stability so I assumed some form of SOLT calibration had been done. What's the point of posting up the attenuator plot if it wasn't made with the Kirkby cal kit? I'm lost...
I also don't see the point of posting up a plot to 6GHz using poor cables and a normalisation. The mismatch uncertainty during the through cal ought to be the main problem, not phase stability. Maybe try it again using attenuators at the cable ends during the thru cal. This will improve the port match.
TheSteve:
--- Quote from: G0HZU on March 12, 2018, 02:45:37 am ---The poor plots were blamed on poor phase stability so I assumed some form of SOLT calibration had been done. What's the point of posting up the attenuator plot if it wasn't made with the Kirkby cal kit? I'm lost...
I also don't see the point of posting up a plot to 6GHz using poor cables and a normalisation. The mismatch uncertainty during the through cal ought to be the main problem, not phase stability. Maybe try it again using attenuators at the cable ends during the thru cal. This will improve the port match.
--- End quote ---
It is fair you are lost. The post was largely irrelevant, just got caught up playing with my toys, sorry guys.
As far as a cal goes for S21 the only cal option I have is to normalize. The FF I have does not do S12/S22 nor phase with S21.
I can do the full OSL for S11 of course.
With respect to the attenuation plots it is quite easy for me to shift the plots around by moving the cable, I did switch to another which isn't as sensitive but it is still easy to see changes.
edit - G0HZU - the plot you made looks great. Do you know what(if any) kind of averaging or smoothing your analyzer is doing? I can easily make my plots look significantly better with just a little bit of smoothing added in firmware.
Added an example showing S21 and S11(well within the spec of the Mini Circuits attenuator), OSL cal for S11, normalize for S21, smoothing turned on).
hendorog:
--- Quote from: TheSteve on March 12, 2018, 03:47:13 am ---
--- Quote from: G0HZU on March 12, 2018, 02:45:37 am ---The poor plots were blamed on poor phase stability so I assumed some form of SOLT calibration had been done. What's the point of posting up the attenuator plot if it wasn't made with the Kirkby cal kit? I'm lost...
I also don't see the point of posting up a plot to 6GHz using poor cables and a normalisation. The mismatch uncertainty during the through cal ought to be the main problem, not phase stability. Maybe try it again using attenuators at the cable ends during the thru cal. This will improve the port match.
--- End quote ---
It is fair you are lost. The post was largely irrelevant, just got caught up playing with my toys, sorry guys.
As far as a cal goes for S21 the only cal option I have is to normalize. The FF I have does not do S12/S22 nor phase with S21.
I can do the full OSL for S11 of course.
With respect to the attenuation plots it is quite easy for me to shift the plots around by moving the cable, I did switch to another which isn't as sensitive but it is still easy to see changes.
--- End quote ---
If you can get all of the data out of your FF then you could have a go at using scikit-rf for the 'one path 2 port' cal.
I will be doing the same when my cal kit arrives and I'm happy to give it a go as a test run if you post all of the files. I don't have a test set, am just using a coupler.
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