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Kirkby calibration kit alternatives?
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hendorog:

--- Quote from: Mechatrommer on February 22, 2018, 01:55:30 pm ---
--- Quote from: G0HZU on February 22, 2018, 01:01:11 pm ---I entered a polynomial for the Lx corrections for my DIY cal kit SHORT and got the result below...

--- End quote ---
what i concluded from your reply #35 and #36 is, are you suggesting that using less quality cal kit in the same VNA will result in more ripple? if that is the case, there is possibility that kirkby did the attenuator report using agilent cal kit as his calibration standard? i'll need to confirm this back to him.

anyway i'm doing the test with cheap crap china sma connection and 50 ohm coax cable. maybe those also contributes to the rippling effect, i'm not sure. what i'm sure is the cabling still give consistent result even if i move them around a little bit... fwiw...

--- End quote ---

I just took a closer look at your attachments in the post above this one.

Few comments which hopefully will help:
* The attenuator return loss measurements, with the free port terminated, is probably not too bad given the device. The return loss of that attenuator with attached terminator is probably pushing the limits of your device.
* The Dr Kirkby data and method you have to use (i.e. using the terminator) don't seem to line up with what he has in his FAQ: http://www.kirkbymicrowave.co.uk/FAQ/How-do-I-verify-the-calibration-kit-is-working-properly/
* The S21 measurements are probably poor as the Deepace doesn't seem to support a 'full 2 port' calibration. Do you know if it supports a full 2 port calibration, or is it just a 'response' calibration? In The Signal Path youtube review it shows a simple response cal only with a through.
* A full 2 port cal can correct for many more errors than a simple response cal can. Since you are using a lower cost, compact device which doesn't have great directivity and port return loss, then you will really need this error correction to get decent results on the S21 test.
* If you can pull the raw data out of the device and get it into touchstone format, then you should be able to use scikit-rf or Metas to do the full 2 port cal.
* According the manual it supports using an external bridge/coupler. Sometimes high quality ones come up on eBay which have come from HP gear.
Mechatrommer:

--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* The Dr Kirkby data and method you have to use (i.e. using the terminator) don't seem to line up with what he has in his FAQ: http://www.kirkbymicrowave.co.uk/FAQ/How-do-I-verify-the-calibration-kit-is-working-properly/
--- End quote ---
i did exactly according to that in my first report to him (see attached version 1 report fwiw). the S11 or S22 (just turning the attenuator upside down on the same VNA port 1) was totally out. in our email conversation he admitted the mistake of procedure in his link and  said he will edit the link, but it seems he havent. he asked me to do the test again with attenuator terminated. with attenuator's end dangling opened (like in the link), the reflection from opened end will affect to the port under test on the under end, something like that according to him.


--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* The S21 measurements are probably poor as the Deepace doesn't seem to support a 'full 2 port' calibration. Do you know if it supports a full 2 port calibration, or is it just a 'response' calibration? In The Signal Path youtube review it shows a simple response cal only with a through.
* A full 2 port cal can correct for many more errors than a simple response cal can. Since you are using a lower cost, compact device which doesn't have great directivity and port return loss, then you will really need this error correction to get decent results on the S21 test.

--- End quote ---
correct, there is no directional coupler (or power splitter) on the other port 2 of the VNA, so it can measure S21 only but not true S12. i have to turn the DUT around to simulate S12. i guess the VNA will try to solve half part of the full 4 port parameter matrix.


--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* If you can pull the raw data out of the device and get it into touchstone format, then you should be able to use scikit-rf or Metas to do the full 2 port cal.

--- End quote ---
what raw data? sorry noob question. but i dont think i can extract anything from the device other than its measurement result.


--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* According the manual it supports using an external bridge/coupler. Sometimes high quality ones come up on eBay which have come from HP gear.

--- End quote ---
thanks for reminding me this. i will study more on this.

ps: albeit more ripples on the output of the KC901V VNA, similar to G0HZU simulation on poorly tuned cal kit, i think we can still do some regression or averaging in our head on the result, since its still following the main path if we can see in G0HZU's report pictures reply #35, #36, #44 overlapped (2nd attachment). so i hope my VNA will give not entirely useless result. i just have to "assume" of lesser ripple in the final output. my further test and measurement will confirm this hypothesis true or false as i go, i just have to understand my tool better. ymmv.
hendorog:

--- Quote from: Mechatrommer on February 26, 2018, 05:32:41 am ---
--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* The Dr Kirkby data and method you have to use (i.e. using the terminator) don't seem to line up with what he has in his FAQ: http://www.kirkbymicrowave.co.uk/FAQ/How-do-I-verify-the-calibration-kit-is-working-properly/
--- End quote ---
i did exactly according to that in my first report to him (see attached version 1 report fwiw). the S11 or S22 (just turning the attenuator upside down on the same VNA port 1) was totally out. in our email conversation he admitted the mistake of procedure in his link and  said he will edit the link, but it seems he havent. he asked me to do the test again with attenuator terminated. with attenuator's end dangling opened (like in the link), the reflection from opened end will affect to the port under test on the under end, something like that according to him.

--- End quote ---

Yep makes sense.


--- Quote from: Mechatrommer on February 26, 2018, 05:32:41 am ---
--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* The S21 measurements are probably poor as the Deepace doesn't seem to support a 'full 2 port' calibration. Do you know if it supports a full 2 port calibration, or is it just a 'response' calibration? In The Signal Path youtube review it shows a simple response cal only with a through.
* A full 2 port cal can correct for many more errors than a simple response cal can. Since you are using a lower cost, compact device which doesn't have great directivity and port return loss, then you will really need this error correction to get decent results on the S21 test.

--- End quote ---
correct, there is no directional coupler (or power splitter) on the other port 2 of the VNA, so it can measure S21 only but not true S12. i have to turn the DUT around to simulate S12. i guess the VNA will try to solve half part of the full 4 port parameter matrix.

--- End quote ---

If you extract the data then you can still do better using scikit-rf. It supports a calibration type called 'Two Port one Path' or something like that. Basically you can do a full 2 port cal with only one directional coupler. You do need to swap around the DUT to measure both ports.
However to do this, first you need to be able to extract the raw data for the sweeps and transfer it to a PC. Then use software on the PC to do the calibration instead of using the software inside the KC901V.


--- Quote from: Mechatrommer on February 26, 2018, 05:32:41 am ---
--- Quote from: hendorog on February 26, 2018, 04:53:53 am ---* If you can pull the raw data out of the device and get it into touchstone format, then you should be able to use scikit-rf or Metas to do the full 2 port cal.

--- End quote ---
what raw data? sorry noob question. but i dont think i can extract anything from the device other than its measurement result.

--- End quote ---

Check the 'Data Saving' section of the manual. I found it online, apparently you can export s1p data files to an SD card in the smith chart mode.

Without doing a cal of the device, you do a sweep of your cal standards, and export them each into different files - i.e. short.s1p, open.s1p, load.s1p, thru.s1p and the device you want to test dut.s1p. Then you should be able to use those files containing 'raw data' with software like scikit-rf or Metas to do a calibration and measure the device on your PC.

Note I haven't done this myself - yet - so ymmv.


in3otd:

--- Quote from: rfspezi on February 18, 2018, 10:25:21 am ---That's why i hope somebody can recommend an alternative.

--- End quote ---

There is a description about using Rosenberger parts, similar to the ones in the SDR-Kits, as calkit, see http://www.hhft.de/index.php?page=competences&subpage=calibration. They just use the offset lengths to describe the standards and leave all the Cx and Lx to zero. It may not be so important to split the femtofarad if you go up to 5 GHz - any excess capacitance or inductance can probably taken into account by adjusting the offset length only.
hendorog:
Metas download link has landed in my spam folder this evening (I use gmail)

So anyone that is waiting, might be worth checking there.
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