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Re: T-Check for my nanoVNA - Results look excellent below 150 MHz and acceptable up to 300 MHz
! ListType=Lin (This addition was probably not needed)Hello Kurt, This 'ListType=Lin' parameter was necessary :-) Question: where did you found that parameter 'ListType=Lin'? I looked in specification touchstone_ver2_0.pdf, and in VNWA_HELP_36.7.8.pdf and in How to perform a T-Check for a VNWA Calibration.pdf and did not found it. Now it works, see attached screen shot VNWA_nanoVNA-Saver_T-Check.png Thank you very much for this hint and you help. 73, Rudi DL5FA |
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Re: T-Check for my nanoVNA - Results look excellent below 150 MHz and acceptable up to 300 MHz
Hi Rudi
Correct about R&S T-Check, no way to get it to run on W10 Kind regards Kurt -----Oprindelig meddelelse----- Fra: [email protected] <[email protected]> P? vegne af Kurt Poulsen Sendt: 6. november 2019 12:46 Til: [email protected] Emne: Re: [nanovna-users] T-Check for my nanoVNA - Results look excellent below 150 MHz and acceptable up to 300 MHz Hi Rudi I did export a s2p file from latest version 1.5 of the NanoVNA-saver and it was imported right away in the VNWA It is in the format RI meaning real Imaginary S parameter so why you have no success with the VNWA is a big question mark I have made a note yesterday about a T-Check file with an extra S at the end of the # line but that is not the case here. I have a comment about calibration when doing a T-Check. When the two test cables are connected to the Ch0 and Ch1 it must be S11 reflection calibrate calibrated with the SMA male SOL standards connected to the female female adaptor so it constitutes a female calibration kit and in the NanoVNA-saver the female kit data entered. This way the reflection calibration plane is identical to the male SMA on the Ch0 test cable. In addition the delay of the female female adoptor must be entered in the nanoVNA-saver for thru calibration. If this methos is not followed the exist serious phase errors between the reflection and transmission measurements and a T-Check will look crazy. Did you follows those guide lines ?? I will do a test with the R&S T-Check software else as you have the VNWA it is much simpler. Import the S11 and S21 s2p file and copy S11 to S22 as well S21 to S12. The open a custom trace and in the Expression line and do a right click, then the T-Check formula is ready to be loaded and after pressing OK then set the trace to linear magnitude reference to 1 and reference position to 5 and the scale to e.g. 0.1/div which means one division equal to 10% and 0.01 equal to 1% / div Give the custom trace a Caption name as T-CHK so the trace is name accordingly. You may save the Custum trace for later use Kind regards Kurt -----Oprindelig meddelelse----- Fra: [email protected] <[email protected]> P? vegne af reuterr@... Sendt: 6. november 2019 07:08 Til: [email protected] Emne: Re: [nanovna-users] T-Check for my nanoVNA - Results look excellent below 150 MHz and acceptable up to 300 MHz On Tue, Nov 5, 2019 at 11:40 PM, Kurt Poulsen wrote: UPS about the R&S TR-Check have you tried to run in W95 compatibilityHello Kurt, After reading T-Check.pdf from you from 2010-01-31, I tried under Windows 10-64 The Installation files are from 1997. When trying to start SETUP.EXE it was not possible. Next I started the MS compatibility check, Windows 8 was recommended, and set. That does not work too. Next with administrator rights, no success. Next try was to install under Windows 7-32. That works. A test with the provided data file ZVR.S2P works. But my from NanoVNA-Saver exported, extended S2P file was not accepted. I could not figure out, what was wrong with the format. Next I tried VNWA version 36.7.8.1 after reading your text from 2014-01: How to perform a T-Check for a VNWA Calibration.pdf A test with data file ZVR.S2P works. But my from NanoVNA-Saver exported, extended S2P file was not accepted. I could not figure out, what was wrong with the format. Next I found the spreadsheet from Erik: Thread: Trying to understand the T-Check outcome of the nanoVNA /g/nanovna-users/message/3020 T-Check.xlsx (199 KB) I could not make it to work with my data file. Then I posted in /g/nanovna-users/message/6502, asking for help. Erik provided a new version of his spreadsheet T-Check.xlsx (220 KB) /g/nanovna-users/message/6505 I imported my data file T-CheckR31.S2P and it worked, see /g/nanovna-users/message/6517 I will optimise this spreadsheet to accept direct NanoVNA-Saver exported S2P files, without modification. I read, that in case of a symmetric T-Check hardware setup you could copy to fill last 4 columns: copy C2-S11Real to C8-S22Real copy C3-S11Imag to C9-S22Imag copy C4-S21Real to C6-S12Real copy C5-S21Imag to C7-S12Imag 73, Rudi DK5FA |
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Re: T-Check for my nanoVNA - Results look excellent below 150 MHz and acceptable up to 300 MHz
Hi Rudi
I did export a s2p file from latest version 1.5 of the NanoVNA-saver and it was imported right away in the VNWA It is in the format RI meaning real Imaginary S parameter so why you have no success with the VNWA is a big question mark I have made a note yesterday about a T-Check file with an extra S at the end of the # line but that is not the case here. I have a comment about calibration when doing a T-Check. When the two test cables are connected to the Ch0 and Ch1 it must be S11 reflection calibrate calibrated with the SMA male SOL standards connected to the female female adaptor so it constitutes a female calibration kit and in the NanoVNA-saver the female kit data entered. This way the reflection calibration plane is identical to the male SMA on the Ch0 test cable. In addition the delay of the female female adoptor must be entered in the nanoVNA-saver for thru calibration. If this methos is not followed the exist serious phase errors between the reflection and transmission measurements and a T-Check will look crazy. Did you follows those guide lines ?? I will do a test with the R&S T-Check software else as you have the VNWA it is much simpler. Import the S11 and S21 s2p file and copy S11 to S22 as well S21 to S12. The open a custom trace and in the Expression line and do a right click, then the T-Check formula is ready to be loaded and after pressing OK then set the trace to linear magnitude reference to 1 and reference position to 5 and the scale to e.g. 0.1/div which means one division equal to 10% and 0.01 equal to 1% / div Give the custom trace a Caption name as T-CHK so the trace is name accordingly. You may save the Custum trace for later use Kind regards Kurt -----Oprindelig meddelelse----- Fra: [email protected] <[email protected]> P? vegne af reuterr@... Sendt: 6. november 2019 07:08 Til: [email protected] Emne: Re: [nanovna-users] T-Check for my nanoVNA - Results look excellent below 150 MHz and acceptable up to 300 MHz On Tue, Nov 5, 2019 at 11:40 PM, Kurt Poulsen wrote: UPS about the R&S TR-Check have you tried to run in W95 compatibilityHello Kurt, After reading T-Check.pdf from you from 2010-01-31, I tried under Windows 10-64 The Installation files are from 1997. When trying to start SETUP.EXE it was not possible. Next I started the MS compatibility check, Windows 8 was recommended, and set. That does not work too. Next with administrator rights, no success. Next try was to install under Windows 7-32. That works. A test with the provided data file ZVR.S2P works. But my from NanoVNA-Saver exported, extended S2P file was not accepted. I could not figure out, what was wrong with the format. Next I tried VNWA version 36.7.8.1 after reading your text from 2014-01: How to perform a T-Check for a VNWA Calibration.pdf A test with data file ZVR.S2P works. But my from NanoVNA-Saver exported, extended S2P file was not accepted. I could not figure out, what was wrong with the format. Next I found the spreadsheet from Erik: Thread: Trying to understand the T-Check outcome of the nanoVNA /g/nanovna-users/message/3020 T-Check.xlsx (199 KB) I could not make it to work with my data file. Then I posted in /g/nanovna-users/message/6502, asking for help. Erik provided a new version of his spreadsheet T-Check.xlsx (220 KB) /g/nanovna-users/message/6505 I imported my data file T-CheckR31.S2P and it worked, see /g/nanovna-users/message/6517 I will optimise this spreadsheet to accept direct NanoVNA-Saver exported S2P files, without modification. I read, that in case of a symmetric T-Check hardware setup you could copy to fill last 4 columns: copy C2-S11Real to C8-S22Real copy C3-S11Imag to C9-S22Imag copy C4-S21Real to C6-S12Real copy C5-S21Imag to C7-S12Imag 73, Rudi DK5FA |
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Re: Chasing ghosts???
#internals
#calibration
So I did the same coax stub comparison between the V2 and the xaVNA (see attached). The measurements agree to about 0.1dB and those ripples are either physical or artifacts of my cal kit. The coax measured is a 15cm semirigid RG405 and the cal kit is a home made SMA female SOL similar to this one: . Ignore the S21 value though, I haven't yet put on the shields on the Nano.
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Re: Chasing ghosts???
#internals
#calibration
If my hypothesis is correct then that means the impedance of the DUT at say 250MHz will affect the measurement at 750MHz. A possible way to check is to measure a resonator with a sharp dip at 250MHz and then sweep the VNA around 750MHz.
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Re: Chasing ghosts???
#internals
#calibration
The NanoVNA plot of the coaxial stub shows a few ripples that are unphysical (see attached image). It is unlikely the loss of the coax suddenly increases like that with frequency, and as your home made VNA shows that ripple isn't actually there. The most interesting thing here is that the "real" S11 of the coax should cross the "open circuit" point (or very close to it) given that it has low loss, which should also be very close to the open circuit standard. If the actual impedance is close to the impedance of the open circuit standard, how come the measurement is so far from it? I think we can rule out linearity error because there can't be much linearity error between two very close measurements. Calibration error can also be ruled out because the S11 of the open standard would have to be >1 to generate those graphs shown. The only thing left I can think of is that the fundamental signal is bleeding in because the mixer has very low IIP3, which means that in harmonic mode the distortion of the fundamental IF signal will create a 3rd harmonic and not just the 3rd harmonic RF signal.
I think it's pretty clear from those plots that your homemade 3GHz VNA is the most accurate out of the 3. |
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Re: NanoVNA-Saver 0.1.5
On Tue, Nov 5, 2019 at 02:12 AM, Rune Broberg wrote:
Rune, Thanks for the new release and your continued work on this project. I took a quick look at your new TDR output. Not sure what is happening with the new TDR plot you are displaying. The impulse TDR seems correct; however, the impedance TDR may not be correct. But, I cannot be sure. The purpose of the impedance TDR plot is to show the impedance as a function of time by transforming frequency domain data into the time domain. Version 0.3.0m firmware (and several others) seem to show what I would expect on the nanoVNA for the Low-Pass Step Transform of the frequency domain data. I give 2 simple examples below. When a length of open ended 50 ohm line is connected to CH0, the impedance should show ~50 ohms for a time that corresponds to the length of the transmission line and then the impedance should go to a very large value. This can be seen in the screen capture of such a cable in the file "RG316_50ohmCable_0.5m_TDR.png which is attached. This is a piece of RG316 that is ~0.5 m long with the end away from the VNA open. You can see the marker at 3.47ns which is equivalent to 359 mm along the transmission line reading 50.3 ohms. I have set the display to read the "resistance" on the nanoVNA and set the scale to 25 ohms per division. Of course, once the end of the cable is reached, the resistance goes off scale toward the top because the cable is open at that distance (time.) Measurements beyond the end of the cable are not often useful but do represent multiple traverses along the cable which are caused by mismatches at both ends of the cable. For the purpose of evaluating the impedance of the transmission line we can ignore information at times (distances) beyond the end of the cable. We can verify that the transmission line is ~50 ohms along its length by moving the cursor in time (or distance.) To make the point further, I have included a second example (75OhmCable_1meter.png) which is a piece of 75 ohm coax that is approximately 1-meter in length. The setup on the nanoVNA was the same. Here we see that the impedance is showing 74.4 ohms at 5.2ns (538mm) along the transmission line. And, again, measurements beyond the end of the transmission line are not important to verifying that the transmission line impedance is good along its length. Again, we can verify that the impedance is good for the entire length. With the TDR plotting in nanoVNA-Saver 0.1.5 I can't see the part that is of interest. I have shown the two plots from the two cables here from nanoVNA-Saver 0.1.5. These attachments are "R316_50ohmCable_0.5m_TDR_nanoVNASaver0_1_5.png" and "75OhmCable_1meter_nanoVNASaver0_1_5.png". A major part of the problem is that the impedance scale does not make observations in the range of interest (50-75 ohms) easily observed. It is not at all important to represent the entire range of impedance measurement but, it is important to enable the user to see what is happening in the early part of the time domain. To facilitate the user observing what is of interest, you need to enable y-axis scaling as you have on other charts. Perhaps setting the minimum and maximum impedance values to display will be enough. The user will know what they are measuring where you cannot know. I hope these examples illustrate why. Thanks for considering this issue in your next release. -- Bryan, WA5VAH |
Kurt Poulsen
Rich NE1EE
OwO
