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On Sat, Jun 11, 2022 at 11:08 AM, Roger Need wrote:

In my experiments I found that parasitic capacitance had considerable affect
on the S21 measurements and I tried several different test jigs to see what
happened.

Here is one of theS11/S21 test jigs I tried. It could use improvement but I don't have the time right now to continue with this project.

Roger

Hi Vaclav Sal,

I just went to “FB Nano VBA and Tiny SA” and saw the messages that you had previously posted regarding your issues.

I believe that your choice to use the alias “Anne Ranch” on various groups.io and FB might be the cause of your issues.

(Using Anne Ranch, AA7EJ on the linuxham group caused confusion.)

Hope that this helps.

Larry
AC9OX

Victor,

Let me preface my comments by saying that I have built several test jigs for measuring impedance using the S21 series method and tried several ways to compensate for errors. None have been very successful and I now just use the S11 reflection method which works up to several thousand ohms of complex impedance with a decent test jig.

I believe the NanoVNA-H4 is just not the right tool for the job for several reasons that I have mentioned before....
- the source and termination impedances are not 50 + j0 ohms and vary with frequency
- the current firmware and PC programs only use 6 term error correction not 12 term

Others have found similar issues using the S21 series method using the NanoVNA and even with higher performance HP VNA equipment. Here are some interesting links. The K6JCA experiments find differences similar to what you have measured.




In my experiments I found that parasitic capacitance had considerable affect on the S21 measurements and I tried several different test jigs to see what happened. The issue of where to establish the reference plane took some consideration. S21 Gain and S21 phase determine the complex impedance of the DUT and even with some type of source (Port1) and termination (Port2) correction the phase was often incorrect. Phase measurement was the problem and in my tests was due to an offset delay across the jig. Another issue I found was that for some reason high DUT impedance resulted in common mode current on the surface of the coax cables connecting the NanoVNA to the test jig. I tried snap-on ferrites and the results changed.

You mentioned that you could do a S11 reflection and S21 series measurement at the same time. You will get different results when the DUT is in series between Port 1 and Port2 compared to when it is across Port 1 alone. Best case is that it will be 50 ohms higher. TIn reality the complex impedance measured when in series is the DUT plus the input impedance of the cable attached to Port 2 (which will deviate from 50 ohms due to Port 2 impedance not being 50 ohms) and any parasitic inductance or capacitance between the DUT and the Port 2 cable.

I wish you good luck in your quest and hope you find a method that works for you and that you find a solution that eluded me.

Roger

Op za 11 jun. 2022 om 08:32 schreef Victor Reijs via groups.io
<pe1atn.victor.reijs@...>:

Hello Roger,

Using Series though, the NanoVNA measures both a S11 and S21 (for that
configuration, which I [of course] calibrated). The link I gave (
), calculates the Zdut using
these Sx1 from the 2port series through measurement.

By the way, NanoVNA Saver uses also these formulas to plot the S11 and S21
for the 2port series through measurements (Sx1 R+jX [series]). IMHO these
two should be quite the same, but they are in my case quite different (as
you could see in the earlier screen grab of NanoVNA Saver.

All the best,
Victor

Hello Roger,

Using Series though, the NanoVNA measures both a S11 and S21 (for that
configuration, which I [of course] calibrated). The link I gave (
), calculates the Zdut using
these Sx1 from the 2port series through measurement. In the case of the
resistive DUTs the S11 measured with 2 port (red blue dotted) is almost
identical with the S11 measured with 1 port (orange dotted). The same I see
with the toroid DUT.
But I am not able to map the Zdut calculated with the S21 (green dashed;
measured in the series through 2 port).

So the Zdut (Zx) using with 2port series through and S11 based is different
from Zdut (Zx) using (the same) 2 port series through and S21 based. So all
stray capacitances, etc are the same (which I see part of the DUT).

All the best,

Victor

Op za 11 jun. 2022 om 07:26 schreef Roger Need via groups.io <sailtamarack=
[email protected]>:

Victor,

I am not sure how you are measuring the DUT using S11 reflection and S21 series methods.

You have to measure them with the correct reference plane calibration and this usually requires two different test jigs. What are you using for S11 and S21 test jigs? Attached is one I use for S11 up to 30 MHz. I tack solder the DUT as shown. My example uses an inductor but you can solder the leads to your choke. The second one I built into a box and it works well too. I posted my S21 series jig in the last topic

Roger

Glad you solved it, and sorry I did not reply earlier . . . we were out for the evening . . .

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Ahoy, Belay my last.... I found my way and cleared out the incorrect firmware. It took much searching thru many messages plus wiggling the usb plug. But now I have the version git-20201013-32077fd loaded and the vna is happy. Thanks to those with suggestions and for the searchable history of this group. Now for a shot at calibration.....but first to buy a quality usb-3 cable.
--
72/73 de k1qed, ?bob.c ? ? ? ? qrp 4evr!

Hi Rich:

Thanks for the correction.
You are absolutely correct as presented, .016 for this leads one to the 35.917 dB answer

And your cell was L4 not M4.

Glad confusion removed on final version.

Enjoyed the Pisacataqua discourse: fastest tidal flowing river in the US, if I correctly recall. Big moon tide took out the tree supporting my antenna end, and headed to Kittery.

Ed McCann
AG6CX

Hello Roger,

I thought that the method I used now for the resistors was working. And it
seems to work at least for these 4 resistors (330, 985, 5160 and 21800);-)
But I now did a 1:1 Guanella choke as dut and it seems to behave
differently in a 2 port measurement...
Here are the 2 port measurements NanoVNA Saver of my 1:1 Guanella choke (I
also attached the 11Guanella-corebraid-1s21.s2p file):
[image: afbeelding.png]
As you can see the S21 R+jX has totally different form (e.g. peaks) than
S11 R+jX.

If I use the formula of (Page
10) :
[image: afbeelding.png]
I can determine with the 2 port measurements Zdut (Zx) in two ways through
S11 and S21 2 port measurement.
Z2pseries(S11)=(Zsource+Zload)*S11/(1-S11)
Z2pseries(S21)=(Zource+Zload)*(1-S21)/S21

[image: afbeelding.png]The green curve should be close to the red (blue
dotted or orange dotted) ones (as when using my method for the resistors),
but with the choke they are totally different. I must be doing something
(obviously?) wrong! But what? Any help is welcome.

All the best,

Victor

Follow up - the new firmware I uploaded was the wrong one, and I cannot get to a dfu mode either by -QT, the screen menus or by toggling the left jog and switching on and off. I went thru all the menu items and can't find any way to change the firmware. I did find a button for "Dump firmware" as follows: Config>Expert Settings>More>Dump Firmware . But tapping this button opens a number/alphabet entry page and the word bin in a white bar at bottom. I'm lost in the forest again. Again, the firmware build date is Apr 3, 2022, and -QT doesn't see the device.
--
72/73 de k1qed, ?bob.c ? ? ? ? qrp 4evr!

Thank you Igor and Dislord.
I just acquired a new NanoVNA H4, after using my original NanoVNA H for the last several years.
With all features of the H4 over the H model, it is like starting all over again.
I was wondering what the save function was really doing.
Both of you now answered it.
I thank those who keep updating and improving the NanoVNAs.
Thank you again,
Clyde Lambert KC7BJE

Hi Tim, brevity did the trick, I was able to get back to life using the left jog and on-off switch. The SAA-2N showed up on the -QT software (on my MacBookPro) and got the prompt to load software. Went ahead, but not sure now which download I loaded.... On the Version screen I see NanoVNA-V2-firmware and a build time of 4/3/22, 13:30:34.
Thks for your encouragement, but now I hope I got the right firmware, I hope it is not too new for a two or three year old SAA-2N. Now let's see what happens!

72/73 de k1qed, bob.c qrp 4evr!

I guess I need to express my gratitude for allowing me to ACCESS the forum, again.

I am still looking for any text form of "menu" symbols AKA "menu dictionary".

( No, I do not desire to be "part of solution" have few "honey does" of higher priority. )

Still OK Neil
Colin MM5AGM

Wow, touchy, ta, ta.

Mike C.

PS I didn't know engines had ears!!

DFU mode does nothing with the screen . . . Perform the steps to enter it (DFU mode) on your unit, and see if it shows up on USB.

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Hi Tim, I would like to get to any mode, but the device does not respond to any input, button or tap. The screen is white and nothing gets a reaction. bob.c

On Thu, Jun 9, 2022 at 03:17 PM, Fred Moore wrote:

Just out of curiosity, is the processor type listed on a display rather
than opening up the unit and looking at the chip?

Yes it is listed under Platform after you enter Config-Version. What I don't know if that is the actual chip on the board or what the developer of the firmware just entered as default text for that field.

Perhaps DiSlord can comment since he created that display page..

Roger

Just out of curiosity, is the processor type listed on a display rather
than opening up the unit and looking at the chip?

On Thu, Jun 9, 2022 at 5:15 PM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

According to Hugen (manufacturer of -H4) the latest firmware can run on a
STM32F302CCT6.

/g/nanovna-users/message/24748

Comparison chart >>


Roger