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On Thu, Feb 20, 2025 at 11:57 AM, diyer wrote:

What are the alternative to vnasaver? I got it running fine but discovered
that it is painfully slow and it doesn't mark frequency line in small
increments.

What I want is something that is fast as the standalone vna so I can do some
what ifs regarding antenna tuning for various frequencies and save the results
as well. Maybe VNA_QT does that?

VNA-QT is not a program for your NanoVNA. NanoVNA-QT (VNA View) is the native software for the NanoVNA V2 Plus4 and VNA6000 series.

There are some very old apps for the NanoVNA like NanoVNA Sharp and NanoVNA Mod3 but they were very basic. NanoVNA App is the one I use and it has very nice features. DiSlord and Owen Duffy have made some nice improvements since the original author OneOfEleven stopped working on the project.

NanoVNA Saver scans reasonably fast if you set the frequency range to your band of interest and then calibrate. Here is a video I made for you showing me matching an antenna for the 20M band using a manual tuner. You can see the SWR, Return Loss and Smith Chart change as I rotate the knobs.

Patience, my boy, patience.

You can widen the RBW and VBW for faster scans. But you will lose noise
floor. You can also decrease the number of segments you wish to scan to
increase speed, but you will lose resolution. You can force more rapid
sweep, but you will lose both peak accuracy and reliability and
resolution. You can also try NANOVNA APP as an alternative. The
trade-offs I've mentioned are basic physics and really can't be overridden
without the compromises I noted.

Patience, my boy, patience.

Dave - W?LEV



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On Thu, Feb 20, 2025 at 7:57?PM diyer via groups.io <m240zz=
[email protected]> wrote:

What are the alternative to vnasaver? I got it running fine but
discovered that it is painfully slow and it doesn't mark frequency line in
small increments.

What I want is something that is fast as the standalone vna so I can do
some what ifs regarding antenna tuning for various frequencies and save the
results as well. Maybe VNA_QT does that?

My surfing on VNA_QT seems to indicate that I would have to reflash my 5
year old VNA. Plus I don't know if its faster or how easily one can store
output files. I've had reasonable luck reflashing other devices so I think
I could do it w/o bricking but if VNA_QT isn't faster then its not worth
the effort.

I know I shouldn't complain, after all its all free.
73

--

*Dave - W?LEV*


--
Dave - W?LEV

What are the alternative to vnasaver? I got it running fine but discovered that it is painfully slow and it doesn't mark frequency line in small increments.

What I want is something that is fast as the standalone vna so I can do some what ifs regarding antenna tuning for various frequencies and save the results as well. Maybe VNA_QT does that?

My surfing on VNA_QT seems to indicate that I would have to reflash my 5 year old VNA. Plus I don't know if its faster or how easily one can store output files. I've had reasonable luck reflashing other devices so I think I could do it w/o bricking but if VNA_QT isn't faster then its not worth the effort.

I know I shouldn't complain, after all its all free.
73

Here's an update on the SVHFS 2025 Conference;
Deadline for papers has been extended to March 17
Conference & hotel registration is open; details are in the attached file.


Thanks,
Robin Midgett K4IDC

Ensure the STM driver is installed for the device. Refer to the wiki on the group website for more information about the driver

It wasn't clear to me whether the 10 pF test load that simulates the capacitance of the circuitry the filter feeds should be reversed along with the filter when doing the reverse measurement. Don had left the capacitor in place on his test board when reversing the filter in a socket. He made some new measurements with no capacitor. The plots show the renormalized response with (red) and without (blue) the capacitor. It has some effect in the stopband but very little in the passband.

Brian

I have found this one useful for initial use of NanoVNA as a beginner
(*Absolute
Beginner Guide to NanoVNA by 9A2JK*) :
/g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf

It mentions connecting to computers for firmware upgrade and software for
PC and smartphone. But I have not tried it out, being an absolute beginner.

73
Jon, VU2JO


On Wed, Feb 19, 2025 at 10:58?PM diyer via groups.io <m240zz=
[email protected]> wrote:

is there a beginners guide to connecting your nanovna-h to a pc?
It may not be as simple as I am thinking.
I have a nanovna-h edy555 ver 0.4.5-1 efbbceca
when I connect it to my pc it shows up as usb std ser com3

then I launch vna-qt but it doesnt seem to know its there. clicking on
devices does nothing.

Is my choice of software wrong?
73
thanks

it works, thanks

All three plots below are for renormalization from 50 to 330 ohms. Red used the forward and reverse measurements while blue is forward only and green is reverse only. The "only" measurements set S12 = S21 and S22 = S11. The curves are virtually identical in the stopband, but they show differences up to 3 dB in the passband.

The bump at 10.78 MHz is coincident with one of the two pronounced passband peaks in the unnormalized 50 ohm data.

Brian

On Wed, Feb 19, 2025 at 09:28 AM, diyer wrote:

then I launch vna-qt but it doesnt seem to know its there. clicking on devices
does nothing.

Is my choice of software wrong?

You should try NanoVNA Saver or NanoVNA app.

is there a beginners guide to connecting your nanovna-h to a pc?
It may not be as simple as I am thinking.
I have a nanovna-h edy555 ver 0.4.5-1 efbbceca
when I connect it to my pc it shows up as usb std ser com3

then I launch vna-qt but it doesnt seem to know its there. clicking on devices does nothing.

Is my choice of software wrong?
73
thanks

Hi Brian,

Thanks big time for sending me the .s2p renormalized file. As a reminder to everyone your renormalized curve used my original forward and backward measurements of my ceramic filter using a 10 pf connected load and the measurement was made with a direct connection to my NanoVNA-F (NanoVNA-F calibrated using 50 ohm loads, and no external matching devices used).

My 10.7 MHz ceramic filter (SFE10.7MA5-A) has a published input and output impedance of 330 ohms.

Attached are 3 files comparing your renormalized curve using my forward and reverse measurement data versus 3 different matching methods that I used to measure the same ceramic filter with the same 10 pf load (all shown connected in the forward connected direction since their impedance matched forward and reverse connected measurements fall almost directly on top of each other). The only difference between the 3 attached files is that I used different scaling on the vertical and horizontal axis to provide some zoomed in and zoomed out views of the frequency response curves.

In the attached plots the curves are identified with the following colors:
Red = your renormalized curve
Blue = 50 to 330 ohm resistive L matching curve
Green = 280 ohm series resistor matching curve
Orange = 2 turn primary, 5 turn secondary BN-73-202 binocular core matching transformer curve (not a perfect match, provided more like 280 ohms whereas it should have been 330 ohms).

I hate to provide a firm opinion but let me make some quick observations to help folks understand what they are looking at as follows:

The renormalization process did a great job fixing my direct measurement curves to form a more realistic frequency response curve of my filter but it was not perfect if you zoom in and compare the very top of the renormalized curve with the curves I obtained using two different resistive matching techniques. The top of the renormalized curve has a premature dip and then a bump. Also if you look way down in the rejection area of the curves you will see the renormalized curve does not agree with my 3 other matching technique curves, especially in the lower frequency direction.

While my matching transformer provided an impedance that did not exactly match the published input and output impedance of the ceramic filter it did a decent job and it provided much better dynamic range which helped when looking at the filter where it provided a lot of rejection (way down in the mud so to speak). I could have added a half turn on my transformers to provide a slightly better match but had to cut my time consumption on this exercise. Not having a perfect match using the transformer appears to have had some slight impact on the shape of the top of the curve as well as a slight downward shift in the frequency response when you look at the zoomed in curve.

At some point it would be interesting to see how your renormalization routine compares with that on the NanoVNAs that have that function but unfortunately my NanoVNA-F does not have that function. Hopefully the work we have done will provide some insight for others regarding what to look for if they want to better evaluate the renormalization routine on the NanoVNAs that have that function. And there also is the big caveat regarding renormalization of nonlinear devices that folks need to be cognizant of.

Thanks again for all your help.

Don

Hi Brian,

Can you post or email me the .s2p file for your renormalized curve (red curve). I want to overlay my curves I obtain with resistive matching.

Thanks,
Don (wd8dsb)

VNA is the wrong tool (coherent detection depending on harmonic structure, and with a single detection bandwidth). Use a nano Spectrum Analyzer

All of this begs a simple question.
Use the NanoVNA as a Field Strength Meter.
Why - Just built a new antenna using the NanoVNA to adjust it to the operational Frequency and adjusted the impedance for a match now it would be nice to be able to have some form of active display of the radiated signal, without blowing up the front end the NanoVNA
While I cause a simple diode detector and a meter using the NanoVNA is another possible use.
Any suggestions on how or how not to do it.
Thanks

I forgot to mention that initially NanoVNA-App would not load the renormalized .s2p file. I had to manually change R 330 to R 50 in the # line to get it to load. Before I discovered this, I used to create the plot I posted. I'm going to leave the renormalized impedance in the file since it's correct. Maybe someone will modify NanoVNA-App to be more tolerant.

It would be neat if NanoVNA-App would do the renormalization itself from forward and reversed .s2p files or live measurements.

Brian

The plot compares S21 of the forward 50 ohm file with S21 after forward and reverse were renormalized to 330 ohms. Stopband details of the renormalized curve differ from your earlier curve using a transformer, but the passbands look similar. Thanks for all your help, Don. Also thanks to John Gord for explaining why renormalization works even with improper device loading, which I didn't expect.

Brian

Hi Brian,

Your wish is my command. See attached .s2p files for my ceramic filter with 10 pf load connected direct to NanoVNA-F ports tested forward and reverse connected.

Note: I set my NanoVNA Saver to 5 sweep segments to provide decent resolution and hope it's adequate for your needs.

Don

Don, how about measuring the filter with a 10 pF load using no impedance matching (50 ohm source and load). Reverse the filter, measure again, and post the two .s2p files. I'm curious what my program will show dozens of dB down where the resistive pads limit the dynamic range.

Brian

Hi Brian,

I repeated the tests but this time using resistive matching pads to provide 330 ohm impedance to both the input and output of the ceramic filter versus using my very broadband transformers that provided a lower impedance (approximately 280 ohms). I also repeated using 270 ohm series resistors for matching. Since we now are only looking at the upper part of the response curve the loss in measurement dynamic range using the two different resistor methods should not be a problem.

Much different looking response using the resistive matching versus the transformers.

I again tested with a 10 pf, 33 pf, and 68 pf cap output loads and my reference curve used no capacitor on the load side.

Just FYI,
Don