Electronics > RF, Microwave, Ham Radio

NanoVNA Custom Software

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--- Quote from: Fred_B on August 29, 2023, 02:06:22 am --- I looked at the LiteVNA, and remember seeing that it was harmonics based for the upper frequencies and that the nano VNA plus4 series used fundamental frequencies. That turned out to be the closing point for me.
--- End quote ---

I'm at a loss on your closing point.  So the V2Plus4 is limited to 4GHzish  without harmonics.  It also has no support to use harmonics beyond that limit.   The LiteVNA is limited to 6GHz without harmonics and has support to use them up around 8GHzish.  Note in my previous graph, you can see the LiteVNA using harmonics to 10GHz (not very useful) and the sharp increase at 6GHz where it changes to use them.    Note the low frequency range where the V2Plus4 is very poor.  There is only a small range where my V2Plus4 will outperform my LiteVNA. 

If you followed my waveguide experiments, you know while I did show the LiteVNA directly making measurements in the X-band using harmonics,  to improve the performance I had put together a frequency extender that works to a bit over 12GHz.

--- Quote from: Fred_B on August 29, 2023, 02:06:22 am ---I then decide to pay the extra nickel for the pro version because I eventually want to create some crystal filters, and thought somehow that the other VNA versions lacked the capability to do that. Perhaps, being a new uneducated initiate of nanoVNAs, I placed too much emphasis on the marketing copy there. :)
--- End quote ---

I've posted many times how the original NanoVNA outperforms all my others when measuring crystal filters.  There's a reason I tell people if you work below 300MHz, that is the best choice.   Above 300MHz, the LiteVNA.  Under $200 total. 

--- Quote from: Fred_B on August 29, 2023, 02:06:22 am ---GitHub is really for application development teams and individuals who compile applications from source code. For people who just want to grab a pre-compiled binary and go it is a good bit of a hassle. Have you had a look at Sourceforge?

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No.  Only Github.  Easy for me and I suspect for most of the youth who grew up with PCs.  Nearly impossible for the old hams, even with explicit instructions.   They need something that works like their PC file manager.   Google Drive, Microsoft One Drive, Dropbox.   Of course we do have a few special people that try and use their cell phones.

Do us a favor.  Calibrate your V2Plus2 Pro using say 800 or more data points over the entire specified frequency range.   Attach the load to port1 and terminate ports2.  Measure S11 and save it to a Touchstone file.    Without changing any of the setup, measure S21 and save it to a Touchstone file.  Use what ever software they are suggesting to make these measurements (or run it stand alone).   Document the firmware you are using and how you have the VNA powered.   If you don't mind, maybe run it powered off your PC as well as with a battery.  It can make a big difference.     Post the Touchstone files here and I will add them to my graph comparing the VNAs. 

I didn't remember my V2Plus4 being that poor of performance at the lower end so I charged up a battery for it and repeated the test.  Results are now much better.   For fun I ran it with and without the leakage term to show the effects at the higher frequencies.     

Basically, it's right on-top of my LiteVNA.  Much more believable.   The V2Plus4 is now $300. The last LiteVNA cost around $130.  The LiteVNA is good to 6GHz without harmonics and maybe 8 with.  The V2plus4 is limited to 4.    The LiteVNA also has the SD card interface.  I've tried it.   It's also small enough to fit in a shirt pocket for the hams climbing around on their towers...

OWO's site talks about the clones averaging to hit the numbers.  In the previous plot, I had used 10 averages with the LiteVNA.   So for a better comparison, I disabled the averages and used the same set of cables that I used with the V2Plus4.     

Basically, it looks like a wash.  Maybe the LiteVNA is a bit better.

Here's a couple of touchstone files. There were made with the battery in the device and the USB cable connected to the PC. The battery was surprisingly difficult to push into the holder when I installed it. When I opened the case up to pull it out, I can see that the holder is bowed out a little bit by the pressure of the springs. I'd need to pry the battery out by sticking something underneath it and prying it up to get it out. I think, I just want to leave it in, until I get some mileage out of it.

I'm still quite unfamiliar with this device, so I hope I got the files done properly. BTW I'm using VNA_Qt. It looks from the display on my PC that my device is doing about 10db worse between 3.5 GHz and 4.0 GHz. That's interesting.

Firmware version: 20220301


I used a flat-top battery in mine which seems to fit.  Leaving the battery in with the USB connection is how I collected that last data, so perfect.

Looking at your S21 data, notice the header states S11 rather than S21.

# MHz S MA R 50
!   freq        S11       
0.050000  0.00132 -161.92

If I plot your s21 data, the first thing I notice is the magnitude is VERY high.   The next thing is the phase is stable.  Think about it, the two ports are not connected to one another and both are terminated.  Wouldn't you expect it to be random?   

I suspect this is actually is S11 and not S21.   I've attached my S21 data for my V2Plus4.  I expect your Pro to be similar. 


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