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When you put a 1000 ohm resistor between CH0 (port1) and CH1 (port 2) of the NanoVNA you should measure an "Insertion Loss" of -20.8 dB if the NanoVNA was a perfect device. It is not for several reasons including impedance of CH0 and CH1 are not exactly 50 ohms and the way calibration is done. So your measurement of 20 db is pretty close.

Your LTSpice and Sig Gen experiment is off by 6 dB because you did not calculate correctly. Try calculating the power in dBm of the 50 ohm load resistor without the 1K resistor and with the 1K resistor. Subtract the two and you get a 20.8 dB difference.

Roger

Why for the same circuit is the NanoVNA (-20 dB), LTSpice (-27 dB), and Scope/Sig Gen (-27 dB) result in different answers. The circuit is a 1,000 Ohm resistor tied from CH0 to CH1. Based on some experiments the input impedance to CH1 is 50 Ohms so the circuit is a voltage divider (see attached Fig. 1 NanoVNA Circuit Setup).

The scope and signal generator were setup to mimic the NanoVNA circuit by using the signal generator to apply potential to a series 1,000 Ohm and 50 Ohm resistor network (see attached Fig. 2 Scope/ Signal Generator Circut Setup). The scope was used to measure the voltage of the applied signal (Vin) and the output across the 50 Ohm resistor (Vout).

The results:
NanoVNA LogMAg = -20 dB @ 1 MHz, Smith 982 Ohms @ 1 MHz,
Scope/Sig Gen @ 1MHz, Vin = 722 mVrms, Vout = 34 mVrms, -27 dB,
LTSpice @ 1MHz, Vin = 452 mVrms, Vout = 21 mVrms, -27 dB.

The Scope/Sig Gen and LTSpice are a good correlation. The NanoVNA is different, why?

Any thoughts?

Wes
W4JYK

On Wed, Aug 16, 2023 at 07:26 PM, Peter (WB3IZU) wrote:

The extracted file is 130K and most of the FWs I see online are under 100K.
That concerns me?

That is OK, because the upload to the PC reads the complete 128KByte from the flash including the unused bytes after the program at the memory end while the FW files of about 100K contain only the program bytes.

I have made some progress. I wanted to be able to extract the FW from my device for backup. I can't seem to find FW that matches mine online. This () seems to be the closest. However, if I download the DFU, convert it to BIN and compare using STM32CubeProgrammer, they do not match. I extracted the firmware using "dfu-util -d 0483:df11 -a 0 -s 0x08000000:leave -U /Users/USERID/DELETE/test.bin". The log is attached. The extracted file is 130K and most of the FWs I see online are under 100K. That concerns me? If I compare using STM32CubeProgrammer, they do match. I then flashed this back to my NanoVNA using STM32CubeProgrammer. The log is attached. If I compare the versions from the VanoVNA (config | version) pre and post, they are identical. I guess next I will flash an updated FW, maybe the one that removes SDcard support and allows for 8 saved calibrations. My only concern at this point is the discrepancy in file sizes. If anyone can explain, I would appreciate it?

73
Peter

On Tuesday 15 August 2023 06:56:54 pm W0LEV wrote:

I would strongly recommend buying from R&L Electronics. You won't get a
clone from them!! Here is the link to them for the NANOVNA-H4:




No connection to them other than having bought a number of NANOVNAs (too
many as they progressed) and TinySAs from them.

Dave - W?LEV

Seconded. I bought mine there, along with two sets of adapters. No complaints...

WD3WTF

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On 8/16/23 8:18 AM, Jim Lux wrote:

On 8/15/23 11:57 PM, Leif M wrote:

After some use I noticed a couple things which could be better in NanoVNASaver.win.x64 software.

First, I posted this also to /g/NanoVNAV2 but after a couple of days it has not appeared there.

First the version text can't be copied to the clipboard. That would make it easier to talk about certain version. I think? mine is quite up to date.

Yeah, I do it by a screen cap of the window (attached, MacOS-X).

with the version screen cap

On 8/15/23 11:57 PM, Leif M wrote:

After some use I noticed a couple things which could be better in NanoVNASaver.win.x64 software.
First, I posted this also to /g/NanoVNAV2 but after a couple of days it has not appeared there.
First the version text can't be copied to the clipboard. That would make it easier to talk about certain version. I think mine is quite up to date.

Yeah, I do it by a screen cap of the window (attached, MacOS-X).

Calibration file should include also the frequency settings. If I have loaded a calibration file with 1MHz to 30MHz, the default frequency values (200MHz and 300MHz) do not make sense. The calibration file should include also averaging and segment values.

The calibration files do have the frequency range:
# Calibration data for NanoVNA-Saver
! SOL Calibration
! 27-30Mhz 101 Points
# Hz ShortR ShortI OpenR OpenI LoadR LoadI ThroughR ThroughI IsolationR IsolationI
27000000 0.948987136 -0.423713696 -0.862881088 0.584374208 -0.584138048 0.409614848
27030000 0.95050944 -0.421384544 -0.86482624 0.58150208 -0.58608 0.407054528
27060000 0.952427776 -0.419021984 -0.866214592 0.578889728 -0.587020096 0.405044192

It doesn't have the averaging or segment values, true.

I don't think the segmentation is captured - the cal file is basically the entire frequency span.. Take a look at a >1000 pt cal file attached.

Setting wrong values or data on the frequency range settings easily crashes the whole program.
Frequency axis of the plots is not good. Probably difficult to get it well, probably the user should do it..
Marker data should show on the text below the image. That would help with bad frequency axis too.
I attached plot of my balun, You can see the frequency axis. The marker value should be somewhere, like text below the image.

My original post (way back) was about how I used my Nano VNA to help make my 140 ft closed loop tune up better on 40m.
It was a simple post about the instrument, the Nano VNA.

I did not intend that post to then become a series of responses about antenna design.

Someone asked about my “vertical” on 40m and 80m.
It was a military surplus alum tubing (very light) that was tapered.
It came in two ft sections that closely fit.
So I put up about 35 ft of alum tubing and just lashed it to a taller fir tree.

I then ran two horizontal counterpoise wires, about 35 ft each, about 10 feet above ground.
So I only had two “radials”.
It was (is) so simple, but it is not ground mounted. Then I’d have to deal with multiple radials on the ground.

When I listen at night to DX stations, this vertical beats my dipole and loop by a few S units.
But it is pretty awful for a short skip (300 mile) daytime contact.

So it shows a simple low-angle propagation path, good for DX, but lousy for NVIS.

Now, getting back tothe Nano VNA.
How did I use the NANO VNA to tune my 140 ft loop? Look at the graphs.
I used it to first check the resonant (zero reactance) frequencies.
I used it to look at the PHASE graph.
I used it to double check the Smith Chart.
The SWR was as predicted, lowest at the low end of the 40 m band.

I really did not “need” the NANO VNA instrument to make my horizontal 140 ft loop work!
but it was reassuring that the graphs did not show me something unexpected.

de k3eui barry

P.S. - I've used 2 different NanoVNAs on the loop and random wire antenna projects, an 'early' clone of the original 2.8 inch, and a NanoVNA-F. Both have been very helpful, and I use them a lot.
--
Doug, K8RFT

I have put up 3 long wire loops around my front yard, over the years. The first was made from several pieces of leftover pieces of 14 or 16 gauge THHN stranded wire, patched together with different joining methods. It was up several years, but finally broke. I salvaged most of the wire, but some was still stuck in tree crotches or tangled in branches.
Then I bought a 500 foot spool of 14 ga. THHN house wire from a building supply store, and ran that around through the trees in a shape as close to a square as I could. The ends of the wire reach down to the ground near the ham shack in my house. It worked well on all the HF bands, and 6 meters, but was a little short for 160 M.
So, a couple of years later, I bought another 500 feet of the THHN, and also a 100 foot reel. That one runs on a slightly different path around through the tress, and is cut to about 535 feet. It works very well on all bands from 160 to 6 meters, with just the tuner in my FTdx10, and a 4:1 balun at the feed point.
There are also 2 vertical antennas, a GAP Challenger and an 84 foot wire going up about 60 feet,over the tree and horizontal for the remaining 24 feet. There's a 9:1 UnUn at the bottom. There is one band (I forget which) that the FTdx10 doesn't quite match.

Over the 5 years I've been active on HF, all using only FT8, I have 161 countries confirmed with LoTW, and 171 total countries logged. It's getting hard to add more! (I only use 10 or 12 watts.)

I'm sure the radiation patterns are awful, and there are directions that my signals don't go, but I'm very happy with the results.
--
Doug, K8RFT

Thank you very much, Roger.
Best regards and have a nice day, Stefan








>-------- Оригинално писмо --------

>От: "Roger Need via groups.io" sailtamarack@...

>Относно: Re: [nanovna-users] NanoVNA App - Installation and Use #applications

>До: [email protected]

>Изпратено на: 15.08.2023 03:40


On Mon, Aug 14, 2023 at 04:44 AM, Stefan Dimitrov wrote:

The situation is:

None on com ports menu and no any list.

The next menu:

"Disconnected"

Looks like no com ports or Windows 10 can't see the program.

You need to use Device manager to see if a COM port is active for your NanoVNA. If it isn't there you need to get it installed somehow. The method depends on which OS you are using.



Once you can select the correct COM port click the Disconnected button and you should be good to go...



Try reading the Absolute Beginners Guide in the files section of this group.



Roger

And of course, the software should remember where it was when it was stopped, so that it would start from there next time.

After some use I noticed a couple things which could be better in NanoVNASaver.win.x64 software.

First, I posted this also to /g/NanoVNAV2 but after a couple of days it has not appeared there.

First the version text can't be copied to the clipboard. That would make it easier to talk about certain version. I think mine is quite up to date.

Calibration file should include also the frequency settings. If I have loaded a calibration file with 1MHz to 30MHz, the default frequency values (200MHz and 300MHz) do not make sense. The calibration file should include also averaging and segment values.

Setting wrong values or data on the frequency range settings easily crashes the whole program.

Frequency axis of the plots is not good. Probably difficult to get it well, probably the user should do it..

Marker data should show on the text below the image. That would help with bad frequency axis too.

I attached plot of my balun, You can see the frequency axis. The marker value should be somewhere, like text below the image.

On 8/13/23 2:41 PM, Brian Beezley wrote:

Thanks, Roger. I've seen plenty of NanoVNA App plots here, but none with phase unwrapped.
Brian

Maybe because nobody bothered to try? <grin>

Sometimes, I find the derivative of unwrapped phase (group delay) more useful, too.

I have a 40m 144' horizontal loop also at about 20'. It is a right triangle. The pointy end is due east and is a little lower. I feed it with BalunDesigns 1:1 balun and then about 55 feet of 450-ohm line . My MFJ-939 or my AT-250 can tune it up on 40m-6m, and the MFJ will even tune it up on 80m. I have worked 115 countries and 50 states on FT8 across various bands in about 7 months, including DX on 40m and even 80m. So I would not say a low loop is NVIS only :) .

Nevertheless, Barry, could you describe your 40' vertical that you say is much better for low-angle DX?

For obligatory NanoVNA content, I will say that the NanoVNA was invaluable in picking the right feedline length. The length is quite touchy, and I did a lot of adding and removing short lengths to find what worked on all bands. The last length is a 3-foot jumper which I sometimes remove for best tuning.

Dan, KB1RT

I like my SAA-2N, it is the one I generally reach for in the shack. It works fine with external programs or standalone, updates work fine, and I like the type N connectors, as my shack is mostly type N. The provided cables and calibration standards appear to be of high quality and performance. Got mine from R&L. Highly recommended and I have been using VNAs since the '70s and am pretty picky about instruments.
73, Don N2VGU

I don't see much mention of the SAA-2N v2.2 Does everyone recommend the H4 over the SAA-2N?
The price difference is not of concern I am more concerned about functionality and support.

Brian
W1BKW

What ever you buy, I'd recommend using its "official shop". There are links on the homepage.

I would strongly recommend buying from R&L Electronics. You won't get a
clone from them!! Here is the link to them for the NANOVNA-H4:




No connection to them other than having bought a number of NANOVNAs (too
many as they progressed) and TinySAs from them.

Dave - W?LEV

--
Dave - W?LEV

Nanovna-H4 is a great basic vna, if you don't need multiple GHz
frequencies. It runs the latest firmware and is actively supported. And
you should be able to get one for less than $100