Date   

Re: nanoVNA Real Resistance Measurement Range

QRP RX
 

Here is also TDR impedance measurement for this transmission line. You can see 1 meter RG58 cable with BNC connectors from 4.7 to 15.1 ns.


Re: Partial calibration for S21?

Warren Allgyer
 

Bruce

For S21 "Through" measurements the only parameter that needs to be calibrated is the Through. Short, Open, and Load will not affect your results. BUT!......... be sure to Reset before performing the through calibration.

Larry

To date I have owned or used five Nanovna and all have been from different manufacturers. I do not see any cases where the out of the box characteristics vary wildly and, in fact, when calibrated using the same loads all produced results with negligible deviation. From my experience to date the distinctions among the different units being sold are insignificant.

Warren Allgyer
WA8TOD


Re: nanoVNA Real Resistance Measurement Range

QRP RX
 
Edited

Also note, that Chinese BNC connectors have bad SWR. For example, here is TDR VSWR measurement for transmission line with two BNC connectors on RG58 cable with 50R terminator at the end of transmission line. As you can see two BNC connectors have ripple up to VSWR=1.08.

PL-239 has even worse ripple up to VSWR=1.2


Re: nanoVNA Real Resistance Measurement Range

QRP RX
 

Tom VA7TA, it drops down, because you didn't compensated transmission line delay (signal delay in BNC connector). If it different at least 1 mm than calibration kit, you will get different values.

For example here is measurement of 500 Ohm terminator. The terminator is connected through SMA-SMA adapter, so the transmission line is about 15 mm longer than calibration kit terminators. The first picture shows measurement as is, with no electronic delay compensation. The second picture shows measurement with 242 picoseconds electronic delay enetered into NanoVNA menu.

As you can see there is very significant difference in measurement result at high frequency.


Re: vna ~ nanovna : (r,x) comparative results but no comments

QRP RX
 

you can find electronic delay of transmission line with no match on the end with Group Delay screen. Then you can enter it in the ELECTRONIC DELAY menu in the NanoVNA.


Re: vna ~ nanovna : (r,x) comparative results but no comments

 

Hello,

Thank you very much for your interesting suggestions !

Sincerely,

yin&pez@arg


Re: Partial calibration for S21?

hwalker
 

Bruce,
That is exactly what I do when I want to quick check the gain of an rf preamplifier. Running a "through" calibration prior to S21 testing normalizes your test set-up, basically zeroing out any in-line connecting cables and attenuators, before the S21 sweep of your filter or coax line.


Re: vna ~ nanovna : (r,x) comparative results but no comments

QRP RX
 

you're needs to setup electronic delay compensation in the NanoVNA to eliminate that curve. it happens because your load connected with different transmission line length than calibration kit load.

For example, here is 500 Ohm load measured with NanoVNA. First picture is how it looks with no electronic delay compensation. And the second picture is how it looks with electronic delay compensation 242 picoseconds entered into NanoVNA. (242 ps = 15 mm connector)

NanoVNA software which allows to see series and parallel RLC charts, can be found here: https://www.rtl-sdr.com/forum/viewtopic.php?f=4&;t=4881


Re: Partial calibration for S21?

Larry Rothman
 

On Tue, Sep 17, 2019 at 07:05 AM, Bruce KX4AZ wrote:


Sometimes I just want to quickly check a filter or coax line for its "through
transmission" properties, i.e.a log S21 plot. Is it necessary to do the full
SOL calibration in addition to a "thru" measurement to get an accurate S21
plot in that situation?
Bruce,
The nanovna is a very useful hobby device but due to the many manufacturers churning them out, out-of-the-box characteristics can vary widely.
The easiest thing to do is to perform a wide-band calibration (where you're using it most of the time., ie: 50K-200M) using the cables and save it to location 0.
Location 0 is loaded every time you turn on the unit so at least you'll have a default cal to use for quick checks.
For the times when you want to check items at a different freq, you can then cal for that.

73
Larry


Re: Yet another NanoVNA PC app

Nick
 

Hello Erik

Some progress using Wine 4.0.2 on Mint Linux 19.2.

Created a new 32-bit wine prefix.

Used winetricks to install vcrun2010, dotnet40, dotnet45, dotnet46, dotnet461. Used dotnet_verifier to test dotnet installation.

Created a symbolic link from COM10 to /dev/ttyACM0.

VNAR4.3 runs but cannot connect to the nanoVNA.

What baud rate, # of bits, parity, # of stop bits does VNAR4.3 assume?

Nick


Partial calibration for S21?

Bruce KX4AZ
 

Sometimes I just want to quickly check a filter or coax line for its "through transmission" properties, i.e.a log S21 plot. Is it necessary to do the full SOL calibration in addition to a "thru" measurement to get an accurate S21 plot in that situation?


Re: NanoVNASaver 0.0.8

Rune Broberg
 

For those who have previously had problems with using newer 10k-1500M
firmwares with NanoVNA-Saver (or other crash issues): On GitHub, the latest
version of the master branch now has a debug function: Use the command line
option '-d' to see debug info, and '-D filename.log' to save debug info to
a file, which you can send to me if you see crashes.

This should help me be able to find out what's going wrong when you see
these crashes.

It will also be included in the next release, including in the Windows
.exe, which will be out this week, maybe tomorrow.

Thanks,
--
Rune / 5Q5R

On Sat, 14 Sep 2019 at 11:45, David J Taylor via Groups.Io <gm8arv=
yahoo.co.uk@groups.io> wrote:

Yes, I've heard someone else mention that. I can't quite think what causes
it, *assuming* the firmware didn't change the format of the commands used.
I currently just have the one NanoVNA, and as I need to use it for
development, I have been a bit reluctant to flash experimental firmware on
it. I may have to try :-)

Rune / 5Q5R
=====================================

Yes, I also have just the one, and that was the first time I'd flashed new
firmware. I was hoping that getting back to a known working version
wouldn't be too difficult if I did need to do that! The flashing is very
quick.

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv





Re: nanoVNA Real Resistance Measurement Range

Tom VA7TA
 

Greetings All,

To test the imaginary high impedance measurement accuracy of the NanoVNA I decided to use a high quality precision capacitor. The best precision capacitor I had on hand for the job was a leaded silvered mica 30pF +/- 0.5pF type. I kept the connection leads to the BNC connector as short as possible.The results from these tests will also reflect the measurement accuracy for inductance which of course would be of opposite sine. As there is no such thing as a pure inductance because of wire resistance, distributed capacity and self resonance characteristics it is not practical to attempt to use an inductor for measuring the capability of the NanoVNA.

I chose to set the sweep to cover 1 MHz to 150 MHz. I limited the high end of the sweep to avoid influence from lead inductance which causes series resonance to occur around 320 MHz. The reactance range for the selected sweep width extends from 5462 Ohms at 1 MHz down to 28 Ohms at 150 MHz. The capacitor measured 29pF at 1 MHz, 31pF @ 50 MHz and 37pF at 150 MHz. Attached are screen captures and s1p files for the calibration steps and measurement. Accuracy at 1 MHz to 50 MHz was within about 3% with the Z 5.5K at the low end. Accuracy deteriorated to 10% at about 100 MHz then dropped off further to 20% at 150 MHz.

It is interesting that according to these test results the shunt measurement method seems also capable of accurately measuring a moderately high imaginary impedance with very little real component. Good news for most of my applications. It appears as if the shunt measurement method accuracy capability is not limited to just a few hundred Ohms for lower frequencies.

Enjoy!
Tom
VA7TA


vna ~ nanovna : (r,x) comparative results but no comments

 

Hello,

1 one-port box + adapter - initial version:
https://www.op4.eu/fora/nanovna-users/20190917/ftpj-v1-i1-p.v4-21.png-50.png

2 one-port box + adapter - modified version:
https://acomelectronics.com/forum/viewtopic.php?p=1264#p1264

3 one-port box + adapter - modified version:

black : vna system
red : nanovna + 31 mm adapter
blue : nanovna - 31 mm adapter mathematically

r : https://www.op4.eu/fora/nanovna-users/20190917/R-box-nanoVNA-RedBlue.png

x : https://www.op4.eu/fora/nanovna-users/20190917/X-box-nanoVNA-RedBlue.png

Sincerely,

yin&pez@arg


Re: Newbie questions

hwalker
 

On Mon, Sep 16, 2019 at 02:58 PM, S Johnson wrote:


RigExpert AA-230 Zoom
The RigExpert AA-230 Zoom is priced about 7 times the cost of the nanoVNA so its really not fair to compare the two. Having said that, other users on this forum have compared the results from the nanoVNA favorably with much higher priced antenna analyzers and VNA's that they own. The RigExpert AA-230 Zoom covers 100K-200M while the stock nanoVNA covers 50k-900M. For antenna tuning, you are pretty well set with the RigExpert AA-230 Zoom unless you need to go beyond 230 MHz. The RigExpert AA-230 Zoom is a one port device so you cannot perform amplifier gain, attenuator loss, filter shape or other two port measurements as you can with the nanoVNA. For me, being able to perform those measurements was worth the $50 I paid for my nanoVNA. If you keep in mind that it is a $50 hobbyist device you won't be disappointed in its performance. I spent more and gotten less from other equipment I own.

The are three primary variants being sold: Hugen's original design with shielded inputs (my personal favorite), the white case design with salamander logo, and a design that is similar to Hugen's but without shielding and the "CH0" printscreen marking is missing. None of our forum members have been able to measure a definitive performance difference between the variants when using the same firmware. If you decide to purchase any of the variants read what is included and examine the photos carefully. Some units are sold without a battery or without a calibration kit included. That's addition money you would need to spend unless you already have those items.


Re: Newbie questions

Oristo
 

2.) which NanoVNA to get? There are hundreds of ads on Amazon, eBay, etc. each at a different price and from different vendor.
Some have shielding, others not, some batteries, others not. Is there one verified good vendor?
Yes, Hugen (who developed the compelling revision of edy255's design)
designates this vendor:
https://www.alibaba.com/product-detail/Original-2-8-Touchscreen-50KHz-900MHz_62232701280.html

here: https://github.com/hugen79/NanoVNA-H


Newbie questions

S Johnson
 

Just joined the forum. By way of introduction, I’m a ham who likes to play with antenna designs and the NanoVNA sounds very interesting. My questions are:

1). I currently have a RigExpert AA-230 Zoom. Does the NanoVNA include all functionality of the RigExpert, or is something lost?

2.) which NanoVNA to get? There are hundreds of ads on Amazon, eBay, etc. each at a different price and from different vendor. Some have shielding, others not, some batteries, others not. Is there one verified good vendor?

Thanks for guidance on this.


Re: New, disappointed member intro

John
 

Supplier has offered me a part refund which I accepted. Took the switch
off, took it apart, adjusted the spring and put it back together. Worked in
theory but not in practice, so I cleaned the solder off the pads and
ordered some tiny push switches. Should have them by Friday.
73 John

On Mon, 16 Sep 2019, 02:32 John Herleman, <jherleman@att.net> wrote:

That is simply incredible. Well done, Sir.




Re: New nanovna mechanics

Larry Rothman
 

Thanks Alan.
It looks like a prototype at this point - especially those buttons.
If you look at the underside of the back cover, there appears to be traces - re-used scrap PCB material?
The cal parts/cables don't seem to be included.
The good part is that not only does the front-end look well laid-out, hopefully all the signal processing areas will be shielded, including the DSP.
But with that said, showing photos with no shields makes me think - no shields.
...and why would anyone use a mini-usb connector?

Oh well - I'll wait until someone on the forum buys one and lives to tell us about it...

On Mon, Sep 16, 2019 at 01:10 PM, alan victor wrote:

Hi Larry,

Here you go:

https://www.ebay.com/itm/New-NanoVNA-Vector-Network-analyzer-HF-VHF-UHF-Antenna-Analyzer-Standing-Wave/274004794211

73' Alan


Re: New nanovna mechanics

alan victor
 

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