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Thanks in advance for any help.

I'm new to VNA's and have enjoyed reading the posts here and starting out with my H4 from Hugen.

I appear to have changed a setting and cannot find how to get rid of it - It sits top left of screen and shows as Edelay with a time in picoseconds and a negative 'm' number to the right of it.
It is throwing the Smith Chart Trace off, displaying what can only be described as an 'etch-a'sketch' type of pattern.

What have I done wrong, please?

Kev
M0TNX

On Thu, Mar 18, 2021 at 07:07 AM, WB2UAQ wrote:

Manfred, Have you ever compared the Q readings measured by the old BRC-160 or
the Hp 4342 Q meters against the Q reported by any network analyzer or even
many of the older 4 terminal instruments from the 70's and 80's and maybe into
the 90's?

There is a technique that has been described by Darko Kajfez (EE Professor Emeritus at the University of Mississippi) that actually gives good results for Hi-Q inductors on a VNA. And there is a Matlab application, available for free (if you have Matlab, I think) that implements the Kajfez technique on either an HP 8753 or HP 3577A VNA.

Some time ago, I compared the Matlab application's results with the measured Q from my HP 4342A, and (if my memory is correct) the results were surprisingly close.

If interested, I've put both the Kajfez paper and the user manual for the Matlab website on Github:
(The user manual gets into the nuts and bolts of how to actually make a measurement using this technique).

- Jeff, k6jca

Hi all,

OK, I have fixed the issue and got it working.
It appears a restart of the PC was needed, and although my nanoVNA showed up in the port area, I had to connect to it regardless.
I had tried that before, but it failed, so I gave up and performed the restart and all is now well.

Thanks for pointers and suggestions!

73 de Phil GU0SUP

Very good. Thanks. I need to update, however what I have is fine. Perhaps you can assist Phil with his issue.

Again, thanks.

No need for that anymore.

To give the nanoVNA a tougher test I tried measuring the Q of a small 50uH inductor across LF to 3MHz. In the plot below it struggles to indicate the Q as the data is very noisy and uncertain. The measurement would benefit from some averaging but it indicates a peak in the Q somewhere around 450 at about 700kHz. Clearly this inductor is at its best across 300kHz to just over 1MHz where it delivers an impressive Q factor. I think the nanoVNA is doing very well here although it would be best to measure the Q using a decent Q meter or by using the nanoVNA in a different way to measure Q.

Hello Phil,

In the past, initial cal must be made on the hardware first. Saved via default in register 0. After that, further cals can be done from the saver routine. At least that was the process using the saver at V0.2.1 version.

Alan

Hi Charlie,

When i click on that, nothing appears to happen.
It says to follow the instructions, and I get a pop-up to that says to ensure the nanoVNA is connected, which it is and shows up in the in the lower left of the main window,

73 de Phil GU0SUP

Did you perform the calibration on nanoVNA saver?

Ignacio EB4APL

--
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.

Did you use the calibration assistant and follow the prompts?

On Fri, Mar 19, 2021 at 12:40 PM, Gary W9TD wrote:

Do you import the s2p from the NanoVNA then to analyze and plot?
Gary
W9TD

Yes, except in this case I'm making a 1 port s11 measurement with the nanoVNA. I use a very basic s1p data dump tool I wrote in VB and then I import the dumped s1p file into Genesys for analysis. It just takes a few seconds to do it all as I have an inductance template in Genesys for this type of analysis.

Here's a nanoVNA-H measurement of a Micrometals T50-6 powdered iron toroid with 22 turns spread over about 270degrees of the toroid. The inductance should be about 2.2uH and you can see the nanoVNA does a good job again. It also has a reasonable stab at measuring the series resistance although the data gets a bit noisy above 20MHz. I keep meaning to add averaging to my PC tools. The nanoVNA is much more powerful than a typical low frequency LCR meter because it can measure the inductance across a wide frequency range. The inductance at the design frequency can usually be measured quite accurately. It often manages to give a reasonable estimate of Q for powdered iron toroids like this.

Do you import the s2p from the NanoVNA then to analyze and plot?
Gary
W9TD

I'm using Eagleware Genesys. This is old RF CAE software from 2004. I've had my nanoVNA-H for quite a while now and measuring the inductance of coils across LF through about 50MHz is what I mostly use it for. It can also give a fairly good indication of the coil Q as long as the Q of the inductor isn't too high.

Hi all,

My name is Phil, and call is GU0SUP.

I am a new user of 2.8" nanoVNA, and I can calibrate it fine using the screen. However, when I start nanoVNA-Saver,set the start & stop frequency limits, I am able to click on the various calibrate options, and it says 101 points, but when I click on apply, it tells me "Two of short, open and load returned the same values at frequency 3600000Hz".

This is despite the fact that I have set the frequency range to the 2m band.

Where have I gone wrong? I can't seem to find any instructions, although I assume they must be somewhere...

Any help or pointers would be much appreciated.

Best 73

Phil GU0SUP

Jmr
What are you using to make your plots?
Gary
W9TD

To test out my nanoVNA-H over LF to about 50MHz I dug out a SMD airwound inductor of just over 240nH. I measured it in three ranges and stitched the results together to allow a log plot from about 100kHz to 50MHz.

The results below are quite good I think. The nanoVNA struggles a bit at 100kHz but from about 500kHz onwards the nanoVNA does a very good/stable job of measuring the inductance of the SMD coil and the red series resistance trace looks good too with a fairly smooth response across the frequency range. The resistance trace starts to misbehave a bit above 35MHz but this is a very good result for a low cost VNA.

when the Nano VNA (connected to Nano Saver) first powers up, the sweep is 50KHz to 3 GHz. I have an antenna connected to port 1. I change the sweep to 900 to 930 MHz and click on Set Reference Sweep, but the graphs still display the default frequencies: 50 KhZ TO 3 GhZ. How do I get the graphs to display same frequencies as the sweep ?

I can calibrate my VNA manually, but I would prefer to calibrate using Nano Saver with my PC since the manual version does not include Isolation test.

When I have completed short, open, load, isolation and thru, I click on "APPLY" the program disappears from my Windows 10 PC.

Thanks to everyone's input - I was able to get things sorted out. I actually tried both methods (Back to Back Method - thanks to Gary and the resistor method - thanks to Roger and found reasonable agreement.

I also compared it with the insertion loss calculated using the Fair-rite 43 permeability values which can be found in Owen Duffy's Blog 43 Ferrite for a 3 turn primary. Interestingly, the computed value is smack in between the resistor method -0.44 dB at 3.5 MHz and the Back-to-Back Method at -.75 dB. The calculated value using the Duffy calculator and the permeability values which ignores flux leakage and conductor losses provides a result of -0.61 dB at 3.5 MHz. This leads me to think that the back to back approach might be more conservative.

The comparison plot from both methods is attached.

Ariel NY4G

?On 3/18/21, 4:57 PM, "[email protected] on behalf of Gary W9TD" <[email protected] on behalf of w9td@...> wrote:

Ariel,
That would be satisfactory but your test fixture looks like ground is connected between inpuy and output anyway so connect to that grounds
Gary
W9TD