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Found several articles and several answers/opinions on this topic :)

If I want to do 2 port measurement in a setup where the input and output
of the DUT do NOT have common ground (let's say an RF transformer, or a
simple current balun), how will internal common ground on nanoVNA ports
affect measurements.

Let's be even more specific - want to do some simple testing of an HF
balun. S21 for differential mode and for the common mode suppression. Just
for the sake of the argument, balun will be wound with a short (comparing
to lambda) piece of coaxial cable, either wound in air or on ferrite
toroid.

In the CMR mode I'l short both sides of the balun, connect to "hot" ends
of both nanoVNA ports, and "rely" on the grounds being connected
internally - is that correct setup?

In the differential mode how will that internal common ground affect
measurements as it will effectively short the current that is supposed to
go through the shield of the coaxial cable making the balun?

So, in one case (CMRR measurement) that internal common ground helps. but
in the other (differential) it does not.

All would be easier if ports on nanoVNA are not bonded internally and I
have an option to connect them or not :)

On Wed, Jul 6, 2022 at 06:03 AM, F1AMM wrote:

It's a pity that your pages are not in HTML; it would have allowed Chrome to
translate them to me in French, online. In English, I can't follow.

Use the deepl translator. It will translate pdf files and keep them in the same format as the original.


Attached is a translation to French of one of Arie Kleingeld PA3A English articles

Roger

Here is

Hello

I have very little experience with toroids. I made some RUTHROFF
transformers but nothing more. On my cores, I note that the Al is not
constant. Is this normal ?

TORUS
====
Outside diameter ? 10 mm
Inner diameter ? ~ 5 mm
height 5mm

Self of 33 turns of ? 0.1 mm
--------------------------------------
Bridge measurement BF Z serie
120Hz: 36.75?H 0.443 Ohms
1kHz: 36.34?H 0.447 Ohm
10kHz: 36.08?H 0.455 Ohms
100kHz: 35.91?H 0.635 Ohms

Self of 21 turns of ? 0.2 mm
--------------------------------------
Bridge measurement BF Z serie
120Hz: 8.081?H 0.0764 Ohms
1kHz: 8.122?H 0.0764 Ohm
10kHz: 8.112?H 0.0771 Ohms
100kHz: 8.084?H 0.112 Ohms

Calculation of aL ? (it-is good ?)
=============
Self 33 turns: 33 nH/turn?
Self 21 turns: 18 nH/turn?

73 QRO
F1AMM (Fran?ois)

Thank you Victor
Hi there

I did well to tell you clearly what I did not understand. Our linguistic
difference plus character encoding problems had greatly scrambled the
transmission. The ? which had been transformed into mu was formidable.

The ""S11 R/Ω & X/Ω"" is what is written on the graph of nanovna-saver

In summary what I understood:

From S11, nanovna-saver calculation Z

When you write Z'=Z/ω you are using the real Z or the reduced z=Z/Zc where
Zc is the normalization impedance (50 ?).

Then nanovna-saver draws the graph of Z' as a function of F= ω/2π by
separating the real part from the imaginary part.

I do some development in C#. I wrote a grinder to, from a CSV, draw a
graph in a .DXF The grinder was in fact to make topographic plotting. These
.DXF (like .DWG but ASCII) I manipulate them with nanoCAD, a version of
which is free. It turns out that in the Smith chart the rectangular
coordinates of the chart (horizontal and vertical) are the coordinates of
S11 (the normalized reflection coefficient with respect to Zc). I have a
Smith chart in bitmap as well as a vectorized chart in my .DXF and I can
superimpose quite easily:
-Theoretical curves, derived from calculations
-Measurements, by processing nanovna-saver .S1P files

It is with sed I transform the .S1P into .CSV I can control this .CSV in
Excel and do calculations on it. It is a very powerful aid.

73 QRO
--
F1AMM Fran?ois

-----Message d'origine-----

De la part de Victor Reijs
Envoyé : mardi 5 juillet 2022 23:13

It's a pity that your pages are not in HTML; it would have allowed Chrome to translate them to me in French, online. In English, I can't follow.

thanks anyway

Dear OM, I'm interested about various measurements with NanoVNA but now I'm fighting with some fundamental questions not related only to nano VNA. but still unable to find answers, even after reading a lot of articles (for example k9yc, palomar engineers, and not only...)

- when I will try to determine ferrite core material by inductance and AL value, how can I be sure about right frequency for inductance? inductance could vary with frequency (various permeability) and then my AL value calculation could be wrong.
- I read somewhere that chokes need higher AL value then transformers. Why chokes requires higher AL value and transformers lower? It is because in chokes big AL value means high inductance with small amount of winding and wire and then high impedance for common mode currents with good efficiency?

Many thanks for answers, hope I will find an answer even when it is not simple topic ?

sources which I used:

Just being a commercial antenna does not mean it is a good antenna.

Thanks, but you were too quick to dismiss the human factor..

It wasn't until this morning that I realised the antenna is rp-sma female
and the nanovna is sma female.. They will screw in perfectly, yet no core
contact... facepalm.

I'll need to buy some adapters.

Have a nice day!

On Jul 5, 2022, at 8:00 PM, Donald S Brant Jr <dsbrantjr@...> wrote:

?But old firmware DOES have "broke" stuff in the form of bugs, etc., that is why the authors push out the new releases.
73, Don N2VGU