开云体育

Thanks for the tip, Harold. I shall have a look. Based on the quality of
the Smith Chart treatment, they must be excellent. Just hope others take
advantage. Have a read of my QRZ page to find out what I'm all about. I
get a lot of satisfaction working technical and teaching with the HS
students at Berthoud, Co., HS

Dave - W?LEV

--

*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*

#106": More On The Fourth Load VNA Trick

@Jeff Anderson - 4 January 2020 - /g/nanovna-users/message/9158

Dear Jeff,

Thank you very much for your most valuable information, by which you declare that
your VNA introduces, to the linear S-parameter equations model, * a d d i t i o n a l *
mathematical expressions, by which it tries to express the "physical impairments"
of the Standards.

This simply means to us that your particular VNA recognizes the most obvious fact:

"The Names of the Standards - that is their Nominal Values (-1, 0, 1) in accordance to
(S, L, O) order - do not express their values".

Thank you very much, indeed !

Because, this is exactly what we are trying to say in this Group from the very beginning.

After that said, also allow us, please, to consider now that our way to use this mathematical
model, that is * w i t h o u t * the introduction of additional mathematical expressions, is by
this very fact the most simple way to confront with this really existing issue - which by way,
it also covers the non-default operation of your VNA - simply because our way covers
the measurements by * a n y * VNA.

And at this very point also allow us, please, to emphatically declare that we don't find
anything erroneous in our point of view, that is the one From A Common User Point of
View FACUPOV, since we already looked ahead to exclude VNA cases in which this
default operation it is not their default. Our claim still holds for all those still existing
VNAs which do consider by default such an Absurdness.

Finally, allow us, please, to also emphatically say that * I F * after all that provisions of
your VNA, the unknown load value is still * c o m p u t e d * using the expressions which
are consequences of this very net linear S-parameter model, * T H E N * you have not
get rid off the Core Uncertainty of the Measurement still existing : (a) in your Standards,
as well as (b) in the inaccuracy of your VNA readings.

And it is still there, because it is * i n s e p a r a b l y * associated * w i t h * the
mathematical model in use itself.

That's all the crystal clear truth.

Anyway, after all that said, may we ask you now, please:

- Do you ever wondered why your VNA still leaves this Absurdness available to its user ?

- Do you ever wondered how its measurement is finally extracted to be presented to the user ?

With our best regards,

gin&pez@arg

On Thu, Jan 2, 2020 at 09:08 PM, David Eckhardt wrote:

Thanks, Dave!
If you remove the filename from that link, e.g., , there's an index of over 300 RF engineering course files there! I collected them all... :-)
--KV5R

Something is escaping me... there are a few reports of persons that are able to run nanovna-saver under Windows XP SP3 (as I have).
But the API in kernel32 that the program complains to be unable to find, was introduced in Windows Vista and it is rightfully absent in XP....
Additionally, when started from a DOS box, I receive this message :

Error loading Python DLL 'M:\Temp\_MEI30322\python37.dll
LoadLibrary: The specified procedure could not be found.

Now, going to the Python Web pages, it is clearly stated that Python 3.7 DOES NOT run under Windows XP....
Confused....

Alberto

On Sat, Jan 4, 2020 at 01:33 PM, gin&pez@arg wrote:

Hi gin&pez

"
Therefore, the Absurdness does not belong to us,
but to VNA itself, because:

(a) It considers by default that all the Standards
of the Whole World are identical and they have
values equal to those of their Names, that is of
their Nominal Values (-1,0,+1), and

Thank you for the clarification.

I am curious why you make this claim (a), because, in my experience, it is not correct. I offer as evidence any number of VNAs (or VNA software) that allow the user to characterize the three standards in terms of their actual physical characteristics (delay, loss, mismatch, and actual impedances (e.g. as a function of fringe capacitance, etc.).

For example, my 8753C does not "consider by default" that the Reflection Coefficients of any SOL standards are (-1, 1, 0). It actually considers *all* standards to have physical impairments that keep them from being the ideal (-1,1,0). And the only way to make the VNA use Reflection Coefficients that are (-1,1,0) is to go through the rather painful process of manually setting to zero (via the 8753C's menu system) each of the impairments for each of the SOL standards that have been pre-programmed (by HP) into the VNA.

"
Does it have an enough crystal clear meaning now?

It is much clearer! Many thanks.

- Jeff, k6jca

@Gary O’Neil, N3GO
/g/nanovna-users/message/9132

Dear Gary,

Well, allow us, please, to remind you that we would not arrive at this
- most spectacular, indeed ! - conclusion, if you did not insist to ask
all those questions, while the only thing we asked from you it was to
be staying tuned...

Kind regards,

gin&pez@arg

On Sat, Jan 4, 2020 at 11:24 AM, gary wrote:

Besides the Steber article on the nanoVNA, there is an article on a "Simple Inexpensive Accurate Vector Impedance Meter" by Koehler on page 23 that describes the design of an instrument nearly identical to the nanoVNA. Good information on the design considerations and how it works, Thirdly, there is a Technical Note on page 32 from Stensby describing a method to determine coax cable losses by making open and short-circuit measurements of reflection coefficients.
================================================================
For those not aware, ARRL has made the associated files for the "Simple Inexpensive Accurate Vector Impedance Meter" article publicly available at, .

As gary noted, the design is built along the lines of the NanoVNA, however; it is a desktop box without a display. An DIY adapter for making coil and capacitor measurements, useable with the NanoVNA, is also included in the file archive.

- Herb

#106': On The Fourth Load VNA Trick

@Jeff Anderson - 4 January 2020
/g/nanovna-users/message/9153

Hello,

Thank you very much for interest in our work,
and especially for quoting this excerpt by us,
as well as for the opportunity you are giving
to us to improve it !

Well, we presume that you are not following
this thread from its very beginning. So, let us
try our best to reshape this excerpt, as follows:

"
Therefore, the Absurdness does not belong to us,
but to VNA itself, because:

(a) It considers by default that all the Standards
of the Whole World are identical and they have
values equal to those of their Names, that is of
their Nominal Values (-1,0,+1), and

(b) It handles these Standard values in the very
same way we use them, that is : with linear
S-parameter equations.
"
Does it have an enough crystal clear meaning now?

Sincerely,

gin&pez@arg

#106':

@Gary
Can you help me to understand the reply from g&p?

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

On Sat, Jan 4, 2020 at 11:51 AM, gin&pez@arg wrote:

Therefore, it not our absurdness the fact that VNA considers by default that
it is enough for it not only to consider All the Standards of This Whole World as
identically having values equal to those of their Names, that their
Nominal Values (-1,0,+1), but in addition to that Absurdness to handle them
in this very same frame of our SOW : with linear S-parameter equations...

gin&pez,

Please forgive me, but your writing style, in my opinion, contains much too much extraneous "verbiage," and it is difficult for me (and probably others) to wade through the unnecessary words and sentiments in an attempt to glean the actual point you are trying to communicate. Trimming your sentences and paragraphs down to the essentials would greatly help you to express your points.

For example, what is the point you are trying to communicate in the paragraph I have quoted, above? Are you saying that all VNA's consider their SOL standards to have Reflection Coefficients of (-1, 1, 0), irrespective of the actual Reflection Coefficients of those standards?

Or are you saying something else? If it is "something else," then could you please explain your point in a clear and concise fashion?

Thank you,

- Jeff, k6jca

#106: On The Fourth Load VNA Trick

@Erik, PD0EK - 4 January 2020 - /g/nanovna-users/message/9131

Dear Erik,

We would like to thank you very much because you revealed at last your Subjective
World. Now, there is a chance to understand each other just on the basis of logical
reasoning, of course.

Well, we already openly set the crystal clear limits of our SOW regarding the kind
of "VNA Measurements" : linear S-parameter equations and their consequences;
nothing more-nothing less, but exactly all of this. All that can be logically concluded
and reasonably described within these very limits - which, by the way, you already
accepted too by proposing to us that picture (alas, still self-contradictory) you are
hosting at your website.

That's all. Crystal clear.

Therefore, it not our absurdness the fact that VNA considers by default that it is enough
for it not only to consider All the Standards of This Whole World as identically having
values equal to those of their Names, that their Nominal Values (-1,0,+1), but in addition
to that Absurdness to handle them in this very same frame of our SOW : with linear
S-parameter equations...

Start at last putting the blame - if you think that is really one such - to where it is belong
exactly, that is to:

The Fourth Load VNA Trick

which comes from that Much Bigger than our Small Objective World SOW, that is from
The Objective World of Linear S-Parameter Equations. And remember, please, that we
didn't invented this World, we simply present what are the unavoidable logical consequences
for anyone who would adopted it, as a whole of course and not by selecting only those parts
of it who thinks he likes because he finds them as most convenient for his purposes - that is
to form a Subjective World instead of an Objective one.

Kind regards,

gin&pez@arg

#106:

Besides the Steber article on the nanoVNA, there is an article on a "Simple Inexpensive Accurate Vector Impedance Meter" by Koehler on page 23 that describes the design of an instrument nearly identical to the nanoVNA. Good information on the design considerations and how it works, Thirdly, there is a Technical Note on page 32 from Stensby describing a method to determine coax cable losses by making open and short-circuit measurements of reflection coefficients.

It occurred to me the T-check is the single vna equivalent of the vna comparison formula (ratio of cross ratios)
The T-check also works if you connect the same single load to port 1 AND port 2 which is exactly what is done in the ratio of cross ratios check.
The T-check compares the two directions of the measurement (port 1 to 2 with port 2 to 1) by taking the inverse of one direction and check if the ratio is one.
Seems the same approach. Correct?
--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

Thank you Lucio for the Web and Android client information! Happy New Year!!

On Sat, Jan 4, 2020 at 08:49 AM, Lucio I?LYL wrote:

A few answers to find here:

===============================================================

Thanks Lucio,
I had already found that article during my research. The pictures referenced in the article were first released at this forum by Gabriel. I've noticed in the past that much of the content regarding the NanoVNA that rtl-sdr.com generates seems to come from this forum. This forum is a trail blazer for other outlets in regards to good solid technical information.

Again, Gabriel's design efforts are well documented. Primarily looking for creditable resources regarding hugen's and edy555's concrete design efforts.

- Herb

- Herb

Very good on the saver. On the hardware side, the delay when entered handles the "de-embedding" or negation directly. In any case, a hands on exercise or experiment is probably with a ton of arithmetic. So try this:

You can readily do this at HF, say calibrate from 100 kHz to 30 MHz. Make yourself a nice 220 ohm load, I used a small 1/8 W resistor. A chip R would be great. But just about anything that is for the most part NON REACTIVE at HF will be fine. Place it at your CH0 port as though this is you antenna under test.

You should see a nice tight single dot on the Chart at 220 ohms.

Now I took a nice piece of 50 ohm cable, TLINE. It was maybe 4 or 5 feet long. Place the 220 ohm R at the END of the cable. Now look at the swept chart s11 trajectory, looking into the cable with you vna. It will be a sweeping arc starts out at 220 ohm and moves clock wise with an ever decreasing R value. The 220 ohm resistor value appears at the input as a new value as altered by the TLINE.

Now, will de embed the TLINE by using the vna electrical delay feature. I dialed in about 13500 psec and your value will be different based on you length of TLINE cable. As you enter in new values of electrical delay you will note the CW rotation of the 220 R begin to collapse back to the original measured dot.

You have de embedded the transmission line. Can you calculate the exact value of delay required? Sure.
Depending on the physical nature of the cable, you can calculate the exact delay. If the cable is well behaved, i.e. uniform, this works very well.

Alan

Be aware you have to enter a negative offset delay in the calibration panel of nanoVNA-saver when de-embedding a cable or stripline
But it works!

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

A few answers to find here:


--
*73, Lucio I0LYL Rome, Italy*

Gabriel Tenna White's version 2 hardware and firmware design efforts are well documented on this forum and on her GitHub pages. Hugen and edy555 reportedly have version 2 efforts in the work, but so far, nothing as concrete as Gabriel's design. Hugen has documented a 4-inch F303 branch, that admittedly is not a version 2 design.

I was just wondering if any forum members have come across credible resources where either Hugen's or edy555's version 2 designs could be followed. My own research has not turned up anything close to what Gabriel has released, but I have not delved into any foreign language resources.

Since edy555 originated the NanoVNA design, I'm surprised he is not at the forefront of the V2 design effort. Gabriel's V2 design appears to have leap-frogged both his and hugen's. Still, its early in the race and the anticipated 2020 releases of the NanoVNA V2 show great promise.

- Herb

Next to the 25ohm check and the T-check, Kurt wrote an excellent proposal on how anyone can check another aspect of the quality of the calibration
/g/nanovna-users/message/4609

What can we use from this "errors of "errors"" discussion to help the community?
Till now I find it extremely difficult to come with something practical

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK