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I use PrintScreen but SnagIt is another good tool. They allow you to select the area that you want to print.On this topic, is there a way to copy and print the whole thread for a topic? This would be very useful.Sent from my Galaxy

Hello Nanovna user group. I have subscribed to this group and have followed many great issues onto resolution.

Allow me to introduce myself, my name is Larry Land (Ki5oez), VP of the McKinney, Texas, Amateur Radio club. One of my duties in the club is to find presenters to present in person or virtually via Zoom to our club members.
I thought I would reach out to your group to see if a member would be interested in doing an in person/virtual presentation to our club on using the NanoVna regarding ham radio.
If instead you have a canned presentation that would be welcomed as well.

Our club meets on the 2nd Tuesday of each month at 7PM Central time with the presentation to start between 7:15-7:30 and duration should be under 45 minutes, but we are flexible.

We would also be happy to pay for your dinner prior to the meeting if presenting in person.

The following dates are available: September 12, and November 14, 2023. (and possibly May 9, but I am holding out for a “contesting” elmer in time for Field day)

Thank you for your time and consideration in this request.

Larry Land, ki5oez
Vice President
McKinney Amateur Radio Club
Cell: (817)-312-4618
10292 Burnt Mill Lane
Frisco, Texas 75035
vicepresident@...


PS. We wish to challenge our members to learn and grow in our radio hobby. This is my first year as VP, and I feel I have been neglecting the more experienced members and need to challenge the less experienced members to grow. I earned my element 4 in late 2021, and the Smith Chart came as a surprise, but it did help demonstrate and iron out impedance issues. It would be great if we could introduce and challenge the general class members and, at the same time, refresh the extra members knowledge base. I believe the NanoVna is a great tool that can help solve many of the Ham’s problems.
Thanks again for your consideration.
Sincere 73,
Larry
Ki5oez

Sorry folks,

I’ve got no explanation for the butcher job my cut and paste formulas on Gamma, rho, and angle turned out to be.

The bits were from the attached article, link below.



Sorry for the wasted space and thanks for your continued interest.

Ed McCann
AG6CX

Correct. For thru the cables are connected together. For isolation I connect a 50 ohm load is to each cable.

Mike N2MS

For the S11 calibration (Open, Short, Load), it does not matter whether
there is a cable attached to the second port or not.
For the Isolation and Thru calibration, the cables should be attached to
both ports. Ideally, for the isolation calibration, you individually
terminate both cables with a 50ohm load (at the clip end of the cable).
Then for the thru calibration, simply connect the ends of the cables
together. You must do the isolation and thru calibrations if you want
accurate results on any thru (S12) measurements, but it is not relevant for
S11 measurements.
Stan

Bryan,

Yes. I use it to check the characteristics of my ferrites. In addition, I have different sizes of Fair-Rite 31 43 and 61 cores so I can compare the unknown cores to the Fair-Rite products.

Mike N2MS

Assuming you are running on Windows, you can a) select the window you want
to share, b) press ALT-PrintScreen on your keyboard. This will put a copy
of the window on your windows clipboard, so you can paste it into a
document or email.

On Sat, Mar 11, 2023 at 8:38?AM Neil Ackerley via groups.io <ackerley.neil=
[email protected]> wrote:

Is there a manual for the nanovna saver software.

I am trying to take a screen view to email to others for opinions

Neil G3RIR

Hi Mike. Thanks for the reply.
Just to be clear, you calibrate at the end of the S11 cable (with both cables in place). Then you connect them together for the through part of calibration.

Regards.
Bryan

I perform a calibration with the cables in place.

I have a S11 cable with two alligator clips, input and ground and a S21 cable with one input alligator clip

The S11 clips are separated for the open cal and connected together for the short cal. I install 50 ohm load (two paralleled 100 ohms) for the load. cal.

I connect the S11 input to the S21 input for the thru cal.

Mike N2MS

Is there a manual for the nanovna saver software.

I am trying to take a screen view to email to others for opinions

Neil G3RIR

I have two short cables with alligator clips that I use for looking at baluns, transformers wound on toroids, tuned circuits and what not.

When calibrating should i just tune the the s11 side or should i connect the two together and calibrate to the end of both of them?
Thanks
Bryan

Didn't know that, it's easy uj design a filter from the measured impedance. You need to check the Q or bandwidth and also harmonic suppression.

The first thing to check is if something is amiss in the calibration
process you are using. One common mistake is that you need to reset the
cal before doing a new one. You can also verify the cal before you look at
SWR or other measurements. See the detailed description of calibration and
verification in "The Absolute Beginners Guide" in the files section of this
group, at the following link:
/g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_5.pdf


On Fri, Mar 10, 2023, 5:31 PM AJC via groups.io <AGCHURCHJR=
[email protected]> wrote:

I have a VNA SAA-2N. It will not calibrate (it says it does) but with a 50
ohm load the swr is significantly high. (i have tried another set of
standards)

Sorry - looks like I might have transposed some gammas and rhos.

What I ness as by was not reproducible on my non-Greek iPhone:

Here’s what I had in mind for
Gamma = rho angle theta :



Reflection coefficient:
ZL – Z0 Y0 – YL
Γ = ρ∠θ = ----------- = ----------- (6)
ZL + Z0 Y0 + YL

The reflection coefficient gamma represents the quality of the impedance match between the source and the measured load. It is a complex quantity, with magnitude rho and angle theta.

The reflection coefficient is small for good matches. The reflection coefficient takes values from ?1 for shorts, stays negative for loads < Z0, is zero for perfect matches, is positive for loads > Z0, and reaches +1 for open loads.

Using normalized impedances:
窜–1 1–Y Γ = ρ∠θ = ------- = -------
Z+1 1+Y From equ.(5), it follows that s11 is:
窜–1
s11 = ------- = Γ
1+Γ
and Z = -------- (7)
Z+1
Here we see that s11 and Γ (the reflection coefficient) are one and the same.

Thanks for your patience

73
Ed McCann
AG6CX

Regarding an excerpt from your post (perhaps missing a word or two?)

“I use toroidal bifilar wound common mode chokes (CMCs) in my antenna feed
system. I have a 450 set of wires fed with parallel conductor transmission
line. In the shack I install the CMC choke between the open wire line and
the input of my home brew single ended (common mode) L-network for matching
what the antenna/transmission line present in the shack to 50 ± j0 ohms. I
use similar chokes wound on both 31 and 43 ferrite material.”

I’m curious.

Could you provide a bit more detail on your description:


1. The actual antenna in the air.

2. You say to this antenna is connected a “450 set of wires”? Can’t imagine what they would be, unless you were trying to say you feed the aerial with a 450 ohm feedline. Is this correct?

3. If so, is your 450 ohm feed feedline actually measured at 450 ohms? Or is it JSC-1318 or something described as Zo = 450 ohms, but really 400 ohms?

4. A description of your CMC choke at the shack, connected on one side to the parallel feedline and out the other to coax? How many cores? Separate bifilar windings on one or two toroids? Or in series with two different materials #31 and a second with #43?

5. Your observed results of Z CMC offered by each CMC choke ? In form Z=R +jX and related Reflection Coefficient Gamma Vector = rho Angle Gamma? Or dB.

Nice explanation offers to inquiring ham looking for insights!


Looking forward to your response.

73
Ed McCann
AG6CX

I have a VNA SAA-2N. It will not calibrate (it says it does) but with a 50 ohm load the swr is significantly high. (i have tried another set of standards)

On 3/9/23 9:56 PM, Bob Ecclestone VK2ZRE wrote:

G'day Jim,
You are quite right of course.
When I wrote the reply to Don I had only just finished reading his referenced Keysight/Agilent/HP document.
I meant to put in a comment that the document was specifically referring to Metrology grade measurements but my head was still spinning from the degree of detail in the document.
It certainly made extremely interesting reading having spent some time in development labs in past lives.
Connector Savers are a real godsend to the fabulous NanoVNAs and TinySAs currently available to us these days. They are the best accessory you can buy for your instruments.
It is interesting also that HP made a range of Connector Savers and Adapters available and characterised the effect they could/would have on measurements.
Cheers...Bob VK2ZRE

And the cool thing is, with the connector saver, the effects of the saver are incorporated in the calibration. They're so short I doubt there's any interpolation or other issues.

On 3/10/23 10:07 AM, Roger Need via groups.io wrote:

Jim,
Take a look at the NanoVNA groups.io with your browser if you are getting late emails.
Owen Duffy has fixed the interpolation issue in NanoVNA App and it is now working correctly for de-embedding long cables. I made a post on the fix ... /g/nanovna-users/message/31708

I saw that, but didn't realize they were coming in late. I'd get a few, and it just seemed that list traffic was slow.

The result worked out GREAT!

I did an experiment with my (adjustable) 80m antenna. The lowest SWR that I was getting was 1.62:1 at resonance (I can adjust the 80m antenna resonant frequency simply by pulling down on the coax to get the antenna to fold up on itself to raise the resonant frequency, reference my QRZ page for a diagram).

Considering that I have the KAT500 tuner that I can use, it really wasn’t necessary to lower the SWR, but when you use the tuner, there is loss in the coax for the full length of coax to the antenna (minimal though). Also, I don’t have a tuner on my solid-state amp, and I don’t want to push that when I tune too far off resonance, I don’t like to stress it.

On the positive side, with about 75’ of coax to the antenna with a 1.62:1 SWR, that’s only a .02dB SWR loss considering the LMR400 coax, and the total loss is .2dB! Not really worth messing with, really, but I like to experiment.

With the NanoVNA at the output of my external antenna switch (~20’ from the 80m feed point) and turned on the “L/C Match” measurement on the NanoVNA.
The 80m dipole shows:
L/C match for source Z0=50.0(ohms)
Src shunt Series Load shunt
1.6uH 298pF <<< I used this solution
1.1nF 3.4uH

So, I found a coil calculator online:
And found that 10 turns at 1.3” dia. for a length of 2.2” was about 1.6uH.

So, I built a little box with 10 turns on about 1.25” PVC form, and two 560pf 3KV caps in series (6kv, 280pf, close enough).
I mounted it at the same point of the coax as the above measurement (on the output of my antenna switch, going to the antenna).

My LP-100A RF Wattmeter shows an SWR at resonance of 1.01:1.

It’s nice when things work out! I have now 124KHz between the 2:1 SWR points on 80m for my home brew solid state amp.
I’m really getting to like the NanoVNA, it appears very accurate!!!
--
Mike, W0IH

On 3/5/23 3:23 PM, Roger Need via groups.io wrote:

OneOfEleven developed the NanoVNA App for personal use and after moving on to other projects kindly posted it as open source for the community to use and modify. Owen Duffy has created a fork of the OneOfEleven App and corrected some of the errors in the program especially on the info sidebar. I assume that he is reading (but unfortunately not posting) this thread because he has written a 3 part informative blog post on calibration in the NanoVNA App. Readers interested in this topic can use these links:
Part 1 -
Part 2 -
Part 3 -
In his discussion he shows that straight line interpolation can result in worse errors than using Cubic spline interpolation. The latter is used in NanoVNA App. He also states that when operating over a wide frequency band that more scan points is better.
With that in mind I did some more tests using a NanoVNA-H4 in standalone mode and with NanoVNA App OD12 and version 5.4 of NanoVNA Saver.
Calibration conditions
-----------------------------
1. In all cases the SOL was done at the end of 3M of RG-316 coaxial cable fitted with SMA male connectors on both ends. A SMA female was used with a pin header to do the SOL calibration. A 50 ohm 0805 SMD resistor was used as one of the cal loads. See attached photo. Sweep range was 50 kHz. to 900 MHz.
2. The NanoVNA was calibrated on the device using 401 scan points with the default bandwidth setting.
3. NanoVNA Saver was configured to use 401 scan points with 5 averaged sweeps for the calibration.
4. NanoVNA App OD12 was calibrated with 401 and 3201 scan points to see if more scan points made a difference. 8 traces were time averaged and trace smoothing set to 3.
Test Conditions
--------------------
A 75 ohm 0805 SMD resistor was used as the DUT and swept over the 50 kHz. to 900 MHZ. range. Note that interpolation was NOT required/used and scan point frequencies were the same as that done for calibration.
The NanoVNA Saver and NanoVNA Standalone DUT measurements were exported as a Touchstone s1p files and imported into NanoVNA app for comparison. The results are attached.
Observations
------------------
NanoVNA standalone and NanoVNA Saver both gave results that are consistent with what is expected for this DUT. NanoVNA app had a downward trend (for 401 and 3201 scanpoints) after 200 MHz. which is not correct.
Conclusions
----------------
My suspicion is that something is wrong with the implementation of the cubic spline interpolation in NanoVNA App. Perhaps DiSlord or Owen Duffy will consider adding linear interpolation as an option and removing or fixing the cubic spline interpolation.
Roger

A bit of a necro post here (for some reason, lots of groups.io messages are coming through a week late)).


Sweep range was 50 kHz. to 900 MHz. The NanoVNA was calibrated on the device using 401 scan points with the default bandwidth setting.

So the delta F between points is 900/400 or about 2.25 MHz.

This is sufficiently close that phase wraps aren't going to occur with a 3 meter long cable. At 900 MHz, lambda (free space) is .3333 meters. Velocity factor is 0.70 (depends on mfr, but close), so the "in cable" wavelength is 0.23 meters

that 3 meter cable is then 12.857 wavelengths long

At the next lower frequency step, 897.75, lambda is 0.334m, 0.2339m in cable, 12.825 wavelengths in the 3m cable. So the phase of the signal changes about 11.5 degrees.

I'm not sure that the interpolation algorithm cubic vs linear is the problem. It might depend on whether the underlying math is using cartesian (R+jI) or polar (mag, phase). interpolating between two points that are say (1.5 @ 357 degrees) and (1.2 @ 7 degrees) doesn't always come out right, if you're not careful about "going the right direction"