nanovna-users@groups.io

Re: Nano VNA BASIC WORKSHOP via Zoom

Hello Barry,

Some of us in the NanoVNA community actually live outside continental USA.
Not sure where your QTH is, but there is also a 5 hour time difference across the continental USA as well.

It would be great to have access to your obvious vast experience in RF topics, especially when it shows the application of the fabulous NanoVNA.

Would you reconsider recording? (Even delay access to encourage as much online participation as possible)

73...Bob VK2ZRE (Downunder in Australia)

Show quoted text

On 15/11/2022 12:38 am, Barry K3EUI wrote:
I have been asked many times if these Zoom sessions on Nano VNA were recorded.
NO. They were not recorded.

The reason is simple: I wanted these sessions to be discussions, not lectures.
Many folks will not ask or answer questions if the session is recorded (from my experience as a teacher/professor).


I will pause during the zoom session and ask folks to contribute (like a live class)
“What is reactance in an antenna?”
And then ask for contributions.
How do you measure reactance with a VNA from inside your shack (at the end of X feet of coaxial feed line)?

“Does SWR change along the feed line if the attenuation is very low?”
That one is interesting.
I suggest you read the Walt Maxwell books on SWR and feed lines from QST articles in the 1970’s.


Sometimes (actually often) an open ended question leads to a lively debate!


I have about 200 slides (PPT) that I made over the past three years covering all aspect of VNA and antennas and Smith charts.
I’d be happy to share those, as a PPT or as a PDF file.
The slides are just key points to get a discussion going.

Learning is an iterative process with a lot of mistakes along the way.

Come join in on the presentation/discussion,

de k3eui. Barry
Philly
Nov 14th

Re: TDR what does it show? #cables

#30272

On Mon, Nov 14, 2022 at 12:53 AM, tuckvk3cca wrote:


When you click on the TDR in Nanovsaver. The length of the cable is already
indicated, which I presume is the physical length once you specify the coax
type or VF. There are two plots on the graph, but what do they show? 
One graph shows the Time Domain response of the cable attached to CH0 (port1).  The other shows the approximate impedance magnitude |Z|.   In the annotated Saver graph below I measured 3M of RG-316 connected to 1.8M of 75 ohm RG-6 with an adapter. 

Roger

RG-316 and RG-6.png

Re: Nano VNA BASIC WORKSHOP via Zoom

#30271

I have been asked many times if these Zoom sessions on Nano VNA were recorded.
NO. They were not recorded.

The reason is simple: I wanted these sessions to be discussions, not lectures.
Many folks will not ask or answer questions if the session is recorded (from my experience as a teacher/professor).


I will pause during the zoom session and ask folks to contribute (like a live class)
“What is reactance in an antenna?”
And then ask for contributions.
How do you measure reactance with a VNA from inside your shack (at the end of X feet of coaxial feed line)?

“Does SWR change along the feed line if the attenuation is very low?”
That one is interesting.
I suggest you read the Walt Maxwell books on SWR and feed lines from QST articles in the 1970’s.


Sometimes (actually often) an open ended question leads to a lively debate!


I have about 200 slides (PPT) that I made over the past three years covering all aspect of VNA and antennas and Smith charts.
I’d be happy to share those, as a PPT or as a PDF file.
The slides are just key points to get a discussion going.

Learning is an iterative process with a lot of mistakes along the way.

Come join in on the presentation/discussion,

de k3eui. Barry
Philly
Nov 14th

Re: Nano VNA BASIC WORKSHOP via Zoom

#30270

On Sun, Nov 13, 2022 at 10:57 AM, Barry K3EUI wrote:


No, I did not record them because I wanted to encourage questions/comments and
when you record these sessions,
(some) folks are hesitant to ask questions or respond.
That is truly unfortunate. I am sure there are hundreds if not thousands of people including myself who would love to watch the presentation, but who got late notice or were not available at the time.   How many viewers fell into the category of too shy to participate?  Could you not record the session, maybe have a recorded Q&A, and then have a closed Q&A at the end? I only ask because this Zoom sounds like a great thing you did, but for very limited benefit.
I am reminded of school classes where a few students were too shy to speak up in class, and therefore they fell behind, eventually failing the class.  If they were lucky there was a teacher who noticed and took them aside, perhaps arranging private tutoring so they would be more comfortable.

Re: Artefacts when capturing the screen #consolecommands #firmware #nanovna-h

#30269

On Sun, Nov 13, 2022 at 09:59 PM, Ho-Ro wrote:


my LCD screens of nano and tiny do not show any artefacts
DiSlord,

Correction: My tinySA shows it on the "VERSION" screen, while the NanoVNA does not.
But this is also more a topic deep in the HW/FW - we should discuss this on GitHub.
Are you still using your repo  because there has been no traffic for a long time? Where can we follow your good work?

Martin

TDR what does it show? #cables

#30268

When you click on the TDR in Nanovsaver. The length of the cable is already indicated, which I presume is the physical length once you specify the coax type or VF. There are two plots on the graph, but what do they show?

Re: Nano VNA BASIC WORKSHOP via Zoom

#30267

Are there recordings?

On Sun, Nov 13, 2022 at 7:21 AM Barry K3EUI <k3euibarry@...> wrote:

The “Five County Digital Training Net” (Philadelphia region) is hosting a
series of Zoom Workshops on Monday evenings at 7-9 pm. The topic: Nano VNA
Fundamentals
All are welcome to join.
Link:


We have already held two sessions covering the fundamentals of what a VNA
is capable of measuring and the second session covered how to CALIBRATE the
VNA over a frequency range.

The 3rd Zoom session on November 14th will cover what a Nano VNA measures
and what it calculates: the forward and the reflected signals are compared
(S11) and the following are calculated:

1) Reflection Coefficient (rho) - a fraction from 0 to 1.0 representing
the ratio of returning signal to incident signal. In an antenna, you do not
want any reflected (return) signal, so the ideal reflection coefficient is
zero.

2) Return Loss (dB) - this is based on the reflection coefficient and
represents the loss of signal, but measured in decibels (dB) rather than as
a percent or fraction. Hams rarely use this measurement. Why?

3) SWR - standing wave ratio  -  We all use this term but what does it
mean? What is an “acceptable” SWR in terms of antenna performance.

I will tie these three measurements into what a Smith Chart reveals.

Come join the discussion.
I am not an RF Engineer - so I try to keep this at a moderate level of
mathematics.

De k3eui
Barry  (k3euibarry - at - gmail.com)
Five County Digital Net manager
Philadelphia PA
November 13 2022







---Chris

Re: Artefacts when capturing the screen #consolecommands #firmware #nanovna-h

#30266

On Sun, Nov 13, 2022 at 08:01 PM, DiSlord wrote:


(you can see it also on Nano or Tiny LCD at right bottom)
Strange, my LCD screens of nano and tiny do not show any artefacts, only the captured data on PC. But it's only a minimal issue in any case.

Re: nanovna_remote.py - Python tool for remote control of the NanoVNA-H from the PC #nanovna-h #scripting #python #nanovna-tools

#30265

On Sun, Nov 13, 2022 at 06:29 PM, G8DQX list wrote:


*However*, the *H4* variant of the nanoVNA and the new tinySA *Ultra* use 4"
480×320 screens.
Robin, 
Good hint, should work for the bigger ones now - untested because of the HW not (yet) available.
Martin

usage: nanovna_remote.py [-h] [-d DEVICE] [-n | --h4 | -t | --ultra] [-z {2,3,4}]

optional arguments:
  -h, --help            show this help message and exit
  -d DEVICE, --device DEVICE
                        connect to serial usb device
  -n, --nanovna         use with NanoVNA-H (default)
  --h4                  use with NanoVNA-H4
  -t, --tinysa          use with tinySA
  --ultra               use with tinySA Ultra
  -z {2,3,4}, --zoom {2,3,4}

as well as

usage: nanovna_capture.py [-h] [-d DEVICE] [-n | --h4 | -t | --ultra] [-o OUT]

optional arguments:
  -h, --help            show this help message and exit
  -d DEVICE, --device DEVICE
                        connect to device
  -n, --nanovna         use with NanoVNA-H (default)
  --h4                  use with NanoVNA-H4
  -t, --tinysa          use with tinySA
  --ultra               use with tinySA Ultra
  -o OUT, --out OUT     write the data into file OUT

Re: Artefacts when capturing the screen #consolecommands #firmware #nanovna-h

#30264

I think this related to LCD driver, on screen capture i read LCD memory and send to CPU (you can see it also on Nano or Tiny LCD at right bottom)

Artefact present on all LCD displays based on ILI9341 driver
On LiteVNA and st7789 LCD driver no visible artefacts.

Re: nanovna_remote.py - Python tool for remote control of the NanoVNA-H from the PC #nanovna-h #scripting #python #nanovna-tools

#30263

Martin,

1) thanks for doing this, it's much appreciated.

2) the link below took one straight to the code, where lines 60-64 show:


# The size of the screen
width = 320
height = 240
which is OK for an original nanoVNA(-H) or a tinySA. *However*, the *H4* variant of the nanoVNA and the new tinySA *Ultra* use 4" 480×320 screens.

I've not had a sensible opportunity to check the script out with my own H4 or tinySA, but thought I'd mention it now, to get a view from yourself.

73, Stay Safe,

Robin, G8DQX

On 12/11/2022 09:19, Ho-Ro wrote:

Hi,
as written just around the corner/g/tinysa/topic/tinysa_remote_py_python/94944540  there's a new tool in my toolbox:



Remote control for the NanoVNA or tinySA - mirror the screen to your PC and operate the device with the mouse. The keys + and - zoom in and out, s takes a screenshot with timestamp, ESC quits the program.

usage: nanovna_remote.py [-h] [-d DEVICE] [-t | -n] [-z {2,3,4}]

optional arguments:
   -h, --help            show this help message and exit
   -d DEVICE, --device DEVICE
                         connect to serial usb device
   -n, --nanovna         use with NanoVNA (default)
   -t, --tinysa          use with tinySA
   -z {2,3,4}, --zoom {2,3,4}
                         zoom the screen image

Martin

Artefacts when capturing the screen #consolecommands #firmware #nanovna-h

#30262

The screen capture shows artefacts at the bottom of the image in the far right column. This is independent of the respective device and the recording program used; tinySA also shows the same artefacts. NanoVNA version 1.2.15, the issue existed also with versions 1.0.64 and 1.1.x, also latest tinySA version.

see also 
and 

Another user's tinySA also shows this, so it is obviously a systematic problem.
/g/tinysa/message/7071

Martin

NanoVNA_capture_artefact.png

NanoVNA_capture_artefact_detail.png

Re: Nano VNA BASIC WORKSHOP via Zoom

Doug

#30261

Hi Barry. This sounds like a really invaluable project. It is just too bad that we didn't know about it sooner, so that we could take in all five sessions.

Is there any possibility that any previous viewers might have copied the first two sessions, or even some screen grabs. I always use PrintScreen to keep a record of any Zoom sessions that I view.

Just a hopeful wish.

Thanks again for your hard work.

Doug

Show quoted text

On 13/11/2022 07:20, Barry K3EUI wrote:
The “Five County Digital Training Net” (Philadelphia region) is hosting a series of Zoom Workshops on Monday evenings at 7-9 pm. The topic: Nano VNA Fundamentals
All are welcome to join.
Link:

We have already held two sessions covering the fundamentals of what a VNA is capable of measuring and the second session covered how to CALIBRATE the VNA over a frequency range.

The 3rd Zoom session on November 14th will cover what a Nano VNA measures and what it calculates: the forward and the reflected signals are compared (S11) and the following are calculated:

1) Reflection Coefficient (rho) - a fraction from 0 to 1.0 representing the ratio of returning signal to incident signal. In an antenna, you do not want any reflected (return) signal, so the ideal reflection coefficient is zero.

2) Return Loss (dB) - this is based on the reflection coefficient and represents the loss of signal, but measured in decibels (dB) rather than as a percent or fraction. Hams rarely use this measurement. Why?

3) SWR - standing wave ratio  -  We all use this term but what does it mean? What is an “acceptable” SWR in terms of antenna performance.

I will tie these three measurements into what a Smith Chart reveals.

Come join the discussion.
I am not an RF Engineer - so I try to keep this at a moderate level of mathematics.

De k3eui
Barry  (k3euibarry - at - gmail.com)
Five County Digital Net manager
Philadelphia PA
November 13 2022

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73

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Re: Nano VNA BASIC WORKSHOP via Zoom

#30260

oops
here is the much better Dummy Load trace

Barry  k3eui

Dummy Load 50 ohm 1 to 30 MHz.jpg

Re: Nano VNA BASIC WORKSHOP via Zoom

#30259

This is what I see with the NANO VNA standard LOAD  (50 ohm dummy load R)
Nothing unusual here.

de k3eui Barry

50 ohm dummy load 1 to 30 MHz.jpg

Re: Nano VNA BASIC WORKSHOP via Zoom

#30258

Nano VNA graphs using VNA SAVER

Lots of folks have asked me how the REFLECTION Coefficient S11 graph, the RETURN LOSS graph (dB) and the SWR graph compare.
Basically they all show similar aspects of the antenna.

This trace around the 80m band, and  is  AFTER  my  CLC  Antenna Tuner - set up for min SWR around  3600 kHz
The antenna is about 30 ft high, 130 ft long, center-fed with RG213 coax.
It is a great NVIS antenna.

Note the similar shapes of the RETURN LOSS (dB) and the SWR curve (both derived from the reflection coefficient (S11)

de k3eui Barry

November 13 2022

80m dipole post TUNER 4G6 Nov 13 2022.jpg

Re: Nano VNA BASIC WORKSHOP via Zoom

#30257

Kirk
No, I did not record them because I wanted to encourage questions/comments and when you record these sessions,
(some) folks are hesitant to ask questions or respond.
Barry

Re: Nano VNA BASIC WORKSHOP via Zoom

#30256

Hi, Barry,
Did you happen to record those previous sessions?
Thanks,
--Kirk, NT0Z

My book, "Stealth Amateur Radio," is now available from www.stealthamateur.com and on the Amazon Kindle (soon)

Show quoted text

On Sunday, November 13, 2022 at 06:21:03 AM CST, Barry K3EUI <k3euibarry@...> wrote:  
 
 The “Five County Digital Training Net” (Philadelphia region) is hosting a series of Zoom Workshops on Monday evenings at 7-9 pm. The topic: Nano VNA Fundamentals
All are welcome to join.
Link: 

We have already held two sessions covering the fundamentals of what a VNA is capable of measuring and the second session covered how to CALIBRATE the VNA over a frequency range.

The 3rd Zoom session on November 14th will cover what a Nano VNA measures and what it calculates: the forward and the reflected signals are compared (S11) and the following are calculated:

1) Reflection Coefficient (rho) - a fraction from 0 to 1.0 representing the ratio of returning signal to incident signal. In an antenna, you do not want any reflected (return) signal, so the ideal reflection coefficient is zero.

2) Return Loss (dB) - this is based on the reflection coefficient and represents the loss of signal, but measured in decibels (dB) rather than as a percent or fraction. Hams rarely use this measurement. Why?

3) SWR - standing wave ratio? -? We all use this term but what does it mean? What is an “acceptable” SWR in terms of antenna performance.

I will tie these three measurements into what a Smith Chart reveals.

Come join the discussion.
I am not an RF Engineer - so I try to keep this at a moderate level of mathematics.

De k3eui
Barry? (k3euibarry - at - gmail.com)
Five County Digital Net manager
Philadelphia PA
November 13 2022

Nano VNA BASIC WORKSHOP via Zoom

#30255

The “Five County Digital Training Net” (Philadelphia region) is hosting a series of Zoom Workshops on Monday evenings at 7-9 pm. The topic: Nano VNA Fundamentals
All are welcome to join.
Link: 

We have already held two sessions covering the fundamentals of what a VNA is capable of measuring and the second session covered how to CALIBRATE the VNA over a frequency range.

The 3rd Zoom session on November 14th will cover what a Nano VNA measures and what it calculates: the forward and the reflected signals are compared (S11) and the following are calculated:

1) Reflection Coefficient (rho) - a fraction from 0 to 1.0 representing the ratio of returning signal to incident signal. In an antenna, you do not want any reflected (return) signal, so the ideal reflection coefficient is zero.

2) Return Loss (dB) - this is based on the reflection coefficient and represents the loss of signal, but measured in decibels (dB) rather than as a percent or fraction. Hams rarely use this measurement. Why?

3) SWR - standing wave ratio  -  We all use this term but what does it mean? What is an “acceptable” SWR in terms of antenna performance.

I will tie these three measurements into what a Smith Chart reveals.

Come join the discussion.
I am not an RF Engineer - so I try to keep this at a moderate level of mathematics.

De k3eui
Barry  (k3euibarry - at - gmail.com)
Five County Digital Net manager
Philadelphia PA
November 13 2022

Re: MOSFET as RF on/off switch and how to measure/what to expect #circuit

#30254

Sorry ... I meant to say:

These parts are designed for turning on MOSFET gates so I suspect they stack as many photodiodes in series as they need to get the required voltage.

Eamon

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