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On Wed, Jul 14, 2021 at 09:49 PM, W3DRM - Don wrote:

I started watching the video this morning and made it through the very basic but good explanation of smith charts; then I ran some errands and started watching again and after 5 minutes the video vanished.

This is a timely thread as I just received my -F this week. My HF antennas
all have PL-259 connectors. To connect them to the NanoVNA, I already have
SO-239 to SMA Male (like these
<>). I don't have PL-259 open,
short, and loads (though obviously open & short would be trivial to build)
and I'm wondering for HF frequencies (up to 30MHz), would the calibration
done on the port (using the supplied calibration connectors) be acceptable,
or I should I get an SMA female to PL-259 (like this
<>)
and calibrate at the female SMA?

The final result (during calibration) would look like: SMA
open/short/load->SMA female to PL-259->SO-239 to SMA male->S11 on NanoVNA.

Is this overkill, and would that last adapter invalidate any
calibration when it's removed to plug in the actual antenna?

73,
David, K2DBK
k2dbk.com
twitter: @k2dbk


On Thu, Jul 15, 2021 at 3:39 PM ward harriman <ward.harriman@...>
wrote:

I am of the practice of ALWAYS doing a calibration. This comes from many
scars of debugging ‘unexpected’ results which, ultimately, turned out to be
calibration problems.

Calibration just doesn’t take that long. I consider it insurance against
my own forgetfulness.

Ward

Lay off the griping and make the measurement in a 50-ohm system. With
that, you'll learn how better to use a VNA.

Grumpy: Dave - W?LEV

On Thu, Jul 15, 2021 at 4:02 PM Dr. David Kirkby, Kirkby Microwave Ltd <
drkirkby@...> wrote:

On Wed, 14 Jul 2021 at 20:02, WB2UAQ <pschuch@...> wrote:

This is a long thread so this might have been mentioned already. I bet I
am way out of line. Sorry.

Why can't the measurement be made with a 50 ohm network analyzer?

It can be, and that's the most sensible thing to do.

Dave

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

On Wed, 14 Jul 2021 at 20:02, WB2UAQ <pschuch@...> wrote:

This is a long thread so this might have been mentioned already. I bet I
am way out of line. Sorry.

Why can't the measurement be made with a 50 ohm network analyzer?

It can be, and that's the most sensible thing to do.

Dave

You can absolutely measure at one impedance and display at another. Most comprehensive Smith chart programs allow the user to ‘change the center of the chart’ to any impedance.

You can just import an impedance file and then set the center to (say) 75 ohms and be done.

I am of the practice of ALWAYS doing a calibration. This comes from many scars of debugging ‘unexpected’ results which, ultimately, turned out to be calibration problems.

Calibration just doesn’t take that long. I consider it insurance against my own forgetfulness.

Ward

NanoVNA is intended as a gateway between measurement and analysis/integration endeavors.

If nanoVNA saver is sufficient for your purposes I suppose you should stay with it. I wrote nanoVNA connect because all I needed from nanoVNA- saver was the ability to initiate measurements and write touchstone files.

NanoVNA Connect simply cuts out the middleman while providing a streamlined path for calibration and measurement.

W

It wasn’t a hard choice. Should Ii have you download and install the software before you have an idea what it does.... or should I show you what it can do and then, if you’re interested, have you download it?

I chose the former.

SimSmith is a circuit simulation and evaluation tool. Think Spice without transient analysis. There are,dozens of videos by W0QE and me (AE6TY) on YouTube. The longer version of the video to which I pointed



Gives you a slightly larger view of SimSmiths generic capabilities.

Sorry for any inefficiencies.

Ward

In starting the cal process, it is assumed you have previously set the
desired frequency range.

Dave - W?LEV

On Thu, Jul 15, 2021 at 11:37 AM Richard Clemens <rich.clemens@...>
wrote:

On Thu, Jul 15, 2021 at 09:27 AM, Jim Lux wrote:
Very helpful -- however when I do a calibration with nanovna-saver's tool
it does not ask for a frequency range when starting the process -
confusion...

2) If the frequency span of the measurements is different than the

frequency

span of the calibration. The NanoVNA does some interpolation, but if

you did

a cal from 0-50 MHz and now you're measuring a DUT from 200-300 MHz, the
measurement might be iffy. Likewise if you did a cal from 0-900 MHz, and

the

measurement is from 20-30 MHz.

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

On Thu, Jul 15, 2021 at 09:27 AM, Jim Lux wrote:
Very helpful -- however when I do a calibration with nanovna-saver's tool it does not ask for a frequency range when starting the process - confusion...

2) If the frequency span of the measurements is different than the frequency
span of the calibration.? The NanoVNA does some interpolation, but if you did
a cal from 0-50 MHz and now you're measuring a DUT from 200-300 MHz, the
measurement might be iffy. Likewise if you did a cal from 0-900 MHz, and the
measurement is from 20-30 MHz.

And they have a bridge! :-)



On Thu, Jul 15, 2021 at 10:55 AM Dragan Milivojevic <d.milivojevic@...>
wrote:

SimSmith is a simulation program with a completely different purpose.

On Thu, 15 Jul 2021 at 14:46, Richard Clemens <rich.clemens@...>
wrote:

How does this differ from "nanovna-saver" and is it better or just
different. I find the <saver> to be extremely useful and helpful.

SimSmith is a simulation program with a completely different purpose.

On Thu, 15 Jul 2021 at 14:46, Richard Clemens <rich.clemens@...>
wrote:

How does this differ from "nanovna-saver" and is it better or just
different. I find the <saver> to be extremely useful and helpful.

On 7/15/21 5:54 AM, Richard Clemens wrote:

Given my limited work with a NanoVNA I ask:

It appears the calibration routine (so far I have only needed for one port) is done without regard to any parameters being set.
Once it is done and saved you can reload it later and use it again.

Questions:
When would be a case that requires a new calibration vs just reloading one that has been saved?
Is it better to do a new calibration each time you fire up the nano rather than used a saved one?
What makes a calibration worth saving? ie. how should they be labeled?

Reasons to recalibrate (as opposed to use a saved cal set):

1) A different test setup, where the "reference plane" for the measurements is different.? For instance, if you have test port cables with different length, and you do the cal at the end of the cables.

2) If the frequency span of the measurements is different than the frequency span of the calibration.? The NanoVNA does some interpolation, but if you did a cal from 0-50 MHz and now you're measuring a DUT from 200-300 MHz, the measurement might be iffy. Likewise if you did a cal from 0-900 MHz, and the measurement is from 20-30 MHz.

3) You can't remember what you did for a cal before

4) The temperature or something else has changed significantly. I don't know how temperature sensitive the NanoVNA is, but things like the bridges and detectors will change somewhat with temperature.? The oscillator frequency also changes, although I would expect that to be a 10s of ppm sort of thing, so unless you're measuring crystals or 2kHz wide filters at 30 MHz, you probably wouldn't see it.

Think of the NanoVNA as being somewhat like a RF Ohmmeter.? When you turn on the ohmmeter you check to see that it reads infinity with the leads apart, and zero with the leads shorted.? Same sort of thing.? Check to see that it reads appropriately with open and load, and if it looks ok, it probably is.? (If you store it with the load on CH0, then when you turn it on, you'll see the good match, and then when you disconnect the load to connect the DUT, you'll see the reflection match, so that's a easy way to check.

Given my limited work with a NanoVNA I ask:

It appears the calibration routine (so far I have only needed for one port) is done without regard to any parameters being set.
Once it is done and saved you can reload it later and use it again.

Questions:
When would be a case that requires a new calibration vs just reloading one that has been saved?
Is it better to do a new calibration each time you fire up the nano rather than used a saved one?
What makes a calibration worth saving? ie. how should they be labeled?

TNX

How does this differ from "nanovna-saver" and is it better or just different. I find the <saver> to be extremely useful and helpful.

On Wed, Jul 14, 2021 at 07:17 PM, Anne Ranch wrote:

How about putting horse before cart and give link to the software before
telling how to use it ?

I would assume it can be found at the same place you got the version you are using now (if you are already using SimSmith). Try here:



Scroll down to download.

On 15/07/2021 06:49, David J Taylor via groups.io wrote:

Many thanks for that! Having fun getting it on my iPad for ChromeCasting to
the TV.
I see Part 2 there, but not Part 1. Am I missing something?

Fixed - file name was confusing!

David
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

On 14/07/2021 19:39, Barry K3EUI wrote:

This is the most recent video on my presentation:
Nano VNA Part I The Basics (not much math)
Nano VNA Part II The Under the Hood Approach (Advanced topics)
I'll also include the latest PDF of the slides - enough for a few hours of discussion
The video listed below was recorded a few days ago by the Leicester Radio Society (UK)
TU G8PGO David Carter.
I'm learning as I am playing, so here are the latest two videos
The Part I is just the "basics" without any of the math. That video was also recorded.
If you spot any errors on either video please let me know. This is rather technical stuff.
The ending on both presentations was a bit abrupt since I ran out of time.
!AtLJBaL57qLbg5sz6VcyxJdPeQaCrw?e=RkNpYx
have fun watching
de k3eui Barry

Barry,

Many thanks for that! Having fun getting it on my iPad for ChromeCasting to the TV.

I see Part 2 there, but not Part 1. Am I missing something?

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

This is really great. Thank you

Martin
N6QLH

How about putting horse before cart and give link to the software before telling how to use it ?