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On 10/14/21 6:03 AM, Roland Turner via groups.io wrote:

On 14/10/21 8:14 pm, Joe Smith via groups.io wrote:

Some background my be found at these two links:



/g/NanoVNAV2/topic/t_check_with_labview_nanovna/85036914?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,0,85036914,previd=9223372036854775807,nextid=1630672957048663752&previd=9223372036854775807&nextid=1630672957048663752

OK, so a cost-and-integration-effort vs. isolation tradeoff. Interesting. Thanks.

I very rarely want to be able to measure all four parameters, but did have an experience recently where the iterative process of tuning a duplexer meant many dozens of cable changes during the process and hands that were sore for days afterwards. A transfer switch — or two analysers — would have been less painful. Although in that particular case the isolation requirements were so high that a suitable transfer switch would indeed have been unworkably expensive and NanoVNAs would generally not have been sensitive enough.

Getting what one pays for...

Exactly... It's what things like 3 and 4 port analyzers were developed for - Simultaneous measurements, with high dynamic range, without needing to cable/uncable or do the math to convert multiple 2 port measurements to N port measurements, etc.

Tuning a ferrite circulator, especially with multiple ferrites, would be another "it would be nice to have a 3 port analyzer" application.


I need to build a little circuit which has a very different S11 and S22 to try it out - a single LC low pass would work nicely. Or even an asymmetric resistive divider (1 series R, 1 shunt R)


But more curiosity than anything else.? The idea of multiple simultaneous measurements (no relays) is intriguing.? One could build a N port analyzer with N sources and N^2 receivers, and choose the stimulus frequencies carefully so that no two are at the same frequency at the same time.? If the receiver is a wideband SDR, then conceivably, the N^2 receivers are implemented in only N pieces of hardware, and the selectivity is in software. With 16 bit ADCs and some averaging, one might be able to get 80-90 dB dynamic range, or better.

On 10/13/21 9:41 PM, Roland Turner via groups.io wrote:

Jim,

On 13/10/21 10:46 pm, Jim Lux wrote:

On 10/13/21 7:33 AM, btomek@... wrote:

How is the sweep synchronized in both of these devices? Unless it

doesn't have to be synchronized, but it seems to me that it does.

You have to turn off the sweep on one while making measurements on the
other. Otherwise there's interference, which shows up in the S21 trace.

Sort of like if you have a transfer switch (or swap cables) and a single
1 way VNA, you make a sweep, flip the switch, make the sweep the other way.

I'm working on some python code to do the sweeps alternately, but
haven't had time to finish it.

What benefit does this approach offer over using a DPDT/transfer switch? Is this just a cost concern?

Pretty much the cost - An extra NanoVNA is another $50, brand new - There are no $50 transfer switches, except used (maybe), and you need to make driver circuits, etc.

The cabling is going to be about the same either way (especially if you build your own resistive splitter) - the performance will be worse (less dynamic range with the pair of NanoVNAs, or source/load impedances that aren't 50 ohms, which might make your DUT unhappy).

I note for example that a transfer switch approach would solve concurrent access to multiple NanoVNAs, impedance matching, simultaneous sweeping, etc.

Sure, but either requires some coding to keep track of which measurement is being made when.

Starting and stopping the sweep is trivially easy driving it from a computer.


I was just intrigued because it was an unusual solution to a problem and decided to try it out.

The last time I needed simultaneous measurements in both directions was when I was adjusting a 3 section filter - S11 shows the resonances of the "input" side better, and S22 shows the resonances of the "output" side better. And as anyone who has adjusted a multi section filter has found, all of the adjustments interact, so it was easier seeing all 4 parameters together. My experience is almost certainly different from others, and I'm sure there are systematic ways of tuning these filters with a "one way" analyzer.


What I'd be more interested in, somewhere down the road, is figuring out whether the NanoVNA (or a similar device) can be used to make measurements of the S22 of a power amplifier, at higher power (for use in phased arrays, where there is mutual coupling among the antennas).

Have nanovna -H I think firmware 1070
Saver ver 3.9
When I measure swr on saver for a known antenna it never shows above 1.13 when I know it higher
on vna screen looks close to correct
what did I mess up and how to fix?
Thank you so much
Dave

On 14/10/21 8:14 pm, Joe Smith via groups.io wrote:

Some background my be found at these two links:



/g/NanoVNAV2/topic/t_check_with_labview_nanovna/85036914?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,0,85036914,previd=9223372036854775807,nextid=1630672957048663752&previd=9223372036854775807&nextid=1630672957048663752

OK, so a cost-and-integration-effort vs. isolation tradeoff. Interesting. Thanks.

I very rarely want to be able to measure all four parameters, but did have an experience recently where the iterative process of tuning a duplexer meant many dozens of cable changes during the process and hands that were sore for days afterwards. A transfer switch — or two analysers — would have been less painful. Although in that particular case the isolation requirements were so high that a suitable transfer switch would indeed have been unworkably expensive and NanoVNAs would generally not have been sensitive enough.

Getting what one pays for...


- Roland 9V1RT

Some background my be found at these two links:



/g/NanoVNAV2/topic/t_check_with_labview_nanovna/85036914?p=,,,20,0,0,0::recentpostdate/sticky,,,20,2,0,85036914,previd=9223372036854775807,nextid=1630672957048663752&previd=9223372036854775807&nextid=1630672957048663752

Jim,

On 13/10/21 10:46 pm, Jim Lux wrote:

On 10/13/21 7:33 AM, btomek@... wrote:

How is the sweep synchronized in both of these devices? Unless it doesn't have to be synchronized, but it seems to me that it does.

You have to turn off the sweep on one while making measurements on the
other. Otherwise there's interference, which shows up in the S21 trace.

Sort of like if you have a transfer switch (or swap cables) and a single
1 way VNA, you make a sweep, flip the switch, make the sweep the other way.

I'm working on some python code to do the sweeps alternately, but
haven't had time to finish it.

What benefit does this approach offer over using a DPDT/transfer switch? Is this just a cost concern?

I note for example that a transfer switch approach would solve concurrent access to multiple NanoVNAs, impedance matching, simultaneous sweeping, etc.


- Roland 9V1RT

On 10/13/21 2:59 PM, Francesco wrote:

hello there is way to connect to PC I got 76 years and got some problem with sight,
*Sent:* Wednesday, October 13, 2021 at 9:12 PM
*From:* "Jim Lux" <jim@...>
*To:* [email protected]
*Subject:* Re: [nanovna-users] two nanoVNA linked for two port setup
On 10/13/21 11:54 AM, Francesco wrote:

The DUT position is on the midle of the T ?

yes - here's some examples (a 21.4 MHz BPF and a 10dB pad)

I've run two instances of NanoVNA-Saver and it seems to work ok - here's a picture of two.? I scaled the image down so it's a reasonable size. I find that setting the font to 12 point makes it more readable, but you need a lot of screen realestate.? Or, you could overlap the windows.

The two units show up as different comm devices (/dev/cu.usbmodem4001 and /dev/cu.usbmodem3) - maybe there's some way to distinguish them, but for now, I just know that my older unit is the 3 and the newer unit is the 4001

I suspect that the other software might also work, but haven't tried them.? It would depend on if they store some sort of configuration file - you might need to have two copies and put them in different directories, or something like that.

Ultimately, I think I'll modify NanoVNA-Saver to support a full four parameter measurement, but that's a bit more work to go.

hello there is way to connect to PC I got 76 years and got some problem with sight,
*Sent:* Wednesday, October 13, 2021 at 9:12 PM
*From:* "Jim Lux" <jim@...>
*To:* [email protected]
*Subject:* Re: [nanovna-users] two nanoVNA linked for two port setup
On 10/13/21 11:54 AM, Francesco wrote:

The DUT position is on the midle of the T ?

yes - here's some examples (a 21.4 MHz BPF and a 10dB pad)

On 10/13/21 11:54 AM, Francesco wrote:

The DUT position is on the midle of the T ?

yes - here's some examples (a 21.4 MHz BPF and a 10dB pad)

I succefully got it ... MNI THANKS
Peter

The DUT position is on the midle of the T ?
*Sent:* Wednesday, October 13, 2021 at 4:56 PM
*From:* "Francesco" <realfran@...>
*To:* [email protected]
*Subject:* Re: [nanovna-users] two nanoVNA linked for two port setup
Hello Jim, I appreciate your availability to teaching and explaining your experiments and test with good manners, this is characteristic of one gentlemen. Thank you.
The VNA is one instrument not in use for my day use work (field engineer) first for is cost, is more used on research and development, I'm drive for curiosity and learn tu use is one my geriatric challenge (76).
I'm proud to be one Radio Ham for many years this whose one stimulus for my passion for the electronics, even I left the work on radio engineer many year ago.
I hope to learn more if my age permit me to do so.
My best regards.
Francesco.
*Sent:* Wednesday, October 13, 2021 at 3:46 PM
*From:* "Jim Lux" <jim@...>
*To:* [email protected]
*Subject:* Re: [nanovna-users] two nanoVNA linked for two port setup
On 10/13/21 7:33 AM, btomek@... wrote:

How is the sweep synchronized in both of these devices? Unless it doesn't have to be synchronized, but it seems to me that it does.

You have to turn off the sweep on one while making measurements on the
other. Otherwise there's interference, which shows up in the S21 trace.

Sort of like if you have a transfer switch (or swap cables) and a single
1 way VNA, you make a sweep, flip the switch, make the sweep the other way.

I'm working on some python code to do the sweeps alternately, but
haven't had time to finish it.

Hello Jim, I appreciate your availability to teaching and explaining your experiments and test with good manners, this is characteristic of one gentlemen. Thank you.
The VNA is one instrument not in use for my day use work (field engineer) first for is cost, is more used on research and development, I'm drive for curiosity and learn tu use is one my geriatric challenge (76).
I'm proud to be one Radio Ham for many years this whose one stimulus for my passion for the electronics, even I left the work on radio engineer many year ago.
I hope to learn more if my age permit me to do so.
My best regards.
Francesco.
*Sent:* Wednesday, October 13, 2021 at 3:46 PM
*From:* "Jim Lux" <jim@...>
*To:* [email protected]
*Subject:* Re: [nanovna-users] two nanoVNA linked for two port setup
On 10/13/21 7:33 AM, btomek@... wrote:

How is the sweep synchronized in both of these devices? Unless it doesn't have to be synchronized, but it seems to me that it does.

You have to turn off the sweep on one while making measurements on the
other. Otherwise there's interference, which shows up in the S21 trace.

Sort of like if you have a transfer switch (or swap cables) and a single
1 way VNA, you make a sweep, flip the switch, make the sweep the other way.

I'm working on some python code to do the sweeps alternately, but
haven't had time to finish it.

Have there been any comparison measurements made against a modern impedance analyzer or against an old Q meter (BRC or YHP)?
It was a long time before modern instruments could agree with the old Q meters never mind a network analyzer. I say this from experience when I worked with various suppliers making inductors for the company I worked for.
Thanks

On 10/13/21 7:33 AM, btomek@... wrote:

How is the sweep synchronized in both of these devices? Unless it doesn't have to be synchronized, but it seems to me that it does.

You have to turn off the sweep on one while making measurements on the other. Otherwise there's interference, which shows up in the S21 trace.

Sort of like if you have a transfer switch (or swap cables) and a single 1 way VNA, you make a sweep, flip the switch, make the sweep the other way.

I'm working on some python code to do the sweeps alternately, but haven't had time to finish it.

How is the sweep synchronized in both of these devices? Unless it doesn't have to be synchronized, but it seems to me that it does.

On 10/13/21 5:35 AM, Francesco wrote:

Hello, how connect two nanoVNA linked for a full two-port setup, I lost some pictures .

My first experiment was just using Ts.? This works, but doesn't present a 50ohm impedance to the device under test (DUT), rather it presents 25 ohms (because you've got two 50 ohm terminations in parallel).? For passive DUTs this probably isn't an issue, since the calibration "takes out" the mismatch.? But for some active devices, the device might not be stable with a 25 ohm termination.

The next step is to build a resistive splitter.? There's two approaches - one is a triple of 16.67 ohm resistors, the other is just to put 50 ohms in series with each VNA.

Resistive dividers have 6 dB loss, so this technique will give a 12 dB hit on the dynamic range. But it is cheap.

Hello, how connect two nanoVNA linked for a full two-port setup, I lost some pictures .

Go to message #25030 from Brian Beezly and the link is there. And Thank You Brian for "coil"

Where COIL v. 4.2.2 is available for dowload ???
Thanks - Peter

On 10/12/21 1:47 PM, John Baines via groups.io wrote:

Andrew,

I’m sorry but I can’t remember. It must have been fairly easy or I wouldn’t have managed it.

I do know that I access it from the terminal by typing;

cd nanovna-saver (ENTER)

NanoVNASaver (ENTER)

and it’s running.

It is running directly on my Mac running High Sierra and not via Wine or other emulator.

I hope this is of some help.

73
John
M0JBA

I think the original question was how to run Brian Beezley's COIL program (which is Windows/DOS)


that is *non-trivial* on a Mac - the *easiest* way is to fire up a virtual machine of some sort, but that requires you have a copy of Windows to install on the VM (Parallels, Virtual Box, etc.) - then you run the VM, and you just install COIL and go to town. That's what I did (using Parallels on my Mac).

You could also set up your computer as multi-boot and just boot Windows on whatever computer you've got.? Bootcamp on a Mac is one way of doing this.


The other way is to install WINE, which provides a "windows like" OS interface to the program - that works on either Linux, or, I think Mac.