Re: 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.
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Re: two nanoVNA linked for two port setup
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.
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Re: two nanoVNA linked for two port setup
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.
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two nanoVNA linked for two port setup
Hello, how connect two nanoVNA linked for a full two-port setup, I lost some pictures .
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Re: Inductor Q Measurement
Go to message #25030 from Brian Beezly and the link is there. And Thank You Brian for "coil"
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Re: Inductor Q Measurement
Where COIL v. 4.2.2 is available for dowload ???
Thanks - Peter
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----- Original Message ----- From: "Brian Beezley" <k6sti@...> To: < [email protected]> Sent: Tuesday, October 12, 2021 9:20 PM Subject: Re: [nanovna-users] Inductor Q Measurement Sorry, Andy. I know nothing about Macs. But googling yields many results for running Windows software on a Mac, including a version of Wine. Here is a screenshot of an actual Litz coil for a crystal set. Note the Q, which quite close to that measured with an HP 4342A. I'm curious to see if this image is displayed. Brian
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Re: Inductor Q Measurement
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.
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Re: Inductor Q Measurement
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
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On 12 Oct 2021, at 20:10, Andrew Kurtz via groups.io <adkurtz@...> wrote:
How did you get it loaded and working?
On Oct 12, 2021, at 3:09 PM, John Baines via groups.io <jbaines@...> wrote:
Andrew,
NanoVNA-saver works fine on my Mac.
73
John
M0JBA
On 12 Oct 2021, at 19:56, Andrew Kurtz via groups.io <adkurtz@...> wrote:
That program sounds wonderful! The only problem is that my computer is a Mac, and I bet it won¡¯t handle it. I know someone might say ¡°O just get Python and change XYZ while uploading ABC from Github¡.¡± and I might as well be listening to Greek. I have not yet succeeded in getting my nanoVNA data other than by hand-typing it into Excel because I can¡¯t get nanoVNAsaver to run. Any way to get your Coil program working on a Mac?
Andy
On Oct 11, 2021, at 7:00 PM, Brian Beezley <k6sti@...> wrote:
Andrew, my coil program might interest you. It calculates inductance and Q for solenoids made of solid or Litz wire. It models a number of wire alloys and form dielectrics, dielectric ribs or ridges, coil leads, and polygonal coil shapes. The program can automatically maximize coil Q while keeping inductance constant.
To validate accuracy, the documentation compares calculated values with hundreds of inductance and Q measurements made with an HP 4342A Q meter on dozens of coils of widely varying size and shape. For the coils from my own junk box, average error magnitude is 2% for inductance and 5% for Q.
The program runs in Windows and is free.
Brian
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Re: Inductor Q Measurement
Yes, thanks, the image looks good. I too have googled Windows apps on a Mac, and they require strange things I have never heard of. I don¡¯t know what Wine is, for example. Nor Python. I followed someone¡¯s simple directions, beginning with entering Terminal, but nothing ever worked...
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On Oct 12, 2021, at 3:20 PM, Brian Beezley <k6sti@...> wrote:
Sorry, Andy. I know nothing about Macs. But googling yields many results for running Windows software on a Mac, including a version of Wine.
Here is a screenshot of an actual Litz coil for a crystal set. Note the Q, which quite close to that measured with an HP 4342A. I'm curious to see if this image is displayed.
Brian
<coil.gif>
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Re: Inductor Q Measurement
Sorry, Andy. I know nothing about Macs. But googling yields many results for running Windows software on a Mac, including a version of Wine.
Here is a screenshot of an actual Litz coil for a crystal set. Note the Q, which quite close to that measured with an HP 4342A. I'm curious to see if this image is displayed.
Brian
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Re: Inductor Q Measurement
How did you get it loaded and working?
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On Oct 12, 2021, at 3:09 PM, John Baines via groups.io <jbaines@...> wrote:
Andrew,
NanoVNA-saver works fine on my Mac.
73
John
M0JBA
On 12 Oct 2021, at 19:56, Andrew Kurtz via groups.io <adkurtz@...> wrote:
That program sounds wonderful! The only problem is that my computer is a Mac, and I bet it won¡¯t handle it. I know someone might say ¡°O just get Python and change XYZ while uploading ABC from Github¡.¡± and I might as well be listening to Greek. I have not yet succeeded in getting my nanoVNA data other than by hand-typing it into Excel because I can¡¯t get nanoVNAsaver to run. Any way to get your Coil program working on a Mac?
Andy
On Oct 11, 2021, at 7:00 PM, Brian Beezley <k6sti@...> wrote:
Andrew, my coil program might interest you. It calculates inductance and Q for solenoids made of solid or Litz wire. It models a number of wire alloys and form dielectrics, dielectric ribs or ridges, coil leads, and polygonal coil shapes. The program can automatically maximize coil Q while keeping inductance constant.
To validate accuracy, the documentation compares calculated values with hundreds of inductance and Q measurements made with an HP 4342A Q meter on dozens of coils of widely varying size and shape. For the coils from my own junk box, average error magnitude is 2% for inductance and 5% for Q.
The program runs in Windows and is free.
Brian
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Re: Inductor Q Measurement
Andrew,
NanoVNA-saver works fine on my Mac.
73
John
M0JBA
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On 12 Oct 2021, at 19:56, Andrew Kurtz via groups.io <adkurtz@...> wrote:
That program sounds wonderful! The only problem is that my computer is a Mac, and I bet it won¡¯t handle it. I know someone might say ¡°O just get Python and change XYZ while uploading ABC from Github¡.¡± and I might as well be listening to Greek. I have not yet succeeded in getting my nanoVNA data other than by hand-typing it into Excel because I can¡¯t get nanoVNAsaver to run. Any way to get your Coil program working on a Mac?
Andy
On Oct 11, 2021, at 7:00 PM, Brian Beezley <k6sti@...> wrote:
Andrew, my coil program might interest you. It calculates inductance and Q for solenoids made of solid or Litz wire. It models a number of wire alloys and form dielectrics, dielectric ribs or ridges, coil leads, and polygonal coil shapes. The program can automatically maximize coil Q while keeping inductance constant.
To validate accuracy, the documentation compares calculated values with hundreds of inductance and Q measurements made with an HP 4342A Q meter on dozens of coils of widely varying size and shape. For the coils from my own junk box, average error magnitude is 2% for inductance and 5% for Q.
The program runs in Windows and is free.
Brian
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Re: Inductor Q Measurement
Correct. Dave - W?LEV On Tue, Oct 12, 2021 at 7:00 PM Andrew Kurtz via groups.io <adkurtz= [email protected]> wrote: Sounds intriguing! I routinely find self-resonance and calculate
parasitic C from that. I see that I could take that R and calculate Q, but
the Q would be for a frequency far from a practical one, and thus that Q
would not relate to my coil when in use¡ Agree?
Andy
On Oct 12, 2021, at 11:15 AM, Gary Rondeau <grondeau@...> wrote:
Quick and dirty method... Just measure the self resonance of your coil. If you calibrate the nVNA to your fixture and then just run the S11
sweep up high enough on the coil, you will undoubtedly see a resonant
peak. At low frequency you can determine the inductor, L. (the nVNA saver
software will do this for you) The frequency of the peak tells you the self
resonant parasitic capacitance, C. From the magnitude of the the
resistance, R, measured at self resonance, and the calculated self resonant
impedance, Z=sqrt(L/C), then Q will be R/Z.
This procedure also shows you explicitly when parasitic capacitance becomes important -- which it often does!
-- *Dave - W?LEV* *Just Let Darwin Work*
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Re: Inductor Q Measurement
Sounds intriguing! I routinely find self-resonance and calculate parasitic C from that. I see that I could take that R and calculate Q, but the Q would be for a frequency far from a practical one, and thus that Q would not relate to my coil when in use¡ Agree?
Andy
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On Oct 12, 2021, at 11:15 AM, Gary Rondeau <grondeau@...> wrote:
Quick and dirty method... Just measure the self resonance of your coil. If you calibrate the nVNA to your fixture and then just run the S11 sweep up high enough on the coil, you will undoubtedly see a resonant peak. At low frequency you can determine the inductor, L. (the nVNA saver software will do this for you) The frequency of the peak tells you the self resonant parasitic capacitance, C. From the magnitude of the the resistance, R, measured at self resonance, and the calculated self resonant impedance, Z=sqrt(L/C), then Q will be R/Z.
This procedure also shows you explicitly when parasitic capacitance becomes important -- which it often does!
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Re: Inductor Q Measurement
You're fine with alligator clips at HF frequencies - especially the BC band for the crystal radio. Don't sweat it !! If your crystal radio operated much above 100 MHz, yes, the alligator or crocodile clips would be an issue. And if the Rs is not measured at the operating frequency it does not reflect skin effect. In your case, the top of the BC band is 1.7 MHz. Rs consists of both the purely resistive component of the conductors and, in addition, the increase in effective Rs due to skin effect which is a function of frequency. Bottom line: you're fine at BC band frequencies. Dave - W?LEV On Tue, Oct 12, 2021 at 6:20 PM Andrew Kurtz via groups.io <adkurtz= [email protected]> wrote: Yes, R cannot be < 0, but my interpretation is simply that the -2 is error
in some small number like, say 1 or 2 ohms. I will admit that many of you
experts talk about how you attach your DUT very carefully, solder it,
sometimes have to throw it away when done testing, and all this sounds
bizarre to a non-EE who is simply playing with crystal radio. My nanoVNA
attaches to my DUT via 2 alligator clips which are on little connectors
(BNC maybe?) which screw into the VNA. I recognize that I am accepting
error, even though I do my calibration at the same alligator clips, but
except for R, I am convinced that the error I am accepting is negligible
when my interest is 0.5 to 25 MHz, picking up AM signals. (I welcome any
insights if you think I am wrong.)
Andy
On Oct 12, 2021, at 10:05 AM, Jim Lux <jim@...> wrote:
On 10/12/21 6:05 AM, DougVL wrote:
On Mon, Oct 11, 2021 at 09:21 AM, Andrew Kurtz wrote:
R is quite low and may vary between -2 and 5 ohms.
That "-2" suggests to me that you're not actually reading 'Resistance' there. Resistance should be positive, but Reactance can be in negative
ohms.
Depending on how the conversion from reflection or transmission
coefficient (gamma) to R+jX is done, a coefficient with magnitude >1 will
result in negative R.
If you're measuring low impedances (so |gamma| is close to 1) then noise
or roundoff errors in a measurement can wind up with gamma>1
-- *Dave - W?LEV* *Just Let Darwin Work*
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Re: Inductor Q Measurement
That program sounds wonderful! The only problem is that my computer is a Mac, and I bet it won¡¯t handle it. I know someone might say ¡°O just get Python and change XYZ while uploading ABC from Github¡.¡± and I might as well be listening to Greek. I have not yet succeeded in getting my nanoVNA data other than by hand-typing it into Excel because I can¡¯t get nanoVNAsaver to run. Any way to get your Coil program working on a Mac?
Andy
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Show quoted text
On Oct 11, 2021, at 7:00 PM, Brian Beezley <k6sti@...> wrote:
Andrew, my coil program might interest you. It calculates inductance and Q for solenoids made of solid or Litz wire. It models a number of wire alloys and form dielectrics, dielectric ribs or ridges, coil leads, and polygonal coil shapes. The program can automatically maximize coil Q while keeping inductance constant.
To validate accuracy, the documentation compares calculated values with hundreds of inductance and Q measurements made with an HP 4342A Q meter on dozens of coils of widely varying size and shape. For the coils from my own junk box, average error magnitude is 2% for inductance and 5% for Q.
The program runs in Windows and is free.
Brian
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Re: suitable software to control full funcion NanoVNA
There are several programs - please browse the forum Wiki for information.
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On Tuesday, October 12, 2021, 02:17:10 p.m. EDT, Francesco <realfran@...> wrote:
Hello, there is one suitable PC software to control the full function of NanoVNA for windows?
73/Francesco
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Re: Inductor Q Measurement
Yes, that article and Alan¡¯s explanation were very helpful. I realize that I had a misunderstanding of where a ¡°parallel¡± resistor would be, and how a resonant circuit can be tested via shunt reflection versus transmission shunt through versus transmission series through. I had even gotten the impression that nanoVNAs really work best in reflection on CH0 only, not so much transmission from CH0 to CH1 even though that is available. For the record, I have been able to calculate that X / Rs = Rp / X exactly!
Andy
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On Oct 11, 2021, at 6:51 PM, Kerry <planningpower@...> wrote:
A useful article;
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Re: Inductor Q Measurement
On 10/12/21 11:20 AM, Andrew Kurtz via groups.io wrote: Yes, R cannot be < 0, but my interpretation is simply that the -2 is error in some small number like, say 1 or 2 ohms. exactly. Let's say the gamma measurement is +/- 5%.? If you convert gamma = 1.05 (angle = 0) you get -2050 ohms and Mag S11 = 0.4238 dB If you convert gamma=0.95, you get 1950 ohms and mag S11 = -.4455 dB Here's some examples (excel attached if you want to fool with it yourself).? For any coil with a reasonably high Q (>100), your DC resistance might be pretty low, especially if the reactance is something like 100 ohms.? In such a case, gamma is VERY close to 1, so small uncertainty in the measurement will result in negative resistance Z = Z0*(1+gamma)/(1-gamma) Z0 50 gamma mag gamma ang complex Z Zreal Zimag 0.5 0 0.5 150 150.0 0.0 0.5 90 3.06287113727155E-17+0.5i 30+40i 30.0 40.0 0.95 0 0.95 1950 1950.0 0.0 0.99 0 0.99 9950 9950.0 0.0 1 0 1 #NUM! #NUM! #NUM! 1.01 0 1.01 -10050 -10050.0 0.0 1.05 0 1.05 -2050 -2050.0 0.0 0.95 90 5.81945516081595E-17+0.95i 2.56241787122207+49.9342969776609i 2.6 49.9 0.99 90 6.06448485179767E-17+0.99i 0.50249987374375+49.9974748750063i 0.5 50.0 1 90 6.1257422745431E-17+i 50i 0.0 50.0 1.01 90 6.18699969728853E-17+1.01i -0.49750012375625+49.9975248750062i -0.5 50.0 1.05 90 6.43202938827026E-17+1.05i -2.43757431629014+49.9405469678954i -2.4 49.9 gamma = (Z-Z0)/(Z+Z0) R X Z Q gamma gamma mag gamma angle 0 500 500i #DIV/0! 0.98019801980198+0.198019801980198i 1.000 11.42 1 500 1+500i 500 0.97981005617555+0.197940625729906i 1.000 11.42 2 500 2+500i 250 0.979422565531214+0.197859946815246i 0.999 11.42 -1 500 -1+500i -500 0.980586447755754+0.198097471880064i 1.000 11.42 -2 500 -2+500i -250 0.980975331346312+0.198173631809246i 1.001 11.42 0 100 100i #DIV/0! 0.6+0.8i 1.000 53.13 1 100 1+100i 100 0.595270216649472+0.793587810491231i 0.992 53.13 2 100 2+100i 50 0.590680100755667+0.787153652392947i 0.984 53.12 -1 100 -1+100i -100 0.604870574953633+0.80638658172728i 1.008 53.13 -2 100 -2+100i -50 0.609882964889467+0.812743823146944i 1.016 53.12 I will admit that many of you experts talk about how you attach your DUT very carefully, solder it, sometimes have to throw it away when done testing, and all this sounds bizarre to a non-EE who is simply playing with crystal radio. My nanoVNA attaches to my DUT via 2 alligator clips which are on little connectors (BNC maybe?) which screw into the VNA. I recognize that I am accepting error, even though I do my calibration at the same alligator clips, but except for R, I am convinced that the error I am accepting is negligible when my interest is 0.5 to 25 MHz, picking up AM signals. (I welcome any insights if you think I am wrong.)
Andy
On Oct 12, 2021, at 10:05 AM, Jim Lux <jim@...> wrote:
On 10/12/21 6:05 AM, DougVL wrote:
On Mon, Oct 11, 2021 at 09:21 AM, Andrew Kurtz wrote:
R is quite low and may vary between -2 and 5 ohms.
That "-2" suggests to me that you're not actually reading 'Resistance' there. Resistance should be positive, but Reactance can be in negative ohms. Depending on how the conversion from reflection or transmission coefficient (gamma) to R+jX is done, a coefficient with magnitude >1 will result in negative R.
If you're measuring low impedances (so |gamma| is close to 1) then noise or roundoff errors in a measurement can wind up with gamma>1
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Re: Inductor Q Measurement
Yes, R cannot be < 0, but my interpretation is simply that the -2 is error in some small number like, say 1 or 2 ohms. I will admit that many of you experts talk about how you attach your DUT very carefully, solder it, sometimes have to throw it away when done testing, and all this sounds bizarre to a non-EE who is simply playing with crystal radio. My nanoVNA attaches to my DUT via 2 alligator clips which are on little connectors (BNC maybe?) which screw into the VNA. I recognize that I am accepting error, even though I do my calibration at the same alligator clips, but except for R, I am convinced that the error I am accepting is negligible when my interest is 0.5 to 25 MHz, picking up AM signals. (I welcome any insights if you think I am wrong.)
Andy
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On Oct 12, 2021, at 10:05 AM, Jim Lux <jim@...> wrote:
On 10/12/21 6:05 AM, DougVL wrote:
On Mon, Oct 11, 2021 at 09:21 AM, Andrew Kurtz wrote:
R is quite low and may vary between -2 and 5 ohms.
That "-2" suggests to me that you're not actually reading 'Resistance' there. Resistance should be positive, but Reactance can be in negative ohms. Depending on how the conversion from reflection or transmission coefficient (gamma) to R+jX is done, a coefficient with magnitude >1 will result in negative R.
If you're measuring low impedances (so |gamma| is close to 1) then noise or roundoff errors in a measurement can wind up with gamma>1
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Francesco
Peter
