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On Sat, Mar 20, 2021 at 05:40 PM, <nc0gnit0@...> wrote:

Thanks - this 1/11 app looks promising !
What driver is required for Windows 7/8/10 ?
I cannot connect so I know I do not have the correct driver.

NanoVNA app only works with the latest firmware from DiSlord or Hugen. The reason is that it uses a different data transfer protocol.

Roger

What is wrong with the device?

Thanks - this 1/11 app looks promising !

What driver is required for Windows 7/8/10 ?

I cannot connect so I know I do not have the correct driver.

Hi Manfred,
I don't have much to offer because you don't have one of the ancient Q meters but with these old instruments you could determine the Q of a cap.
I also have a GR-821 A Twin T Impedance Measuring Circuit that can determine the Q from 0.5 to 30 MHz. It measures the capacitance and the conductance.
Also, I have the old GR1608A that can directly measure the D factor at 1 kHz and with a simple correction factor it can measure the D factor at other frequencies from 20 Hz to 20 kHz.
73

this is insteresting

On 3/19/21 5:00 PM, Roger Need via groups.io wrote:

On Fri, Mar 19, 2021 at 12:06 PM, Jim Lux wrote:

Is this the python application you're referring to? I've been using pieces of
it and I've got the architecture pretty well figured out- my version is 13
August 2020 (V0.3.7 in the changelog.md). If someone points me to the "most
recent" repo, I can see about picking up maintenance.

Yes... Larry Rothman gave you the link to it. There are quite a few outstanding issues.


Roger

I see that zarath is making changes.. Maybe some of them are fixing the problems?

the "master" appears to be pretty similar to what I have from August.

Well, that's difficult to say, having no "standard" crystal. With my limited recent experience, I think it compares well with other methods. I'm accustomed to seeing differences of 2% or sometimes more between different methods and different people measuring the same crystals at their own workbenches.

PHSNA is definitely not absolute. But when evaluating its performance I saw that its results fell in alongside those from other methods.

In a presentation on crystal measurements and filter design, I compared several methods and/or instruments and plotted their results for four crystals which were tried on different equipment. See page 21 of this PDF:



For the "actual" value of the crystals, I took the average of two measurements I thought were most trustworthy. On in which and employee at International Crystals used their commercial equipment. I think s.s. might mean Squires-Sanders. The other was measurements taken by Bill Carver using a VNA. The other measurements I did myself using various methods. PHSNA isn't listed since this presentation predates PHSNA.

Mr. Hayward said "... where Lm is the motional inductance and the reactance slope is approximated by ΔX/ΔF". In his simulation, the simulated 100 mH was calculated to be 99.93 mH using the method. If real life measurements agreed as closely as that approximation, we're in good shape.


73-

Nick, WA5BDU

Jeff,

There is a technique that has been described by Darko Kajfez (EE Professor
Emeritus at the University of Mississippi) that actually gives good results
for Hi-Q inductors on a VNA.

I just had a quick look at those papers. I didn't read them fully, and I didn't work through the maths, since obviously this isn't what I'm looking for. Unless I missed something, he just describes a method for measuring inductor Q by resonating it with a good capacitor and measuring the Q of the resulting resonant circuit.

What I'm looking for is a method to measure the Q of capacitors, NOT that of inductors. Capacitors tend to have a Q roughly an order of magnitude higher than that of inductors, so one cannot measure the Q of a capacitor by resonating it with an inductor.

Even comparison to a capacitor of known high Q, resonated by a high quality inductor, would be rather imprecise, due to the fact that the resonant circuit's Q will always remain dominated by the inductor.

So, if anyone knows how to measure the Q of a capacitor, over a given frequency range (not just at a single frequency), I would love to learn!

Dear all,

I've been using the RF Demo Kit for calibrating my VNA when measuring devices behind a U.FL connector (I'm only using fields 13, 14, 15 - short, open, load). I found out that I get better results if I take into the account that the "open" standard has some stray capacitance. Otherwise I commonly get S11 logmag as >0 dB when measuring passive circuits. I estimated the stray capacitance as 0.6 pF. Details of the estimation method are in this blog post:



I just though this might be interesting, since there was a discussion here about accuracy of the circuits on the demo kit. I'm mostly using this with my own home-made VNA. It should be possible to repeat the same capacitance estimation steps with a NanoVNA - you only need the electrical delay feature. However as far as I know, NanoVNA's firmware doesn't support specifying stray capacitances/inductances for the calibration standards.

Best regards
Toma?

Yes I was wondering how accurate is his method as he said it's only an approximation. Is the PHSNA value an absolute measurement?

On Fri, Mar 19, 2021 at 12:06 PM, Jim Lux wrote:

Is this the python application you're referring to? I've been using pieces of
it and I've got the architecture pretty well figured out- my version is 13
August 2020 (V0.3.7 in the changelog.md). If someone points me to the "most
recent" repo, I can see about picking up maintenance.

Yes... Larry Rothman gave you the link to it. There are quite a few outstanding issues.


Roger

Hello builders -

I was reading some of W7ZOI’s old website entries and found one on
determining a crystal’s motional parameters by measuring the rate of change
of X (reactance) at the resonant frequency. I’ve no doubt seen this before
but how to make that measurement wasn’t readily apparent before the
nanoVNA. I’d already done a crystal characterization using the 3 dB
bandwidth technique and had good results.

The formula used with this method is

Lm = delta_X/(delta_f * 4 * PI)

I pulled out an 8 MHz EVS HC-49/W crystal which I’d previously measured
with my PHSNA system. I had done a 12 segment calibration close to 8 MHz
for my previous measurement so I applied it using nanaVNA Saver. I
connected the crystal to CH0 using a female SMA connector soldered to a
piece of PC board to which I soldered the crystal. No impedance
transformation jig required here.

I did a sweep of a few hundred Hz centered on the series resonant
frequency. The plot of X in the “S11 R + jX” plot was pretty straight.
First I picked values 100 Hz apart yielding X values of –j1.69 and +j26 for
a delta_X of 27.69 ohms. The formula gave an L value of 22 mH. This
compared pretty well with my previous PSHNA measurement of 21.54 mH. That’s
within 2%

If you know Lm, you also know Cm:

Cm = 1(4*f^2*PI^2*L) where f is the resonant frequency.

The nanoVNA will give the series resistance at resonance directly. In my
case it was 8.84 ohms versus 8.7 ohms with the PHSNA.

I thought I’d try another look with a smaller delta_f. Taking readings only
10 Hz apart I came up with Lm = 21.7 mH. That’s closer to my PHSNA value
but I won’t say with certainty that the smaller delta_f made it better. I
do think a small delta_f close to the resonant frequency is probably best.

Next I wondered if the large number of calibration points close to the
crystal frequency is necessary. So I tried a 4.9152 MHz crystal I’d
previously measured and this time used a 1.5 MHz to 10.5 MHz calibration
data set done in four segments.

I calculated an Lm value of 63.42 mH compared with 63.13 mH done previously
with PHSNA. Pretty close at 0.46%. My Rs value wasn’t as close this time:
12.26 ohms versus 10.7 ohms with PHSNA. I’m not sure of the reason for the
variation. The Rs measurement method in PHSNA is a little complicated.

So there’s another method of measuring crystal parameters with the nanoVNA.

73,

Nick, WA5BDU

I think it's this:

"Yes I have had this same problem sometimes with NanoVNA Saver. It is unpredictable when the program will crash after a calibration and the windows will all close. It probably has to do with a calculation going out of bounds.

The original developer Rune had to step back from development due to health issues and the fellow that took over did quite a few changes but seems to have stopped any further work on the program."

Is this the python application you're referring to? I've been using pieces of it and I've got the architecture pretty well figured out- my version is 13 August 2020 (V0.3.7 in the changelog.md). If someone points me to the "most recent" repo, I can see about picking up maintenance.

Folks can always try out OneOfEleven's NanoVNA-APP . It also has a calibration function built-in.
It's in the releases area:?
There is no user manual but almost all graphics menus are through the right-click on your mouse.
It can also be used to flash firmware into your Nano

Thanks. I'll probably have to do a firmware upgrade to start playing with the latest third party tools. There seems to be a lot of choice for nanoVNA firmware and I'm not sure who provides the most robust firmware upgrade for my nanoVNA-H (2.8") at the moment. There are a few niggly bugs with my existing (old!) firmware.

On Thu, Mar 18, 2021 at 06:16 PM, <nc0gnit0@...> wrote:

I can calibrate my VNA manually, but I would prefer to calibrate using Nano
Saver with my PC since the manual version does not include Isolation test.

When I have completed short, open, load, isolation and thru, I click on
"APPLY" the program disappears from my Windows 10 PC.

Yes I have had this same problem sometimes with NanoVNA Saver. It is unpredictable when the program will crash after a calibration and the windows will all close. It probably has to do with a calculation going out of bounds.

The original developer Rune had to step back from development due to health issues and the fellow that took over did quite a few changes but seems to have stopped any further work on the program.

Roger

On Fri, Mar 19, 2021 at 05:45 AM, jmr wrote:

Here's a nanoVNA-H measurement of a Micrometals T50-6 powdered iron toroid
with 22 turns spread over about 270degrees of the toroid. The inductance
should be about 2.2uH and you can see the nanoVNA does a good job again. It
also has a reasonable stab at measuring the series resistance although the
data gets a bit noisy above 20MHz. I keep meaning to add averaging to my PC
tools. The nanoVNA is much more powerful than a typical low frequency LCR
meter because it can measure the inductance across a wide frequency range. The
inductance at the design frequency can usually be measured quite accurately.
It often manages to give a reasonable estimate of Q for powdered iron toroids
like this.

If you make the measurement using the NanoVNA app by OneOfEleven you will see that it has adjustable sweep averaging and data smoothing built-in. You can also import the s1p file for post processing. The graphing capability is quite good with many scaling options. Once I starting using this tool I stopped using NanoVNA Saver. The calibration routine is very nice as well.

Roger

Kev,

You can set it to back to zero from the menu item "electrical delay". You should have received a menu map with your -H4. If you lost it try this one.... /g/nanovna-users/files/NanoVNA-H4%20Menu%20Structure%20Map_2.pdf

You will probably find the Absolute beginners Guide (files section of this group) and the wiki for this group will answer most of your questions.

Roger

"Joeqsmith" is a very knowledgeable fellow when it comes to VNAs in general and the NanoVNA in particular. He has quite a few interesting videos on his YouTube channel. His latest one is all about protecting the NanoVNA from damage from ESD and when connecting it to antennas that may have a charge on them.

He discusses gas discharge tubes and transient voltage suppressors. At the end he uses a piezo BBQ starter on the input of a NanoVNA fitted with his protection circuit.

This video is quite long but well worth watching.



Roger