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What files should I use?
Only DMR-CLEAR_MEMORY_DFU.dfu ?
Where I find the flash-program?

I would like to go around my NanoVNA 2.8"TFT with the Gecko-logo, color whide.
Info Hardware:
Kernel: 4.0.0
Compiler: GCC 5,4,1 20160919
Architecture: ARMv6-M
Core Variant: Cortex-M0
Port Info: Preemption thorough NMI
Platform: STM32FxB Entry Level Medium Density devices
Board: NanoVNA
Build time: May 5 2019 - 80:35:00

Thanks
Rob

Jim,
Larry pulled his original PDF document in favor of this link, /g/nanovna-users/wiki/shellcommands .

Herb

What files should I use?
Only DMR-CLEAR_MEMORY_DFU.dfu ?
Where I find the flash-program?

I would like to go around my NanoVNA 2.8"TFT with the Gecko-logo, color whide.
Info Hardware:
Kernel: 4.0.0
Compiler: GCC 5,4,1 20160919
Architecture: ARMv6-M
Core Variant: Cortex-M0
Port Info: Preemption thorough NMI
Platform: STM32FxB Entry Level Medium Density devices
Board: NanoVNA
Build time: May 5 2019 - 80:35:00

Thanks
Rob

On Wed, Sep 25, 2019 at 12:17 PM, Larry Rothman wrote:

Markers: outputs: marker#, index#, frequency. What is the 'index' number

Index is the number of the point [0-100]

Capture: this is a new command. What does it do? If you run it in the console,

Dumps the screen content so you can make a "screenshot"

Sample: samples gamma, ampl or ref - how is it used?

sampe [gamma|ref|ampl]
select the data to be measured:
gamma: amplitude / reference signal, this is what you want, do not use the others
ref: measure the absolute strength of the reference signal
ampl: measure the absolute strength of the bridge/CH1 signal

Time: is still there and increments the counter - but how can it be set to

Can not be set, it is the Linux "time" command
Usefull only if you have a RTC in the system

DAC: does the dac variable control the DSP gain

No, it seems to set the output voltage of an analog output of the STM
The adc gain is automatic set depending the selected frequency

If you want to build a clone of the sdr-kits *Testboard*,
and have no experience with the *2.54 mm round Female Pin Header Socket*,
here a link to a cheap source:
$ 1.33 for 5 x 40 pin sockets


You can use those *pin sockets*
also as *pin headers*, and also as a *carrier for parts to measure*,
either by plugging in, or soldered.

So, they are very universal to use.

A good explanation for a 68 pF capacitor measurement with the nanoVNA:
/g/nanovna-users/message/3865

73, Rudi DL5FA

Thanks Brian,
It shows that you cannot arbitrarily use any sweep parameters, like what I did in my fist attempt (50K-300MHz).
I'll be making more measurements...
Paul

Thanks Larry, but I already mentioned in my post that I fully calibrated the VNA with the fixture attached.

What good does that do?
Mike WY6K


"... somewhere in the distance, there's a tower and a light, broadcastin' the resistance, through the rain and through the night..."

Larry, I can't find the Console Command pdf New name? Folder?
Thanks,
Jim, KA6TPR

maybe it is time to start using hash tags #component #measurement. first person to start a thread puts #hash #tag in the subject line

Here is some more stuff to contemplate.

I "modeled" so to speak the inductor under test, the DUT, as a perfect inductor. No SRF.

I added the measured fixture parasitic obtained from the "perfectly calibrated VNA". I cascaded these elements into the simulator and as expected, looking into the VNA port, port 1, we return a S11 and an equivalent parallel inductance of 1.3 uH. As measured our 1 uH inductor appears as a 1.3 uH inductor and reasonably constant at low frequencies as long as we stay well below the SRF... Huh! What SRF? I stated the SRF of the inductor was NOT present. Well, it is not, but the fixture has created its own! Namely the 10 pF fixture C shunts the 1 uH and there is a MEASUREMENT SRF introduced. Proper de-emdedding if you keep your wits together will permit you to get the proper answer right through and past the resonate point introduced by the FIXTURE! This example exemplifies how KEY fixture details are and if not considered, will render measurement error.

Alan

Take a look at this:



I've ordered a $18 SOL kit from ebay. I'll be adding comparisons to the Anritsu to the thread when they come in. I'll drag the 8753B to where I can power it up for that. So I'll have TDR to 20 GHz and VNA to 3 GHz.

The more I use my Tek 11801 the more I wish that there was a cheap sampling scope that would work with one of Leo Bodnar's pulsers. While the 20 GHz of an SD-24 or SD-26 would be very difficult to match, one might be able to get to 5-6 GHz with a clever design which was cheap to make using modern parts.

The great thing about the time domain is you can tell which part in a series of connectors is doing what.

Have Fun!
Reg

On Fri, 4 Oct 2019 at 00:49, sala nimi <sala.nimi@...> wrote:

I had some time and tested some terminators for fun. I thought that
commercial terminators are nearly perfect, but not mine. I have a N
terminator perhaps from Digikey, and It was worse than my very old self
made terminator from UKW berichte or VHF communication. Homemade terminator
was dot or comma in the Smith chart but commercial one had a clear arc.

But so much depends on what you use to perform the calibration with. To
take an extreme example

* 50 ohm system
* Load used for calibration has an impedance of 30 ohms
* DUT #1 is a resistor of 49 ohms
* DUT #2 a resistor of 31 ohms.

Although the 49 ohms resistor has a much better return loss in a 50 ohm
system than the 31 ohm resistor, the VNA would indicate the opposite
because it was calibrated with a load close to DUT #2.

It is very easy to fool yourself with VNA measurements.

Dave

--

Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

On Fri, Oct 4, 2019 at 02:49 AM, sala nimi wrote:

Homemade terminator was dot or comma in the Smith chart but commercial one had
a clear arc.

probably it just means that you calibrated your VNA with bad terminator. So, now it shows good terminators as bad, because they are not bad as one which is used for calibration :)

I had some time and tested some terminators for fun. I thought that commercial terminators are nearly perfect, but not mine. I have a N terminator perhaps from Digikey, and It was worse than my very old self made terminator from UKW berichte or VHF communication. Homemade terminator was dot or comma in the Smith chart but commercial one had a clear arc.

Thank you all for helpfull posts and links.

Do you have any gnuplot code which can import a Touchstone file and plot it on the Smith Chart?

Nope, I always reformat data before gnuplot so that it reads in
traditional columns.

Attached should be the gnuplot Smith Chart command files

Thanks for all the feedback.

First to clarify, the correction process is 2 -step for the BNC-alligator clip lash up. One is the removal of the shunt C of the OPEN clips and Two is the total series inductance of the clips and wire attached to the BNC-SMA adapter. Of course without mention, that BNC-SMA adapter adds its own parasitic but were lumping that into the alligator clip leads and wires parasitic.

Now, I just did the "Mickey-Mouse" cal process. That is to say, OSL cal with no regard to what this OSL is really. The open, the dangling alligator clips, the short, just short them together and the load, a 1/8 W carbon film resistor. As far as the VNA firmware algorithm is concerned, these are ideal elements. A measurement at 3 MHz revealed the inductance at 1.05 uH. Wow!

Well, before you go off with jubilation, we need to take a close look at the S11 reflection sweep for both cases. And I suppose I should take pictures and record. However, I will try to describe because it is quite simple but an eye opener. Although the MM-cal routine returned a reasonable value of the L at one frequency, the trajectory of the S11, reflection coefficient was totally off base. S11 and the corresponding Z showed a marked decrease in reactance as the frequency lowered and at frequency approaching 30 MHz the S11 value spiraled inward demonstrating a horrible reduction in Q. All of this is WRONG. The prior measurement after corrections provided a S11 and a subsequent Z vs frequency that made perfect sense. The Q and hence resistance component were high/low through out the measurement range as it should since we are well below SRF. The S11 hugged the unit circle as it should over the entire sweep. The MM cal routine would be hard pressed to permit us to investigate where SRF occurs.

I think it is key to recognize that the identification of the cal pieces EXACTLY is paramount in obtaining a corrected VNA measurement response for ALL frequencies involved. The same is required of the test fixture, it must be properly characterized at all frequencies of interest so the proper un-raveling of the DUT (so called de-embedding) from the measurement system is possible.

Alan

Thanks!

WB2UAQ,

Between the HP8721 directional coupler and HP 85032 calibration standard you've got some pretty expensive toys there. The NanoVNA must feel outclassed when used with them :)


Herb