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You can all thank AJ3DI Jim, my benefactor, for introducing me to this gadget called Nano NVA.
It forced me to take another look at many concepts: resistance, reactance, impedance, PHASE, and of course, how useful (or bewildering) a Smith Chart can be.

Of course, at my PhilMont Mobile Radio club presentation (over an hour) it was recorded, and although Jim missed the first couple of (very essential) slides, the talk can be viewed by anyone.

Each time I give this talk, I learn more about what the hurdles are. I find, as a teacher, we can "say the words and answer multiple choice exams without any REAL understanding".

My goal was to slow down enough for folks to see "resonance" and "phase" like a kid swinging on a swing and grampy (our feed line) giving the essential push to keep the current (kid) swinging.
A crude analogy, of course, for resonance in an antenna.

So have fun watching the video if you choose to spend an hour that way.
I usually prepare for many more slides than I actually show (rookie error).

Feedback is apprediated: K3euibarry at gmial.com

73
Barry

Sorry Richard, its two points not two cogs in the NanoVNA-App software to upgrade the firmware. Hopefully there's a picture attached.

BTW James THANKS for the step by step...

this will help others a lot... the shorting of VDD and BOOTI was confusing since most procedures and comments talked of a JUMPER... there was none here...

James, thanks for the input, as I stated below l was able to get the device in DFU mode after shortening the pins (not a jumper on this version)

found the device...

was able to load it

but as I stated below, the unit boots up after power-up reset to a blank white screen

the unit cannot be reached via the VNA-QT application

note please I have another unit that CAN be reached with VNA-QT

Larry also very good point about trying via the Win10 app did not work will try terratem to see and let you know

Larry Battery issuesw is a valid point, I had tried that alrady sorry to say! :( Next!

Here is a list that I've made with the steps that I took to get the device to be seen by my compute Richard.

Hopefully others can expand on this if I've missed any steps out.

Hope it helps.

Connect your NanoVNA to the computer via USB.

Put the NanoVNA into DFU mode (Short out the Boot0 and VDD)

NanoVNA screeb should be white.

Open up device manager on the computer.

Look down the list of items and look for Universal serial Bus Devices.

Hopefully you will see STM Device in bootloader mode.

Right click the device.

Select update driver.

Select browse my computer for drivers.

Select Let me pick from a list of available drivers on my computer.

Make sure show list of compatible drivers is ticked.

You should be able to see an option listed as STM Device in DFU mode.

Select this and install this driver.

The STM Device should then show up in the Universal serial bus controllers as STM Device in DFU mode under Universal serial bus controllers.

Run NanoVNA-App software and use this software to upgrade the firmware.

There are two cogs at the top of the NnanoVNA-App software to run the upgrade process.

Running these will show another window with available firmware for your NanoVNA.

I selected the first option of firmware to choose from and went with that.

Regards, James.

Just to add to this Richard, i could only see STM Device in bootloader in Universal serial bus devices within device manager before doing a right click and update driver which let me select the driver for STM DFU mode.

After this it disappears from Universal serial bus devices and should only then appear in Universal serial bus controllers.

Hope this helps, if not post again as to where your up to with it.

Regards, James.

Hello Richard.

It seems like you're having similar problems to me yesterday.

It was diving me mad too.

The advice about reading the Absolute Beginners Guide to NanoVNA v1_5.pdf helped me out but it was a little bit convoluted.

For me, i went into device manager and could see that the STM32 was listed in Universal serial bus "devices" yet the device wasn't showing in the Universal serial bus controller as it should.

Even though my nanovna WAS in DFU mode as it was just a white screen.

I then right clicked on the device in Universal serial bus devices and selected update driver.
I then searched Browse my computer for drivers which gave the option to select Let me pick from a list of available drivers on my computer.

Here i found the driver for STM Device in DFU Mode which i selected and installed.

This then made available the STM device within the Universal serial bus controllers.

After this i was able to update the software with the NanoVNA-App as I could now connect to the software to run the firmware update.

Hopefully I've attached a screen shot of my driver upgrade and how it should eventually look after you update the driver.

I hope this helps and not add to your frustrations as I was ready to literally put a brick through my VNA yesterday morning HiHi.

Regards, James.

Richard,

maybe these instructions might help you?
Absolute Beginner's Guide to The NanoVNA ,
Chapter "NanoVNA FIRMWARE UPGRADE".

It is in the files section of this group.

73
Martin 9A2JK

Hi Richard,
Okay, I see you've gotten to the point where you have a white screen (if all is true, it's because your device is in DFU mode).
Please turn it on if the screen is still white and I assume that because the display is not damaged, the device is in DFU mode.
In the earlier versions, the white state on the 2.8 "screens indicates the DFU mode.
This changes in later versions so that you can switch from the menu to the DFU state.

Important: the device cannot be used in DFU mode only firmware upload or download!
When connected to a computer in DFU mode, you should see "STM Device in DFU mode" in the USB controllers in Device Manager.
If you see this, your computer will see the device.
You can only change this if you upload the .dfu file correctly, which is a prerequisite for the tool to work.
If you make a mistake here and there is no hardware error, DFU mode will remain and the device cannot be used to measure.

If it is not visible, you need to short-circuit BOOT0 and VDD in the corner next to the battery on the device's motherboard when the power is off.
You insert a small wire into the hole galvanized hole, then turn on the device. Your device is now in DFU mode. Nano VNA_ (hw-3.4) .jpg
You can only change this if you upload the .dfu file correctly, which is a prerequisite for the tool to work.
If you make a mistake here and there is no hardware error, DFU mode will remain and the device cannot be used.

I attach an image The "Choose ..." and "Upgrade" buttons at the bottom right of the DfuSe Demo program must be used to upload.
(the one on the left is used to read the .dfu in the device). DfuSe_Demo_upgrade.png
Before I wrote this message, I also uploaded Hugen's 1.0.45 firmware to my 2.8 "device.
In this version, the captions are larger than the ones made by the original author DiSlord - I think it will be more readable for you.
Hugen_v1.0.45_screenshot.png

Once the firmware upload is successful, the power must be disconnected and remove BOOT0-VDD short-circuit, then turned on.
You must then log in correctly.

73, Gyula HA3HZ
--
*** If you are not part of the solution, then you are the problem. ( ) ***

Thank you so much for this tutorial! It is so good!!!

Terry NQ4Y

Ditto. Would love to hear the presentation accompanying the slides.

Jim
KQ9I

Very good Barry! Please let us know when you finally decide to release a YouTube recording of you narrating your slide presentation. I will be first in line to watch it!

Regards,
Gregg

--
VE6WGM

One of the pitfalls of making component measurements is using the wrong impedance measurement technique.

In this post I am using a NanoVNA-H4 and measuring a 1K and a 3K resistor to see how accurate the resistance can be calculated by connecting it to CH0 with a SMA test jig (shown in previous posts) and doing a S11 measurement. The NanoVNA hardware measures the reflection coefficient Gamma (Γ) and firmware on the device calculates impedance by the following equation Z = Zo * ((1 + Γ) / (1 - Γ)). Zo is 50 ohms and Z and Γ are complex numbers. Z calculated using this method is in the form R +/- jX which is known as a "serial impedance" representation and can be plotted on the NanoVNA device by selecting the appropriate traces. A plot of the 1K SMD 1206 resistor using this standard method is shown below. Actual DC resistance on a DE-5000 LCR meter was 997 ohms. Note how the calculated value is very close to 997 ohms at 10 kilohertz but quickly drops to 950 ohms at 250 MHz. At first glance it seems that the NanoVNA cannot do a good job of measuring this component at higher frequencies and some users might put this down to being so far away from the 50 ohm system impedance of the NanoVNA hardware.

However a real world resistor is not a pure resistance but has inductance in the leads and a stray capacitance in parallel with the resistance. This is shown in the simplified model below. In the case of a small SMD resistor this lead inductance is very small and the capacitance across the resistor is the dominate reactance. The first plot was a "series impedance" measurement of the 997 resistor which is a standard way of plotting impedance but it does not represent the actual physical component. An alternate form is the "parallel impedance" which is R // +/-jX and unfortunately is not available for plotting on the NanoVNA itself. Some PC packages like NanoVNASharp MODv3 and NanoVNA app by OneOfEleven do have this calculation capability and it is very useful. The parallel impedance plot below takes into account the parallel capacitance across the resistor and we can see the resistance is fairly consistent across the frequency range and deviates by a maximum of 10 ohms from the 997 ohms at DC. The next plot shows the capacitive reactance and if we calculate it by C= 1(2*pi*freq*X) it varies from 0.14 to 0.15 pF which is a very small.

The last test measured a SMD 1206 3K resistor on the same SMA test jig. This part has a DC resistance of 3003 ohms. Serial and parallel impedance plots are below. In a similar fashion the serial impedance method results in a poor estimate across the frequency range but the parallel method is much better and is off by up to 100 ohms maximum or 3.5% which is fairly reasonable.

I hope this post provides some insight into the measurement capability of the NanoVNA-H4 at higher impedances.

Roger

Richard, verify you can access the unit via the console through a terminal app like putty or teraterm. If you can access that way, you have a display issue.?
Some forum members, including myself, have had to resolver the display ribbon to the PCB.?


On Wed., 24 Feb. 2021 at 3:56 p.m., VE2DX<ve2dx@...> wrote: OK, was finaly able to get the NanoVNA-H in DFU mode and was able to find it in DfuSeDemo...

loaded the proper firmware DFU file and loaded it correctly as per the procedure...

the unit is still dead!...

While in DFU mode the Blue LED stopped flashing and did comeup in win10 as STM32 Bootloader like it should be...

the DfuSeDemo found the unit, I was able to load the proper firmware even did a VERIFY and confirmed it was loaded.

removed the jumper

rebooted the NanoVNA-H, blue led started flashing again and... wait for it... NOTHING

Just a white screen!

looks to me like the unit is not having firmware issues...? instead I think this is a HARDWARE display issue???

comments or suggestions please

73

Richard VE2DX

Unsolved the battery and see if it runs when connected by USB. Sometimes, a dead liion battery will prevent the inverter from starting up.?


On Wed., 24 Feb. 2021 at 4:47 p.m., Charlie N2MHS via groups.io<ucfargis1@...> wrote: Not to be offensive but have verified 3 volt and 5 volt power? LEDs lit>

/almost/ all of it.....



Enjoy!

--
jim fisher
Jedijf
AJ3DI
www.aj3di.com
HamshackHotline ext: 14423
"Do, or do not. There is no 'try.'"
-- Jedi Master Yoda

Thanks, Barry, you did a good job on this. I was only wishing you had narrated or provided slides with your explanations as well, though.
I agree with Jim Lux, your PowerPoint should be on YouTube, so others can learn from you.

73
W7BPG

On 2/23/21 5:38 PM, Michael wrote:

Now let's go off the deep end -

how do you characterize ferrites and powder iron (rod and toroid) for useable frequency as inductors/choke, transformers, and wide band transformers?

Mike
N9XYP

a) You wind a few turns on a core and measure the R and X, then back that out to u' and u'' vs frequency.

b) Or you use the manufacturer's data sheets with the same information.

One could probably come up with a procedure to use a NanoVNA and a few turns to "identify" core materials, by matching measurements (a) with data sheets (b).


The real value is when you actually build that choke, transformer, or other widget. The NanoVNA helps you figure out if your performance matches the expectations, because there's always parasitic C issues, R loss, etc.