.NanoVNA-H v3.5_L: white screen - how do I connect USB to fix?
I couldn't connect to the unit and somehow managed to wipe the processor.
I've tried resetting it to reconnect, but the only response I get is in
STM32Cube Programmer 'UR is set by HWrst' or something similar.
I tried shorting BOOT0 to VDD as noted, screen remains white, no connection.
Any suggestions would be appreciated!
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Re: Help with LPF Measurement
Things are beginning to look a bit more like a LPF with the "ground" connected! Other suggestions have been made which are right on. Keep us posted on your progress. Dave - W?LEV <> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Thu, Mar 13, 2025 at 4:27?AM Mitch NK3H via groups.io <mitch= [email protected]> wrote: Dave,
Thank you for your reply. Very much appreciated.
In order:
1) Done.
2) Yes, I measured all components with my LCR meter (DE 5000).
3) Correct. 50 ohms confirmed by others for this filter.
4) It's possible that some capacitors aren't right for this frequency
range. I'll look into that.
5) I posted the S21 imaged from the VNA, not the SAVER program. I'll work
on that next.
6) Signal generator does not sweep; that's a good idea and will try to
figure something out.
Thanks for your help. I'll spend most of tomorrow working on this. Best,
Mitch NK3H
-- *Dave - W?LEV* -- Dave - W?LEV
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Re: Help with LPF Measurement
You may be looking for the graphical version of the map, but I threw this into the AI Grok app on my iPhone and it listed them all out.
“ Menu Structure Map for the NanoVNA F V2.”
You may or may not know, but these AI apps are amazing and scary all wrapped together but I don’t use search engines any longer, too much hunting and pecking to find the answer where the AI app responds with all the information already consolidated. If you haven’t, I would recommend at least trying it out ..
Tom
73
"Reality is the moment in which we live,
all else is just a memory...
"Make the MOST of Reality”
? KTCNC ?
???????
"Kick the Dust Up"
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On Mar 13, 2025, at 08:59, CLIFTON HEAD via groups.io <aecret@...> wrote:
?Off subject, does anyone know where to get a Menu Structure Map for the NanoVNA F V2. My new one did not come with one. Thanks
________________________________
From: [email protected] <[email protected]> on behalf of John Gord via groups.io <johngord@...>
Sent: Thursday, March 13, 2025 1:54 AM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Help with LPF Measurement
Mitch,
Try making the ground connection to your filter very short, say 5mm or so. Also, try multiple ground wires. The currents to ground from all the capacitors in the filter flow through that ground connection, and if it has much inductance it will have a voltage drop that limits the rejection of the filter.
If you have the connectors available, a better connection method is to solder an SMA connector shell directly to your ground plane at the input and another directly to the ground plane at the filter output. Then connect the center pins of the connectors to the input and output and connect your cables.
If you just have some SMA pigtails (or can make a couple by cutting an SMA cable in half), you can connect the shield of a pigtail to your ground and the center wire to your input and similarly connect an output pigtail. Then connect those pigtail connectors to the NanoVNA.
As others have mentioned, making all the component leads as short as you can will help, but the grounding is probably the bigger factor at this point.
--John Gord
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Re: Help with LPF Measurement
There are a bunch of them online. Have you tried Googling? Compare the menu that you think is right to your NanoVNA because there are several variations. On Thu, Mar 13, 2025 at 8:59?AM CLIFTON HEAD via groups.io <aecret= [email protected]> wrote: Off subject, does anyone know where to get a Menu Structure Map for the
NanoVNA F V2. My new one did not come with one. Thanks
________________________________
From: [email protected] <[email protected]> on behalf of John
Gord via groups.io <johngord@...>
Sent: Thursday, March 13, 2025 1:54 AM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Help with LPF Measurement
Mitch,
Try making the ground connection to your filter very short, say 5mm or
so. Also, try multiple ground wires. The currents to ground from all the
capacitors in the filter flow through that ground connection, and if it has
much inductance it will have a voltage drop that limits the rejection of
the filter.
If you have the connectors available, a better connection method is to
solder an SMA connector shell directly to your ground plane at the input
and another directly to the ground plane at the filter output. Then
connect the center pins of the connectors to the input and output and
connect your cables.
If you just have some SMA pigtails (or can make a couple by cutting an SMA
cable in half), you can connect the shield of a pigtail to your ground and
the center wire to your input and similarly connect an output pigtail. Then
connect those pigtail connectors to the NanoVNA.
As others have mentioned, making all the component leads as short as you
can will help, but the grounding is probably the bigger factor at this
point.
--John Gord
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Re: Help with LPF Measurement
Off subject, does anyone know where to get a Menu Structure Map for the NanoVNA F V2. My new one did not come with one. Thanks ________________________________ From: [email protected] < [email protected]> on behalf of John Gord via groups.io <johngord@...> Sent: Thursday, March 13, 2025 1:54 AM To: [email protected] < [email protected]> Subject: Re: [nanovna-users] Help with LPF Measurement Mitch, Try making the ground connection to your filter very short, say 5mm or so. Also, try multiple ground wires. The currents to ground from all the capacitors in the filter flow through that ground connection, and if it has much inductance it will have a voltage drop that limits the rejection of the filter. If you have the connectors available, a better connection method is to solder an SMA connector shell directly to your ground plane at the input and another directly to the ground plane at the filter output. Then connect the center pins of the connectors to the input and output and connect your cables. If you just have some SMA pigtails (or can make a couple by cutting an SMA cable in half), you can connect the shield of a pigtail to your ground and the center wire to your input and similarly connect an output pigtail. Then connect those pigtail connectors to the NanoVNA. As others have mentioned, making all the component leads as short as you can will help, but the grounding is probably the bigger factor at this point. --John Gord
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Re: Help with LPF Measurement
Mitch,
Try making the ground connection to your filter very short, say 5mm or so. Also, try multiple ground wires. The currents to ground from all the capacitors in the filter flow through that ground connection, and if it has much inductance it will have a voltage drop that limits the rejection of the filter.
If you have the connectors available, a better connection method is to solder an SMA connector shell directly to your ground plane at the input and another directly to the ground plane at the filter output. Then connect the center pins of the connectors to the input and output and connect your cables.
If you just have some SMA pigtails (or can make a couple by cutting an SMA cable in half), you can connect the shield of a pigtail to your ground and the center wire to your input and similarly connect an output pigtail. Then connect those pigtail connectors to the NanoVNA.
As others have mentioned, making all the component leads as short as you can will help, but the grounding is probably the bigger factor at this point.
--John Gord
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Re: Help with LPF Measurement
Hi Jim,
Thank you for your suggestions. I will shorten leads and properly dress the components tomorrow. BTW I had no 270 caps but had 50s and 220s, hence the two caps in parallel.
You make a really good point in saying "the filter's not working right...." But what I don't understand is why the results from the sig generator/oscilloscope show the filter is filtering out high frequency harmonics pretty well, but the NanoVNA shows a very weird S21 result. It improved slightly when I added the ground leads between the board and the test rig (my bad for missing that!!), but it's not even close to what it should look like. Onwards....Thanks again. Best, Mitch NK3H
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Re: Help with LPF Measurement
Hi Jim,
Correct. I failed to connect them. I've repaired it and get a slight improvement. See pic just posted. Many thanks. Best, Mitch NK3H
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Re: Help with LPF Measurement
Alan, exactly right. I failed to do it. I just posted a pic of the result of adding leads from copper plane to the ground on the test rig. Thank you. 73, Mitch
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Re: Help with LPF Measurement
Correct. I failed to connect the ground plane to the connector grounds. I did just that with hookup wire soldered to the copper and connected to the ground of the test rig. A slight improvement. See pic. Many thanks for your help. 73, Mitch NK3H
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Re: Help with LPF Measurement
Alan,
I agree 100% on neatness, lead length, etc. This was supposed to be just a test project in anticipation of properly building the filter. From your comments and others', it appears I need to use appropriate methods from the very start in order to get results even in the ballpark. Advice appreciated. Thank you.
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Re: Help with LPF Measurement
Dave,
Thank you for your reply. Very much appreciated.
In order:
1) Done.
2) Yes, I measured all components with my LCR meter (DE 5000).
3) Correct. 50 ohms confirmed by others for this filter.
4) It's possible that some capacitors aren't right for this frequency range. I'll look into that.
5) I posted the S21 imaged from the VNA, not the SAVER program. I'll work on that next.
6) Signal generator does not sweep; that's a good idea and will try to figure something out.
Thanks for your help. I'll spend most of tomorrow working on this. Best, Mitch NK3H
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Re: Help with LPF Measurement
HI Dave,
Yes, it's there. The line goes across the very top of the screen, and the print shows "S21 LOGMAG 10 dB/-0.00 dB" in gray. Thanks for any help. Best, Mitch NK3H
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Re: Help with LPF Measurement
The only measurement noted at the top of the screen was S11. Was S21 also there? I didn't see it. Dave <> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Thu, Mar 13, 2025 at 12:39?AM Mitch NK3H via groups.io <mitch= [email protected]> wrote: Hi Dave,
S21 is the gray, I think (the not yellow one -- I'm color blind) print at
the top right of the screen in the last two images I posted. It's line is
flat at 0 dB across the frequency range with the test rig shorted and gives
the unusual curve I showed when the filter is used. Connecting the Ports 0
& 1 of the VNA together (without the test rig) also show 0 dB flat across
the frequency range. Is that what you meant?
Many thanks.
Mitch NK3H
-- *Dave - W?LEV* -- Dave - W?LEV
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Re: Help with LPF Measurement
Well, there's a long history of dead bug construction, and 3D sculptures. But it's the short leads thing that's biting you here. You can solder the capacitor lead to the copperclad really close and use the capacitor as a sort of standoff sticking up. Then solder the lead to the inductor to the other cap lead really close. Extra length in the inductor isn't so bad. And, be careful about the inductor windings being close to the copper clad - the capacitance from the winding to the copper clad is essentially shunting. (The overall effect would be to lower the cutoff frequency of the filter).
This is actually pretty useful for you - the NanoVNA said "the filter's not working right", and as you change things, you'll see it improve. Which is a whole lot better than a sort of handwavey - lead lengths are important. You have a chance to quantitatively see how long a lead makes a difference.
BTW, people designing and building these filters often take the original design, build it up, find out it doesn't quite work, and then adjust the values of the components until it does. Maybe they change the 270 pF to 330pF (to account for the inductance in the leads). This is a lot of the "art" of building RF circuits with real, non-ideal components.
I think we've all been burned by something like this (resistors that are inductors is a notorious one)
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-----Original Message----- From: < [email protected]> Sent: Mar 12, 2025 6:10 PM To: < [email protected]> Subject: Re: [nanovna-users] Help with LPF Measurement On Wed, Mar 12, 2025 at 05:54 PM, John Gord wrote:
It looks like the ground (copper plane) of your filter is not connected to the
grounds (outer conductors) of the cables.
That would make a big difference.
EXACTLY... As I was walking away from the screen shot and getting ready to pull the plug! Again... NEATNESS COUNTS in this process.
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Re: Help with LPF Measurement
I don't see a connection of the ground to the copper clad.
But more than that, the leads are pretty long. A rule of thumb is that 1 cm is 10 nH, so it looks like you've got 40-50 nH in series with those capacitors.
So what you really have is a 40 nH inductor in series with a 270 pF capacitor.
At 20 MHz, the impedance of the capacitor is about 0.25 ohms (i.e. it shorts the input to ground), but it's in series with a 5 ohm impedance of the inductor, so it's like the capacitor isn't even there.
You need the leads *really* short - even if you got them, say, 5 mm long, instead of 2cm each, you've still got 10 nH in series, which is 1.25 ohms.
This is why you see chip caps and if you're using disks, they're on a pcb and really trimmed short.
Also, why do you have TWO capacitors on the ends, 270 pF is a standard value. And having two in parallel makes it even more tricky (the inductances would be less, maybe) but...
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-----Original Message----- From: < [email protected]> Sent: Mar 12, 2025 5:39 PM To: < [email protected]> Subject: Re: [nanovna-users] Help with LPF Measurement Hi Dave, S21 is the gray, I think (the not yellow one -- I'm color blind) print at the top right of the screen in the last two images I posted. It's line is flat at 0 dB across the frequency range with the test rig shorted and gives the unusual curve I showed when the filter is used. Connecting the Ports 0 & 1 of the VNA together (without the test rig) also show 0 dB flat across the frequency range. Is that what you meant? Many thanks. Mitch NK3H
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Re: Help with LPF Measurement
I see two yellow wires for input and output but NO ground lead from the copper board to each of the coax connectors
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Re: Help with LPF Measurement
On Wed, Mar 12, 2025 at 05:54 PM, John Gord wrote:
It looks like the ground (copper plane) of your filter is not connected to the
grounds (outer conductors) of the cables.
That would make a big difference.
EXACTLY... As I was walking away from the screen shot and getting ready to pull the plug! Again... NEATNESS COUNTS in this process.
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Re: Help with LPF Measurement
Here's a plot of the expected response from Elsie
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-----Original Message----- From: < [email protected]> Sent: Mar 12, 2025 4:11 PM To: < [email protected]> Subject: [nanovna-users] Help with LPF Measurement I've searched through the message list looking for symptoms similar to mine and didn't find anything. I'm somewhat new to this and would appreciate any help you can offer. I've been trying to get my NanoVNA-F (firmware 1.0.5) to show the results of a 40-meter low pass filter I've built. I know I'm doing something wrong here but can't figure it out. The VNA image is calibrated (including pass-thru), set for the range 6.5 to 29 MHz and logmag S21. Shouldn't this give a flat area leading up to the design frequency followed by a significant roll off through the remainder of the frequency range? My setup is very similar to W2AEW's YouTube demonstration of the NanoVNA with a LPF but gives entirely different results. The image is entirely different, with very large insertion loss and a steep area of suppression peaking at 11 MHz followed by a steep recovery. I worried that my filter wasn't what I thought it was so I tested it with a 7 MHz square wave, looking at input and output with the FFT function of my 'scope. The before and after images show several things: (1) the square wave (yellow trace) is hardly a square wave. It wasn't much of one before attaching to the input of the filter but it's definitely loaded and distorted by the filter. (I can live with the distortion in the test, since the filter is supposed to reduce the high freq distortion anyway, right?) (2) The purple trace is the filter output--pretty nice sine wave. (3) The FFT shows a good 40+ db suppression of the harmonics, especially the odd numbers. So the filter seems to be doing its job. There may be some things not right about my testing of the filter using signal generator and oscilloscope -- I'm new at this. For example, the shoulder on the filter output at about 10 MHz is troublesome, but still the logmag S21 output shouldn't be affected, should it? Any help in understanding why my results look as they do would be greatly appreciated. Best & 73, Mitch NK3H
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Re: Help with LPF Measurement
One thing you could also try is running the filter in a program like Elsie (which is free, for Windows only, though) and look at the S11 plot from Elsie and see if it looks like what you're measuring for S11. A huge mismatch out of band isn't unusual, but it should be fairly decent below the filter cutoff.
Other things to check - self resonance on the inductors? Or capacitive coupling around the filter. The S21 shows the rolloff, but then bounces back up. That's sort of suspicious. It almost looks like not all the sections are active (or that there's some other resonances, like in an Elliptic, you see a bounce back up)
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-----Original Message----- From: < [email protected]> Sent: Mar 12, 2025 4:11 PM To: < [email protected]> Subject: [nanovna-users] Help with LPF Measurement I've searched through the message list looking for symptoms similar to mine and didn't find anything. I'm somewhat new to this and would appreciate any help you can offer. I've been trying to get my NanoVNA-F (firmware 1.0.5) to show the results of a 40-meter low pass filter I've built. I know I'm doing something wrong here but can't figure it out. The VNA image is calibrated (including pass-thru), set for the range 6.5 to 29 MHz and logmag S21. Shouldn't this give a flat area leading up to the design frequency followed by a significant roll off through the remainder of the frequency range? My setup is very similar to W2AEW's YouTube demonstration of the NanoVNA with a LPF but gives entirely different results. The image is entirely different, with very large insertion loss and a steep area of suppression peaking at 11 MHz followed by a steep recovery. I worried that my filter wasn't what I thought it was so I tested it with a 7 MHz square wave, looking at input and output with the FFT function of my 'scope. The before and after images show several things: (1) the square wave (yellow trace) is hardly a square wave. It wasn't much of one before attaching to the input of the filter but it's definitely loaded and distorted by the filter. (I can live with the distortion in the test, since the filter is supposed to reduce the high freq distortion anyway, right?) (2) The purple trace is the filter output--pretty nice sine wave. (3) The FFT shows a good 40+ db suppression of the harmonics, especially the odd numbers. So the filter seems to be doing its job. There may be some things not right about my testing of the filter using signal generator and oscilloscope -- I'm new at this. For example, the shoulder on the filter output at about 10 MHz is troublesome, but still the logmag S21 output shouldn't be affected, should it? Any help in understanding why my results look as they do would be greatly appreciated. Best & 73, Mitch NK3H
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Taracait
