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Date
Re: Stimulus Span change a bit the Smith measurement

 

Making the turns closer together increases the resistance, because of proximity effect (like skin effect, but from an adjacent conductor) - it squeezes the current to the inside and outside of the winding, and away from the part of the conductor close to the adjacent wire.

On Feb 5, 2025, at 10:31, Bob Larkin <bob@...> wrote:

?Interesting calculation, Jim. Your conductive tube is very descriptive,

It points out that when designing an inductor, one should use the biggest wire that is consistent with the mechanical problems of winding on the core. I say that in a broad sweeping way, but there are cases where the eddy currents in the wire surface an add losses. That is the argument for Litz wire. At some lower frequencies, Litz wire is argued to be better.

Also, squeezing the turns tightly on the core is usually higher Q. The argument here is that squeezing the turns raises the L value, while leaving the resistance as is, so wL/R gets bigger. One often sees the turns spread around the core.
Re: Stimulus Span change a bit the Smith measurement

 

Interesting calculation, Jim. Your conductive tube is very descriptive,

It points out that when designing an inductor, one should use the biggest wire that is consistent with the mechanical problems of winding on the core. I say that in a broad sweeping way, but there are cases where the eddy currents in the wire surface an add losses. That is the argument for Litz wire. At some lower frequencies, Litz wire is argued to be better.

Also, squeezing the turns tightly on the core is usually higher Q. The argument here is that squeezing the turns raises the L value, while leaving the resistance as is, so wL/R gets bigger. One often sees the turns spread around the core.
Extra QEX copy

 

Does anyone want a copy of the January/February 2025 issue of QEX? The ARRL
sent me two copies. It has the tinySA tracking generator design article in
it.

Of so *respond to me privately* at

kc0wjn at gmail dot com

Responses to the list will be ignored.

The magazine is free; shipping cost from 32754 USA to be paid to me by
PayPal F&F (the shipping cost using USPS Media Mail is probably trivial).

DaveD
KC0WJN
Re: H4 Firmware update error

 

NanoVNA App need use DFUSe driver for device in DFU mode, by default windows install driver for STM32CubeProgrammer (this driver allow flash in this software, but not work for NanoVNA-App or DFUSeDemo)
H4 Firmware update error

 

Tried to update my H4 with the app and got this error:

Opening \\?\usb#vid_0483&pid_df11#206a31562031#{a5dcbf10-6530-11d2-901f-00c04fb951ed}

?open failed

Device Manager shows NanoVNA-H4 is connected.

What to do?

Mark Jordan, PY3SS
Re: NanoVNA-H4 number screen malfunctioning

 

Before re-installing firmware, I would try a 'clear config' (under expert settings).
That will help reset internal parameters, in case something amiss there is affecting this.

Regarding new firmware, when you put the nanovna in DFU mode, it will remove the com port, and a new entry will appear in device manager under the 'Universal Serial Bus Controllers' or 'Universal Serial Bus Devices'. It will either be titled "STM Device in DFU Mode" or "STM BOOTLOADER".

If it says "STM BOOTLOADER", use STM32CubeProgrammer to update the firmware.
If it says "STM Device in DFU Mode", use nanovna-app or DfuseDemo to update the firmware.
Otherwise it won't connect. Unfortunately the drivers are not the same for the different applications.
Stan KC7XE
Re: NanoVNA-H4 number screen malfunctioning

 

As it should! Dfu is *NOT* a COM port, and requires it's own driver which is provided with the app of your choice.

On February 4, 2025 8:18:44 PM EST, "Steve Johnson via groups.io" <cascadianroot@...> wrote:
I can't get the device to connect with a Windows computer in DFU mode. I can connect in normal mode with COM4. As soon as I put the device in DFU mode it disconnects and COM4 disappears from Device manager. I tried with both nanoVNA-App and STM32, both act the same.




--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
Re: NanoVNA-H4 number screen malfunctioning

 

I can't get the device to connect with a Windows computer in DFU mode. I can connect in normal mode with COM4. As soon as I put the device in DFU mode it disconnects and COM4 disappears from Device manager. I tried with both nanoVNA-App and STM32, both act the same.
NanoVNA-H4 number screen malfunctioning

 

I have a NanoVNA-H4 which has been working for months. Today I needed to test a broadcast band filter and when I try to enter any number on the number screen (for setting stimulus start/end etc.) the screen goes fully white. All other functions of the NanoVNA seem to be working fine, only the touchscreen is bad. I've re-done the touchscreen calibration (which works normally), saved it, and done the touchscreen test which doesn't indicate any problem -- I can drag the guitar pick up, down, right, left, and diagonally in any part of the screen and it looks fine.

I see in searching for this problem many people have had touchscreen issues, but none just like this. I will try flashing a different version of the firmware (this is Dislord's 1.2.40) and following that if needed I'll disassemble the case to inspect the ribbon cable. Any other suggestions?
Re: SWR readings change when NanoVNA is held

 

Hi Coyote,

As others have already mentioned having a good choke on the feedline is the key.

When operating mobile (40 and 20 meters) with a ham stick or hustler mobile antenna I use approximately 9 of the Fair-Rite 0431167281 clamp on cores and place them on the coax right before it enters the passenger compartment by taping that section of coax to a rail on the roof top luggage rack to keep them from banging around, or I tape them to the coax right after the coax enters the passenger compartment. I have also at times used a single FT240-31 toroid core with at least 8 turns of the coax wound on it. My test to see if I have enough of the clamp on cores on the coax is to touch the NanoVNA while watching the SWR or touch the coax anywhere in the passenger compartment and if the SWR changes drastically (noticeable shift in resonate frequency, etc.) I then add more cores.

Mike (W9RE) and I (WD8DSB) operated CW mobile in the Indiana QSO party last year and we used the 9 clamp on cores as mentioned above on our 40 and 20 meter hustler antenna feedline to stabilize the SWR. We also tried running a trailer hitch mounted 80 meter hustler mobile antenna and without clamp on cores we could only run 30 watts as our keying would lock up (computer running N1MM with a K3 transceiver) so we installed some clamp on cores on the 80 meter antennas coax external of the passenger compartment and that allowed us to run full power (100 watts) without any keying problems.

Using a good choke on the feedline really helps provide a stable and repeatable system and as an example I would never cut the stinger on a mobile antenna based on resonate frequency measurement without first having a good choke on the feedline.

73,
Don (wd8dsb)
Re: NanoVNA update

 

Thanks for the well-worded clarification Stan. I think I¡¯ll go with
STMCubeProgrammer since I already have too many other custom drivers
installed for FPGA tools and dev boards.

Tony

On Tue, Feb 4, 2025 at 12:24?AM Stan Dye via groups.io <standye=
[email protected]> wrote:

You use the DFU file with DfuseDemo
You use the bin file with STMCubeProgrammer (current downloadable version)
I think either version works with nanovna-app (but I don't remember for
sure).

DfuseDemo and nanovna-app require the driver that shows up in Device
Manager under "Universal Serial Bus Controllers" as "STM Device in DFU
mode". This driver needs loaded into Win10 or Win11 if you haven't already
done it, and is part of the DfuseDemo package.

STMCubeProgrammer requires the driver that shows up in Device Manager
under "Universal Serial Bus Controllers" or "Universal Serial Bus Devices"
as "STM BOOTLOADER". This one is the standard driver in Win10 and Win11.

If you do not already have the driver set up for nanovna-app and
DfuseDemo, I recommend using STMCubeProgrammer, which you can download
from the ST.com site - simply because you don't need to deal with windows
driver issues.

Regarding the MS vs SI version: they both use the same firmware build.
Just go into the Config - Expert Settings menu and select the SI or MS
mode. [At one time DiSlord and others were making separate builds for the
two, but the only difference was the initialization of the processor mode
parameter.]
Re: TDR maximum length NanovnaH4

 

very long... It's driven by the lowest frequency in the sweep, which is something like 50 kHz. You want the thing being measured to be less than half a wavelength long. So 50kHz >> 3km.

-----Original Message-----
From: <[email protected]>
Sent: Feb 4, 2025 9:00 AM
To: <[email protected]>
Subject: [nanovna-users] TDR maximum length NanovnaH4

Hello, has anyone measured or knows what is the maximum length that nanovnatdr can measure
NanovnaH4
TDR maximum length NanovnaH4

 

Hello, has anyone measured or knows what is the maximum length that nanovnatdr can measure
NanovnaH4
Re: Stimulus Span change a bit the Smith measurement

 

This isn¡¯t too far off from what you¡¯d expect just from the difference in diameter of AWG22 and AWG 26 wire ( 644 and 405 microns) - the Skin Depth at 14 MHz is about 17 microns, so they¡¯re really a tube, so the resistance will go as the diameter.

Since Q is X/R, you¡¯d expect the Q to be in the ratio of the resistances.
405/644 =0.629
140/176 ??=?0.795

Obviously there are other factors involved (loss in the core, for one)

On Feb 2, 2025, at 14:27, Bob Larkin <bob@...> wrote:

?Thanks Brian for steering me to this discussion. It looked like an opportunity for me to compare my measurements using this much discussed T37-6 with 8 turns. I have a bag of T37-6 that had come from Amidon (and almost for sure are Micro-Metals manufacture). So, I wound and measured one with #22 wire and one with #26 wire, all at 14.1 MHz.

#22 Wire, 260A Q-Meter L=250 nH, Q=164
#22 Wire, Insertion loss method (-46.0 dB) Q=176

#26 Wire, 260A Q-Meter L=248 nH, Q=138
#22 Wire, Insertion loss method (-44.25 dB) Q=140

A couple of notes. My 260A is really old, but through some miracle has all original tubes, including the very special detector tube. It also has the original thermocouple. It behaves just like it did 40 years ago. I have a box of "standards" that were measured in the 1960's on an almost new 260A (a different one). The checks with those are still close. Also, the 260A instruction manual notes a need for a correction due to the coupling resistor of 20 milliOhm, that appears in series with the inductor. This needs to be subtracted for low series resistance inductors. I did that for the numbers shown.

The attached shows how they look physically.

My Q numbers are enough lower than Brian's to be interesting to track down. Brian, can I mail you the coils?

Bob W7PUA





<T37-6_8.jpg>
Re: SWR readings change when NanoVNA is held

 

To state the obvious, the feed line and termination are, in this case, part of the antenna. In some cases an advantage, but not for reliable measurements of an antenna.

Lester B Veenstra K1YCM M?YCM W8YCM 6Y6Y W8YCM/6Y 6Y8LV (Reformed USNSG CTM1)
lester@...

452 Stable Ln
Keyser WV 26726 USA

GPS: 39.336826 N 78.982287 W (Google)
GPS: 39.33682 N 78.9823741 W (GPSDO)


Telephones:
Home: +1-304-289-6057
US cell +1-304-790-9192
Jamaica cell: +1-876-456-8898

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Coyote via groups.io
Sent: Tuesday, February 4, 2025 12:37 AM
To: [email protected]
Subject: Re: [nanovna-users] SWR readings change when NanoVNA is held

Thanks for all of the responses and the assistance. I haven't tried again, but will soon.
I did put a choke on, and it greatly increased my SWR ---- hmmm.

I'm encouraged from the responses. I thought my Nano was broken.

Thanks, All - Coyote
Re: NanoVNA update

 

You use the DFU file with DfuseDemo
You use the bin file with STMCubeProgrammer (current downloadable version)
I think either version works with nanovna-app (but I don't remember for sure).

DfuseDemo and nanovna-app require the driver that shows up in Device Manager under "Universal Serial Bus Controllers" as "STM Device in DFU mode". This driver needs loaded into Win10 or Win11 if you haven't already done it, and is part of the DfuseDemo package.

STMCubeProgrammer requires the driver that shows up in Device Manager under "Universal Serial Bus Controllers" or "Universal Serial Bus Devices" as "STM BOOTLOADER". This one is the standard driver in Win10 and Win11.

If you do not already have the driver set up for nanovna-app and DfuseDemo, I recommend using STMCubeProgrammer, which you can download from the ST.com site - simply because you don't need to deal with windows driver issues.

Regarding the MS vs SI version: they both use the same firmware build. Just go into the Config - Expert Settings menu and select the SI or MS mode. [At one time DiSlord and others were making separate builds for the two, but the only difference was the initialization of the processor mode parameter.]
Re: SWR readings change when NanoVNA is held

 

Thanks for all of the responses and the assistance. I haven't tried again, but will soon.
I did put a choke on, and it greatly increased my SWR ---- hmmm.

I'm encouraged from the responses. I thought my Nano was broken.

Thanks, All - Coyote
Re: NanoVNA update

 

Stan,

I have the same unit as Richard, v4.3-MS. Is dfuse the best way to update
to 1.2.40 or is it better to use the .bin file? Also, I was under the
impression that there were two versions, one for Si5351 and a different one
for MS5351 but I don¡¯t see separate ones on DiSLord¡¯s GitHub. Somewhat
³¦´Ç²Ô´Ú³Ü²õ¾±²Ô²µ¡­

Thanks,

Tony AC9QY (also hesitant lol)

On Mon, Feb 3, 2025 at 6:21?PM Stan Dye via groups.io <standye=
[email protected]> wrote:

Richard, it is safe to continue and update with that message. I think it
is a feature of the final DFuseDemo version.
It also appears on my Win10 computer, and I proceed and update and it
works fine. I just tried it again now to verify.

Stan KC7XE
Re: SWR readings change when NanoVNA is held

 

Can only imagine from whence DJ0IP lifted the drawing with his name on it,
given the difficulty he has supporting his ¡°material¡± to an original
source.

Maynard¡¯s diagram certainly covered the concept.

Here is Owen Duffy's more recent view, and another from the dim past of
1985 from W7EL.

73,

Ed McCann
AG6CX

On Feb 3, 2025, at 4:24?PM, Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

?On Mon, Feb 3, 2025 at 03:56 PM, Maynard Wright, P. E., W6PAP wrote:


A diagram which illustrates your description of the skin effect in coax is

attached (hopefully),



Maynard - Thanks for drawing. Here is another one that illustrates what I
was posting.
It is from this site -->>






<Real-World_Dipole-1920w.png>

Duffy 34798 Common mode current and RF feed lines ¨C owenduffy.net.pdf
Duffy 34798 Common mode current and RF feed lines ¨C owenduffy.net.pdf
4 Lewallen W7EL Baluns What they do and how they do it ARRL Ant Compendium 1.pdf
4 Lewallen W7EL Baluns What they do and how they do it ARRL Ant Compendium 1.pdf

Re: SWR readings change when NanoVNA is held

 

On 2/3/25 16:24, Roger Need via groups.io wrote:
On Mon, Feb 3, 2025 at 03:56 PM, Maynard Wright, P. E., W6PAP wrote:


A diagram which illustrates your description of the skin effect in coax is
attached (hopefully),
Maynard - Thanks for drawing. Here is another one that illustrates what I was posting.
It is from this site -->>
Hi, Roger,

That is a good diagram. Thanks for pointing that out.

73,

Maynard
W6PAP
1081 - 1100 of 39697