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Stan and Thomas..

Thank you! The menu is very helpful! Got a whole lot of learning to do, i'll be fun!

--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

Dave,

That's very interesting. That is what I came across the datasheet of the capacitors I bought. Look at the picture, I think that's what you're talking about. Unfortunately, it is not mentioned in the inductor datasheet.

I tried it out tonight. Unfortunately, The match get worse (no as worse) but in the same direction as when I've put the inductor. I didn't have an 18 gauge on hand though, only 22AWG.

When you say "clean" the ground plane, do you mean that below the footprint occupied by the inductor, there should have no ground plane in a "copper at all" beneath it ? In this case, doesn't it creat a return path discontinuity for the transmission line ? I've attached a picture for clarity.

Thanks

Dave, the first photo is with the 10pf cap and at 150mhz it measures 10pf.

Since you mention measuring all components, do you have any tips on getting a 50ohm match on the inductor at the desired frequency? I've tried a few different diameters and numbers of turns, I'm close to the inductance needed but can't seem to get the impedance right

When constructing filters, I ALWAYS measure every component before building
the filter! With that, I seldom have to do ANY tweaking with the completed
filter.

If your first image is without anything installed in your fixture - the
binding posts - after a good calibration, the marker over your sweep range
should be a single point at the extreme right and on the center horizontal
line with no capacitive trace below it.

If your first image is with a 10 pF capacitor, the S11 measurement at the
marker indicates a frequency of 3.9 MHz. What is the capacitance at 150
MHz? You want this capacitor to be "good" per your required value from
"DC" to at least 150 MHz, and preferably to 900 MHz (and above).

Dave - W?LEV

On Tue, Mar 18, 2025 at 7:59?PM KJ5FRJ via groups.io <coreyjenkins24=
[email protected]> wrote:

There's a lot of information here and I appreciate everyone's input- I
reset and recalibrated the nanovna after finishing up the test rig
according to Dave's build, i missed the copper tape on the edges. I'm sure
the capacitance had quite an effect. I tested with a 10pf vishay hi Q cap
and it's accurate along with my smith chart not running off the graph- I
tested a coil and per the coil calculator I used it seems accurate. Now the
fun part- trying to wind coils for the impedance I'm looking for at the
frequency range I need?
If anyone sees anything here that looks amiss I'm all ears

--

*Dave - W?LEV*


--
Dave - W?LEV

Zack,
Here's a link to the filter I'm building. It's not a chebyshev, there was an article in QEX about it comparing the two.

And the qex pdfs

Where did you get the filter design you are using? Playing around with my
filter design program, I found it appears you are using a 7th order
Chebyshev low pass filter, inductor input. Possibly a Butterworth, as the
values it gives are fairly close to those of the Chebyshev. This would
require two inductors of 72.8 nH and two of 214.8 nH. Is there any way you
can go to a capacitive input filter? That would use inductors with larger
values.

I usually don't measure the inductance directly for filters like that. I
wind the inductors according to formula (in this case simple wirewound
inductors), build the circuit, connect that to the NanoVNA and push the
inductors to make the windings closer together or farther apart with a
plastic diddle stick. I adjust until it gives a cutoff of the appropriate
frequency for a low pass filter.

Zack W9SZ

On Mon, Mar 17, 2025 at 2:29?PM KJ5FRJ via groups.io <coreyjenkins24=
[email protected]> wrote:

Hello, new to this group. I've learned a lot from reading here, but i seem
to have run into some issues and could use some advice. I'm building a low
pass filter, and trying to learn to measure inductance using the nanovna.
I've built a test rig that I found on one of the threads here somewhere-
three pieces of double sided pcb for OSL, and I'm soldering my air core
inductors to that. I'm trying to use the S11 shunt method for a coil that
needs to be 72.4nH.

Ive got a couple things I'm not understanding- should my coil be adjusted
for the necessary inductance at the frequency for the filter of 50-55mhz?
And does it need to be adjusted for impedance at that band as well? I've
attached photos- my 90deg phase and 50 ohm mark is at 112mhz, but this
inductor is for the 6m filter.

Another thing I'm not understanding is the 5khz self resonance dip seen at
the beginning of the sweep, shouldn't it be reading capacitive since it's
after the phase reversal?

Any help is appreciated

<>
Virus-free.www.avg.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

look in files section, menuand notes by bruce dated 2024, good menu map and notes

There's a lot of information here and I appreciate everyone's input- I reset and recalibrated the nanovna after finishing up the test rig according to Dave's build, i missed the copper tape on the edges. I'm sure the capacitance had quite an effect. I tested with a 10pf vishay hi Q cap and it's accurate along with my smith chart not running off the graph- I tested a coil and per the coil calculator I used it seems accurate. Now the fun part- trying to wind coils for the impedance I'm looking for at the frequency range I need?
If anyone sees anything here that looks amiss I'm all ears

Success!

1. Shorted BOOTP and VDD pins
2. Connected USB-C to PC (MacBook Pro 2016)
3. Started STM32CubeProgrammer
4. Loaded latest NanoVNA .HEX file
5. Started Download
6. Success! NanoVNA working as expected.

Thanks, for all the help; Dfu appears to be obsolete, STM32Cube works, and
I don't need to run it on Win10 via Parallels ?

On Sun, Mar 16, 2025, 17:37 Siegfried Jackstien via groups.io
<siegfried.jackstien@...> wrote:

maybe the case is pressing on the touch screen? ... or the screen cable
is not well fitted

did you try to connect it to pc (example nanovna app)??

dg9bfc sigi

Am 16.03.2025 um 23:31 schrieb Taracait via groups.io:

Battery is fine, 3.7VDC; checked at the unit PCB.

And the screen is lighting up (white), so power isw not the problem

I'm not aware of an updated menu structure map, nor of a consolidated description of features of the current 1.2.40 firmware.
Unfortunately, it takes a bunch of time and effort to create such documentation, so I'm not sure if anyone has donated such an effort.
You can look at the release notes for each of the versions to get the info (but that's a lot of release notes).
And there are lots of youtube videos that touch on one or more of the features. And lots of past messages in this forum, which you can search for a particular menu item you may be interested in.

Maybe someone else here is aware of good places to look...
Stan

I called R&L electronics today. They're going to replace the unit. A+ service from R&L.

Stan,

thank you for the advice. As mentioned, I became familiar with the H4 one or two years ago (my past dims) and -- per your advice -- I did go ahead and upgrade from 0.5.0 to 1.2.4 and, my word, the features abound.

I guess my work is cut out for me inasmuch as the 1.2.40 display is loaded with features versus the old and lowly 0.5.00 release. Is there documentaiton and/or a menu structure map for this newer version?

Obliged!

--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

Since you are dealing with SM inductors, I remembered something I've
learned and practiced for a couple of decades. In mounting SM inductors it
matters how they are constructed internally. The suppliers do not publish
this data. As such, I have always required the PCB layout engineers clean
the "ground" plane from under any and all SM inductors. Depending on the
internal construction of the SM inductor, the close proximity of planes and
traces immediately beneath the inductor will alter its characteristics and
in-place inductance. Even on 2-layer boards at microwave frequencies, this
is a concern. I may even require cleaning the common plane and all traces
from any of the layers under the SM inductors.

Instead of using your 10 nH SM inductor, a 0.5-inch of AWG #18 solid copper
wire would yield something very close to your target inductor. Install it
between the pads intended for your SM inductor and make a very wide hairpin
out of the wire. Even a hair pin will introduce additional inductance over
a linear straight conductor, so you may require a bit less than
0.5-inches.

Dave - W?LEV

On Tue, Mar 18, 2025 at 2:56?AM Nico via groups.io <nicolassimard=
[email protected]> wrote:

Roger,

Thanks for the idea. I already tried sending them an email a while ago for
that exact request ! The phone is still ringing, nobody answered yet at the
other end ;( But I should throw the fishing stick once again using my email
address from the office, that would look more serious... I'll let you know.

In the meantime, I've conducted one more test tonight, with interesting
but a little disappointing results. arrrrgg, I'm missing the knowledge and
there may be something obvious I don't get. Maybe someone has the right
batteries to fit my torch !

I've cut on end of a 36" long RG316. I soldered it to the PCB. I
reinstalled the pcb in its case and made the cable going through a hole on
the underside. Straight out the box I wrapped the cable 3 times around a
Fair-Rite 61 material that has a 0.9" inside diameter. I connected this to
another 12" premade cable then to the VNA just to give me some length. That
is for sure, I took the time to calibrate OSL right before mounting all
that. BTW the load has been done a 50 Ohm 0603 chip resistor at 0.1%
accuracy spec (at 3$ a piece !!).

Picture 1 : Test setup (the same as all my other tests)
Picture 2 : Measurement in this condition (no matching network, only a 0
ohm resitor to pass through)
Picture 3 : Data from the VNA plotted in SimSmith,
Picture 4 : Expected reading (or close) after putting a 10nH in series.
Picture 5 : Actual reading I got after installing the inductor.

Every time I tried to correct/match the antenna it gave me horrible
results like that. There must be something obvious I don't see.

At the end, I do not expect to achieve the 1.5 VSWR flat as in the
datasheet. It is a personal project after all. But if I could at least
match it down to 2, I would be more than happy. This module will be
installed in my backyard and the receiver will be at less than 50 feet. It
is more a matter of learning new things. The one thing I want to avoid
though, is to make it work by pure luck without knowing why.

I'm searching for a needle in the haystack, can someone lend me a metal
detector please !!

Nico

--

*Dave - W?LEV*


--
Dave - W?LEV

A couple more notes:
1 - If your primary use of the nanoVNA is HF up to about 450MHz, then there is no need to buy a new model. I am still actively using my nanoVNA-H4 from 2020, and it is all I need for HF/VHF work. If you plan to use a vna at 900MHz and above, you do want to get a model that handles the higher frequencies better, such as the V2 models or liteVNA64.
2 - I also normally subscribe to the "if it ain't broke don't fix it" model - but the newer firmware for the H4 has extended its functionality quite dramatically. So after you have a good working relationship with your H4, if you want to have more functions to play with, do upgrade to the latest DiSlord release of firmware from here: (get the one with H4 in its name). And if you have not recently done a firmware upgrade on a device like this, you will need to make sure you have the correct driver installed, so please read the firmware update instructions in this group's wiki, and this document that I put together some time ago to make sure you have the correct driver:
/g/nanovna-users/files/Miscellaneous/DFU-mode%20Driver%20for%20Win10Win11
Stan

Gentlemen,

Thank you for the recommendations: if it works, don't fix it and last year's model/FW version works fine if it works fine.

Probably better my devoting my time to [re-]learning and using my H4 as is.

By the way, this seems like a very helpful group and tolerant of we beginners. I promise to scour the threads to as pick up the fruit -- either low-hanging or on the ground -- before plunging ahead.

Again, thank you!

--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

I generally update the firmware whenever a newer version is available.
There have been some improvements made in some of the versions that were
worth having.

Zack W9SZ

On Tue, Mar 18, 2025 at 8:27?AM Leif M via groups.io <leif.michaelsson=
[email protected]> wrote:

Are you having problems. If it works all right, why bother changing.
Yes, new models sure look good. Like Pro model of
But if it
works, don't fix it. If you mean firmware, there are so many basic
NanoVna versions that I would not dare to touch any new firmware.

Have you tried measuring components. Vna is good for that, too. If you
get good results, everything works?

Just for fun, I fed my original post into ChatGPT to see if "she" had any insights, and here was "her" response.....a fun exercise..

"What you're describing is a fascinating experiment! It sounds like you're observing the effects of an asymmetrical antenna design, and there are a few key factors to consider that could explain the differences in the SWR and Smith charts when you reversed the dipole legs.

1. **Non-Balanced Antenna and Common-Mode Currents:**
Since the antenna is a form of off-center fed dipole (OCFD), it is inherently unbalanced. An off-center fed dipole typically has a significant imbalance in the current distribution between the two legs, which results in common-mode currents on the shield of the coaxial feedline. The role of the coax shield becomes crucial, as it can have a different effect on the antenna impedance depending on the configuration of the dipole legs.

Reversing the two dipole legs changes the relative phase and current distribution between the two antenna legs. As a result, this can alter the electromagnetic field around the antenna, affecting the impedance seen by the transmitter and causing different interactions between the antenna and the coaxial feedline. The coaxial cable’s shield could be acting differently in each configuration, either radiating or picking up different signals depending on how the antenna’s currents are distributed.

2. **Impact of Asymmetry:**
In an ideal balanced antenna (like a center-fed dipole), the two legs of the antenna are of equal length and the currents in each leg are balanced. However, in your case, the legs are of different lengths and are presumably attached to the transformer in a way that creates an imbalance. When you reverse the legs, the imbalance changes, which likely affects how the antenna is coupled to the environment and the transmitter.

In terms of impedance matching, reversing the legs could change the impedance seen at the antenna terminals. This could be why you observe different SWR, return loss, and Smith chart behaviors — it's reflecting a change in the impedance that the transmitter sees. This effect could be accentuated by the unbalanced nature of the antenna and the non-ideal placement of the coaxial shield.

3. **Coaxial Shielding and Proximity Effects:**
Since your coax shield is short (4 feet) and potentially has significant current on it due to the unbalanced antenna design, the proximity of the coax to the walls (and to the antenna) could influence the impedance. Even though the nanoVNA was dangling hands-free, subtle changes in the position of the shield, or how the shield is coupled to nearby structures (walls, etc.), might affect the measurements. This is especially true when dealing with an unbalanced antenna where the coax shield may not behave symmetrically in each configuration.

4. **Transformer Characteristics:**
The transformer you're using has a 6:4 turn ratio, which means the impedance transformation may also behave differently depending on how the antenna legs are connected. If the two dipole legs are different lengths, the impedance seen by the transformer secondary might change, which could lead to significant variations in the reflected impedance. This could explain the differences you’re observing in the SWR/return loss between the two configurations.

### What Could Be Happening:
- **Reversing the dipole legs likely changes the current distribution** and the balance between the two legs of the antenna. This results in different impedance characteristics and different interactions with the feedline.
- The **coaxial shield** might be more involved in one configuration than the other, leading to different behaviors in the SWR/return loss measurements.
- **The transformer’s impedance transformation** could also be affected by the dipole leg configuration, which would further explain the differences in the measured SWR.

### Suggestions for Further Investigation:
- **Try using a balun:** A simple 1:1 or 4:1 balun could help balance the antenna, reducing the impact of common-mode currents on the coax shield and potentially stabilizing the impedance.
- **Check the positioning of the coax shield:** Experiment with different orientations or placements of the coax cable and observe how that affects the measurements. Small changes in the physical setup might reveal further insights into how the shield and antenna interact.
- **Use a longer feedline:** If possible, try a longer feedline to see if the behavior changes, as the coax shield’s interaction with the antenna may be more pronounced over a longer distance.

Your experiment is a great example of how even small changes in antenna configurations and feedlines can lead to noticeable differences in impedance measurements. The combination of antenna imbalance, coaxial shield effects, and transformer characteristics all play a role in shaping the observed results."

Are you having problems. If it works all right, why bother changing. Yes, new models sure look good. Like Pro model of But if it works, don't fix it. If you mean firmware, there are so many basic NanoVna versions that I would not dare to touch any new firmware.

Have you tried measuring components. Vna is good for that, too. If you get good results, everything works?

Ali Express should be legit. But I have purchased a NanoVNA H4, TinySA and
TinySA Ultra as well as many other products from R & L Electronics. They
are legitimate and reliable and have great service.

Zack W9SZ

On Tue, Mar 18, 2025 at 7:20?AM k6whp via groups.io <k6whp=
[email protected]> wrote:

Just joined and here goes my newbie message. Sorry.

(1) I have an H4 from 2020 with the 0.5.0 FW version. I am guessing that
an upgrade would be in order?
(2) Also looking into an "F" and saw some being sold on AliExpress for
102.93 marked down from $205.86 (50% off)
..is this a reliable source and product (link below) or, in not, what is
reliable?

Thank you in advance.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

On Mon, Mar 17, 2025 at 03:13 PM, W0LEV wrote:

... If you used only the NANOVNA connected to NOTHING, not even holding the VNA, you might
not see as much difference.
...You need to decouple the feedline/NANOVNA/PC/laptop from the transformer!

Yeah, I've been thinking about that...although I will note that the laptop was NOT plugged into the AC adapter when I made the two measurements. What I'll try on my next visit will be to leave the nanoVNA dangling without ANY connection to the laptop, and then see if the patterns look more similar when reversing the dipole wires. And of course, I can also observe the impact of touching the nanoVNA SMA and see how that impacts the view...a classic test for common mode effects in the unbalanced system. But all of this points out the challenge of trying to capture what the Zachtek is actually "seeing" when connected to the antenna. It seems that with this type of setup it would be very difficult to get an accurate picture...not that it really matters much, though, given it's tolerance of any load.

I will say that based on the WSPR performance over the past day, reversing the dipole wires does seem to have had a positive effect (567 versus 504 unique spots for W9HIF), assuming the solar activity has been similar to that earlier in the week. And if that holds, that is consistent with the SWR pattern showing a lower average for the higher frequency bands...even if that means the transmission line is "participating" more to radiate some of the RF energy.