开云体育

I'm hoping to have access to a more expensive VNA later this week for comparisons but for now, the nanoVNA-H looks very promising in terms of accuracy near the top of its frequency range:



73,
--
John AE5X

Not sure why it's not click-able...probably needs the prefix.

--
John AE5X

Edy555 also has been experimenting with an IF of 12kHz as this frequency enables a reduction of DSP processing power required. Not sure if the experiment came to a conclusion.


--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

On Mon, Mar 30, 2020 at 08:41 AM, Nbridgema wrote:
After installing ttrftech/NanoVNA version 0.7.1, F_min is again 50 KHz and F_ max is 2.7 GHz, although noisy > 1.5 GHz.
Confirm?
==========================================================
Nbridgema,
I can confirm. edy555 opened the max frequency up to 2.7 GHz in the 0.7.0 release to to allow NanoVNA-H 3.4 version devices to experiment past 1.5 GHz. The hardware changes to the 3.4 version boards made operation to 1.8 GHz pretty good, and from 1.8-2.0 fair to poor. Past 2.0 GHz measurements are not reliable.

I expect similar performance on the NanoVNA-H4 as its hardware improvements are at least as good as the version 3.4 boards.

edy555 also changed the lower operating frequency from 10 kHz back to 50 kHz in the 0.7.0 release. If enough people lobbied for a change back to 10 kHz, I don't see a technical reason for not doing so. I do know edy555 doesn't want the lower operating frequency to get too close to the IF frequency.

- Herb

There are several dozen videos on Larry Benko’s website showing Smith chart basics AND exploring various RF topics.

A good start might be



When I was first introduced to the smith chart it took me a year to get comfortable. Nowadays with the computer doing all the heavy lifting, it’s easy to explore and learn how the Smith chart can be used to gain insight to many RF circuit design prolblems.

Ward
Ae6ty

On Mon, Mar 30, 2020 at 07:39 AM, Jos Stevens wrote:

...works normally under NanoVNASaver. ?
... The extra bandwith settings seem to work when standalone
... I see that the smaller the bandwith, the slower the display updates.
... The DFU option does not work on the H4.
===============================================
DiSlord,
I'm adding the following comments to Jos' reply:

1. The beta firmware is also working fine with all the current software applications I am using. The only thing that isn't working, that was working before, is a script for capturing the NanoVNA-H4 display using the "capture" console command. The following worked previously:

image_data = ser.read(320 * 480 * 2)
rgb_data = struct.unpack(">153600H", image_data)

After updating to the beta firmware, a "struct.error" is always thrown at the second line. All other console commands seem to work.

2. The DISPLAY-BANDWIDTH menu option is a nice addition to the NanoVNA-H4. My expectation was that decreasing the bandwidth would decrease the noise floor, but what actually happens is that the trace is smoothed. It would probably be more accurate to call the menu AVERAGE or VIDEO AVG. As would be expected, the lower the bandwidth setting (higher number of averages applied) the slower the sweep.

3. As Jos noted, the NanoVNA-H4 cannot enter DFU mode from a firmware menu option and you can delete CONFIG-DFU from your code.

4. The bigger font sizes really improve readability of the display. This is especially true of the menu fonts. The menu fonts are now more legible on the 4" NanoVNA-H4 display than they are on my 4.3" NanoVNA-F display, which has an 800x400 resolution.

5. The improved UI features from the 0.7.1 firmware release make navigating the display better. The display markers are easier to grab, and tapping a marker to change trace selection is easier.

6. I noticed vbat_offset, color and bandwidth console commands have been added in this beta release.

Really a nice piece of coding. Its hard to believe you didn't even have a NanoVNA-H4 to work with while writing the beta firmware. I hope hugen decides to merge most or all of the changes into his next official release. Please let me know if you have an idea of what has changed with the "capture" command.

- Herb

At whis version added all my additional Bandwidth improvements, speed

optimizations + bigger font from my old fixes to AA version

Jerry, thanks; it was enough to point out that I really hadn't missed some piece of information. I understand what you pointed out although I hadn't followed it through as thoroughly as you. You were hearing my frustration of not being able to follow the statement verbatim.

Now retired, I've been re-engaging with RF electronics, which was a childhood fantasy. So I've been looking for tutorials on any number of subjects, like the Smith chart (as a refresher), and Python (about which I know less than zero, and lack any programming knowledge).

I observe a common denominator: the one skilled in a subject forgets how much they already know that will be required of the listener to understand their explanation. And I can't throw stones!! I now know I must have done the same thing explaining some aspect of propagation in optical fiber, and saw the listener's eyes glaze over!

-Paul
I_B_Nbridgema

Well John, I'm sure that you love me but what the heck is up with that link?

After installing ttrftech/NanoVNA version 0.7.1, F_min is again 50 KHz and F_ max is 2.7 GHz, although noisy > 1.5 GHz.
Confirm?
--
I_B_Nbridgema

I ordered mine from this Amazon vendor:
shorturl.at/ahsS7

Order placed on Saturday, Amazon said it would arrive Monday (today) but it was delivered at noon yesterday, 20 hours after placing the order. Compared to the first of these nanoVNA's I ordered 6 months ago, this one seems much more refined in terms of packaging, having a hard case included, etc.

--
John AE5X

On Sun, Mar 29, 2020 at 08:39 AM, jac hil wrote:

The problem with P O Box is the battery in the VNA.
PO rules prohibit a lot of things that burn and record how the parcel was
shook in transit.

That is absolutely not true. The only restriction for Lithium batteries (or any other hazardous materials) is air freight. Nothing to do with a PO Box being the final recipient. The problem is not at the destination, but rather in the process to get it there. I have received many times various Lithium batteries for radios, cell phones etc, even the backup cell I needed to refit in my HP3468A DMM via my PO Box absolutely without any issues. Some of the bigger packages even had the Lithium battery inside sticker warning as required.

The ONLY valid reason to exclude a PO Box is if the shipment is being sent by UPS, Fedex, or DHL, which require a signature upon delivery, so they do not deliver to a PO Box address.

There are US based sellers on ebay (a lot of them chinese) that advertise shipping with USPS in capital big letters and still exclude PO Box on various smallish items, nothing hazardous. The reason is usually that they are drop shipping, and are not really the entity that will handle the shipping so they have no control over it, and are not even able to provide you with a tracking number, or just send you a fake one. Sometimes you end up with an Amazon box even tough you made your purchase on ebay. Been there seen it happen, now I steer clear of any seller that is US based that excludes PO Box. Something funny going on there for sure. Life is short why waste time with drop-shippers.

And as I said before, the PO Box address is my ONLY practical option for small packages. I am not in the US. I do have a street address as well, but only for freight cargo so it has a base charge and does not make sense for small items. Been doing mail forwarding for many years with 99.99% success rate.

Hi

I flashed this firmware into my NanoVNA-H4 and itworks ! .Anyhow it works normally under NanoVNASaver. ? In the menu I see several addon's but these are not (yet ?) supported by NanoVNASaver ofcourse.

The extra bandwith settings seem to work when standalone? , I see that the smaller the bandwith, the slower the display updates. The DFU option does not work on the H4.

Jos

Op 30-3DiSlord:-2020 om 08:44 schreef Compile version for NanoVNAt -H4 (0.7.1-20200321+ last improvement

you mention the schematic - can it be seen somewhere online?
=============================================
Marko,
The attached file is the version 2_2 schematic provided by Gabriel.

- Herb

Schematics at:
gEDA format.

Hello Herb,

you mention the schematic - can it be seen somewhere online?
I will definitely buy this, but I can not do it currently from Tindie, not shipping to Slovenia (in fact, there is a quite long list of "no ship" countries there). Hopefully, this will change - don't want to pay double at Ebay.
Also, currently the postal service here in Europe is out of whack because of COVID, I am waiting for some other parcels for quite long now, if they will arrive at all. I will wait a bit anyway, order later, if still alive.
So, in the mean time I would like to at least study the schematic :-)

Marko Cebokli

Compile version for NanoVNA-H4 (0.7.1-20200321 + last improvements)



Idon`t have hardware H4 for tests, but must work

At whis version added all my additional Bandwidth improvements, speed optimizations + bigger font from my old fixes to AA version

Nbridgema wrote:

Reading off the chart, we see the following values:...
Would you please explain where these values are seen?

The answer is, you cannot directly read frequency off of the Smith chart.
There should be little notes and arrows added as annotation to the chart,
telling where the 14.0mhz, 14.175mhz, and 14.35mhz points of the blue arc are at.

The blue arc goes clockwise from 14.0mhz in the upper left to 14.35mhz in the lower right.
If you zoom in and put on your best reading glasses, you may see a little green pixel in the blue arc
just below the horizontal line identified as "0.2", this point on the blue arc is 14.175mhz.

The first entry of the table after the chart says that the reflection coefficient at 14mhz
is (-0.12, j0.26). That's a complex number, having a real part of -0.12 and an imaginary part of j0.26.
This corresponds to the upper left end of the blue arc.
The real part of -0.12 is slightly to the left of the center vertical axis of the chart, a bit more than halfway to that first -0.2 vertical line.
The imaginary part of j0.26 is up from the center horizontal axis of the chart, a bit above the first horizontal marker at 0.2.


There's all of four sentences in this tutorial describing the central concept of what a Smith Chart is:

Radio operators are inherently familiar with the concept of standing-wave ratio, i.e., a measure of how well a load
is matched to a transmission line. A slightly more obscure concept is that of the reflection coefficient.
Notated using the Greek letter gamma (Γ), the reflection coefficient describes how much of an
electromagnetic wave is reflected by an impedance discontinuity such as a mismatched load. ...
First, let’s plot the real and imaginary components of Γ for this DUT on a rectilinear graph.

So I'd say Aldo's tutorial is not very useful to someone starting out, you pretty much have to already know
what a Smith Chart is. The title should give a hint of this: "Revisiting the Smith Chart".
But if you do understand the basics, there is plenty of good information there.

Here's an old post about a different Smith Chart tutorial: /g/nanovna-users/message/5223
This tutorial does try to explain in simple terms what a Smith Chart is.
That entire thread might still be of interest to those thinking about how to better document these VNA's.

Another good resource for understanding the Smith Chart is at

Jerry, KE7ER

Thanks for trying to help, Tom in AZ, but what good will it do to study hundreds of hours to try to make sense of that one line?
That is, I do not see on the chart any markings that allow scaling frequency relative to the (nearly invisible) green mark.

I used Smith charts to guide fabrication of waveguide filters, more years ago than I care to remember! : > )

--
I_B_Nbridgema

On Sun, Mar 29, 2020 at 11:27 AM, CT2FZI wrote:

Do you think a specific groups.io group would help?
==============================================
尝耻í蝉,
So far only about 150 S-A-A-2 units appear to have been sold before the first production run ended. I don't know if that is enough volume to warrant another user group, but only time will tell. This groups.io forum and the NanoVNA Facebook page also support the S-A-A-2. If you can get the S-A-A-2 manufacturer to designate your forum as an official support site that would be advantageous.

- Herb

There several tutorials in the files section, I've spent may years in
electronics and I still need a refresher from time to time. Read the
tutorials and it will clarify
Tom Sides KI7FTK
skype: Thomas Sides
4243 e. st Charles ave
Phx AZ 85042



On Sun, Mar 29, 2020 at 11:38 AM Nbridgema via Groups.Io <nbridgema=
[email protected]> wrote:

Aldo, in your tutorial is said:

Reading off the chart, we see the following values:...

Would you please explain where these values are seen?

Thanks!!
--
I_B_Nbridgema