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Magnetic materials are incredibly complicated. Contrary to the opinions here saying "Yes, very simple", there are no other elementary circuit components with such complex behaviour. The properties of a given material are quite non-linear, and vary widely over frequency and power level. Unless you really understand what you're asking for, you won't know how to interpret the result.

However, for HF use in an antenna system, you first want ferrite - weed out any iron dust cores. These are used for power converters up to a few hundred KHz, because they contain a distributed "air gap" that stores energy in the magnetic field. You can probably spot those because they will have low permeability.

Then you want something that works over your frequency range. I would suggest connecting the transmit port of the VNA to a primary coil, and the receive port to a secondary coil, and looking at the response over your target frequency range.

That still won't tell you about hysteresis, but it's not a bad start.

On Wed, Apr 15, 2020 at 02:16 PM, Neal Pollack wrote:

... Switching context over to the NanoVNA; There is a certain pleasure, a smile, and ease of sleeping at night, knowing that they only cost $50 each. No mistake will ever cost me more than $50....
========================================
Neal,
I totally agree. Since buying the NanoVNA, I've learned more in the last year about using a network analyzer then I have in the previous 5 years of working with a HP8753C VNA. Mainly because there are measurements that I can grab and try on the NanoVNA that I would never perform on the HP8753C out of fear of mistakenly making a incorrect connection that would result in costly repairs.

I can also control and collect data from the NanoVNA using open source software that is unavailable for the HP8753C. The GPIB interface module for talking to the HP8753C can set you back the cost of 3 to 4 NanoVNA's. For hobby use, the NanoVNA meets all my requirements.

- Herb

On Wed, Apr 15, 2020 at 01:30 PM, <aleks07111971@...> wrote:

3.2 dumas do not suit me, the improvement is too small.
It takes 4 inches.
==========================================
Aleks,
Gabriel plans on supporting the ST7796S 4" display and said there is "good command set compatibility between the ST7796S and ILI9341".

It looks like all the V2 display modules will plug into the 18 pin socket and be easily changed by the user. That is great for repair and upgrading. You can purchase the V2 now and order and plug-in the 4" module when it becomes supported. I ordered, but have not received, the 3.2 " module and will order the 4" ST7796S module when it is supported in firmware.

The display module at this link, , looks like the 4" (3.95) display that will eventually be supported. Gabriel said that if you currently plug it into the NanoVNA only a postage size image is displayed, which indicates the command set is compatible with the ILI9341.

I'll re-use the old displays in my ardunio projects after they are replaced.

- Herb

At work, where the microwave VNA's cost over $100,000, and the Spectrum Analyzers are around $95,000, we have fellow
engineers cross-check each other before applying power. We use boxes of attenuators and adapters. We fear making a
costly mistake like too much input power. They all have max input power levels ranging from 0 dBm to +30 dBm, depending
on brand.

Switching context over to the NanoVNA; There is a certain pleasure, a smile, and ease of sleeping at night,
knowing that they only cost $50 each. No mistake will ever cost me more than $50. Heck, a speeding
ticket is 10 times that around here :-) Dropping a good glass of red wine can almost cost that much :-)

And, depending how busy you are and what you value your labor rate at, it may be cheaper to keep several
NanoVNA's on the shelf, rather then the time spent soldering/repairing/re-testing one that you burn. :-)

Cheers,

Neal

Igo51,
the app is a AppImage, so no root is necessary.
Anyway, thanks for your reply.

Peter

Gabriel,
that it was :)

I remember that there has to be done something to enable USB
but didnt remember what.

Thank you !

On Wed, Apr 15, 2020 at 04:01 AM, Glen K4KV wrote:

... One big limitation for me is to be able to SAVE a scan for later download to a PC...

...The H4 was outstanding except for weak brightness outdoors.
========================================
Glen,
One possible solution to both problems is to connect the H4 to your cell phone using the NanoVNA android app when you are taking measurements outside. The phone's display is brighter and the android app will allow you to save the scan to s1p or s2p format for later use on a PC. It does mean one more cable and device, but most of us are tethered to our cellphones anyway.

- Herb

I once took a Tupolev airplane from Cubanair in mars 1995
I was going from Montreal Canada to Varadero Cuba.

I dont remember what model it was. But I was surprised about the brand.

I carefully re-read everything regarding ssa V2, but 3.2 dumas do not suit me, the improvement is too small.
It takes 4 inches.

On Wed, Apr 15, 2020 at 10:41 AM, <aleks07111971@...> wrote:
Any news when support for large displays appears?
=====================================================

Aleks,
You must have missed the topic in this group titled "3.2 inch screen for version2" a few days ago. There is already a 3.2" drop-in display module available for the V2 that is supported in the current firmware. Gabriel is also working on driver support for a 4" display.

- Herb

On Tue, Apr 14, 2020 at 10:53 PM, Joe Burkleo wrote:

Our preamps have 15 db gain so with the input at -10 db, the output from the
preamp to Port 2 was in the +5 db neighborhood.

Joe,

I think some of the latest firmware by Hugen has been increasing the output from the NanoVNA from around -10 dBm to 0 dBm so this will affect how much gain a preamp can have before damaging the input of CH1.

Roger

Are you running as 'root' or an unprivileged user?
"whoami"
If the later, either prepend commands with "sudo " [no quotes]...
.or. issue "sudo su" to become 'root' and then issue commands.

Cheers

Hey.
Any news when support for large displays appears?

Add yourself to the "dialout" group or chown /dev/ttyACM0 to your username.

Hello,
I need somebody who is fine with Ubuntu.

Problem:
Just installed a new Ubuntu system and tried to
connect the V2 to /dev/ttyACM0.

Got and error msg that there
is no permission to connect.

As the AppImage run on the old installation I'm pretty
sure I have to do "something" at the console....?!??

Anybody out there to help please?
Thank you.

Regards
Peter

On Wed, Apr 15, 2020 at 06:24 AM, hwalker wrote:

Поддержка незанятой карты флэш-памяти уже
включена или для нее также потребуется
часть ~ 176 КБ?

I port H version to H4, no support SD cart in H, but not big problem add it. ( then i test FAT32 support in arduino, it not need big amount flash space).
In most cases big amount of flash need for images, texts and UI. In H4 version exist ~112kB free flash space, and ~30kB RAM. But if use next ChibiOS 18 (as in release it require more flash and ram for work).

I show easy way for increase calibration slot amount, need just optimize properties struct size, but answer - use better CPU.
At this time i can`t work under code (at another town work under this , and need full day in work)

Tad,
This group's Wiki page has a lot of information related to both of your questions plus lots of other info that you should check out.

/g/nanovna-users/wiki/home


-Herb

I have an AURSINC H4 nanoVNA and have learned how to calibrate it for 3 - 4
MHz, and used it to measure SWR and find the best match with a manual
antenna tuner for my 40-10 meter OCF - was a great tool! My device is on
version 0.4.5-7-g57d62f2 with a build date of January 1, 2020 - 17:27:30



Two questions:

* When calibrating it, I could only enter the first digit of the start
and stop frequency using a stylus. For everything else I had to use the
track ball to scroll to and then enter the info. I calibrated the screen
and the stylus seems to work for some features and not for others. In
general what can be selected with the stylus and what must be selected via
the track ball?
* It looks like there is a new version compiled on 2/21, and one of
the fixes is for insensitive touch screen -
Where can I find complete
step-by-step instructions for how to download the new version (to my Win 10
pc?) and update the VNA without bricking it?



Thank you in advance for the help!



Tad Danley, K3TD

On Tue, Apr 14, 2020 at 10:53 PM, Joe Burkleo wrote:

I will say that I have used the NanoVNA to demo our ICS preamps at several shows where the unit ran for 6 to 8 hours steady with no issues.

Our preamps have 15 db gain so with the input at -10 db, the output from the preamp to Port 2 was in the +5 db neighborhood.

No complaints so far. Even with the hard life it has had the unit is just as happy as it can be.
==============================================================
Joe,
Thanks for the real world use feedback. The +20 dBm port specification is actually pretty robust compared to other high end test equipment I 've used. I believe the receiver port on the HP8753 VNA was specified at 0 dBm, although actual destructive levels was probably more around the +20-30 dBm range.

I've also tested pre-amps without damaging the NanoVNA. I normalize the test set-up by using the same amount of in-line attenuation as the expected gain of the pre-amplifier. I haven't tested my rf power amps (10-20 watts) yet, and thinking I might use couplers for that testing rather than attenuators.

The cautions about fundamentals being higher than the test frequencies when sweeping above 300 MHz apply to the NanoVNA variants. The S-A-A-2 does not use harmonics for high frequency testing so it may be preferable for sweeping active devices. The waveforms output by the ADF4350 and si5351 synthesizers in the S-A-A-2 are not sinusoidal so harmonics are produced, but they are not intentionally used for high frequency operation as in the NanoVNA design.

- Herb

That problem still appears on many prg's.
Thank you Gabriel.