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On Fri, Nov 29, 2019 at 01:40 PM, <Nulluser00@...> wrote:

Can the NamoVNA be used to charctorize a receveiver antenna input impedance?

yes, you can use NanoVNA to measure receiver input impedance

(from list co-owner) -

As the initiator and one of the two co-owners of this list, I have configured the list to maximize user privacy to the best of my ability and understanding. With about 2800 members since June, it isn't practical to screen each new e-mail address that arrives (many look plain weird, but then again as I've discovered, it's a way to be creative!)

That said, I share below the group's privacy configuration in force since day 1, and seek any practical input from any list member regarding security or privacy concerns going forward. Should you wish to contribute recommendations regarding privacy and security configuration, I urge you to reply in "private" mode (or send a message to [email protected]) unless you are certain your input is directly germane to the nanovna, as I seek to keep S/N here maximized - I don't want to launch into a long generic thread on privacy or security, and will stop threads that diverge from issues that are of immediate and direct concern to *this* group and the nanovna.

This group is and has been since inception (June 2019) configured as follows re privacy:

Visibility: Group listed in directory, publicly viewable messages

Member Directory: Moderators and Owners (who can view the member directory, there are exactly two people fitting that classification)

Members Visible: Owners only (who can view the list of members; the same two people)

Hide Email Addresses In Archives: Mask all e-mail addresses in archives

Thank you for your interest in and support of nanovna-users on groups.io.

Dave

It depends on how you've set up your profile and how active you are on the forum.? Have a look below and you see your email address.?
Any time I get something suspicious, I browse the source of the page. The email I got had Dropbox icons being loaded from Wikipedia of all places.?



On Fri, 29 Nov 2019 at 5:54 PM, Terry VK5TM<vk5tm@...> wrote: I can't see any members email addresses listed anywhere if you use the web interface, so don't think the archives being visible to anyone is a problem.

Also, apologies to Michael VE3WMB, when I was looking around at the various options used for replies, I hit the wrong button and sent a blank private message from me, disregard it.

--
Terry VK5TM
( )

Rune,

I understand your use of 3.7 save for when it becomes 3.8 or 4 then what?
Python is a rapidly evolving language, That reason alone is why I dislike it.
Stability is a good thing. It means you will have a later version, more
likely sooner than later.

As an old programmer that ran unix-V6 current keeping old software alive
especially when well debugged is sometime a very valuable thing. But
to have the latest and greatest break it is a liability. I also have a wider
range of environments I use and support (like 32bit without PAE)

Yes, I do use wine (and dosemu) as then I can support 4NEC2, and a raft
of good but old software that I'd not found suitable replacements for.
See others complaining of breakage for older winders aps because
current wine is apparently broken.

A-

-----------------------------
I don not accept private email due to forum scraping groups.io

Jim N7JA,

I do not update willy nilly for fun and giggles. Next jump will be current soon as the
140GB backup is complete and I know I can recover if something breaks. Plus putting
together a script to install the needed packages. The general goal is to have a stable
system. Installing new version rarely insures that and often brings new problems or
old software breakages. At a minimum a lot of time spent adding in packages I require.
I know its old but it is stable for my general useage, for now.

For now its in a sloggy laptop running MINT-19.3.

-----------------------------
I don not accept private email due to forum scraping groups.io

I can't see any members email addresses listed anywhere if you use the web interface, so don't think the archives being visible to anyone is a problem.

Also, apologies to Michael VE3WMB, when I was looking around at the various options used for replies, I hit the wrong button and sent a blank private message from me, disregard it.

--
Terry VK5TM
( )

eddy_555 just released this 8 hours ago...
ver 0.5.2
Now shows multiple marker information
adds marker delta mode
here :-

I noticed that the group message archives are visible to non-subscribers, I am not sure if this is intentional.
If you look at group settings on the homepage it says : Archives are visible to anyone.

I am also not sure if this exposes the emails of those posting.

Cheers

Michael VE3WMB

For me too the USB cable had problems. I put two ferrites and solved.

I had someone join our group on groups.io who I didn’t recognize … so blocked them…
I wonder if this is part of a pattern to raid e mails…

Dana VE3DS

Hey ya'll? I'm a total idiot but this is my first try at this.

Kenwood ham radio 1200watt amplifier 80 meter input matching network was designed wrong, high radio SWR.

Here is the deal.? Want to match the 50+j0 radio to the amp on 80M.

Amp has known design problem.? 80M is L10.

*INPUT CIRCUIT FOR 80 METERS*

It was found that in 2 different TL922's it wasn't possible to get the input SWR down sufficiently. This isn't accidentally but a design fault. Even with a variable capacitor instead of fixed ones, the results were not consistent. If there was a good SWR at the start of the band, it was bad at the end or visa versa. Also the length of the cable between exciter and amplifier has an influence on the SWR on all bands.

It was discussed on the Internet that what was ok for one person, didn't work for somebody else. I blame this on variations in the way the input circuits were manufactured (fig?.) The circuits are in a Faraday cage and don't allow the RF current to return to ground directly. You can put an insulated tinned copper wire through the hole of where a ground pin uses to be and use this as a central grounding point (left). The best way to do this to ground all capacitors of the input filters on this earth wire. In the meantime this was only done for the 10, 15 and 80 meter input circuits.



After a bit of experimenting a better compromise was reached for 80 m by removing 2 turns of L10 and to increase a number of the capacitors in parallel to the existing ones (fig ?). The range of the inductor was changed from 2.7 – 3.2 μH to 2.5 – 3 μH. Ifyou want a different inductor value, you can calculate this with the formula L(μH) = 9n? χ1000, "n" is the number of turns.

Attention:In the circuit diagram C57 and C59 is 120 pF respectively 220 pF. In my amplifier the manufacturer had a 120 pF capacitor for both C57 and C59!


Jumped bandswitch and used a NanoVNA to look at the modded GI-46b Russian tubes input impedance directly thru input 259 connector. Here is the tube input impedance with the band switch strapped out and no parallel caps.

So tubes look like 33+j9.8.

Then designed, implemented and measured the circuit performance.

Went from 1:10 + swr to 1:1.3 first try.




Looking into tube input bandswitch matching jumped

So I take the tube input impedance and drop it in Simsmith (free)? and design a simple L filter.

--
Then I cut a coil (measure with MFJ B measure inductor @ 3.822MHZ) and made the filter above.
Nano VNA measures 1.15 SWR
Radio measures 1.3-1.4 SWR

Here is NanoVNA measurement looking into the tubes but thru the L network.


Fun for a first try and usable. Seems like I missed 50 ohms but SWR is close.? I think my inductance measurements are off.

--

*Cheers,* Signature

Jim Ball?? KK4NOZ

Be sure to do a reset, before doing the cal.

Is correction (based on the calibration) enabled in the menu?

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

Hello user group,
I just realized having a problem with calibration OPEN

Going through the device calibration process and everything goes well and I save data at Cal-x

However when I check S0 on SmithChrt it doesn't show OPEN correctly.
The marker should be far right at infinite. However it circles somewhere between 50@ and infinite.

It does not matter if I clibrate directly on the SMA connectors or having a cable in between, effect is the same.
It also doesn't matter whether I leave S0 completely open or having an OPEN-standard connected.

Is something wrong with that device, or does someone know that effect?

PHISHING EMAIL ALERT

Some entity appears to have scraped the email addresses of NanoVNA forum members and are sending emails supposedly with a link to Dropbox.

If you click the link, it asks you to login to Dropbox with one of several email addresses - IT'S ALL FAKE.

You can stick whatever garbage you want into the login fields and you will be 'logged-in' and shown a business PDF document.

Please DELETE any messages that appear to come from forum members directly unless you confirm they were sent by that member.

I just received one supposedly from Alan Victor but you might see these appear from myself or others - just delete them.

Thanks,
Larry Rothman

From: Richard Perlman

Several comments about buying the larger screen. However, all I can find are the 2.8" screen versions. Where/How can I find the larger version -- or, is the 2.8" screen the larger version?
===============================

Richard,

The large screen device is a nanoVNA-F which has a 4.3-inch screen, and their official store is here:



There are some comparative photos in a presentation I did recently:



Cheers,
David
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

The issue is not the VNA, but rather? your lack of undertsanding as to how antennas perform/function.The way you have it set up, the outside of the coax shield and your VNA are part of the antenna structure. You would be well served to get a copy of the ARRL Antenna Handbook.Dale W4OPSent from my Galaxy Tab? E

Several comments about buying the larger screen. However, all I can find are the 2.8" screen versions. Where/How can I find the larger version -- or, is the 2.8" screen the larger version?

Great thanks for you answers!! I think I understand things much better now.
Yes, the radiating emlement is parallel to the ground plane in this setup for reducing space, but it can be changed to perpendicular.
I ordered some ferrites and also will increase the distance between VNA and antenna.
I'll tell you how the modification works...

Bernd

Hi,
I am facing similar in fact worst situation. Just using the same coaxial cable you showed in your picture and connecting to its end a 20 cm bare copper wire (that I am planning to use as an antenna) to measure its impedance, or even connecting this bare copper wire directly to CH0 through an SMA connector. Moving my hand around the nanoVNA, and trying to tap on the LCD changes significantly the readings on the nanoVNA. My nanoVNA has no shielding inside it. So, may be this is making things worst.

Seems from the replies that this an expected behavior, and I should connect the antenna under test through a long cable to keep it away from the nanoVNA.