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Date
Re: New member intro

 

Hi Ben -

what was going on here
Please check out the Wiki
/g/nanovna-users/wiki
New member intro

Ben Hall
 

Good morning all,

Just signed up for the list and thought I'd introduce myself. Name is Ben Hall, ham call KD5BYB. Was introduced to the NanoVNA buy an article on the RTL-SDR blog talking about an e-book on Amazon for the NanoVNA. The article also mentioned an upcoming NanoVNA 2.0 with additional frequency range. I was floored when I saw the specs of the original NanoVNA on Amazon and had to know more! So I joined up to the list to see what was going on here. :)

Thanks much and 73,
Ben, KD5BYB
Re: Interpreting TDR, aka when to worry #nanovna-saver #tdr

 

NanoVNA can do the TDR measurement without external software
FWIW, the Wiki main page /g/nanovna-users/wiki/home#Documentation
now clarifies that measurement techniques and tips are collected here:
/g/nanovna-users/wiki/Application-Notes
Re: Re : NanoVNA-Saver Linux update procedure

 

On Fri, Jan 17, 2020 at 11:03 PM, Bob Larkin wrote:

Nick, might your issue with PyQt5 be the installation of that package, not a
Python3.6 (source language) issue?
Bob

Yes it is an issue with installing PyQt5==5.14.1 on LM19.3 (and other distros from what is reported here).

I have not used Python3.6 for any of my tests, only Python3.7.

73
Nick
Re: Re : NanoVNA-Saver Linux update procedure

 

On Fri, Jan 17, 2020 at 07:28 PM, Denis Collins wrote:

Thanks again for the hack
Thank you for your results Denis.

The final post here



indicates that pip 19.3.1 fixed the problem on Debian Buster, whereas it didn't for you.

Built nvna-a 0.2.2 with python 3.7.6 on Win7 x64 (mingw64) first with pip 19.2.3 then pip 19.3.1. Everything including PyQt5==5.14.1 was installed without a hitch!

Do not know what to make of all this. Will do more tests.

73
Nick
Re: Connectors on RF Test Board leads

 

IF you need a little more flexible test board, take a look on SDR-Kits :

Not all software functions of the DG8SAQ software can be used, but the supplied experiments can also be done with a NANO-VNA. The Training slides needs some basic RF knowledge to follow: it is not fully "entry level". So I would recommend a look into the slides and the assembly instruction before ordering.

There is no need to go to high frequencies (>100MHz) to understand the functionality of an VNA. The standard measurement functions and limitations get already visible on the lower frequencies.

vy73 de Karsten, DD1KT
Re: Interpreting TDR, aka when to worry #nanovna-saver #tdr

 

Hello Chris,

the NanoVNA can do the TDR measurement without external software (Firmware updated last year November) :

- CH0 Real (Display-> Format -> more-> Real), Smith
- Display -> Transform -> Low Pass
- Transform on
- Velocity factor to be defined in % e.g. 0.6 = 60% (is needed to determine the right distance)

In the attachment a twisted pair cable with 50Ohms Termination was measured.
The 103 Ohms is compared to the ~150 Ohms determined by L (shorted) and C (open) a bit low and the 50Ohm return not perfect, but it can be used as indicator for line impedance changes.

One comment to your mesurement:
"8) Comet duplexer and antenna"

The VNA TDR measurement consists of calculating results of a frequency sweep. For this the cable should have the same impedance for the hole frequency range used in the measurement. This is not the case with having an antenna at the End of the cable. Best would be to replace the Antenna with 50 Ohms Termination to measure the cable!

This is the difference to TDR measurements with the reflection method, where steep short pulses are used for the measurement.

vy73 de Karsten, DD1KT

twisted_Kabel_50_TDR.png

Re: Interpreting TDR, aka when to worry #nanovna-saver #tdr

 

On Fri, Jan 17, 2020 at 07:43 PM, Chris Prosser wrote:

" My return loss measurement is just fine, -35dB at 2m, -55dB at 70cm. So...do I care? "
====================================================================

If you your concern is the impedance measurements; then no, I wouldn't. care. The NanoVNA-saver impedance plot tends to stack impedances and both Rune and Sali (the originator of the impedance algorithm) are working towards future solutions. So far the only program that accurately returns NanoVNA TDR impedance measurements is written in MATLAB, but the functions used are not available in the language (Python) that NanoVNA-saver is written in.

- Herb
Re: Interpreting TDR, aka when to worry #nanovna-saver #tdr

 

Hi Chris,

Somehow it looks like your 30ft length(5) is not lmr-400. On both ends the jump in impedance as well as the reflection do not match.
Could you try to measure just the 30ft peace?

The return loss might be good depending on the position. Just 1/4 wavelength more and it might be very poor.

Eric
Interpreting TDR, aka when to worry #nanovna-saver #tdr

 

Hi Folks,

A hats off to everyone who has contributed to the NanoVNA. I got mine last week and what a fantastic tool for the cost.

I'm trying to understand the TDR measurements. I've attached a plot from my setup. You can easily see the following parts:
1) This is the SMA->UHF cable, about 1M long.
2) impedance bump from the connector
3) 10ft of cable in the shack
4) female uhf barrel connector through a door
5) 30 ft of lmr-400
6) female to female connector
7) 10 more feet of lmr 400
8) Comet duplexer and antenna

My return loss measurement is just fine, -35dB at 2m, -55dB at 70cm.

So...do I care?

thanks!
--chris
ki7dln

TDR-cheap-yagi.png

Re: could use a little help with getting Nano Saver to work with my NanoVNA

 

Oristo wrote:
Scroll down to the "Drivers" section
/g/nanovna-users/wiki#Drivers
(SHHHH!!!! If they scroll down, they might, by sheer luck or perhaps chance, see some of the other topics. This cannot be a bad thing....)

--
wes will
n9kdy
Re: Add FAQ document to the Wiki or Files section #faq

 

I was thinking more of a FAQ page with numbered contents that hyperlink to the appropriate content within the page.
The only way that I have found for hyperlinks to content within
groups.io Wiki pages is by
not only forcing those entries to be headings, but also forcing (IMO
ugly) table of contents on each of those pages.
Re: Nano VNA

 

From the link at the Wiki section:


It states that top frequency range is 900MHz:
Some day, I will get around to updating that.

--------------------------------------------------------------------------------------------------------
nanoVNA-H commercialized by Hugen reduced cost and enhanced usability

working LiPo
refined touch screen
better PCB layout, RF shielding
third harmonic operation 300-900MHz
Touchstone file export
standalone PC software
--------------------------------------------------------------------------------------------------------

According to this it seems the 1.5GHz top frequency for the H version was not
implemented since the beginning, but was rather a later improvement?
Even some genuine Hugen devices cannot overclock to 300mHz,
so firmware was updated with console command `threshold`
for altering 300mHz to whatever value t<=300 works for any given device.
QRP added firmware to warn when a device threshold is unstable.
Another firmware hack enabled operation beyond 3*t,
by switching to 5th harmonic (I blame erik and QRP),
although most 'Hugen classic' and clone devices crap out around 1200MHz
for reasons other than clock generation.

I would assume there might still be earlier legitimate H units out there being
advertised as 900MHz top frequency, specially by non tech savvy sellers.
Most sellers are not tech savvy and may stock and ship multiple versions from multiple sources.
Many of us received devices that did not match sellers' images,
and some listings include images of more than one version.
Re: could use a little help with getting Nano Saver to work with my NanoVNA

 

Scroll down to the "Drivers" section
/g/nanovna-users/wiki#Drivers
Re: Re : NanoVNA-Saver Linux update procedure

 

On Fri, Jan 17, 2020, Rune Broberg wrote:

So 3.7 it is, though it might work with 3.6 - I
just don't test it with that. :-)

Thanks, Rune. A quick update as I push the simple laptop idea is that Python 3.6 continues to show no problems, but Python 3.5 will NOT work, as (for at least one) it does not support "type hints"

Nick, might your issue with PyQt5 be the installation of that package, not a Python3.6 (source language) issue?

I think that 3.6 will be fine for what I need to do. More later.

Bob W7PUA
Re: could use a little help with getting Nano Saver to work with my NanoVNA

 

Ray, W4BYG wrote:
Herb,
Thank you for taking the time to respond to my query.
I am running the latest 64 bit, Win 7. The USB cable is the one that came with it. It does charge OK.? I assume it is good.
/g/nanovna-users/wiki/Home

Scroll down to the "Drivers" section. Look under the "Drivers" heading for the "Installing the STM32 Virtual COM port drivers" subtopic. Instructions and links to the Win7 drivers and install routines are there along with "completion" messages and other hints.

--
wes will
n9kdy
Re: could use a little help with getting Nano Saver to work with my NanoVNA

 

Ray,

Check the Wiki for this group and it will point you to the drivers you need for Win 7 or Win 8.1...

Roger
Re: could use a little help with getting Nano Saver to work with my NanoVNA

 

Herb,
Thank you for taking the time to respond to my query.

I am running the latest 64 bit, Win 7. The USB cable is the one that came with it. It does charge OK.? I assume it is good.

So my further question is can you be more specific?? Can you advise which driver for Win 7 and where it can be found?? My Nano version is v 0.2.3-2-g8ac9166, build Oct 18, 2019.
Ray, W4BYG

On 1/17/2020 4:04 PM, hwalker wrote:
On Fri, Jan 17, 2020 at 11:26 AM, Ray, W4BYG wrote:

NanaoSaver 0.2.2 loads up OK and the VNA boots fine but can't seem to get it to connect.
===========================================
Ray,
Getting NanoVNA-saver to work on some systems seems to be a topic begging for a FAQ section. The problem happens not only on Windows OS, but judging from the volume of messages the past few days, on the LINUX OS too.

Windows 10 should not require you to install any additional drivers and NanoVNA-saver should automatically detect your NanoVNA, if it is already powered-on when start the NanoVNA-saver executable. If you are running Windows 10 and your NanoVNA is not being detected then the first order of business should be to check your USB cable. If you are sure the cable is not a fault then report back and we can try to help you from there.

If you are running Windows 7 then installation can be more problematic. Of course you want to also verify your USB cable connection, but several users have also reported needing to upgrade to the latest service pack and install the correct 32-bit or 64-bit STM drivers.

- Herb


--
They say a smart person learns from their mistakes. A
wise person learns from the mistakes of others.
Re: Add FAQ document to the Wiki or Files section #faq

 

willing to be proved wrong
The FAQ at /static/help appears to be classic HTML, not wiki.
Something similar could implemented e.g. by linking to HTML source at github with multiple collaborators
Re: Add FAQ document to the Wiki or Files section #faq

 

On Fri, Jan 17, 2020 at 01:11 PM, Oristo wrote:

It could be implemented as a file e.g. in /g/nanovna-users/files
.. but I guess that implies a single FAQ owner/hero (certainly not I).
===============================================
Oristo,

A document file would probably not work for the same reason the Wiki and Files section don't get utilized the way they should, that is there is no hyper-linked TOC that allows members to easily pinpoint the subject matter they are looking for.

I was thinking more of a FAQ page with numbered contents that hyperlink to the appropriate content within the page. That how most OEM sites construct their FAQ pages. I'm not a web page designer so I don't have any idea as to how such a page would be put together but I definitely, along with other members, would be happy to provide and update content. For content that is already available in our Wiki and Files section hyperlinking to that content would not be duplication of effort but more ensuring efficient use of that content and less unnecessary bandwidth in the message section.

You and Larry have contributed so much of your free time to this forum and most members don't realize it. I was hoping someone else with experience designing a FAQ page might step up to the plate with ideas.

- Herb
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