soil conductivity map of the US
If you like other people¡¯s measurements, you might like
a map of ground conductivities of the US at ¡°broadcast band¡± frequency.
(Chuck KF8TI)
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On 7/21/20 3:47 PM, Chuck wrote: I do work for an SDR developer whose radios span < 1MHz to > 18GHz. We have all the "good gear" for test and measurement because our customers often insist on it.
That said, below 500Mhz there isn't enough noise introduced in a 'finger tight' SMA to worry about. As you get into higher frequencies there are two problems that introduce errors, the first is that the small "gaps" between the threads form an insufficient shield resulting in RF leakage around the connector. The threads shouldn't make any difference in leakage on an SMA. The mating surface is the shield, and the threads are just there to "push" the connector together tightly. After all, there are SMA feedthrough barrels (Jack/Jack) that are "D" cross section, so the threads aren't even continuous. It is true that manufacturing tolerances may make a connector that isn't flat and perpendicular, particularly on the Plug side when you're using 0.141" compression connectors, where the semirigid shield might stick up and interfere with the mating a bit, if it wasn't trimmmed just right. The easiest way to see/measure/characterize this that I have found is to use a near field EMC probe attached to sensible LNA and hooked into a nice spectrum analyzer. Then walk the Specant through the frequencies with a 4000MHz bandwidth window (to avoid raising the noise floor too much) and look for spurious signals. Once you've scanned, turn off the device under test and scan again. Then turn on the device and scan a third time. Repeat the exercise with the connector tightened to the specification.
If your experience is similar to mine, you will observe a variety of spurious signals that are observable in the two cases. The "big" spurs in my experience are from leakage (your RF signal is leaking out between the threads) and spurs from your connector acting as a mixer and generating harmonics.
Given that the output of the NanoVNA that I've measured is < -25dbM, and that the sampling width of the ADC is small, it is unlikely that you will see any difference between DC and 1GHz with a finger tight SMA connection. Cheap connectors might have tolerancing issues (and those are likely with NanoVNAs which are a cost sensitive market- the two thru cables that came with mine - one doesn't smoothly mate - you have to get it started coorrectly) I agree though, finger tight or wrench snug is probably good enough.
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Re: NanoVNA firmware user interface mod
#mods
On Sun, Jul 19, 2020 at 06:07 PM, DMR wrote: OneOfEleven,
If possible, add more markers as in the earlier version. 3 is small.
And an item in the tracks menu -- LogMag S21 and SWR --
Thank! I haven't added the graph/trace type you wanted, but I have made it so that you can now have two separate graphs on show at the same time so that you can choose whatever combination you like DMR, I think that's better than me trying to add all the combinations possible.
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I do work for an SDR developer whose radios span < 1MHz to > 18GHz. We have all the "good gear" for test and measurement because our customers often insist on it.
That said, below 500Mhz there isn't enough noise introduced in a 'finger tight' SMA to worry about. As you get into higher frequencies there are two problems that introduce errors, the first is that the small "gaps" between the threads form an insufficient shield resulting in RF leakage around the connector. The easiest way to see/measure/characterize this that I have found is to use a near field EMC probe attached to sensible LNA and hooked into a nice spectrum analyzer. Then walk the Specant through the frequencies with a 4000MHz bandwidth window (to avoid raising the noise floor too much) and look for spurious signals. Once you've scanned, turn off the device under test and scan again. Then turn on the device and scan a third time.
Repeat the exercise with the connector tightened to the specification.
If your experience is similar to mine, you will observe a variety of spurious signals that are observable in the two cases. The "big" spurs in my experience are from leakage (your RF signal is leaking out between the threads) and spurs from your connector acting as a mixer and generating harmonics.
Given that the output of the NanoVNA that I've measured is < -25dbM, and that the sampling width of the ADC is small, it is unlikely that you will see any difference between DC and 1GHz with a finger tight SMA connection.
--Chuck
AI6ZR
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Re: Useful frequency range of NanoVNA H-4?
They are TOKO 5HT filters. The tuning element is a ferrite with a slot in the top of it. I don't know if the e-mail allows photos, but I attached one. I did the full OSLT cal and stored it in one of the memory slots. I was using the native NanoVNA instrument, no computer connected. How high is the NanoVNA H4 frequency supposed to go> Zack W9SZ On Tue, Jul 21, 2020 at 2:44 PM David Eckhardt <davearea51a@...> wrote: How are the resonators tuned? Screws through a soldered-in-place nut do
not make a good solid contact. I've tried it many times at both 1296 and
the H1 line (1420.405 MHz), and the result is unstable. However, if this
were the case, I'd also expect the S11 measurement to be unstable. If this
technique is used, a lock nut is required (which makes proper adjustment
even more 'tricky').
Did you complete and store the full OSLT cal? Are you using the native
NANO instrument or Saver on a PC/lap?top?
Yea, I know. More questions than answers.......??
Dave - W?LEV
On Tue, Jul 21, 2020 at 8:17 PM Zack Widup <w9sz.zack@...> wrote:
I thought I'd use my NanoVNA H-4 to tweak a 3-pole helical filter for 1296
MHz that I have for a transverter. The helical filter is mounted on a pc
board with SMA input and output. I calibrated the NanoVNA for 1280 to 1320
MHz and connected the filter to it. The NanoVNA displayed s11 as I expected
(a good dip which I could adjust to 1296 MHz). However, the s21 did not
display what I expected. I expected a response that a normal bandpass
filter would have. Instead, I had pretty much a straight line for s21
across the frequency range that fluctuated with each reading.
Is the performance poor at 1296 MHz?
Zack W9SZ
<
Virus-free.
www.avast.com
<
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
--
*Dave - W?LEV*
*Just Let Darwin Work*
<> Virus-free. www.avast.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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Re: Useful frequency range of NanoVNA H-4?
I love it. One question spawns many more, the number of questions
increasing in excess of the geometric progression, 1, 2, 4, 8, 16......
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Jul 21, 2020 at 8:55 PM <david.hostetler@...> wrote: What bandwidth are you expecting? At least one triple resonator 1296 MHz
filter that I have seen recently is wider than the 40 MHz you are sweeping.
What loss is the S21 indicating? What is it bouncing between?
--
*Dave - W?LEV*
*Just Let Darwin Work*
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Re: Determination of Soil Characteristics with Nanovna
On 7/21/20 12:03 PM, Juan Pablo EA4CIV wrote: This may help you
Juan Pablo
EA4CIV
This is the open-wire line approach first described by George Hagn. Rudy Severns isn't so wild about it. He uses a probe and ground screen approach.
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Re: Determination of Soil Characteristics with Nanovna
Hi all
I cant thank you enough for all the helpful replies I have received
In retirement I seem to have become a historian! See QRZ.com
My interest in ground electrical properties stems from my researches into the Phantom Regiment of WW2 and especially the communications problems of the Battle of Arnhem. Many books and papers have been written and I think I have read them all!
I was especially interested in Brian Austin's papers which lead me to examine the contribution of the soil characteristics at Arnhem. However the more I look the more complicated it gets. In the 1970's Longmire has shown that both conductivity and the dielectric constant of soil not only vary with moisture content at a particular site but both vary with frequency!
Thanks so much again
John Moyle G1AWJ
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Re: Useful frequency range of NanoVNA H-4?
What bandwidth are you expecting? At least one triple resonator 1296 MHz filter that I have seen recently is wider than the 40 MHz you are sweeping.
What loss is the S21 indicating? What is it bouncing between?
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Re: Useful frequency range of NanoVNA H-4?
How are the resonators tuned? Screws through a soldered-in-place nut do
not make a good solid contact. I've tried it many times at both 1296 and
the H1 line (1420.405 MHz), and the result is unstable. However, if this
were the case, I'd also expect the S11 measurement to be unstable. If this
technique is used, a lock nut is required (which makes proper adjustment
even more 'tricky').
Did you complete and store the full OSLT cal? Are you using the native
NANO instrument or Saver on a PC/lap?top?
Yea, I know. More questions than answers.......??
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Jul 21, 2020 at 8:17 PM Zack Widup <w9sz.zack@...> wrote: I thought I'd use my NanoVNA H-4 to tweak a 3-pole helical filter for 1296
MHz that I have for a transverter. The helical filter is mounted on a pc
board with SMA input and output. I calibrated the NanoVNA for 1280 to 1320
MHz and connected the filter to it. The NanoVNA displayed s11 as I expected
(a good dip which I could adjust to 1296 MHz). However, the s21 did not
display what I expected. I expected a response that a normal bandpass
filter would have. Instead, I had pretty much a straight line for s21
across the frequency range that fluctuated with each reading.
Is the performance poor at 1296 MHz?
Zack W9SZ
<
Virus-free.
www.avast.com
<
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
--
*Dave - W?LEV*
*Just Let Darwin Work*
|
Useful frequency range of NanoVNA H-4?
I thought I'd use my NanoVNA H-4 to tweak a 3-pole helical filter for 1296
MHz that I have for a transverter. The helical filter is mounted on a pc
board with SMA input and output. I calibrated the NanoVNA for 1280 to 1320
MHz and connected the filter to it. The NanoVNA displayed s11 as I expected
(a good dip which I could adjust to 1296 MHz). However, the s21 did not
display what I expected. I expected a response that a normal bandpass
filter would have. Instead, I had pretty much a straight line for s21
across the frequency range that fluctuated with each reading.
Is the performance poor at 1296 MHz?
Zack W9SZ
<>
Virus-free.
www.avast.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
|
Re: Determination of Soil Characteristics with Nanovna
This may help you
Juan Pablo
EA4CIV
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I saw a comparison of Nano vna with expensive devices, the graphs are very similar! So no need to kill the brain of radio amateurs!
This device is made for them!
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This thread is degenerating into a here is why everyone asking questions is stupid.
All those with such great knowledge have made their point and need to move on. Those of us without great knowledge in digital measuring instruments are reading this to improve our understanding and ability as an Amateur Radio Operator.
Help us do that. Do not repeatedly put down our questions on significance and caution. Or our desire to not prematurely damage the equipment we have invested in.
73
de KEoZUW - John
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Show quoted text
On Jul 21, 2020, at 3:24 AM, Dave_G0WBX via groups.io <g8kbvdave@...> wrote:
You're going to need something *Very Much* better than even the best
NanoVNA to do those tests!
Horses for courses, why would you use a ?50 "analyser" (that does work
amazingly well) for any reallyencritical measurements? Torquing or not
the cheap Chinese SMA connectors on them isn't going to make any
difference you can readily tell, but if wiggling the cable/connector
causes the trace to move, something needs looking at..
Plus, you'll need phase stable cables, and metrology grade calibration
standards too. A bit pointless, considering how the NanoVNA can drift
over even a short time in some circumstances.
But otherwise, yes, if you're using a metrology grade
HP/Agilent/Keysight/R&S etc analyser, cables and adapters etc, it can
make or break a test. But, even one metrology grade connector is going
to cost you way more than even the most expensive NanoVNA varient, while
the analyser will probably be worth (new) more than a container load of
NanoVNA's.
And just so it is said, you can over-torque connectors too, after which,
even for day-to-day utility use, they are often no use any more at
anything above 50MHz.
Don't get me wrong. The NanoVNA is a truly amazing bit of kit for the
price, but a "Measuring" instrument it is not.
73.
Dave G0WBX (who for a crust, wrangles RF to 10's of GHz, and many kW's,
sometimes at the same time!)
--
Created on and sent from a Unix like PC running and using free and open source software:
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Re: Intro and Noob Question
Will it run under Windows 10 64 bit, and if so how? Command line entry??
Thanks
Darrell
N5FTW
Sent from my over-rated IPhone 7 Plus. Any Mis-spellings or grammar errors are due to my IPhone auto correct feature.
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Show quoted text
On Jul 21, 2020, at 01:20, mike.carden <mike.carden@...> wrote:
?On Tue, Jul 21, 2020 at 3:14 PM Charles Albert <cma_1956@...> wrote:
Will the (various) software packages for PC run under Linux (Mint 20 to
be exact), perhaps using WINE, or are there Linux versions out there
that I have missed?
Hi Charles.
Nanovna-saver is a Python app which runs pretty much everywhere. I run it
on Fedora Linux but any fairly modern Linux will work.
Just visit github and choose the download/install method that suits you
I just clone the git repo and run the application with python3.7 and it
works a treat.
--
MC
VK1MC
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Re: NanoVNA firmware user interface mod
#mods
One more question.
Is it possible to enable the color command?
I modified the color of the strokes a little and I would like to do the same on your FW.
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Re: nanoVNA vs nanoVNA-F vs nanoVNA-H What is the difference??????
On Mon, Jul 20, 2020 at 11:24 AM, Mark Schoonover wrote:
I'd start with the wiki: /g/nanovna-users/wiki
Thank you! I didn't know there was a wiki. I could not find one using due duck go; I guess I just didn't use the proper verbiage to get where I wanted to be. larry
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Re: nanoVNA vs nanoVNA-F vs nanoVNA-H What is the difference??????
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Re: NanoVNA firmware user interface mod
#mods
Thank you OneOfEleven !!
I have now tested nanoVNA.exe because I had not yet tested it. I liked the software, it has all the necessary information.
Perhaps the slightly larger letters would help (mouse information).
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Re: Intro and Noob Question
Mint 20 is "a bit new", so you may have to fiddle somewhat, as I did to
get it working on Mint 19.3.
In the end, I commented out Line 17 in the main .py file!? (I forget the
name, not in front of that PC just now)? It starts up and runs fine
after that...?? (Some warning file dependency, that seems not to be
needed.? I didn't dig any further, the program runs without complaint or
issue..)
Otherwise, the documented install/build procedure went fine.
Make sure your logged in user persona, is a member of the "dialout" group.
??? sudo adduser $USER dialout
And use your login password when asked.
($USER is a system variable containing your logged in username.)
You can use:
??? dmesg | tail
to find out what /dev/ttyUSBx has been assigned to the NanoVNA when
you've connected it.? The software makes a guess, but on my system, the
guess was wrong.? Pointing it at the correct device, and it all sprang
to life.
73.
Dave G0WBX.
--
Created on and sent from a Unix like PC running and using free and open source software:
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Chuck
Juan Pablo EA4CIV
John Nicholas
Darrell Carothers
Igor - PY3IG