Re: Determination of Soil Characteristics with Nanovna
The soil conductivity and permittivity change with frequency and over a very small area. Rudy Sevens wrote a paper on how to model a low dipole over ground and then change the ground characteristics with a VNA and by this method get the numbers you want. These numbers will only be good for the area very near the test antenna. There is no reliable way to measure these characteristics with ground probes. Rudy also has a paper on measuring the ground with ground probes but found that you get differing readings by moving the probes only a few feet.
Roger K7RXV
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On 7/20/2020 3:43 PM, John Moyle wrote: Hi
I am new to the Nanovna and I apologise if this question has be asked before.
I want to measure soil conductivity and relative permittivity.
Are there standard electrode dimensions and positioning?
I am studying ground wave and NVIS propagation.
Any advice appreciated.
Thank you
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Re: NanoVNA firmware user interface mod
#mods
Great, now you can set minimum and maximum in SWR, now it works.
There are also many markers, more than three. It is perfectly. I only use this program. it is very stable, I would say, it works for me without a single freeze, unlike others.
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John,
Thanks. Nice to read that it is possible what I was looking for. Sure.
I discovered that it is possible to position the reference point not only on the gridlines, but also between them.
However I expected that only integers 0...8 were allowed.
It might be more intuitive when the existing Reference button changes its name into Reference Position
and a new button in the menu is added with the text Reference Level.
Then the Reference Postion button accepts only integer values between 0 and 8 and the Reference Level button accepts any real value between, for example,-99.0 and +99.0 (dB).
The chosen Reference value for the (active) channel should then be visible anywhere along the edge, outside the grid of the display.
In this way you can show the trace how you want it in combination with the scale setting (scale/div).
If I have it right you now can select any real value for the scale/div as well.
I think it should then be more intuitive to select from fixed values like (0.1, 0.2),1, 2, 5, 10, or 20 dB/div.
One of these values are then visible on top of the display.
I have described the LOGMAG but I can imagine that something like written above can also be made for the other formats.
During a lot of years I have used several type of Scalar- and Vector Network Analyzers.
With that experience I tried to play with this NanoVna-H4 as the operation of the buttons is concerned.
May be it is worth to give it a chance for implementation in the NanoVna-H4.
Is it worth to add the limits of what you may use for that selection at the input field of the num. keyboard?
I have tried to choose a number for the display brightness. Finally I tried 2000,
but is it not more intuitive to select from 1 to 5 as an example?
At the moment I see there always a big integer value with one red digit. Have these a special meaning?
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On Mon, 20 Jul 2020 16:19:34 -0400, you wrote: Is anything more than finger tight really necessary?
Aldo
W2AGC
Yes. Finger tight leaves small gaps around the fittings which act as HF cavities. The material has to be stressed into plastic deformation, which limits the number of installs to ten times for one particular SMA connector-jack pair. That's what the specs say. N connectors can be mounted 30 times. Also with torque wrench, but the mechanical function is better than SMA. Nobody uses SMA for serious HF. Use SMB, for example. OE8UWW
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As a mechanical engineer I have known about torque wrenches for years There
have been studies of their accuracy and it can be said that overall it is
generally +/- 50 percent. There are several factors r effecting this.
Thread condition including accuracy and finish. Cleanliness. Alignment.
Even more for bolted joints.
Industries requiring accurate tightening to meet tightness requirements and
stress levels in the joint use more sophisticated methods.
Admittedly most industrial applications are larger but the basics are the
same.
For my purposes I carefully align the sma ends and finger tighten until the
two seat together.
Paul Ostand, P.E.
W8SBH
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On Mon, Jul 20, 2020, 3:18 PM Dave Merrill <r390a.urr@...> wrote: Hello group,
I found this 8mm torque wrench on eBay:
It is factory preset for 0.59N-m which is just below the upper limit for
brass SMA connectors. It seems to do the job and the price is very
reasonable for the quality represented.
Might be worth a look. I have no relationship with the seller.
Dave N9ZC
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Usually, yes!
RF connectors that are insufficiently tightened usually work loose with even
trivial handling, leading to poor (and intermittent) shielding integrity, mysterious
resonance dips that come and go, etc. As you go higher in frequency problems
of this sort get worse.
Also, even if tight enough to avoid the above, finger tightened connectors are
not consistently tightened. Every connector adds a little impedance bump
whose details and severity depend on the degree of tightness and also gets
worse at higher frequencies. This leads to devastating difficulties if the cable in
question is used in critical metrology applications. The only way to minimize
such problems, especially at higher frequencies, is consistent tightening by
torque wrench.
I'll admit that I feel a bit uncomfortable tightening to specified maximum torque
with SMA connectors and often tighten to lesser torques. I get away with it only
because I'm not working anywhere near the rated maximum working frequencies
of the SMA connectors, and perhaps also have a personal guardian angel watching
over my affairs.
Note that SMA connectors as a family are extremely delicate and easily wrecked
by overtightening as well as by other seemingly-innocent misdeeds. SMAs have
a well-deserved reputation for very short life (expressed as tightening cycles).
Some say their life is only a handful of cycles; others do much better, probably due
to more careful handling and a certain knack for the medium.
The SMA's close cousin, the "3.5mm" connector, is quite a bit more robust and
I'd not be sorry to see SMAs go the way of the dinosaurs. At present the 3.5mm
connectors are quite a bit more expensive than SMAs, but I suspect that if made
in the quantities that SMAs currently are, their price would come down to not
much more than that of SMAs.
Dana
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This offer is just for the USA.
The rest of the world can buy for a similar price from:
THGS Mxita SMA drehmomentschl¨¹ssel RF stecker ?ffnung 8MM
It is also adjustable via 5 mm allen wrench (hexagon socket).
73, Rudi DL5FA
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Is anything more than finger tight really necessary?
Aldo
W2AGC
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On Mon, Jul 20, 2020, 3:18 PM Dave Merrill <r390a.urr@...> wrote: Hello group,
I found this 8mm torque wrench on eBay:
It is factory preset for 0.59N-m which is just below the upper limit for
brass SMA connectors. It seems to do the job and the price is very
reasonable for the quality represented.
Might be worth a look. I have no relationship with the seller.
Dave N9ZC
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Determination of Soil Characteristics with Nanovna
Hi
I am new to the Nanovna and I apologise if this question has be asked before.
I want to measure soil conductivity and relative permittivity.
Are there standard electrode dimensions and positioning?
I am studying ground wave and NVIS propagation.
Any advice appreciated.
Thank you
|
Hello group,
I found this 8mm torque wrench on eBay:
It is factory preset for 0.59N-m which is just below the upper limit for
brass SMA connectors. It seems to do the job and the price is very
reasonable for the quality represented.
Might be worth a look. I have no relationship with the seller.
Dave N9ZC
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Re: NanoVNA Saver 0.3.3 or 0.3.4
Can someone please send me the link to the Windows 10 64 bit Nano Saver 0.3.6 EXE file? Thanks *Clyde K. Spencer* On Sun, Jul 19, 2020 at 1:09 PM Enrique A. Wembagher LU8EFF < lu8eff@...> wrote: Perfect explanation !
Enrique
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Re: NanoVNA USB C connector is stuck
Anne, with your great sense of humor this will only be a minor setback.
From someone who can usually find their hammer.
Good luck!
Allen
KI4QCK
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On July 20, 2020, at 10:34 AM, n2msqrp <mstangelo@...> wrote: If this is a H4 model the plastic case overhangs the USB port and should be removed and filed down. If the stuck USB plug is with the H model I would dispose of the cable. The USB cable that was supplied with my H model was tight so I got rid of it and use a cable that is easily insert able. Mike N2MS
On 07/20/2020 12:37 AM John Nicholas < stnick@... > wrote:
Be careful with the case fouling the connector when you are plugging in. I
have had a lot of trouble with cheap
and expensive USB cords on my phone depending on the case.
73
de KEoZUW - John
On Jul 19, 2020, at 6:35 PM, G8DQX list < list@... > wrote:
There is not much case clearance, so there is a possibility of the plug
fouling the case, but it seems unlikely. More likely that the plug
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Re: NanoVNA firmware user interface mod
#mods
I've re-enabled SD card Igor, though this is the compile without the external 32k xtal enabled - for now.
I've not yet added the dual graph DMR wants, but will get there. I've done a lot of other updates though to the PC test software, all the graph min/max scales are now working and saved/restored - hopefully.
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Re: nanoVNA vs nanoVNA-F vs nanoVNA-H What is the difference??????
The answer is in the WIKI, see the link below in your mail.
A lot of answers are there.
Kind regards,
Arie
Op 20-7-2020 om 17:16 schreef Lawrance A. Schneider:
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Hello,
I have asked a number of individuals separately and received no replies.
I keep reading about new software, new firmware, new external options, new screen sizes, .....
BUT, what is the basic difference between the various nanoVNA's. Why choose one as opposed to another. Is there a table wherein they are compared. How do you choose intelligently?
I thank anyone having the curtesy to reply, larry
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Re: nanoVNA vs nanoVNA-F vs nanoVNA-H What is the difference??????
Larry, I'd start with the wiki: /g/nanovna-users/wiki73! Mark KA6WKE Latest Video: Website: On Mon, Jul 20, 2020 at 8:16 AM Lawrance A. Schneider < llaassllaaass@...> wrote: Hello,
I have asked a number of individuals separately and received no replies.
I keep reading about new software, new firmware, new external options, new
screen sizes, .....
BUT, what is the basic difference between the various nanoVNA's. Why
choose one as opposed to another. Is there a table wherein they are
compared. How do you choose intelligently?
I thank anyone having the curtesy to reply, larry
|
nanoVNA vs nanoVNA-F vs nanoVNA-H What is the difference??????
Hello,
I have asked a number of individuals separately and received no replies.
I keep reading about new software, new firmware, new external options, new screen sizes, .....
BUT, what is the basic difference between the various nanoVNA's. Why choose one as opposed to another. Is there a table wherein they are compared. How do you choose intelligently?
I thank anyone having the curtesy to reply, larry
|
Re: NanoVNA USB C connector is stuck
If this is a H4 model the plastic case overhangs the USB port and should be removed and filed down.
If the stuck USB plug is with the H model I would dispose of the cable. The USB cable that was supplied with my H model was tight so I got rid of it and use a cable that is easily insert able.
Mike N2MS
toggle quoted message
Show quoted text
On 07/20/2020 12:37 AM John Nicholas < stnick@... > wrote:
Be careful with the case fouling the connector when you are plugging in. I
have had a lot of trouble with cheap
and expensive USB cords on my phone depending on the case.
73
de KEoZUW - John
On Jul 19, 2020, at 6:35 PM, G8DQX list < list@... > wrote:
There is not much case clearance, so there is a possibility of the plug
fouling the case, but it seems unlikely. More likely that the plug
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Re: NanoVNA USB C connector is stuck
Thanks for replies.
Luckily I do not have a case , and that is the only reason I need to unplug it so I can build one.
The USB C connector went in with noticeable click.
Anne
PS
Not to worry , I cannot find the hammer.
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Re: NanoVNA firmware user interface mod
#mods
If it did save 6k of flash, I'd be able to add a proper small (minor flash size usage) spline interpolation routine that would be far better than linear interpolation, so I'll look at that then at some point DiSlord.
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Re: NanoVNA firmware user interface mod
#mods
On Mon, Jul 20, 2020 at 12:07 AM, OneOfEleven wrote: It's because their's not enough flash space in the CPU for everything at the
same time, 10k of flash is at the moment laying empty and wasted and unusable,
which is very bad really, it needs to be sorted. I can suggest one thing (want test result, but not found time for it): in code sin and cos functions used only in static void apply_edelay(void)
{
.......
float s = sin(w);
float c = cos(w); If you remove this use - it allow save ~6-7k flash. sin cos functions use big size tables for calculations, but i think possible use more small float value table for 1/4 round (possible use from fft.h) and made interpolate (yes error exist, but small, error noise more big).
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Aldo Cugnini
Dave Merrill
Arie Kleingeld PA3A