开云体育

I was fortunate enough to get some high-quality PTFE (Teflon) coax (RG-174
sized) SMA to BNC jumpers - and these hold up much better, probably because
they have a small piece of heat-shrinkable tubing at the interface between the
connector and the cable which distributes stress over a larger area

These have heat shrink (one layer) twice the length of crimp ferrules;
34cm is longer than typically needed,
so splurged another ~ US$6.50 on four more with 15cm length.

A source for durable pigtails would be good to know.

Rich,

Current calibration is calculated per frequency point so no relation whatsoever with any other point in the scan.
See here:
/g/nanovna-users/wiki/Application-Notes
for the harmonic switch frequencies

I do see however very different behavior once the nanoVNA switches to harmonics mode but this does not influence the regular calibration currently implemented.

At low frequencies the bridge correction model is fairly easy as its impact is in sync with the rotation of the S11 angle. At higher frequencies the observed impact gets out of sync with the observed S11 angle so I am wondering what mechanism causes S11 impact depending on a cable (the rotation speed versus frequency is roughly proportional with the length of the cable) but with a different rotation speed?
I'm observing a sin(f)*e(f) effect
Could this be the cable capacitance????
--
Erik, PD0EK

Install the antenna on the working position

How distant is working position?
USB extender up to 150ft costs < US$10

On Sun, Nov 3, 2019 at 04:07 PM, Clint Turner wrote:

If I could, I would put more heat-shrinkable tubing on them, but this is
difficult with the already-attached connectors.

I have used two alternatives: wrappable heat shrink and Silicone Rubber Self Fusing Tape. The tape come in different thicknesses and widths. A life-saver during some high-altitude balloon missions, because it goes on by itself in the field.
Not as much luck with the wrappable stuff, but if you have some shrink tubing with a high shrink ratio, you can pre-wrap with other material, the slide a larger sleeve over. I have done this, and admit that it can look clunky, but function wins over form for me here.
--
On the banks of the Piscataqua
Rich NE1EE

The ability to resize to fit the display would be a great improvement. My laptop has a 17" display running at 1600x900 but still have the scroll bar for vertical position of the chart. It would be nice not to need to modify my screen settings.


Thank you for all the hard work you put into the software for the Nanno VNA.

73,

Wes
WA5TKU

This may be because it doesn't work on v6x, or maybe the authors have not
configured the page correctly?

The author does not own older Android, so configured the app support for his versions.

you are probably correct, my older android is ver7

On Thu, Oct 31, 2019 at 01:50 AM, Alex OE3JTB wrote:

Tried to install on my Droid running v6x, and the Play page says that it is not compatible. This may be because it doesn't work on v6x, or maybe the authors have not configured the page correctly?
Any suggestions, besides rooting my device?

--
On the banks of the Piscataqua
Rich NE1EE

On Sun, Nov 3, 2019 at 08:34 AM, <erik@...> wrote:

VNA 1 (nanoVNA) seems at low frequencies to have a Z0 that best matches the
impedance of the cables but shows a substantial deviation above 600MHz

I am new to VNAs, but have wondered during these past few weeks as I experimented with my NanoVNA-H if it is better to calibrate /within/ the 3 bands that use different harmonics.
0-299MHz
301-599MHz
601-900MHz
I suggest this, because I don't know where the Nano switches modes, and staying within the harmonic bands should guarantee that each cal uses a single harmonic. I do all my cals this way, and don't see a penalty, because as a ham, I don't expect to use the same antenna for HF and (example) U/VHF. I think that I need to recal for each geometry anyway, so no point trying to cal to the whole bandwidth.

I see all these traces, and it strikes me that we are looking at a sin(f)*e^(-f)...that is, some sort of sine wave response that decays exponentially. Just a guess...but still wonder what you results would be in each of the 3 Nano harmonic bands.
--
On the banks of the Piscataqua
Rich NE1EE

On Sun, Nov 3, 2019 at 04:41 PM, Rune Broberg wrote:

I think maybe the Windows 10 task bar is a few pixels more than the Windows
7 one?

I park my taskbar on the left, because most screens these days have lots more pixels in width than in height, and I auto hide the taskbar.This is especially useful when running several fldigi apps (flmsg, etc.) and onscreen oscope.
--
On the banks of the Piscataqua
Rich NE1EE

No. nanovna-saver is written in python, it runs anywhere you can get
python.
I use it on my linux systems.
Shouldn't be hard to add an interval timer to it.

However, I've thought that maybe it would be interesting to make a stripped
down version that is just a panel full of buttons to trigger recording data.

On Mon, Nov 4, 2019 at 07:02 AM, Rich NE1EE wrote:

How about connecting a Pi or summat running *nix and Python.

I like nanovna-saver, but that runs only on Windows? And I don't know that it has an interval timer for data acquisition.
--
On the banks of the Piscataqua
Rich NE1EE

On Thu, Oct 24, 2019 at 09:47 AM, Martin wrote:

Is it possible to take a sweep & capture with the standalone Nano VNA then
connect to NanoVNA Saver at a later stage and download the previous sweep
parameters for display ?

How about connecting a Pi or summat running *nix and Python. Not an expert w either one, but have tinkered w the Pi (and others, such as Propeller)

and did a lot of high-altitude (near-space) data acquisition.

So maybe this is a low-cost alternative? Prolly the Pi//Linux/Python (I guess that I should learn Python...sigh) could be running some sort of loop that acquires data at intervals? This is what I did with the Propeller, and the Pi is higher up the food chain.
--
On the banks of the Piscataqua
Rich NE1EE

Hi Larry, Erik, Jim,

Thank you very much for your replies, seems what I am after is possible but not as straight forward as I had hoped. Well, need to find the time to experiment a little and see how far I get.

73 Elia,
M0ZHN

I see that I am not the only one who wants to know how to contact developers. I looked on github, but didn't twig to the usefulness of this feature. Oristo replied to another post with this suggestion.

If latest firmware release does not behave as wanted, then add an issue, e.g.,



Thanks to Oristo for this tip to us newbie GitHub users.
--
On the banks of the Piscataqua
Rich NE1EE

On Thu, Oct 24, 2019 at 12:35 PM, Oristo wrote:

If latest firmware release does not behave as wanted,
then add an issue, e.g.
( )

Thanks for this tip...I have been wondering how to provide feedback and recommendations to developers.
--
On the banks of the Piscataqua
Rich NE1EE

Hi Rune,

Could I also add a request to be able to change the size of the markers on the graphs.

When larger line and plot sizes are used, it can become difficult to see the actual markers.

Thnaks,

Martin - G8JNJ

Thank you Oristo.
I'm not sure how to press pause when the unit is hanging on the antenna up
in the air, that's the reason I think a *scheduled *one scan+pause will do
it.
To clarify my request, let's imagine the following sequence:

1. Prepare the scheduled scan on the NanoVNA (for example set delay 10 min)
2. Connect NanoVNA to the antenna
3. Install the antenna on the working position
4. Wait for the scan+pause to start/finish
5. Bring antenna down and save the data from the NanoVNA via USB

I know there's another solution to this problem: to calibrate NanoVNA with
a piece of cable long enough to reach the antenna in the working position.
However, I think the measurement with NanoVNA connected directly to the
antenna would be more accurate.

Hi Ady

regarding saving the scan and download it later, I think a nice firmware
feature would be to schedule a delayed scan followed by a pause after the
scan.

This is already possible using

This will allow to hang the NanoVNA to the antenna (for example HF multiband
dipole like FD4, or VHF YAGI) and perform a scan without the feeder.
The delayed start of the scan is necessary to allow enough time to install the
antenna in the position.

Not sure why delaying start is necessary; scans until pause are discarded.
Only the final scan before pause is available to upload when USB is reconnected.

G=m/s

The results of this exercise appear to confirm your conclusion in that paper.
I am amazed by how close they agree with those of the full one-port cal and
that of your mini-equation.

That works when short and open results are similar and load signal is small.
Small load signal is generally easy for resistance bridge at low frequencies,
not so much for reflection bridge and higher frequencies.

Open = short works better for nearly no distance from bridge to DUT,
not so well for real cables of some length.