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nanovna-saver v0.4.0 binary release
OS Ubuntu 22.04 64bit

After doing a calibration in nanovna-saver I can apply it OK and then when attempting to save the calibration it will cause nanovna-saver to crash.

error:
****
(nanovna-saver:123904): Gtk-WARNING **: 12:33:33.004: Could not load a pixbuf from icon theme.
This may indicate that pixbuf loaders or the mime database could not be found.
**
Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /usr/share/icons/Yaru/16x16/status/image-missing.png: Unrecognized image file format (gdk-pixbuf-error-quark, 3)
Bail out! Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /usr/share/icons/Yaru/16x16/status/image-missing.png: Unrecognized image file format (gdk-pixbuf-error-quark, 3)
Aborted (core dumped)


The file /usr/share/icons/Yaru/16x16/status/image-missing.png does exist and displays OK for a regular user.

Any suggestions?

TIA
Glenn VE9GJ

I use my 4' Pickett when I need real precision.

Hey, that's a greedy slide rule! It wants money! One dollar to pose for a photo. How much does it ask to calculate a square root? :-)

Hi Dave
Thanks for the input. Yes you are correct, this switch does have both "antennas" configured as an X and they are both always connected.
The switch is based on the work of I8CVS. I should have included the link in y original post.


The antennas I am using are the Wimo X-quad so both antennas are offset by zero degrees.


This is very much a learning exercise for myself. I will need to obtain some more BNC to sma jumpers or adaptors to do some more testing.
I also started using nanovna-saver and getting some crashes but that will be a separate post.

73
Glenn VE9GJ

I was an organic chemistry major and graduated with my BS in the late-60s long before electronic calculators. (We had honking-big Marchant mechanical calculators in a room somewhere in the building and they were almost always occupied at most convenient hours and the next best calculator was the slide rule.)
I had an organic quant prof who expected us to be able to hold our writing instrument in one hand and hold a slide rule in the other and do the math with his exams timed with that capability in mind without ever putting either down.. He even had sessions after his classes instructing in the proper use of the "slip-stick" and ways to achieve greater precision which he expected to be at least 2 significant digits approaching 3 which was about the width of the scribes on the rule. In fact, I believe he claimed there was some relationship between the precision of those scribes and the capability of the slide rule but I can't recall his rule. Of course, he advocated a circular slide rule as the better choice over a linear slip-stick as it was far more compact for the precision. I have a small Fullerton 1450, 85mm circular in my desk and a slightly larger one in my go-bag which I keep against the time when the revolution starts. I had a K&E about 2.5 inches wide, a wooden - not bamboo - slide rule that got stuck when humidity was high, a couple of Dietzgens, Pickets, etc. I wish I had any one of those to show my sons and their kids - they wouldn't believe how such arcane devices landed us where we are now.
Of course, the E6b is nothing but a special purpose circular slide rule which scares many student and novice pilots but I felt quite comfortable with it during pilot training and still keep one handy in the cockpit.
So ends my paean to the lowly but powerful mechanism of the "bad old days".

So this switch actually has BOTH antennas connected ALL the time for ALL modes, so the nominal 3 dB loss from the input to each antenna is present at all times. Be sure to terminate the antenna connector not being measured for good results. Their assumption is that the crossed antennas are mounted in an X with respect to the horizon rather than a plus (+). On the website you linked they have VNA measurements for each mode and both antennas. If the driven elements are located at the same point on the boom, the feedlines should be the same length, but the length isn't critical. If they are offset (which is common), you will need to adjust the feed line to one of the antennas so the phase matches the at the switch antenna connectors.

On 2022-08-11 21:25, Jim Lux wrote:

On 8/11/22 12:13 PM, Glenn VE9GJ wrote:

?I recently finished building some Sat antenna polarity switches. (2M and 70CM)
They switch between Horz, Vert, RH or LH polarization.
I think all is OK but how would I use a nanovna to confirm that they are within spec? I am still a naonvna beginner and have not tried to measure anything like this before.
TIA

This unit takes a single feedline from the Tx/Rx to two antenna ports.
In linear pol, it should be a straight feed through one of the two
antenna ports, with the other port terminated (or open, I couldn't
find a schematic).
So it's kind of like doing it with an ohmmeter.
Let's call the outputs H and V.
First test, CH0 of VNA to Tx/Rx port. LOad on H, Ch1 connected to V.
Set the switch to V-pol, you should see |S21| nearly 0dB loss, and
|S11| as a "good match". Disconnect the load on H. You should see no
change. Put the load back on.
Now select RCP - you should see S21 decrease by about 3dB (because
half the power goes to each output), and there will be some phase
shift. Record that number.
Select LCP, Should see the same S21 as RCP, but the phase will be
different, record that number.
Put the load on V, and Ch1 on H output.
Select H pol - should see low loss, good match
Select V pol - should see no power, but good match (looking into the load)
Select RCP, should see S21 go down by 3 dB, and the phase shift should
be either identical to what you measured on the other port, or be 90
degrees different (it depends if you're driving a crossed yagi that's
offset by lambda/4 or if it isn't)
Select LCP, see S21 same as for RCP, but the phase shift is flipped or
the other 90 degrees relative to what you measured last time.

Thanks for the great explanation Jim! I think I understand what to do now as your instructions make sense to me.

73
Glenn VE9GJ

On 8/11/22 12:13 PM, Glenn VE9GJ wrote:

?I recently finished building some Sat antenna polarity switches. (2M and 70CM)
They switch between Horz, Vert, RH or LH polarization.
I think all is OK but how would I use a nanovna to confirm that they are within spec? I am still a naonvna beginner and have not tried to measure anything like this before.
TIA

This unit takes a single feedline from the Tx/Rx to two antenna ports. In linear pol, it should be a straight feed through one of the two antenna ports, with the other port terminated (or open, I couldn't find a schematic).
So it's kind of like doing it with an ohmmeter.

Let's call the outputs H and V.

First test, CH0 of VNA to Tx/Rx port. LOad on H, Ch1 connected to V.
Set the switch to V-pol, you should see |S21| nearly 0dB loss, and |S11| as a "good match". Disconnect the load on H. You should see no change. Put the load back on.

Now select RCP - you should see S21 decrease by about 3dB (because half the power goes to each output), and there will be some phase shift. Record that number.

Select LCP, Should see the same S21 as RCP, but the phase will be different, record that number.

Put the load on V, and Ch1 on H output.
Select H pol - should see low loss, good match
Select V pol - should see no power, but good match (looking into the load)

Select RCP, should see S21 go down by 3 dB, and the phase shift should be either identical to what you measured on the other port, or be 90 degrees different (it depends if you're driving a crossed yagi that's offset by lambda/4 or if it isn't)

Select LCP, see S21 same as for RCP, but the phase shift is flipped or the other 90 degrees relative to what you measured last time.

I recently finished building some Sat antenna polarity switches. (2M and 70CM)
They switch between Horz, Vert, RH or LH polarization.



I think all is OK but how would I use a nanovna to confirm that they are within spec? I am still a naonvna beginner and have not tried to measure anything like this before.

TIA
Glenn VE9GJ

Thats nice. Its sliderule week.

On Thu, Aug 11, 2022 at 9:47 AM Rebel Thompson <hamnotspam@...>
wrote:

I use my 4' Pickett when I need real precision.

I use my 4' Pickett when I need real precision.

Yes, that is the application of SWR circles on the Smith Chart. For
example, any combination of R and ±jX so long as it lies on that 2:1 circle
(real radius intersects at 25 and 100-ohms), the SWR / VSWR / ISWR will be
2:1. Same for any SWR circle on the chart.

Dave - W?LEV

On Thu, Aug 11, 2022 at 4:28 PM Manfred Mornhinweg <manfred@...>
wrote:

Addition to my previous post:

Whether you display the results on a Smith chart, or a standard XY chart,
or a table, or whatever, doesn't matter at all! What matters is what you
are displaying: SWR, or impedance.

A Smith chart allows to see both of them. Depending on where you place the
NanoVNA in the line, the trace will appear rotated due to the impedance
changes, but with the same shape and center, indicating same SWR per
frequency. Diehard Smith chart users, please correct me if I'm wrong in
that, because I'm only an occasional Smith chart user!

--
*Dave - W?LEV*
*Just Let Darwin Work*


--
Dave - W?LEV

Addition to my previous post:

Whether you display the results on a Smith chart, or a standard XY chart, or a table, or whatever, doesn't matter at all! What matters is what you are displaying: SWR, or impedance.

A Smith chart allows to see both of them. Depending on where you place the NanoVNA in the line, the trace will appear rotated due to the impedance changes, but with the same shape and center, indicating same SWR per frequency. Diehard Smith chart users, please correct me if I'm wrong in that, because I'm only an occasional Smith chart user!

SWR measurement can be done at any point of the line, even over a wide frequency range, and will be correct except for effects produced by line loss. The impedance instead will vary according to line length, or to the location of the measurement.

This is the basic concept that needs to be remembered: Impedance (R and X) varies along a mismatched transmission line, while the SWR stays constant except for parasitic effects like line loss.

Manfred

those are nice. you still have manual for one.

Martin
N6QLH

On Thu, Aug 11, 2022 at 9:09 AM Manfred Mornhinweg <manfred@...>
wrote:

Well, here is mine! Complete with plastic case, original cardboard
packing, and instruction manual!

Replaced in 1982 by a Sharp EL-507 scientific calculator, which I still
use...

Manfred, XQ6FOD

Well, here is mine! Complete with plastic case, original cardboard packing, and instruction manual!

Replaced in 1982 by a Sharp EL-507 scientific calculator, which I still use...

Manfred, XQ6FOD

All I remember is any good math teacher had a massive K&E slide rule hanging from the ceiling in the class room. More functions on it than most of us ever used at least in undergrad work.

And then in 1972 I paid over $100 for a digital calculator at our local W T Grant store just to do my taxes that year. With red LED readouts. Wow! I was on top of the world. Just starting my medical internship…. Didn’t make much and could have done it all (taxes) by hand but just had to have it and gave a weeks worth of income to get it. My future mother in law offered to let me use her Victor crank adding machine but I was above that old cranky thing. And one of the surgeons I was working with had a new watch with the red LED numbers but he had to push a button on the side to see the time and it cost a ton more….. he was upscale too!

Dave K8WPE

David J. Wilcox’s iPad

What kind of battery does it use, and where do you put it in? I hope they took the battery out years ago or it will be all corroded. Ha! Wish I had kept mine but being a poor student needed cash all the time and sold whatever I wouldn’t need in the future.

Dave K8WPE
David J. Wilcox’s iPad

Not so. In a 50 ohm system you can measure swr with a bridge or the nano at
any point between tx and the antenna.

It's true for the SWR

This is true at a fixed frequency but the nanaoVNA works at a variable frequency; it follows that the shape on the Smith is not the same over the length of the coaxial. It comes from the fact that all the points do not turn at the same angle since the wavelength is not the same for each of the points.

The modification is all the more important as the strip is wide and the coaxial long.

Is this correct?
--
Fran?ois

-----Message d'origine-----

De la part de tuckvk3cca
jeudi 11 ao?t 2022 11:01

Good, now take a current probe and do the same and you will get and ISWR. They are reciprocals. Once upon a time there was a myth that you must measure your antennas swr at the feedpoint. Not so. In a 50 ohm system you can measure swr with a bridge or the nano at any point between tx and the antenna.