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On 10/3/21 5:30 PM, Roger Need via groups.io wrote:

From what I understand you are resetting the cal in the NanoVNA before connecting to NanoVNA Saver. When calibrating with the Calibration Assistant in the PC program NanoVNA Saver you should already have the NanoVNA calibrated over a range larger than the range you want. This was made clear by the the original author, Rune, in a post when he first released NanoVNA Saver. You can search the group for his post.

I'm not so sure about that.? The interface (over the USB) doesn't expose any way to know whether the nanovna is sending calibrated or uncalibrated data to NanoVNA-saver. The data command with arguments 2,3,4,5,6 allow dumping the calibration coefficients in use, so maybe you could infer whether the results returned by data 0 or data 1 are calibrated or not.

Therefore, the key is that the nanovna is in a state that matches the state it was in when the cal was done with NanoVNA-saver. You could "stack" calibrations, for instance.

In general, though, the cal tables in the nanovna are for the 101 data points (on the base unit), with interpolation used for frequencies not in the table. NanoVNA-saver, though, can store calibration tables with arbitrary numbers of points (it's using scikit-rf's implementation of calibration)

I would argue, then, that you should "reset" (i.e. remove) the calibration on the NanoVNA (since that's a known state) before doing the cal on NanoVNA-saver.

From what I understand you are resetting the cal in the NanoVNA before connecting to NanoVNA Saver. When calibrating with the Calibration Assistant in the PC program NanoVNA Saver you should already have the NanoVNA calibrated over a range larger than the range you want. This was made clear by the the original author, Rune, in a post when he first released NanoVNA Saver. You can search the group for his post.

Roger

Some preliminary results.

Connected two NanoVNAs using Ts (so the impedance at the ports presented to the external device is ~25 ohms).

See setup2.jpg - You can see the interference when one nanovna happens to sweep across the receiver of the other. So I'd suggest setting up the software driving the two nanovnas to sweep one at a time. (sweep3.jpg shows what it looks like with one sweeping, the other set to a fixed frequency)

Cal works fairly straightforward, - pause the sweep on one unit, do the cal on the other. Then swap.? With a python script this will be easy.

Now for some results - I happened to have a 10dB pad and a 21.4 MHz BPF to fool with.

10dB pad produces results about like you'd expect (10db.jpg) . Each VNA is set up for S11 (yellow) and S21 (blue trace).

So does the filter (filter1.jpg) .? Note the difference between the S11 looking into the filter with the other side of the filter open (filter2.jpg) and terminated (filter3.jpg).

Next step is to work out some code to systematize the cals and measurements. I'll probably just modify nanovna-saver, since it already uses scikit-rf, and that has the calibration algorithms built in.

After having done a 2-port BNC calibration from 100 kHz to 2 MHz with the Nano-H4 (version 0.5.0) then the CH1 LOG MAG =0.01...0.02 dB of the Cal Thru. Perfect!
When I connect the H4 to the PC and use Nano-Vna saver 0.39 then before I press Connect to Device I select the Cal menu on the H4 and press Reset.
Then I press Connect to device and select my frequencies (100 kHz to 2 MHz) with 1 or 4 segments.
In Sweep settings menu the Attenuator in port CH1 (s21) in dB = 0.
Then I press Calibration and press RESET. Calibration components show all UNCALIBRATED.
I am using the Calibration Assistant.
At the end of the calibration I press Apply. As a result the s21 curve of the Cal Thru is a horizontal line with a possitive value of 0.15 dB.
I repeat the calibration on the H4 and again the result of the Cal Thru is CH1 LOG MAG =0.01...0.02 dB.
After repeating the Calibration with Nano-VNA saver the result is the same as the first time a horizontal line with a possitive value of 0.15 dB.
Is 0.15 dB as a result for a (not removed) Cal thru a usual value or has it also to be 0.01...0.02 dB?
I had expected 0.01...0.02 dB in both cases.

Any idea?

Kees

On Sun, Oct 3, 2021 at 04:52 PM, Foxy Fox wrote:

Many of the motherboards of the televisions made by Vestel have such a
joystick. Definitely find one at TV repair shops.

Thank you but I fear, in the UK, finding a TV traditional repair shop will be harder than finding a switch ;-)

73
Brian

On Sun, Oct 3, 2021 at 03:50 PM, Jim Shorney wrote:

Here you go:



So cheap I bought an extra as a spare.

73

-Jim
NU0C

Thank you.

I've EMailed a friend in the US and asked him to buy a couple and pop them in the post- I will send the money via paypal, that will reduce the shipping!

Paying DHL etc $16 seems crazy ;-)

73
Brian
G8OSN

On Sun, Oct 3, 2021 at 07:39 AM, Brian Reay wrote:

The joggle switch was broken off. Initially, I hoped it would be possible to
reuse it but there the damage to the switch is worse than I initially thought
.
Thanks to another amateur, I was pointed here where I found evidence they are
available but no ready sources.

Can anyone recommend a source please? Ideally in the Uk but if overseas, so be
it.

Here is an overseas source for a direct replacement. Cost is less than a dollar and 2 week shipping is reasonable... FedEx or DHL if you need it real quick but costs a lot more.



Roger

Many of the motherboards of the televisions made by Vestel have such a joystick. Definitely find one at TV repair shops.

Here you go:



So cheap I bought an extra as a spare.

73

-Jim
NU0C


On Sun, 03 Oct 2021 07:39:44 -0700
"Brian Reay via groups.io" <g8osn@...> wrote:

I’m trying to repair a damaged NanoVNA for a family member.

The joggle switch was broken off. Initially, I hoped it would be possible to reuse it but there the damage to the switch is worse than I initially thought .

Thanks to another amateur, I was pointed here where I found evidence they are available but no ready sources.

Can anyone recommend a source please? Ideally in the Uk but if overseas, so be it.

It seems a shame to scrap the beast for want of a switch. I appreciate it can be operated via a PC etc but the owner likes to use it hand held as he experiments with antennas etc.

Thank you in advance & 73

Brian
G8OSN

I’m trying to repair a damaged NanoVNA for a family member.

The joggle switch was broken off. Initially, I hoped it would be possible to reuse it but there the damage to the switch is worse than I initially thought .

Thanks to another amateur, I was pointed here where I found evidence they are available but no ready sources.

Can anyone recommend a source please? Ideally in the Uk but if overseas, so be it.

It seems a shame to scrap the beast for want of a switch. I appreciate it can be operated via a PC etc but the owner likes to use it hand held as he experiments with antennas etc.

Thank you in advance & 73

Brian
G8OSN

I have ordered two batches of boards from JLCPCB for the QEX September/October 2021 “Miniature SMA Step Attenuator” pp 9-21 by Tom Alldred VA7TA. There is a quantity of excess PCBs available. I do not anticipate that I will place another order, but I will continue to accept orders until my supply is gone.

More information is available on my web page

I expect to receive the second set boards near the end of October. The first board orders will be mailed next week about October 5, 2021.

Dick K9IVB

On 9/27/21 12:58 PM, Jim Lux wrote:

I'm trying to control a second nanovna (identified as HW V3.5. FW version 1.0.45) with nanovna.py and I'm getting an error



jimlux$ ./nanovna.py? --start 1000000 --stop 2000000 --points 201 -o test9 --port 0
{'rawwave': None, 'plot': False, 'smith': False, 'polar': False, 'delay': False, 'groupdelay': False, 'vswr': False, 'phase': False, 'unwrapphase': False, 'tdr': False, 'scan': False, 'start': 1000000.0, 'stop': 2000000.0, 'points': 201, 'port': 0, 'device': None, 'verbose': False, 'capture': None, 'command': None, 'save': 'test9'}
[]
1000000.0 2000000.0 201
set_frequencies 1000000.0 2000000.0 201
Traceback (most recent call last):
? File "./nanovna.py", line 422, in <module>
??? n.write_touchstone(opt.save)
? File "/Users/jimlux/opt/anaconda3/lib/python3.8/site-packages/skrf/network.py", line 1958, in write_touchstone
??? + c2str_A(self.s[f, 0, 0]) + ' ' \
IndexError: index 100 is out of bounds for axis 0 with size 100


works fine on an older version of the firmware on a different device.

I suspect there's some command that's being sent (or not being sent).

Before I start digging in, if anyone has had a similar issue, what was it...


Here's a good run (FW version 0.4.5-1)


jimlux$ ./nanovna.py? --start 1000000 --stop 2000000 --points 201 -o test9 --port 0
{'rawwave': None, 'plot': False, 'smith': False, 'polar': False, 'delay': False, 'groupdelay': False, 'vswr': False, 'phase': False, 'unwrapphase': False, 'tdr': False, 'scan': False, 'start': 1000000.0, 'stop': 2000000.0, 'points': 201, 'port': 0, 'device': None, 'verbose': False, 'capture': None, 'command': None, 'save': 'test9'}
[]
1000000.0 2000000.0 201
set_frequencies 1000000.0 2000000.0 201
(base) MT-211249:nanovna jimlux$

Turns out that the new firmware doesn't support the "port" command. I'm not sure if it's useful anyway, I think it was tied to the dump raw samples, which is also removed.?? you still need the --port %d on the command line, because that's how you distinguish between S21 and S22 for an output file.

I'm trying to control a second nanovna (identified as HW V3.5. FW version 1.0.45) with nanovna.py and I'm getting an error



jimlux$ ./nanovna.py? --start 1000000 --stop 2000000 --points 201 -o test9 --port 0
{'rawwave': None, 'plot': False, 'smith': False, 'polar': False, 'delay': False, 'groupdelay': False, 'vswr': False, 'phase': False, 'unwrapphase': False, 'tdr': False, 'scan': False, 'start': 1000000.0, 'stop': 2000000.0, 'points': 201, 'port': 0, 'device': None, 'verbose': False, 'capture': None, 'command': None, 'save': 'test9'}
[]
1000000.0 2000000.0 201
set_frequencies 1000000.0 2000000.0 201
Traceback (most recent call last):
? File "./nanovna.py", line 422, in <module>
??? n.write_touchstone(opt.save)
? File "/Users/jimlux/opt/anaconda3/lib/python3.8/site-packages/skrf/network.py", line 1958, in write_touchstone
??? + c2str_A(self.s[f, 0, 0]) + ' ' \
IndexError: index 100 is out of bounds for axis 0 with size 100


works fine on an older version of the firmware on a different device.

I suspect there's some command that's being sent (or not being sent).

Before I start digging in, if anyone has had a similar issue, what was it...


Here's a good run (FW version 0.4.5-1)


jimlux$ ./nanovna.py? --start 1000000 --stop 2000000 --points 201 -o test9 --port 0
{'rawwave': None, 'plot': False, 'smith': False, 'polar': False, 'delay': False, 'groupdelay': False, 'vswr': False, 'phase': False, 'unwrapphase': False, 'tdr': False, 'scan': False, 'start': 1000000.0, 'stop': 2000000.0, 'points': 201, 'port': 0, 'device': None, 'verbose': False, 'capture': None, 'command': None, 'save': 'test9'}
[]
1000000.0 2000000.0 201
set_frequencies 1000000.0 2000000.0 201
(base) MT-211249:nanovna jimlux$

NanoVNA have L/C Match function (Marker->Measure->L/C Math in last firmware)
This function calculate how compensate measured impedance to 50 Om

Albert,

My take... When one talks of distributed circuits like a coax cable or
waveguides, the space (and time) origin to solve the Maxwell equations must
be set: in the case of guided propagation like in the coax/waveguide
examples, the propagation occurs in one direction (along the cable) and the
fields are essentially solved on the (x,y) plane where they stay the same
because they do not propagate.

Since the measurement the NanoVNA offers is ideally under steady state
conditions (where the solution to the Maxwell equations is not too
complicated), the reference plane can be thought of as the point in space
along the direction of propagation where the phase of the incident signal
is set to 0.

Hope it makes sense, it's a nice question!

Thanks,
Luciano



On Sat, Sep 25, 2021, 11:23 AM kk7xo via groups.io <kk7xo=
[email protected]> wrote:

As far as I can tell, calibration is done at a single point in a circuit.
A plane suggests two dimensions, and that anywhere on that two dimensional
object, the calibration is the same. But everyone knows that even for a
solid copper plane, only one point can be considered 0 volts, and every
other point on that plane has resistance, inductance, and capacitance
relative to that one point.
So, why do people talk about the "plane" of calibration, rather than the
point of calibration?

73 de Albert KK7XO

You could define it as a POINT on the Smith Chart (the impedance coordinates or the mag and angle of the reflection coef at that point).

Hi Albert,

Just so you know your question posted although you didn't ask who does not use the NanoVNA with waveguides. I have no need of waveguides at the frequencies where I live.

73,

Bill KU8H

bark less - wag more

OK, I buy this. So another question, how many of you use the NanoVNA with waveguides?

de Albert KK7XO

It's a two-dimensional boundary separating two three-dimensional regions, hence "plane".

Phil M1GWZ

There are actually two charts as you can see overlaid, usually in two colors to assist reading. The chart on your vna is the Z plane chart. After rotating it 180 degrees it becomes an admittance chart. Upon over laying the 2 charts, the composite chart is referred to as the IMMITANCE chart. The charts Together facilitate conversion of series complex impedances to parallel complex admittances. That process in it self assists in simple impedance matching or transforming Z from one level to another. There is a simple algebra proof and manipulation of converting a series circuit to its parallel equivalent. The chart does the process graphically. However, it is worth going through the math once to see how it develops. Then I think you will understand better the MOTIONS on the chart as you add series and shunt elements to build a match network.