Moderated
Re: Another off-topic about Smith chart
Hi all, A bit late in posting this, but to all those who are just starting out, and having a learning curve approaching the Smith Chart, I have put together an introductory article.? You can find it here: 73's Aldo W2AGC
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On 3/27/2020 9:39 AM, Aldo Cugnini via Groups.Io wrote: Exactly. The real axis coordinates are scaled as (1+¦£)/(1-¦£), i.e., the real part of the normalized impedance Z_L / Z_o .
-- Aldo
On 3/26/2020 8:52 PM, WB2UAQ wrote:
The Smith Chart is a plot of the reflection coefficient where it's magnitude covers 0 to 1 having a phase angle from 0 to 360 degrees (0 to 2pi radians) (vector....mag and phase angle).? The impedances, the three circles, correspond to mag and phase of the reflection coefficient.? Basicallya these three circles are over laid onto the reflection coefficient.
I agree that it is not easy to be very accurate.?? Tough to mark and read off the impedance coordinates in many places on the chart.
--
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*Aldo Cugnini*
/908-867-8550/
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Moderated
Re: Another off-topic about Smith chart
Exactly.? The real axis coordinates are scaled as (1+¦£)/(1-¦£), i.e., the real part of the normalized impedance Z_L / Z_o .
-- Aldo
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On 3/26/2020 8:52 PM, WB2UAQ wrote: The Smith Chart is a plot of the reflection coefficient where it's magnitude covers 0 to 1 having a phase angle from 0 to 360 degrees (0 to 2pi radians) (vector....mag and phase angle). The impedances, the three circles, correspond to mag and phase of the reflection coefficient. Basicallya these three circles are over laid onto the reflection coefficient.
I agree that it is not easy to be very accurate. Tough to mark and read off the impedance coordinates in many places on the chart.
--
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*Aldo Cugnini*
/908-867-8550/
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GREAT Article, Aldo - Thanks!
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On Friday, March 27, 2020, 9:31:15 a.m. GMT-4, Aldo Cugnini <acugnini@...> wrote:
Hi all,
A bit late in responding, but to all those who are just starting out,
and having a learning curve approaching the Smith Chart, I have put
together an introductory article.? You can find it here:
73's
Aldo
W2AGC
--
------------------------------------------------------------------------
*Aldo Cugnini*
/908-867-8550/
|
Hi all,
A bit late in responding, but to all those who are just starting out, and having a learning curve approaching the Smith Chart, I have put together an introductory article.? You can find it here:
73's
Aldo
W2AGC
--
------------------------------------------------------------------------
*Aldo Cugnini*
/908-867-8550/
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this can also be a solution. The problem is not with nanovna, but with the pc operating system. If you know google you shouldn't have asked the question here.
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i had this issue after a windows update,had to use system restore then it was ok,that was using win 7 64 bit.
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after removing it, install the driver, don't wait for your computer to look for a driver.
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Hi Claudio, I think you should read and apply this: /g/nanovna-users/message/7284You may also need to reboot your PC and nanovna. (Turn off then turn on.) Hope this helps. 73, Gyula HA3HZ
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Hugen Can I suggest you use the same values of R25 and R24 in the attenuator circuit for the CH1 input as those used in for the reference SA612? And then set R22 to come to 50 ohm? This will reduce the amount of calibration deduced compensation needed for S21 measurements and thus noise. Interesting you found the unbalance less noisy. In my experiments I found the balanced less noisy. Not sure why????. Possibly because I was doing experiments on an unshielded PCB and we have rather strong DAB and mobile phone signals here and in a balanced configuration these could be eliminated because of the SA612 differential input???? -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
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thanks Hugen!
but unfortunately I haven't a spare cable and can't go out to buy one: thanks COVID-19! hahaha
I checked the socket and it's OK: I didn't need to enlarge the hole of the case.
Claudio
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Moderated
Re: Another off-topic about Smith chart
In the immortal words of Arte Johnson...verry interesting...
In over 20 + replies only handful actually answered or came close to answer my question.
As of now , here are MY observations.
The Smith chart scale is logarithmic - from "zero" to 1 and from 1 to "10" .
(The boundaries / end points can be labeled to your liking - zero or infinity - computer does identify log(0) as "inf".)
The "accuracy" of computer generated chart is as good as the actual graphical display.
Coding the graph "circles" - using OpenGL (C) - is not trivial when dealing with values approaching "infinity".
( But that is definitely off topic subject here ).
Appreciate all comments.
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Moderated
Re: Another off-topic about Smith chart
The Smith Chart is a plot of the reflection coefficient where it's magnitude covers 0 to 1 having a phase angle from 0 to 360 degrees (0 to 2pi radians) (vector....mag and phase angle). The impedances, the three circles, correspond to mag and phase of the reflection coefficient. Basicallya these three circles are over laid onto the reflection coefficient.
I agree that it is not easy to be very accurate. Tough to mark and read off the impedance coordinates in many places on the chart.
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Another solution comes from the suggestion of Massimo. Changing the input of SA612A to single-ended can eliminate the influence of the capacitance of one of the input pins. Maybe this modification is more appropriate, I am testing.
¡°
R22 = 68 ohm 0603 1% resistor
R23 = 0ohm 0603 shunt
R24 = 120ohm 0603 1% resistor
R25 = 22ohm
Note that it has changed form differential to single ended, just because it was a nonsense. The driving signal of the SA612D mixer was in-phase on both sides of R25, so there was no advantages using that configuration. I found this configuration less noisy indeed and best matching the CH1 input port impedance for higher frequencies, that thanks to the higher value of R22 that is the one which influence more the capacitive behaviour of the CH1 input port trought the mixer input capacitance.
¡±
hugen
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Is the USB cable faulty? Try replacing the USB typeC cable.
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Re: Analysing Input Impedance Matching Circuit for the NE602
Kerr,
I was curious to see what would happen if the turns count was reduced to 7 from 8. The results were better with an improvement in S11 and S21. I have attached some plots showing the difference. I then made measurements with a 3.26k resistor on the secondary which is an approximation to the impedance of your NE602 in balanced mode.
Regards - Roger
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Moderated
Re: Another off-topic about Smith chart
OP: For technical topics, Wikipedia is actually pretty good. Case in point, I think this link directly answers your question.
TLDR, it's a Mobius transformation. That's kinda cool! Maybe it was mentioned, but I don't remember that description in six+ years of University. (BS+MS in USA)
No matter if you learned the Smith Chart on a computer last week, or you derived it in crayon in kindergarten, I think with both the impedance and admittance plots in red and green it's an awesome Christmas decoration.
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Re: NanoVNA-V2 from Tindie - First impressions
Hello and thanks for your update.
Could you please share some more photos and details of the V2?
Waiting for it also.
And nanovna-saver will be updated to make it compatible with the V2, once
the developer has his own unit and time :)
All the best!
*73 de Lu¨ªs, CT2FZI*
*QRV @ 145.300 MHz | **CQ0VMST (VHF REP Monsanto)*
<>
<>
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On Thu, 26 Mar 2020 at 20:24, Wolfgang Kiefer <woki@...> wrote: Today the parcel has arrived. Connected to a PC (Micro USB plug), it runs
without problems.
A 50 Ohm load connected, tested the frequency limit: very impressed - 4.5
GHz are displayable. Good results until 3.5 GHz.
New functions: maximum and minimum search of the cursor. Screef flip
(rotates 180 degrees). Three dip switches instead of the jog. (Very small.)
Unfortunately the NanoVNA- Saver does not connect to the new device. But
there is another solution (see the pictures). It is called VNA_QT.exe.
My resumee: For about 60 € a very good deal!
Wolfgang Kiefer
DH1AKF
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I received the H4 a few days ago.
I played with it in a "stand alone" configuration (not connected to the PC) and it worked very well.
than I connected it to my PC to charge the battery and did not noticed that the PC was loading a driver...and disconnected it!
PC gave the alarm that the driver was not succesfully loaded.
I connecte the H4 again and checked the device manager: actually a driver "STMsomething" was there...but not operational.
I tried to reinstall it looking both in my PC and than in the net, but no way to find a good one.
so I deleted the driver, switched off the H4 and rebooted the PC to start again.
but when I reconnected the H4 I got the "error 43" message: unknown device.
no way to make the PC recognize the H4.
OS. win7 home
H4: firmware 4.0.5-7 -g57d62f2 built time:01.01.2020.
I also connected the H4 to another PC running win10PRO with the same result: "error 43"...
I am a little desperate!
best 73
de
i2NDT Claudio
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Re: NanoVNA-V2 from Tindie - First impressions
hallo Liber Wolfgang, wie gehts dir.....
60€ mit versand? alles ?
danke!
Em qui., 26 de mar. de 2020 ¨¤s 21:24, Wolfgang Kiefer <woki@...>
escreveu:
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Show quoted text
Today the parcel has arrived. Connected to a PC (Micro USB plug), it runs
without problems.
A 50 Ohm load connected, tested the frequency limit: very impressed - 4.5
GHz are displayable. Good results until 3.5 GHz.
New functions: maximum and minimum search of the cursor. Screef flip
(rotates 180 degrees). Three dip switches instead of the jog. (Very small.)
Unfortunately the NanoVNA- Saver does not connect to the new device. But
there is another solution (see the pictures). It is called VNA_QT.exe.
My resumee: For about 60 € a very good deal!
Wolfgang Kiefer
DH1AKF
|
Re: NanoVNA-V2 from Tindie - First impressions
Today the parcel has arrived. Connected to a PC (Micro USB plug), it runs without problems.
A 50 Ohm load connected, tested the frequency limit: very impressed - 4.5 GHz are displayable. Good results until 3.5 GHz.
New functions: maximum and minimum search of the cursor. Screef flip (rotates 180 degrees). Three dip switches instead of the jog. (Very small.)
Unfortunately the NanoVNA- Saver does not connect to the new device. But there is another solution (see the pictures). It is called VNA_QT.exe.
My resumee: For about 60 € a very good deal!
Wolfgang Kiefer
DH1AKF
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Aldo Cugnini
Gyula Molnar
Roger Need
CT2FZI
Wolfgang Kiefer
