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Re: First PCB pictures of the V2
Didier Juges
On Thu, Jan 2, 2020 at 01:38 PM, Mel wrote:
Have you tried to solder the resistors upside down such that the resistive element is on the same plane as the trace? I have not tried it but it seems that it would improve the behavior of all low value resistors connected to transmission lines. Just a suggestion, maybe not easy to implement in practice with automated assembly unless you have the parts re-reeled. Didier -- Didier Juges KO4BB.com |
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
Herb,
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I fully agree with your comments,? the NanoVNA is an excellent device and definitely on the money, I read on giithub that Hugen even has idea's to improve the impedance of CH1 !! When hardware changes are neccessary for that (component changes) , I wonder if I dare to open this nice case. Best Regards Jos Op 26-1-2020 om 14:25 schreef hwalker: On Sun, Jan 26, 2020 at 04:38 AM, Jos Stevens wrote: |
Windows 10 Python scripts
#consolecommands
#scripting
For driver documentation testing, I installed Python 3.7.6 from
Windows 10 Microsoft Store. Unlike much Windows software, Microsoft Store only installs apps separately for each user on a PC. This allows duplicating bugs: 1) the installed pip hangs after successful completions, requiring e.g. [Ctrl]+[C] This is addressed by: python -m pip install -U pip (requiring Ctrl+C after e.g. "Successfully installed pip-20.0.2") ... also, to run scripts e.g. for nanoVNA: pip install pyserial pip install numpy pip install pillow 2) My scripts, which worked on both older and newer versions installed from other sources were broken by this Python version. That was addressed by changes pushed to GitHub: If folks are interested in a version of screenV.py for Hugen's larger H4 screens, as modified by Herb Walker: /g/nanovna-users/message/10096 .. let me know what name is wanted for that bigger screen script. Now, for the >>really weird<< part. The first few times this screen copy script is run, after changing "COM3" in screenV.py to your virtual COM port, e.g. python screenV.py foo .. it will hang, because this Python version will not return enough data. This is repeatable by adding another Windows 10 user and reinstalling Python from Microsoft Store... If you want, this can be observed in screenV.py by commenting line 61 and uncommenting lines 62-65. The workaround: * Ctrl+C and rerun the script a few times until it DOES work. After a first success, the script always works thereafter..??!! Bottom line: * despite its popularity, Python is neither robust nor stable. |
Re: characteristic impedance
On Sun, Jan 26, 2020 at 04:51 AM, Andy UA3RAW wrote:
Herb, it seems to me that a half-way around the smith chart is 1/4 wave length. Isn't it? ))) ========================================================================= Andy, You may be able to put it in better terms than I did, as I was only parroting back what I understood from the original poster. I have only used smith charts sparingly in my career. The key thing that stuck in my mind was the original poster saying the 1/8 method started from the same position as a short on the first revolution around the smith chart. Since the actual method has always worked for me I didn't give it any deeper thought. If the terminology I used needs correcting please add to the discussion so I can correct my notes and not perpetuate incorrect information (i.e. if that point is 1/4 wave length why is it called the 1/8th method). - Herb |
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
Oristo,
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Thanks for your information abt. the serial port, actually I am using a version 3.1 comport and sofar I saw no problems in comunicating with theNano VNA-H4 , with the firmware as supplied by Alibaba. This problem was sollved by executing a new device stand alone calibration and saving it to CH0 of the device. Best Regards Jos Op 26-1-2020 om 14:03 schreef Oristo: it appears that at start NanoVNA-Saver is using the C0? calibration ofYesNanoVNA, untill now I thought these calibrations were independant.No, USB serial communication from nanoVNA to Python is not reliable for |
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
On Sun, Jan 26, 2020 at 04:38 AM, Jos Stevens wrote:
"This is an eye opener for me, it appears that at start NanoVNA-Saver is using the C0 calibration of NanoVNA, untill now I thought these calibrations were independant." - It always helps to get a different perspective from someone else. Especially true when you are doing everything "right" and you still get unexplainable results. "I just made a new 100 Segs calibration. Please see the attached results." - Your after calibration thru results are definitely on the money. " NanoVNA-H4 is a great device, just the CH1 impedance could be a bit better and the enclosed 50 Ohms standard I measure (4 point measurement @ 10kHz) 50.940 Ohms, also could be a bit better, I use one that I previously received wich I measure 49.850 OHms and correct it in NanoVna-Saver's "Calibration" window. Yes I can do that for the portsavers also." - For $60 usd delivered via parcel post, you can't expect too much better quality than what is already in the package. The terminator actually measures better than some name brand units I have, and the return loss is very well behaved. I always keep in mind that hugen developed the NanoVNA to "to attract more young people to pay attention to radio frequency and wireless" and that tempers my expectations regarding any meteorologist level performance. The volume of sales world wide over the past few months indicates he not only has attracted some youngsters to RF measurement techniques, but given some of us older people access to measurement capability that we previously lacked. Regards, - Herb |
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
it appears that at start NanoVNA-Saver is using the C0? calibration ofYes NanoVNA, untill now I thought these calibrations were independant.No, USB serial communication from nanoVNA to Python is not reliable for all firmware, USB cables and versions of Python. Using a USB 2.0 (rather than 3.0) port e.g. by hub sometimes helps. Adding ferrite beads to USB cable may help. Some firmware and Python serial implementations are simply flakey. Rune's workaround is to depend on nanoVNA C0 calibration returning data values nearly correct. |
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
Herb,
toggle quoted message
Show quoted text
This is an eye opener for me, it appears that at start NanoVNA-Saver is using the C0? calibration of NanoVNA, untill now I thought these calibrations were independant. I just made a new 100 Segs calibration. Please see the attached results. NanoVNA-H4 is a great device, just the CH1 impedance could be a bit better and the enclosed 50 Ohms standard I measure (4? point measurement @ 10kHz) 50.940 Ohms, also could be a bit? better, I use one that I previously received wich I measure 49.850 OHms and correct it in NanoVna-Saver's? "Calibration"? window. Yes I can do that for the portsavers also. Best regards, Jos Op 26-1-2020 om 01:24 schreef hwalker: On Sat, Jan 25, 2020 at 03:58 PM, Jos Stevens wrote: ![]()
Smith before calibration 100 segs.png
![]()
Smit after 100 Segs calibration with portsavers.png
![]()
S21 With portsavers. before caluibration 100 Segs.png
S21 With portsavers after calibration .png
|
Re: nanovna-users]NanoVNA-H4 2Port calibrationof
Eric Furness
On 1/25/2020 3:37 PM, Jos Stevens wrote:
Hi Oristo and Herb, The RG174 jumpers that came with my Nano were very noisy.? I bought a kit of 5 teflon cables, now cal works good and no more noise.Eric WA3UYI |
Re: problems with SWR reading in nanovna-h v3.4
#measurement
#calibration
#nanovna-h_v3dot4
Oristo, thanks a lot! I will try and let you know, best,
°ä¨¦²õ²¹°ù. |
Re: Wireless control of NanoVNA
If the NanoVNA had a WiFi transceiver on board in addition to the USB port, soIf nanoVNAs had BlueTooth, then they could also be controlled by iOS apps. There are fairly cheap BlueTooth modules with programmable microcontrollers and also fairly cheap USB host shields. Firmware integrating those for a dongle could work for all nanoVNAs, not just H4s.. |
Re: characteristic impedance
the 1/8 wave methodadded to /g/nanovna-users/wiki/Application-Notes#Collected-wisdom |
Re: Clear config NanoVNA
Hi Hans -
and advise is clear "config"see /g/nanovna-users/message/10215 Is calibration also required ?It will be, after clearconfig |
Re: problems with SWR reading in nanovna-h v3.4
#measurement
#calibration
#nanovna-h_v3dot4
Before all that, check for SMA connector integrity.
|
Re: problems with SWR reading in nanovna-h v3.4
#measurement
#calibration
#nanovna-h_v3dot4
Hi Cesar -
I suppose that your issues are related, and I suggest that the problem is/was corrupted calibration data area which has been my experience with first calibrations with some new firmwares. The workaround: ---------------------- Using a serial terminal program to communicated with nanoVNA's USB virtual COM port (e.g. PuTTY ) invoke the console shell command `clearconfig 1234` /g/nanovna-users/files/NanoVNA_Console_Commands_Dec%209-19.pdf then power off and back on then recalibrate the touch panel using touchcal and touchtest /g/nanovna-users/message/7759 perhaps check vbat and tweak by vbat_offset /g/nanovna-users/message/6549 /g/nanovna-users/message/9868 then saveconfig then, by touchscreen menu CAL->RESET then CAL->CALIBRATION /g/nanovna-users/message/7759 /g/nanovna-users/message/7810 |
Re: Cheap calibration loads
#parts
Thanks Herb for confirming my suspicion.
I've looked at the specs once again: VSWR: 1.05 + 0.008 f (GHz) max @ DC - 18.0 GHz, 1.30 max @ 18 - 26.5 GHz so I would expect 1.30 at frequencies above 18GHz, which is not my case. PS: I did compare with Radiall SMA terminators rated up to 4GHz and I don't see such behaviour at low frequencies. |
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