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Completely crazy SWR measurement


Hipolito Luiz Carign 2021/01/23 16:06

Hello everyone,

Completely crazy SWR measurement

These days I received the equipment, I found it very well built and with excellent quality, the only detail that it came with the crumpled metal casing in front of the display, nothing that prevents the operation as far as I could notice, but a small quality detail.

On the day I received it, I calibrated for VHF and measured my antenna from 144 to 148 without major disappointments (I already have a mini60 (sark 100) and also a Nanovna).

I acquired this model for going up to 4ghz, because I am making some antennas for 2.4 ghz for operation with eshail.

I took a previous measurement for adjustments, and yesterday 22/01 finally after the adjustments I went to make another measurement at the end of the day. The fine tuning of the helix antenna was pending today.

I had been using a notebook since the beginning, but today I decided to install the software on the nanoVNA V2 Plus4, on the shack PC.

Without any major problems, I started the measurement and adjustments without any major problems, (I recalibrated the equipment together with the new software installation for the 2.4Ghz frequency).

After some adjustments to the antenna, I went to perform a new measurement and when turning on the equipment and connecting again to the PC, I noticed that the graphics in the software which I keep with sweep on, were with the crazy SWR parameters.

I tried several adjustments and recalibration in both software (nanoVNA-QT and NanoVNA-Saver) without success, I also tried reset and recalibration directly on the device without success (when I reset the calibration is normal, after running and applying it is lost).

I also tried to reload the firmware without success, it returns to the same symptom.

About the firmware I noticed that the forum mentions version 20201122, which must be downloaded in Firmware downloads:
https://nanorfe.com/nanovna-versions.html however at the address the only one available is 20201013 which came originally loaded in my equipment.

Another question, does anyone know how to keep the screen rotation setting?

Any way is welcome for a more in-depth analysis and solution

73 PY5HC Hipolito

Hipolito Luiz Carign 2021/01/23 16:10

Hello everyone,

Completely crazy SWR measurement

These days I received the equipment, I found it very well built and with excellent quality, the only detail that it came with the crumpled metal casing in front of the display, nothing that prevents the operation as far as I could notice, but a small quality detail.

On the day I received it, I calibrated for VHF and measured my antenna from 144 to 148 without major disappointments (I already have a mini60 (sark 100) and also a Nanovna).

I acquired this model for going up to 4ghz, because I am making some antennas for 2.4 ghz for operation with eshail.

I took a previous measurement for adjustments, and yesterday 22/01 finally after the adjustments I went to make another measurement at the end of the day. The fine tuning of the helix antenna was pending today.

I had been using a notebook since the beginning, but today I decided to install the software on the nanoVNA V2 Plus4, on the shack PC.

Without any major problems, I started the measurement and adjustments without any major problems, (I recalibrated the equipment together with the new software installation for the 2.4Ghz frequency).

After some adjustments to the antenna, I went to perform a new measurement and when turning on the equipment and connecting again to the PC, I noticed that the graphics in the software which I keep with sweep on, were with the crazy SWR parameters.

I tried several adjustments and recalibration in both software (nanoVNA-QT and NanoVNA-Saver) without success, I also tried reset and recalibration directly on the device without success (when I reset the calibration is normal, after running and applying it is lost).

I also tried to reload the firmware without success, it returns to the same symptom.

About the firmware I noticed that the forum mentions version 20201122, which must be downloaded in Firmware downloads:
https://nanorfe.com/nanovna-versions.html however at the address the only one available is 20201013 which came originally loaded in my equipment.

Another question, does anyone know how to keep the screen rotation setting?

Any way is welcome for a more in-depth analysis and solution

73 PY5HC Hipolito

barnc4br 2021/01/24 09:54

for the screen rotation, you must SAVE it.
First rotate it, then cal it, then save it. When Cal make sure you push your probe into the very corner.
You can tell if you do not when you test it and the trace runs ahead of your probe as you near the edge. It will also produce stray marks on the screen near/at the left edge (screen flipped).

Firmware is confusing. There are a number of options, but 10-13 is the only one I can find as "official". The 1122 one I believe is for a different unit. But as I said, confusing.
So far I have found these:
binary_st7796_20201004.bin ( https://ojisankoubou.web.fc2.com/nanovna/nanovnav2.html )
nanovna-v2-20201124-experimental-v2plus4.bin ( https://nanorfe.com/downloads/20201124-experimental/ )
NanoVNA-V2-firmware-master DiS-20201229.zip ( https://github.com/DiSlord/NanoVNA-V2-firmware )
NanoVNA-V2-firmware-master.zip ( https://github.com/nanovna/NanoVNA-V2-firmware )
and this one that has 511 points and I have no idea where it came from but was posted here
V2Plus4 511p no smooth.bin
I have not tried any yet. The BIN files are directly usable. The ZIP file needs to be compiled and they need to be compiled for the ST7796 display which appears to be unique to the V2plus4. Some BIN files may not be compiled for the ST7796.

I have had the same symptom you have and it has been intermittent and for different reasons.
The first time I saw it I was confused and noticed that it went away if I turned off APPLY, which turns off calibration.
What I finally figured out was that I was using the ports backwards. CH0 is on the right with screen flipped.

The second time it was intermittent and sometimes worked for short periods - a few seconds.
The LED 401 was intermittently going off. You must remove the cover to see it - blue one on the bottom of the PCB on the right. It was OK under 140MHz and sometimes over about 2300MHz. They replaced the board and so far so good but I have not had it very long.

Siegfried Jackstien 2021/01/25 03:58

the 511point version is made from dislord

dg9bfc sigi

Am 24.01.2021 um 17:54 schrieb barnc4br@gmail.com:

Hipolito Luiz Carign 2021/01/27 05:18

Tnks for reply

I registered a support request with the text shown above, with the Aliexpress seller at the official store who promptly attended to me, requested some specific images and issued the following opinion:

"Hi, can you send a picture of the display without calibration (click CALIBRATE / RESET ALL) and with nothing connected to the ports? And then with the 50ohm load connected to port 1 (CH0)? Thanks"

I sent the images as requested

and he replied:

"Hi, it looks like the port 1 ECAL switch (U801) is unresponsive, it's usually a soldering defect on U303 or U801 or ESD damage. You can try applying flux to U303 and drag soldering it, or if you can't do that we can send you a new main board. Thanks "

It is important to note that the ESD problem is very unlikely due to the high humidity that we have in Brazil, especially at this time of the year (summer). In all my years with electronics, whether as a hobby or professionally in the IT area, (servers) I never had problems with ESD even in data center installations and of course in controlled environments always with anti-static kit, at home I always take care to download any Possible charge to earth by touching the grounded frame on the shack bench for a few seconds.

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