I just thought I would let y'all know that I had the spaghetti display problem above 140MHz and found a quick fix.
This is the same issue in the thread "can I repair this V2 plus 4?" and thanks to the info there I was able to demonstrate that this spaghetti display was only above 140MHz.
Thank you *barnc4br* and *OwO* for making it so easy to troubleshoot!!
I opened the unit up and found:
1) LED401 was not glowing solid blue the way it should
2) there were little bits of metal shorting the SMT pads of a chip under the metal shield
3) U401 looked like the solder hadn't really reached liquidus
4) when I looked at the other QFNs they had a similar morphology
The fixed was super simple... Apply a little bit of water soluble flux, touch up each joint, clean up and test.
When I heated the pads the solder sucked right under the chips in all cases, so I felt pretty confident that this would help.
Once I plugged it in... WOW!! This is GREAT!
Since this was a brand new unit, I suspect that the assembly house is rushing things and that they didn't take the time to "tune" the process.
Too bad, because I now have an additional 22 units I'm using for a class that I will need to test. :-(
If I have more with the same problem, I'll crank up the camera on my microscope and share some photos.
Thank you for letting me "bend your ear" and I hope it is helpful for anyone else finding that they have a spaghetti display.
Northern CA, USA
Beware of cheap underperforming clones
As of 2022 there are many badly performing clones on the market. V2/3GHz NanoVNA uses parts like ADF4350 and AD8342 which are costly and clones have been cutting costs by using salvaged or reject parts.
See official store and look for V2 Plus4/V2 Plus4 Pro versions only to avoid getting a bad clone. We have stopped selling V2.2 versions since October 2020, so all V2 hardware that are not Plus or Plus4 are not made by us and we can not guarantee performance.
Click here to join and see most recent posts.
Spaghetti display fixed
To reply to this topic, join https://groups.io/g/NanoVNAV2