Repair NanoVNA V2 Plus4 Pro

Beware of cheap underperforming clones

As of 2023 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.

NanoVNA V2 Forum

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yoppy.chia 2022/10/19 23:34

Hi all,

I've just got a NanoVNA V2 Plus 4 Pro.
After using for a week, the reading becomes erroneous.
What I did before is that I use the nanovna to measure in-circuit impedance by means of an RF current probe.
Below is attached the largest output waveform from the RF current probe measured on a 1MOhm terminated oscilloscope.
Is the level harmful? What is the maximum power input handling of the port?

Also I attach the display capture for open (reset cal), load (reset cal), and load (cal-ed).
Any suggestion what could be done for repairing?
Thanks all!

Regards.

RF current probe output waveform.jpeg

nanov2support 2022/10/20 22:02

Hi, the uncalibrated chart position of open circuit looks like the port 1 RF switch is damaged and has become resistive, this is commonly due to ESD or overvoltage. You can repair it by replacing U801, part number MXD8641, available from LCSC. Thanks

yoppy.chia 2023/05/08 01:02

Hi,

I've just got the chance to replace the U801.
And it works again now.
Thanks a lot for the directions.

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