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.

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Random results on my NanoVNA V2 Plus 4

Anssi K 2022/10/26 12:57

Seem like I damaged my NanoVNA V2 Plus 4. I measured wire with capacitance at the far end. Probably it was still charged to 24V when connected.

All measurements look the same, calibrated and uncalibrated. Also connecting load or short have no effect to results. Uncalibrater pictures attached. Other functions seem to work normally, Led601 and Led401 are on. I have also checked that Port1 outputs frequencies normally over the full frequency range in CW mode.

I thought this was easy fix and I have changed some of the MXD8641 switches with no luck.

Any hints what could be broken?

Eugen YO9WHI 2022/10/29 00:43

When you do the calibration, are you 100% sure that the 3 probes make contact?
Check this again. When you mount the probes, the dot on the screen must move in certain positions, if it does not move, it means that it does not make contact.
Eugen - YO9WHI

john davis 2022/10/30 11:35

On a dirrerent topic is there a transfer swtch available  for nanaovna ? (diy or built)
john davis

Anssi K 2022/10/30 13:00

Yes, I am sure I did it correctly. I cheated a little and did not insert the open standard as seen in pictures.

It used to work logically before. At the moment any kind of load at port 1 (CH0) has no effect to results. Connecting port 1 to port 2 moves the CH1 logmag ~+60dB.



Anssi K 2022/11/25 13:23

I finally got some time to play a round with my broken unit. I took x-rays of the board at work. All the bond wires on chips were intact. There was bad solder joint on one of the undocumented pars under the white coating. I took off the coating and corrected the soldering but that had no effect.

Those QFN-14L packages are a quite tricky to measure in reliable manner. Every time I think I found the faulty part, re-measurement gives an opposite conclusion.

Some Good hints are still wanted. Feels like I need to force myself to measure all the passives or to make a simulation model to verify my measurements.


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