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.
Thank you for getting back. Check resistor values and change them if needed. Also the dielectric constant could have changed in the burned area of the PCB and may also cause insertion loss in the RF paths in this area of the PCB. Glad to help. God bless you, John
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