My NanoVna V2+ has suddenly become noisy above 3.8 GHz Below 3.8 GHz, the unit functions normally. When a LOAD is connected to port 1, the S11 suddenly increases above 3.8 GHz (blue trace in Cartesian plot below). On the Smith chart, the defect manifests as a wildly swinging trace above 3.8 GHz.
When the two cables are joined together to form a THRU, both S11 and S21 have abnormal spikes above 3.8 GHz (image below). The un-calibrated S21 starts at -10 dB because I have inserted a 10 dB attenuator in port 2. After calibration, the S21 is flat 0 dB over 50-3800 MHz, but above 3.8 GHz, the S21 has an abnormal spike (red trace in Cartesian plot below). The S11 (blue trace in Cartesian plot) also has a spike above 3.8 GHz.
My unit was bought from the Tindie store.
SN: 38584742-01033533-36343234.
