Hi, We use a E5071C for tuning NMR probes here in our lab.
We use very few of the options available, mainly use for fault diagnosis on probes and tuning to a resonant frequency.
We normally look at S11,S22 and S33 of the 4 available ports.
This last week an unusual display popped up on S11, it's a sinusoidal waveform across the whole spectrum.
This is with a 0.5m cable attached.
removing the cable and the display becomes flat.
We have tried swapping the cables around but it has the same effect so have rules out the cable itself.
Attached is a photo showing the display, normally we would expect a straightish line dependant upon calibration.
Would anyone be able to advise on why we have this waveform present.
Could that port be defective and we need to have the instrument serviced/repaired?