[G0HZU_JMR]

The smith chart plot shown later does suggest that there has at least been a partial success with the calibration because there would be lots of rotations around the smith chart caused by the cable length if the calibration was disabled. So the calibration must be active.

There's no way the Minicircuits amplifier will have significant return loss ripple like that with peaks every 300MHz. Therefore, I can't explain why it looks like that unless the VNA is poor/faulty or the calibration hasn't been done correctly.