We have done a more precise measurement of the open loop TF (with the old servo) between 70 kHz and 170 kHz. (See attached pdf).

Data can be found here:

https://drive.google.com/drive/folders/1HrR6Bq3lwTRyxw1Q6pXoPU0TxDqfFtRs?usp=sharing

(AMP2.CVS and phase2.CVS)

We have also recorded the error signal spectrum with the new servo. The shape changes quite a lot when changing the gain from 4 to 5. (see pic 1 and 2)

We also recorded the error signal in time (gain 0.7) where an oscillation at about 285 kHz is visible. (pic 3)