Nutsinee and I looked at LLO alog #64483 from Masayuki where LLO had a found 2050Hz peak in DARM when ZM4 PSAMS are at 200V. 

We do have this 2050Hz peak in DARM but only when the PSAMS are actively changing. See attached. These PSAMS will not be adjusted while Observing. Nutsinee suggests it could be a jitter coupling with an alignment change. When The SQZ ASC are changing without PSAMS there seems to be a smaller 2033Hz peak.

I compared three times (2023/04/10 02:35 - 03:05 UTC; 2023/04/14 00:18 - 1:53UTC; 2023/04/20 08:53 - 10:23UTC) where we changed PSAMS between <150V and 200V and didn't see any peaks in the 2000Hz region before/after the change, only during.