TJ, Jeff K, Jim W, Sheila

We are on 45 mHz blends today, with microseism and wind that TJ will post. The first attached screenshot shows that today at least the optical levers show more motion when we are on 90 mHz blends. 

We are also running with low gain in the SOFT loops today.  We struggled with locklosses when turning up the gain in these loops (similar story in alog 22447).  This seems to be related to the 45mHz blends, because the gain peaking with these blends is unfortunately near something a little unstable in these loops with their nominal gains.  So it may be that we are best off to use low gains when we are on 45 mHz blends (FM1 off for all soft loops)  screen shot is attached.  Operators can probably let these come on in ENGAGE_ASC_PART3 and then manualy turn them off.  If this is not woking you can call me, we can add a check on the blend configuration in the guardian.  With low gain in these loops we do not have the large fluctuations in power build ups we had when we locked with 45 mHz blends in the past. The attached screenshot shows that when we used the 45 mHz blends in the past (22477), there were rather large fluctuations in POP LF (500 counts peak to peak)  Tonight with low gain in the SOFT loop the fluctuations are more like 100 counts peak to peak.  

For a good part of the afternoon we were struggling to lock because the recylcing gain was too low when the PRC2 loop came on.  We already had a check on recycling gain in the guardian, but the threshold was set too low, 31.5 (or 1050 in TR_X and TR_Y).  I increased the threshold to 34.5 (or 1150 in TR_X and TR_Y).  This means that the operators are now more likely to get an error message in ENGAGE_ASC_PART1 that says "Low recycling gain! Align by hand or redo Intial alingment"  If this happens people can try to align things by hand, (adjusting PR2 would be a place to start, maybe ITMs).  If we loose lock it is probably best to just redo inital alingment.  

We were also loosing lock when the SRC loops were re-engaged after being turned off for the CARM offset reduction. 22554 We edited the guardian to leave them on all the time, because I don't think that was really the problem with the locklosses durring CARM offset reduction. The good news is that we didn't have any trouble with these locklosses today, despite high ground motion.