WP 8188
I made I slight adjustment to the light level on the PMC locking PD to hopefully alleviate the constant increase in the relock counter we've been seeing lately (LHO alog 48568 & FRS 12753). I began by tweaking the alignment into the PMC locking PD, which did not change the PD voltage. I then slightly tweaked the TFP directly in front of the PD to increase the PD voltage; this had a small effect on the PD voltage. The changes are:
I did not change the PMC gain. I reset the PMC relock counter at 18:44 UTC (11:44 PDT) and will monitor this over the next few days before closing the work permit.
FAMIS 10708
Both PSL power watchdogs were reset at 18:35 UTC (11:35 PDT). This completes FAMIS 10708.
Other Work
I happened to notice that the ISS diffraction % was at ~1.7% with the just the 1st loop locked; the diffracted power should be between 2% and 3%. I changed the ISS Reference Signal from -2.08 V to -2.07 V; this brought the diffraction % to ~2.1%. The change was accepted in both the SAFE and OBSERVE SDF files.
In almost 3 days there have been 0 relocks on the PMC, see attached. Increasing the light level on the diode cured the behavior. This closes WP 8188 and FRS 12753.