We looked into the PLL which seemed to be ok (see other entry 3601). We didn't pay much attention to the RefCav yet, as we want to to make the cavity lock again. To make this happen we had to reset the ETMY HEPI, lucky Fabrice was here to help. The output on ISC BLEND_RZ was off. All is well.

We have fringes again, and the REFL_PWR_MON seems to be at its previous healthy ~11000 counts level. When engaging the cavity locking (CMB-B), it seemed to be ok until is starts the oscillation at 10-20 sec period. I turned the first boost filter off which didn't seem to help much. The VCO frequency drifts upto 39.78 MHz (from 39.603 MHz nominal). It almost looks like there is a sign wrong, it locks, fluctuates around 0 then creeps to the -10V limit. When you look at the VCO frequency it keep slowly climbing. At the same time the cavity power drops. Hmm, maybe still something in the PLL servo is not right.

We have two new indicator on the OAT screen, 'RefCav Trans (V)' and 'Beatnote at (Hz)'. The first one is nominal at 1.1 V (has a green box when above 0.8V, and a red box when <0.4V), and indicates if the RefCav is locked. The Beatnote shows the VCO frequency in Hz, nominal at 39.603 MHz.

I left the cavity unlocked, but the PLL engaged.

A good .snap time is Wed July 25 2012, 20:00h (and half hour from now).