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Entry  Wed Dec 18 11:37:12 2013, Jenne, Update, LSC, POP22 and POP110 demod phases 
    Reply  Wed Dec 18 18:45:39 2013, Jenne, Update, LSC, REFL 165 demod phases 
       Reply  Mon Jan 6 22:11:46 2014, Jenne, Update, LSC, PRCL sideband locking still not so happy 
Message ID: 9487     Entry time: Wed Dec 18 11:37:12 2013     Reply to this: 9491
Author: Jenne 
Type: Update 
Category: LSC 
Subject: POP22 and POP110 demod phases 

Somehow the POP22 and POP110 demod phases weren't correct anymore.  I guess Den saw this after he changed the setup for the REFL165 PD at the LSC rack, but didn't elog it. 

I went out to the LSC rack, and found that the power supply that is supplying the amplifiers for both POP22/110 and REFL165 was set to ~16V each channel.  I put it back to 15V for each channel.  I don't know what Den intended for the 165 amplifier (more volts is more gain), but the POP22/110 amplifier usually runs with 15V. 

I also reset the POP22 and POP110 demod phases.  Since I'm not able to lock PRMI on sideband this morning (why?!?!), I locked on the carrier, and moved the phases around until POP22 and POP110 were both maximally negative.  The phases are/were:

  OLD [deg] NEW [deg]
POP22 107.2 -165.0
POP110 95.0 150.0

This is a ~60 degree change for both PDs. 

I am not sure if Den ever checked the demod phase of REFL165 after he put in the new SMA cable (there's no mention of it in the elog!), so I'm going to check that to see if it helps get PRMI locking back.  I know that Den had also been using REFL11 for PRMI locking, but the parameters he used for that aren't in the log either.

ELOG V3.1.3-