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Entry  Mon Jul 7 21:36:33 2014, Jenne, rana, Update, PSL, PMC local oscillator is going wonky PMC_LO_failing.pdf
    Reply  Mon Jul 7 22:18:26 2014, Koji, Update, PSL, PMC local oscillator is going wonky 
       Reply  Tue Jul 8 15:28:32 2014, Koji, Update, PSL, PMC local oscillator is going wonky 
          Reply  Wed Jul 9 00:47:22 2014, Koji, Update, PSL, PMC local oscillator is going wonky 
             Reply  Wed Jul 9 11:41:12 2014, Koushik, Update, PSL, PMC local oscillator is going wonky 
                Reply  Wed Jul 9 19:53:34 2014, rana, Update, PSL, PMC LO monitor trend (5 years) LODET.png
                   Reply  Thu Jul 10 01:02:13 2014, rana, Update, PSL, more PMC science PMCloCal.pdf
          Reply  Wed Jul 9 00:59:09 2014, rana, Update, PSL, PMC local oscillator is going wonky PMC_RFslider.pdf
Message ID: 10146     Entry time: Mon Jul 7 21:36:33 2014     Reply to this: 10148
Author: Jenne, rana 
Type: Update 
Category: PSL 
Subject: PMC local oscillator is going wonky 

The PMC local oscillator is going a little weird dyingWe need to check out why the level is fluctuating so much.

Here's a 6 month plot, where you can see that the lower level keeps getting lower (y-axis is dBm):

PMC_LO_failing.pdf

This LHO entry from 2008 shows where we first discovered this effect. As Rick Savage and Paul Schwinberg later found out, the ERA-5SM+ amplifier slowly degrades over several years and was replaced for both of the eLIGO interferometers. We have spares in the Blue box and can replace this sometime during the day.

Our PMC LO is made by this obsolete crystal oscillator circuit: D000419. There are many versions of this floating around, but they all have the ERA-5 issue.

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