40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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Entry  Sat Nov 21 00:45:30 2015, Koji, Update, IOO, IMC fix PDRFsignal_cable.JPGQsignal_cable1.JPGQsignal_cable2.JPGQsignal_cable3.JPG
    Reply  Sat Nov 21 00:46:33 2015, Koji, Update, IOO, IMC OLTF IMC_OLTF.pdfPMC_noise_comparison.pdf
       Reply  Sun Nov 22 12:12:17 2015, Koji, Update, IOO, IMC OLTF 
    Reply  Sun Nov 22 07:09:01 2015, rana, Update, IOO, IMC fix 
       Reply  Sun Nov 22 12:07:09 2015, Koji, Update, IOO, IMC fix 
          Reply  Mon Nov 23 22:12:10 2015, Koji, Update, IOO, LO level check for the IMC demod board IMG_2137.JPGIMG_2138.JPG
             Reply  Wed Nov 25 04:24:21 2015, rana, Update, IOO, LO level check for the IMC demod board 
                Reply  Wed Nov 25 10:07:10 2015, Koji, Update, IOO, LO level check for the IMC demod board 
                   Reply  Wed Nov 25 16:46:10 2015, Koji, Update, IOO, LO level check for the IMC demod board D990511-40m_151123.pdf
                      Reply  Wed Nov 25 20:07:35 2015, rana, Update, IOO, LO level check for the IMC demod board 
                   Reply  Mon Nov 30 14:12:14 2015, ericq, Update, LSC, LO level check for the LSC RF distribution box 
                      Reply  Mon Nov 30 15:17:57 2015, Koji, Update, LSC, LO level check for the LSC RF distribution box 
Message ID: 11807     Entry time: Wed Nov 25 04:24:21 2015     In reply to: 11802     Reply to this: 11808
Author: rana 
Type: Update 
Category: IOO 
Subject: LO level check for the IMC demod board 

Hmmm. Very non-standard demod. From the photo, looks like someone did some surgery with the attenuators (AT1, AT2, AT3) in the LO path. (might be me from a long time ago).

-8 dBm input to a circuit is a not a low noise situation. It would be best to remove the amplifiers in the I&Q paths and just have a single amplifier in the main path. Ideally we want the LO to never go below -3 dBm and certainly not below 0 dBm while outside of the board.

I doubt that all of the LSC demods were modified in this way - this one ought to get some sharpie or stickers to show its difference.

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