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Entry  Tue Mar 2 19:52:46 2021, gautam, Update, LSC, REFL55 demod board rework 
    Reply  Wed Mar 3 22:13:05 2021, gautam, Update, LSC, REFL55 demod board rework 
       Reply  Thu Mar 4 23:16:08 2021, Koji, Update, LSC, REFL55 demod board rework D990511-00_REFL55.pdfP_20210304_215602.jpgP_20210304_222400.jpgP_20210304_222412.jpg20210304234400_IMG_0526.jpg
          Reply  Fri Mar 5 13:53:57 2021, gautam, Update, LSC, REFL55 demod board rework 
             Reply  Fri Mar 5 15:31:23 2021, Koji, Update, LSC, REFL55 demod board rework 
                Reply  Fri Mar 5 16:24:24 2021, gautam, Update, LSC, REFL55 demod board re-installed in 1Y2 REFL55.pdfdemodNoise.pdf
                   Reply  Fri Mar 5 22:25:13 2021, gautam, Update, LSC, PRMI 1f SB locking recovered PRMI1f_noArmssensMat.pdf
Message ID: 15867     Entry time: Fri Mar 5 13:53:57 2021     In reply to: 15864     Reply to this: 15869
Author: gautam 
Type: Update 
Category: LSC 
Subject: REFL55 demod board rework 

0 dBm ~ 0.63 Vpp. I guess there is ~4dB total loss (3dB from splitter and 1dB from total excess loss above theoretical from various components) between the SMA input and each RF input of the JMS-1-H mixer, which has an advertised conversion loss of ~6dB. So the RF input to each mixer, for 0dBm to the front panel SMA is ~-4dBm (=0.4 Vpp), and the I/F output is 0.34Vpp. So the conversion loss is only ~-1.5 dB? Seems really low? I assume the 0.34 Vpp is at the input to the preamp? If it's after the preamp, then the numbers still don't add up, because with the nominal 6dB conversion loss, the output. should be ~2Vpp? I will check it later.

Quote:

With LO3dBm. RF0dBm, and delta_f = 30Hz, the output Vpp of 340mV and the phase difference is 88.93deg. (Attachment 3/4, the traces were averaged)

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