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Entry  Thu Sep 4 19:39:36 2014, Tara, Evan, DailyProgress, FSS, TTFSS OLTFs pdhTFs.pdf
    Reply  Sun Sep 7 11:54:21 2014, Evan, DailyProgress, FSS, TTFSS OLTFs, residual frequency noise pdhTFs.pdfoltfNorth.pdfoltfSouth.pdffrnoise.pdfnoiseBudget.pdf
       Reply  Mon Sep 8 04:20:41 2014, rana, DailyProgress, FSS, TTFSS OLTFs, residual frequency noise 
       Reply  Wed Oct 2 19:09:31 2019, anchal, DailyProgress, FSS, TTFSS OLTFs; Repeated this 5 year old measurement FSS_OLTF.pdf
          Reply  Thu Jan 9 19:00:19 2020, anchal, DailyProgress, FSS, TTFSS OLTFs FSS_OLTF.pdf
             Reply  Wed Jan 22 14:16:28 2020, anchal, DailyProgress, FSS, TTFSS OLTFs FSS_OLTF.pdf
                Reply  Wed Jan 22 16:00:26 2020, anchal, DailyProgress, FSS, TTFSS OLTFs with Maximum Gain FSS_OLTF.pdf
                   Reply  Thu Jan 23 19:23:03 2020, anchal, DailyProgress, FSS, NFSS Boost Stage NorthFSSBosstStageTF.pdf
Message ID: 1504     Entry time: Sun Sep 7 11:54:21 2014     In reply to: 1502     Reply to this: 1507   2443
Author: Evan 
Type: DailyProgress 
Category: FSS 
Subject: TTFSS OLTFs, residual frequency noise 

Acutally it does look like it's a 50 Ω loading issue. I find that when 50 Ω inline terminators are added to OUT1 and OUT2, the measured OLTF is reduced by a factor of 1.6. This explains the discrepancy between the SR785 and HP4395 measurements. I've attached the corrected OLTF plots, along with plots of a vector fit, and the expected residual frequency noise [assuming a free-running NPRO noise of 104 Hz/Hz1/2 × (1 Hz / f)].

South UGF is at 200 kHz with almost no phase margin. We need to fix this.

Attachment 1: pdhTFs.pdf  127 kB  | Hide | Hide all
pdhTFs.pdf
Attachment 2: oltfNorth.pdf  110 kB  Uploaded Sun Sep 7 12:55:33 2014  | Hide | Hide all
oltfNorth.pdf
Attachment 3: oltfSouth.pdf  109 kB  Uploaded Sun Sep 7 12:55:45 2014  | Hide | Hide all
oltfSouth.pdf
Attachment 4: frnoise.pdf  102 kB  Uploaded Sun Sep 7 12:56:01 2014  | Hide | Hide all
frnoise.pdf
Attachment 5: noiseBudget.pdf  1.052 MB  Uploaded Sun Sep 7 12:56:51 2014  | Hide | Hide all
noiseBudget.pdf
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