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