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Entry  Fri Aug 30 18:40:01 2019, anchal, Notes, BEAT, Quick note: BN detector changed to NF1811 
    Reply  Wed Sep 4 14:41:33 2019, anchal, Notes, BEAT, Quick note: BN detector changed to SN101 and other changes 
       Reply  Thu Sep 5 19:52:06 2019, anchal, Notes, BEAT, Quick note: FSS gain reduced, Moku input range changed 
          Reply  Tue Sep 10 19:43:02 2019, anchal, Notes, BEAT, Quick note: Detector changed to NF1811 
             Reply  Mon Sep 16 18:03:33 2019, anchal, Notes, BEAT, Quick note: Detector changed to Sn101 
                Reply  Tue Oct 1 17:28:25 2019, anchal, Notes, BEAT, Quick note: Moku connected with USB 
                   Reply  Tue Oct 15 13:23:16 2019, anchal, Notes, Safety, Quick note: Shutting Down Lasers as Safety Sign is not working 
                      Reply  Tue Oct 15 18:53:00 2019, anchal, Notes, Safety, Quick note: Lasers started again 
                         Reply  Wed Oct 16 19:11:11 2019, anchal, Notes, BEAT, Quick note: Cavities locked; Changed BN Freq Counter Poll Rate 
                            Reply  Fri Oct 18 17:47:49 2019, anchal, Notes, BEAT, Quick note: BN Noise bakc to where it was. 
                               Reply  Mon Nov 4 20:13:44 2019, anchal, Notes, BEAT, Quick note: FSS Loop Gain Changes 
                                  Reply  Wed Jan 22 15:20:00 2020, anchal, Notes, BEAT, Notch improved on FSS RFPDs. Gain values increased as well. 
                                     Reply  Thu Jan 30 10:55:22 2020, anchal, Notes, BEAT, Lowest ever beatnote spectrum today. CTN_Daily_BN_Spec.pdf
                                        Reply  Wed Feb 12 10:01:04 2020, anchal, Notes, BEAT, Increased sampling rate to 125kSa/s; lowest noise in higher frequencies 
Message ID: 2516     Entry time: Wed Jan 22 15:20:00 2020     In reply to: 2473     Reply to this: 2523
Author: anchal 
Type: Notes 
Category: BEAT 
Subject: Notch improved on FSS RFPDs. Gain values increased as well. 

New Gain Values:

South Common Gain: 24 dB , Fast Gain: 18 dB

North Common Gain: 14 dB, Fast Gain: 14 dB

I incrased the above values as much as I could without getting oscillations in the loop.

RFPD Changes:

  • The North FSS RFPD SN009 (CTN:2512) and South FSS RFPD SN010 (CTN:2514) have been improved in terms of ratio of their peak transimpedance to their notch transimpedance by implementing an active notch in the output RF amplifier.
  • This was supposed to reduce non-linear effects (if any) because less of the 2-Omega frequency would go through the amplifier.
  • It seems like it didn't help at all as the beatnote noise spectrum is at the same place as before.
  • While the gain values of FSS have increased, the transimpedances of the RPFDs decreased after the changes,

Latest BN Spectrum: CTN_Latest_BN_Spec.pdf

Daily BN Spectrum: CTN_Daily_BN_Spec.pdf

Parallel relevant threads:

CTN:2514 : FSS Diagnostics - SN010 (South RFPD) Notch Improved

CTN:2517: TTFSS OLTFs with Maximum Gain

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