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Entry  Mon Dec 2 00:27:20 2019, gautam, Update, ALS, Green ALS resurrection ALSnoiseComparison.pdfALS_TR_RIN.pdfGreemAM.pdf
    Reply  Mon Dec 2 18:20:29 2019, gautam, Update, ALS, EY uPDH post mixer LPF EY_uPDH_LPF.pdfEY_uPDH_OLTF.pdf
       Reply  Mon Dec 2 20:18:18 2019, rana, Update, ALS, EY uPDH post mixer LPF 
          Reply  Tue Dec 3 18:15:42 2019, gautam, Update, ALS, EY uPDH post mixer LPF 
             Reply  Tue Dec 3 21:28:24 2019, gautam, Update, ALS, EY uPDH post mixer LPF uPDH.pdf
       Reply  Tue Dec 3 00:10:15 2019, Koji, Update, ALS, EY uPDH post mixer LPF 
          Reply  Tue Dec 3 00:51:25 2019, gautam, Update, ALS, EY uPDH post mixer LPF 
Message ID: 15064     Entry time: Tue Dec 3 00:51:25 2019     In reply to: 15063
Author: gautam 
Type: Update 
Category: ALS 
Subject: EY uPDH post mixer LPF 

I'm not sure - maybe it was measurement error on my part, I will double check. Moreover, the EX and EY boxes don't seem to use identical designs, if one believes the schematics drawn on the Pomona boxes. The EY design has a 50ohm input impedance in the stopband, whereas the EX doesn't. Maybe the latter needs a Tee + 50ohm terminator at the input?

Judging by the schematics, the servo inputs to both boxes are driving the non-inverting input of an opamp, so they see high-Z.

Quote:

I got confused. Why don't we see that too-high-Q pole in the OLTF?

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