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Entry  Wed Nov 5 01:58:54 2014, ericq, Update, LSC, 3F RFPD RF spectra Nov52014_3fPD_DRMIspectra.zipREFL165_DRMIspectrum.pngREFL33_DRMIspectrum.png
    Reply  Wed Nov 5 11:09:44 2014, Koji, Update, LSC, 3F RFPD RF spectra 
       Reply  Wed Nov 5 22:25:42 2014, ericq, Update, LSC, 3F RFPD RF spectra REFL165_demod_DRMIspectrum.png
          Reply  Thu Nov 6 01:58:55 2014, Koji, Update, LSC, 3F RFPD RF spectra 
             Reply  Thu Nov 6 11:49:58 2014, ericq, Update, LSC, 3F RFPD RF spectra 
                Reply  Thu Nov 6 14:41:49 2014, Koij, Update, LSC, 3F RFPD RF spectra 
                   Reply  Fri Nov 7 02:21:12 2014, ericq, Update, LSC, 3F RFPD RF spectra 
                      Reply  Fri Nov 7 14:41:18 2014, ericq, Update, LSC, 3F RFPD RF spectra 165_ampSaturation.png165_HPatPD.png
                         Reply  Fri Nov 7 16:15:53 2014, Jenne, Update, LSC, 3F RFPD RF spectra 
                            Reply  Sat Nov 8 11:35:05 2014, rana, Update, LSC, 3F RFPD RF spectra 
                            Reply  Mon Nov 10 18:11:57 2014, ericq, Update, LSC, 3F RFPD RF spectra 165signals.pdf
Message ID: 10669     Entry time: Wed Nov 5 11:09:44 2014     In reply to: 10668     Reply to this: 10673
Author: Koji 
Type: Update 
Category: LSC 
Subject: 3F RFPD RF spectra 

If you look at the intermodulation at 14 (4+10) and 16 (6+10), 15 (5+10) would make any problem, thanks to the notch at 1f and 5f.

BUT, this absolute level of 165MHz is too tiny for the demodulator. From the level of the demodulated signal, I can say REFL165 has
too little SNR. We want to amplify it before the demodulator.

Can you measure this again with a directional coupler instead of the direct measurement with an attenuator?
The downstream has bunch of non-50Ohm components and may cause unknown effect on the tiny 165MHz signal.
We want to measure the spectrum as close situation as possible to the nominal configuration.

90MHz crap is the amplifier noise due to bad power bypassing or bad circuit shielding.

I have no comment on REFL33 as it has completely different amplification stages.

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