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Entry  Wed Jan 20 18:07:09 2021, Anchal, Summary, BHD, HAM-A Coil Driver measurements before modifications 7x
    Reply  Mon Jan 25 18:18:04 2021, Anchal, Summary, BHD, Satellite Amplifier Transfer Functions and noise D1002818_S2100029_TFandNoiseSpectrum.pdfD1002818_Testing.zip
       Reply  Wed Feb 3 16:27:19 2021, Anchal, Summary, BHD, Satellite Amplifier Transfer Functions and noise After modifications D1002818_S2100029_TFAfterChanges.pdfD1002818_S2100029_OutputNoiseSpecAfterChanges.pdfD1002818_S2100029_InputRefferedNoiseSpecAfterChanges.pdfD1002812_S2100029_After_Modifications_Feb3.jpgAfterChanges.zip
          Reply  Wed Feb 10 11:45:59 2021, Anchal, Summary, BHD, Satellite Amplifier Very Low frequency noise After modifications 6x
             Reply  Wed Feb 10 15:07:50 2021, Anchal, Summary, BHD, Satellite Amplifier Output Offset measurements 
                Reply  Wed Feb 10 15:25:45 2021, gautam, Summary, BHD, Satellite Amplifier Output Offset measurements 
                   Reply  Wed Feb 10 17:18:03 2021, Koji, Summary, BHD, Satellite Amplifier Output Offset measurements 
             Reply  Thu Feb 11 11:10:05 2021, Anchal, Summary, BHD, Satellite Amplifier Very Low frequency noise After modifications AfterChangesSpectrum_AC.zipD1002818_S2100029_OutputNoiseSpecAfterChanges.pdfD1002818_S2100029_InputRefCurrentNoiseSpecAfterChanges.pdfD1002818_S2100029_InputRefDispNoiseSpecAfterChanges.pdf
                Reply  Thu Feb 11 16:58:52 2021, rana, Summary, BHD, Satellite Amplifier Very Low frequency noise After modifications 
    Reply  Thu Jan 28 12:53:14 2021, Anchal, Summary, BHD, HAM-A Coil Driver measurements before modifications D1100117_S2100027_Current_Noise_Spectrum.pdfD1100117_S2100027_Voltage_Noise_Spectrum.pdfD1100117_S2100028_Current_Noise_Spectrum.pdfD1100117_S2100028_Voltage_Noise_Spectrum.pdfSpectrumMeasurement.zip
       Reply  Thu Jan 28 18:04:55 2021, Anchal, Summary, BHD, HAM-A Coil Driver measurements After modifications D1100117_S2100027_TF.pdfAfterChanges.zip
          Reply  Thu Jan 28 21:44:45 2021, gautam, Summary, BHD, HAM-A Coil Driver measurements After modifications 
             Reply  Fri Jan 29 15:39:30 2021, Anchal, Summary, BHD, HAM-A Coil Driver measurements After modifications TF and Noise S2100027 D1100687_S2100027_After_Modifications_Jan28.jpgD1100117_S2100027_TF.pdfD1100117_S2100027_Voltage_Noise_Spectrum.pdfD1100117_S2100027_Current_Noise_Spectrum.pdfAfterChanges.zip
                Reply  Tue Feb 2 11:57:46 2021, Anchal, Summary, BHD, HAM-A Coil Driver measurements After modifications TF and Noise S2100028 D1100687_S2100028_After_Modifications_Feb01_2021.jpgD1100117_S2100028_TF.pdfD1100117_S2100028_Voltage_Noise_Spectrum.pdfD1100117_S2100028_Current_Noise_Spectrum.pdfAfterChanges.zip
Message ID: 15799     Entry time: Wed Feb 10 15:07:50 2021     In reply to: 15797     Reply to this: 15800
Author: Anchal 
Type: Summary 
Category: BHD 
Subject: Satellite Amplifier Output Offset measurements 

I measured the output DC voltage of the satellite amplifier box at PDMon port when the PDA input was shorted and got following offsets:
 

CH Output Offset (mV) CH Output Offset (mV)
1 6 5 750
2 140 6 120
3 350 7 537
4 40 8 670

However, I think I'm making a mistake while measuring this offset as well as all the noise measurements of this satellite amplifier box so far. Since it is a current input, transimpedance circuit, the noise of the circuit should be measured with open input, not closed. Infact, by shorting the PDA input, I'm giving DC path to input bias current of AD833 transimpedance amplifier to create this huge DC offset. This won't be the case when a photodiode is connected at the input which is a capacitor and hence no DC path is allowed. So my issue of offset was bogus and past two noise measurements in 40m/15797 and 40m/15793 are wrong.

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