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 Mon Jul 7 21:36:33 2014, Jenne, rana, Update, PSL, PMC local oscillator is going wonky 
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 Mon Jul 7 22:18:26 2014, Koji, Update, PSL, PMC local oscillator is going wonky
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Tue Jul 8 15:28:32 2014, Koji, Update, PSL, PMC local oscillator is going wonky
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Wed Jul 9 00:47:22 2014, Koji, Update, PSL, PMC local oscillator is going wonky
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Wed Jul 9 11:41:12 2014, Koushik, Update, PSL, PMC local oscillator is going wonky
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Wed Jul 9 19:53:34 2014, rana, Update, PSL, PMC LO monitor trend (5 years)
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Thu Jul 10 01:02:13 2014, rana, Update, PSL, more PMC science
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Wed Jul 9 00:59:09 2014, rana, Update, PSL, PMC local oscillator is going wonky
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Message ID: 10162
Entry time: Wed Jul 9 11:41:12 2014
In reply to: 10159
Reply to this: 10167
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| Author: |
Koushik |
| Type: |
Update |
| Category: |
PSL |
| Subject: |
PMC local oscillator is going wonky |
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| Quote: |
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Koushik replaced an ERA-5 in the PC path. We put the module back to the rack and found no change.
The epics LO level monitor monitor is still fluctuating from 6~11dBm. We need more thorough investigation
by tracing the signals everywhere on the board.
Despite the poor situation of the modulation, PMC was locking (~9PM). Rana suspect that the PMC demodulation
phase was not correctly adjusted long time.
Koushik has the measured power levels and the photos of the board. I'll ask him to report on them.
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Updates from Koushik:
The power levels measured (before and after relacement of ERA-5) are as follows:
LO to Servo : Vout = 2.3 Vpp / Pout = 11.21 dBm at f = 35.5 MHz
RF to PC : Vout = 354 mVpp / Pout = -5.1 dBm at f= 35.5 MHz
The measurements were done using an oscilloscope with 50 ohms load impedance. Unfortunately the photos are not available from the camera. |