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40m Log |
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Thu Mar 18 10:46:51 2010, Koji, Update, ABSL, PLL reconstructed
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Thu Mar 18 12:27:56 2010, Alberto, Update, ABSL, PLL reconstructed
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Thu Mar 18 13:40:35 2010, Koji, Update, ABSL, PLL reconstructed
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Thu Mar 18 21:42:26 2010, Koji, Update, ABSL, PLL reconstructed
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Mon Mar 22 22:11:26 2010, Mott, Update, ABSL, PLL reconstructed
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Mon Mar 22 23:37:32 2010, Mott, Update, ABSL, PLL reconstructed 
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Tue Mar 23 18:44:46 2010, Mott, Update, ABSL, PLL reconstructed
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Wed Mar 24 03:58:18 2010, kiwamu, matt, koji, Update, Green Locking, leave PLL locked
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Wed Mar 24 04:22:51 2010, kiwamu, matt, Update, Green Locking, two NPRO PLL
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Wed Mar 24 14:52:02 2010, Alberto, Update, Green Locking, two NPRO PLL
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Wed Mar 24 15:59:59 2010, kiwamu, matt, Update, Green Locking, leave PLL locked
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Thu Mar 25 17:29:48 2010, kiwamu, mott, Update, Green Locking, PLL two NPROs
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Message ID: 2696
Entry time: Mon Mar 22 22:11:26 2010
In reply to: 2684
Reply to this: 2697
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Author: |
Mott |
Type: |
Update |
Category: |
ABSL |
Subject: |
PLL reconstructed |
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It looks like the PLL drifted alot over the weekend, and we couldn't get it back to 9 dBm. We switched back to the new focus wideband PD to make it easier to find the beat signal. I replaced all the electronics with the newly fixed UPDH box (#17) and we aligned it to the biggest beat frequency we could get, which ended up being -27 dBm with a -6.3V DC signal from the PD.
Locking was still elusive, so we calculated the loop gain and found the UGF is about 45 kHz, which is too high. We added a 20 dB attenuator to the RF input to suppress the gain and we think we may have locked at 0 gain. I am going to add another attenuator (~6 dB) so that we can tune the gain using the gain knob on the UPDH box.
Finally, attached is a picture of the cable that served as the smb - BNC adaptor for the DC output of the PD. The signal was dependent on the angle of the cable into the scope or multimeter. It has been destroyed so that it can never harm another innocent experiment again! |
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