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Entry  Wed Apr 3 17:40:18 2013, Jamie, Configuration, Electronics, putting together a 110 MHz LSC demod board 
    Reply  Wed Apr 3 18:41:22 2013, Jamie, Configuration, Electronics, putting together a 110 MHz LSC demod board 
    Reply  Wed Apr 3 22:26:51 2013, rana, Configuration, Electronics, putting together a 110 MHz LSC demod board 
       Reply  Thu Apr 4 14:37:15 2013, Jamie, Configuration, Electronics, putting together a 110 MHz LSC demod board 
          Reply  Mon Aug 26 18:55:18 2013, Jenne, Configuration, Electronics, putting together a 110 MHz LSC demod board for AS AS110_demod_board_modifications.pdf
             Reply  Mon Aug 26 20:13:17 2013, rana, Configuration, Electronics, putting together a 110 MHz LSC demod board for AS 
                Reply  Tue Aug 27 15:31:48 2013, Jenne, Configuration, Electronics, putting together a 110 MHz LSC demod board for AS 
                   Reply  Tue Sep 3 21:10:36 2013, Jenne, Configuration, Electronics, putting together a 110 MHz LSC demod board for AS 
             Reply  Tue Aug 27 17:32:52 2013, Jenne, Configuration, Electronics, putting together a 110 MHz LSC demod board for AS 
                Reply  Tue Aug 27 18:21:35 2013, Jenne, Configuration, Electronics, 110 MHz LO options 
                   Reply  Tue Aug 27 18:58:52 2013, Koji, Configuration, Electronics, 110 MHz LO options 
                   Reply  Mon Sep 2 16:46:32 2013, Jenne, Update, Electronics, RF distribution box is on the bench 
                      Reply  Mon Sep 2 18:06:21 2013, Jenne, Update, Electronics, RF distribution box: 110 MHz LO options RF_distribution_box_proposed_modifications.pdf0902131751.jpg0902131751a.jpg
                         Reply  Tue Sep 3 21:08:13 2013, Jenne, Update, Electronics, RF distribution box: 110 MHz LO options 
                            Reply  Wed Sep 4 16:06:40 2013, Jenne, Update, Electronics, RF distribution box: Reinstalled 
                               Reply  Wed Sep 4 21:44:54 2013, Not Jenne, Update, Electronics, RF distribution box: Reinstalled 
Message ID: 9062     Entry time: Mon Aug 26 18:55:18 2013     In reply to: 8415     Reply to this: 9067   9071
Author: Jenne 
Type: Configuration 
Category: Electronics 
Subject: putting together a 110 MHz LSC demod board for AS 

I have modified one of the spare demod boards that was sitting above the electronics bench (the one which was unlabeled - the others say 33MHz, 55MHz and 165MHz) to be the new AS110 demod board.  In place of the T1 coil, and the C3 and C6 resistors, I have put the commercial splitter PSCQ-2-120+.  In place of U5 (the low pass for the PD input) I have put an SCLF-135+. 

In order to figure out how to make the pinout of the PSCQ match up with the available pads from T1, I first pulled the "AS11" board (it's not something that we use, so it would be less of a tragedy if something happened while I had the board pulled).  However, while the PCB layout is the same, the splitter for the low frequencies (PSCQ-2-51W) has a different pinout than the one I need for the 110MHz.  So, I put AS11 back, and pulled the POP110 board. (After I noted the pinout on POP110, I reinstalled that board.  To get it out, I had to unplug the I and Q outs of POP22, but I have also replugged those in).

For my new AS110 demod board, I copied the pin connections on POP110.  I have made a little diagram, so you can see what pins went where.  The top 2 rectangles are the "before" installation cartoon, and the bottom is the "as installed" cartoon.

AS110_demod_board_modifications.pdf

The one thing that must be noted is that, because of the pinout of the splitter and the constraints of the board layout, the +0 degrees (I-phase) output of the splitter is connected to the Q channel for the rest of the demod board.  This means that the +90 degrees (Q-phase) output of the splitter is connected to the I channel for the rest of the demod board.  This is not noted for POP110, but is true for both:  The I and Q channels of the 110 MHz demod boards are switched.  In practice, we can handle this with our digital phase rotation.

Daytime tomorrow, I will test my new board as Suresh did in elog 4736.  Before we get to use AS110, we need (a) some LO juice from the RF distribution box, and (b) a spot to plug the board in, in the LSC rack.  Meditating on how those are going to happen are also tasks for daytime tomorrow.

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