From jdotson Fri Aug  8 19:05 CDT 1997
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	id TAA02016; Fri, 8 Aug 1997 19:05:34 -0500
Date: Fri, 8 Aug 1997 19:05:34 -0500
From: jdotson (Jessie Dotson)
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Subject: CMU visit
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Status: RO

Giles -

Our trip to CMU was quite fruitful.  The dewar fit fine - with a little
more room to spare than I was expecting.  It took a day to rig up a 
dewar stand to interface with their instrument platform.  Some of the
items learned during the fit check are:
  - We'll move the pillow blocks (which slide onto the rails on the 
        instrument platform) 1.25" closer to the end of the dewar.  This
        doesn't put our expected focus in the middle of the range, but
        will set us up to hit the stops on the end of the rails before
        we hit the tertiary.
  - We must build an extension (either attached to dewar or dewar stand)
        to hook to the instrument focus motor.
  - There's plenty of room for the He3 tanks as currently built.  Dave
        will place the external He3 plumbing below the He3 tanks.  This
        leaves more room for both the He3 plumbing and the preamp box.
  - PreAmp boxes the same size or smaller than the KAO design will
        fit fine.
  - The dewar stand as currently built places the focus 3/4" too high
        when the instrument stage is in the nominal position.  Our 
        options include:
        1) use the instrument stage adjustability (+/- 1") to bring
             dewar focus down to telescope focus.
        2) rebuild the dewar stand
        3) relocate our optical axis.  This is an unnecessarily
             complicated solution.  The only reason to pursue this if
             it somehow simplifies the layout internal to the dewar.
             Currently it only requires remaking the dewar case lid.
             Would have to be pursued IMMEDIATELY to be viable.

I talked briefly with Mark Thoma about the external electronics.  If
we duplicate their insulated boxes we'd have 36" vertical of rack space.
These racks mount on the back of the primary - one on the left, one on
the right.

I also discussed the computer control scheme with Matt Newcomb.  The
master computer is currently a pentium machine running linux.  The control
is executed via a family of tcl scripts.  In principle these scripts
can be sent by any computer.

Some follow-up on the following issues should be pursued asap:
  - If we tell Matt N soon how many fiber optics we need, he'll piggy
       back it onto their order.
  - Further coordination with Thoma about the external electronics rack
       is called for.  (ie, let's give him a formal go ahead)
  - I realised on the way back that I didn't see (or hear about) the
       telescope mounted patch panels we've been discussing.  The only
       patch panel I saw was mounted onto Mike's receiver.  We should
       track this down asap.  (If it doesn't exist, we've got alot more
       cables to build!)

One last bit of mis-information to clear up.  The "control room" is in
what we've been calling the mil-van.  According to Matt N. there is
*very* little room in MAPO allocated for Viper.  Probably something
like enough space for a single unix machine.  The control computer
is currently slated to go in the control room.  Matt suggested we
talk to Mark about how much space we need in the control room.

hope you had a good vacation