[Almacal] Re: [mmaimcal] Meeting today

[Al Wootten]

Stéphane Guilloteau writes:
 > A 08:42 11/05/2005 -0400, Al Wootten a écrit :
 > >Hi Stéphane
 > >
 > >Thanks.  Indeed that is a good point.  I'll talk to Skip about this but
 > >I think it is really the magnitude which causes problems.  It is no problem
 > >at the moment because they are using a x6 multiplier for B9.  However, I
 > >am told that there is a x5 solution 'almost ready' for implementation, and
 > >that for this it is very difficult to switch by 0.03%.  Since we cannot
 > >ascertain lock at 10ms anyway it would be quite reasonable to relax that
 > >somewhat.
 > Well, the 0.03 % shift problem is really for band 3 and below: how does 
 > Band 3 perform in this respect ?
 > One solution would be to split the spec as
 >          - XX ms for a shift of 0.05 % for Band 3 and below
 >          - YY ms for a shift of 0.02 % for Band 4 and above
Folks,

I discussed this with the LO group.  Their plan is to effect frequency switching
in the 1st LO through the FLOOG.  At present, the magnitude of the switch
which can be made with the FLOOG is 20 MHz.  With a small amount of work it
can be made to switch by 25MHz.  It would be difficult to make a larger switch.
Therefore the best engineering solution is to switch by up to and including
25 MHz.  This gets multiplied up of course according to band.  It allows
us to accomplish our goals at Band 3 but would not be capable of canceling
standing waves between reflector and subreflector at the lowest bands.  I think
that isn't a major fault, scientifically.  So the proposed spec would be

          -- 10 ms for a shift of 25 MHz or less for any band.

Clear skies,
Al