ATM Trying to get rid of tube currents in a Newton telescope

[Bob Rubendunst <softm@softm.com>]

Keep the baffles, but improve the cooling.

After adding baffles, tube currents got worse for me. The first thing I did
was mount an indoor/outdoor thermometer on my scope: the mirror was often
10 degrees hotter than ambient, and thermal equilibrium never happened.

The solution was two fans: a tiny one that sucks air across the back face
of the mirror through the mirror cell, and another fan on the exterior that
sucks all of the first fan's exhaust, and more, out the back of the tube.
Tube currents are gone, and contrast is better with the baffles.


 +------------------+
 |      mirror      |
 +------------------+
   X              X
 +------+   +-------+
 |      |   |       | <- mirror mount board
 +------+   +-------+
      +-------+
      |  fan  |
      +-------+

+---+------------+---+
|   |   F A N    |   | <- outside board w/ collimating screws
+---+------------+---+