Mark IV Progress Report #4

[Tom Droege <droege@wwa.com>]

Reading below you should get the impression that I am busy running a 
production operation that is trying to turn out 8-10 dual systems.  
That is what we are doing.  

Ten sets of camera parts have arrived and a camera head has been 
assembled.  Almost everything fit together as planned.  One exception 
was the shutter motor mount.  Not quite the correct screw spacing.  
But the motor is plastic and stretched into place.  The shutter has 
been built and works OK.  The next version will use parts 
electrochemically machined by my brother who is in the business.  Each 
one I build is a little better.  Eventually I will get one that is 
light tight. 

All the major boards have now been operated.  The Stamp/Scanner board 
has been corrected and is out for 20 copies.  The ADC board has been 
corrected and we are out for 20 copies.  The Motor driver board has 
been tested, and most corrections have been made to the PC board.  We 
tested the TEC driver board today, and corrections are being made to 
the PC board as I type. 

This means that everything has worked to the extent that we can test 
it a part at a time.  Almost all the corrections have been made, and I 
should be able to get the boards out to the vendor next week.  This 
will mean 2nd and 3rd generation (but not necessarily perfect) PC 
boards will soon be here.

We have 3 (of 4 assembled) memory boards working.  20 new ones will be 
here next week.

I have been testing the completed camera head with its temperature 
servo this morning.  We got to -35 C with 25 C cooling water and at 
1.7 amps.  This is a comfortable operating point.  Everything is 
stable and I like the way it runs.  I can actually get 2 C or so 
cooler, but this is nearing the top of the curve where running the 
current higher results in less cooling.  I am quite happy with this 
performance.  -35 C is quite cold enough for us to run in non-MPP 
mode where we get a larger dynamic range.  

Mike is busy designing the mount.  Most of the little parts have been 
detailed, and he is busy making assembly drawings.  I will put these 
up as soon as Mike finishes them.  Probably next week.  

Tom Droege