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AIDC 3733 downconverter cold weather problems

Well I am going to try again.  I have two 3733 downconverters that exibit the
same problem.  They do not seem to work properly when the temps drop below
freezing.  What makes this strange is that I have a local signal source and
can hear it.  Signal source is in the house and in a controlled temp
One downconverter is on an offset dish the other on a 8ft prime focus dish.

What I have done is to place a series string of resistors around the
downconverter to act as a heater.  The downconverter is wrapped in fiberglass
pipe insulation.  In cold weather the downconverter is over 100Khz low in
receiving the test source.  Once I heat it up I can bring the signal back to
a nominal 144Mhz on the receiver.  I can vary the voltage to the series string
to control the temp.

Now to add to the confusion, while I can hear the local signal source I can't
copy AO-40.  I use NOVA to track the bird and I follow the times it is
visible,  squint and MA so that I have an idea when to look for the signal
from the bird.

Is anyone using the 3733 downconverter now ?  Have you experienced any temp
related problems?  Have you found a solution?  Is anyone willing to work with
me on this type of problem?

I have done a Google search and can't find any helpful info.
I can go into greater detail of the tests and what I have done to try to 
solve the problem.  If anyone is interested let me know.

Bill K0QK

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