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RE: Downconverter noise



> > > Should I have an S 5 reading just with the downconverter sitting on
> > > the bench, or should I only expect an increase in noise when the
> > > downconverter is fixed to the dish?

Yes, these things have plenty of IF gain, so expect to see lots of noise
into your HAM rig which you are using as the IF.  If the downconverter has
a reasonable noise figure, it should get 'quieter' when you put it on the
dish and point the dish skyward.

It gets quieter because it is no longer seeing the 300 kelvin noise
temperature of its terrestrial surroundings, but is now seeing the 4
kelvin temperature of space.  But this assumes that the noise Temperature
of the down converter is less than 300 itself..

Bob, WB4APR



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