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Re: Downconverter noise

On Monday, May 26, 2003, at 19:36 America/Chicago, Phil wrote:

> 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?

I would hope not.  If the noise level of your d/c is S5 w/no antenna 
and no signal, then I think  you would have a problem.  I don't know 
why the instruction sheet says that.  Are you sure that's correct?  
These are supposed to be relatively low noise d/cs.

> Another question, at the focal point is a thick circular aluminium 
> plate which
> has three grooves machined in it and a central hole about 70 mm in 
> diameter.
> The fellow that I bought the dish from referred to it as a choke. I 
> have had
> the patch aerial mounted directly to that choke, could that be a 
> problem?

Depends on the frequency of the choke.  You might want to cover it over 
with some foil tape or a plate of your own.

> Finally, my dish is a steel petal type 1.8 metres in diameter. It's a 
> little
> awkward to maneuver but I think I've been reasonably accurate in 
> pointing it
> in the correct direction. Should I expect to hear the beacon if I'm 
> say 10
> degrees off?

Probably not.  That's a big dish and it has a lot of gain.  With a dish 
that size, you need to be pretty accurately aimed.  Even with smaller, 
lower gain dishes, the bird is not copyable 10 degrees off.  With yours 
it will be even worse.


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