Re: [amsat-bb] Primestar Dishes: Cheap and Frustrating

[Jim.Walls@xxxxxxx]

Bill - W1PA said (in part):
> I assume I would see the same if I put a 2.5 turn helix on it (Jim,
> K6CCC... didn't you write once that you thought your Primestar
> performed better with 2.5 turns?)....  the 2.5 turn helix feed now
> sized for the long dimension beam width vs. the short.

Yes I did.  I range tested my PrimeStar starting with a 7 turn (IIRC) helix
and cut it down 1/4 turn at a time all the way to only 1/4 turn.  I
measured receive signal strength at the 123 MHz IF output of my TranSystems
downconverter.  2 3/4 turned out to be maximum signal.  As part of your
discussion that I did not include here points out, that a helix this short
is likely over illuminating the dish so I am likely picking up some extra
noise due to the spillover on the truncated portions of the dish.  As my
tests only considered signal strength, that factor was not considered.

-----------------------
Jim Walls - K6CCC
k6ccc@amsat.org
Mobile Radio Operations
Southern California Edison Co.
Ofc:   626-302-8515   -   PAX   28-515
FAX:   626-302-7501   -   PAX   27-501



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