Re: [amsat-bb] 18" RCA Dish Question

[Paul Yeager <w4ski@xxxxxxxx>]

Hmm....  I'm trying to figure out if that was a compliment!  :^)

This was not an act of pure recklessness.  Someone (was it G3RUH?) 
published an article years ago describing construction of a prime focus 
helix feed for a 60 cm dish, for 2400 MHz.  In the article, the author 
stated that it was not necessary to "sweat the details" too much... get 
things close and it would work just fine.  Since then, my research has 
revealed the broad-banded nature of the axial mode helix, which would tend 
to make it forgiving of small dimensional errors.

I have also seen in many web articles on the subject that many construct a 
"cup" of some sort around the fed end of the helix, and the saucepan lid 
provides this effect.

My small-town location makes it a bit difficult to find an appropriate 
piece of sheet aluminum, but the saucepan lid was easily found at a thrift 
store.  Since I constructed the antenna, a friend has provided a nice piece 
of sheet aluminum, I just have not had time to rebuild the feed yet.

Besides...  the first reaction to the whole assembly is usually a laugh.... 
and you can't get too many of those, especially for something that works!

73,

Paul W4SKI
At 11:06 PM 7/11/02 +0000, you wrote:
>  Paul Yeager writes:
>
> > I mounted a 5 3/4 turn helix to a N connector mounted on a suacepan lid,
> > then mounted the saucepan lid to the LNB mounting arm of a Dish Network 
> dish.
>
> > but.... IT WORKS
>
>Now thats what I call *amateur* radio. Nice one Paul.
>
>73
>Richard W L Limebear G3RWL
>g3rwl@amsat.org
>FOC # 1188
>
>           So many beautiful girls ..... (sob) so little time
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