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Re: IC-910 / 3731




----- Original Message -----
From: "Anthony Monteiro"

> Hi Drew,
>
> Nice to hear from you (enjoyed the symposium!)
>
> I don't see how a center fed 60cm dish could work very
> well since the feed blockage is so severe at 2.4 GHz
> whereas a 60cm offset-fed would seem passable if
> fed correctly. Don't you think?
>
> I think most of the problems with offset fed dishes
> is that people try to feed them with a helix which
> picks up too much ground noise.
>
> Any comments?
>
> Tony AA2TX
>
>

I'd say it depends on the size of your feed. The G3RUH 60 cm dish/patch
combo seems to work well. I think if you modeled it the blockage is so small
a portion of the total area the difference would be negligible.
Empirically, I've worked a lot of guys using 60 cm dishes (them). Most of
them seem to hear fine. Look at the fine results with W9AE's DXpedition
setup with just a AIDC D/C, no preamp......

I think I'd take noise from the sidelobes of a helix (which you can reduce
with a cupped reflector) over the noise from overilluminating a offset dish
with a patch feed.

>From my experience, having used a BBQ (K5GNA), Primestars (both normal size
and 1.2 m), DSS 18" dish (as VP2EAG), and now a 3ft prime focus (pansat Ku
tv dish), the prime focus is by far the easiest to set up and use. Easy to
point, easy to not overilluminate with the right F/D, and makes a good
birdbath after Florida thunderstorms....

73, Drew KO4MA

P.S. I enjoyed the heck out of the symposium, and can't wait to see what you
dream up for next year...


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