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Re: AO40 dish



At 03:35 PM 9/3/2002 +0200, Jonathan Naylor wrote:
>It seems to me that if you have the space and ability to track a 10ft 
>dish, why not think about EME ?
>
>On 23cms, you only need a few hundred watts and such a dish and you are 
>on the edge of having a usable EME system that is capable of working a 
>great many of the already active stations. Obviously more is better, 
>but as a first stage it is very good.
>
>I just wish I had the space for a 10ft dish, sigh.
>
>Jonathan  HB9DRD/G4KLX
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> 

A ten foot dish:
1)  Can be used for the family's TV, and used for AO-40 downlink by
mounting a feed to the side of the TV feed (just below will give a pointing
offset in the desired direction).  Your TV dish points at the equatorial
orbit (slightly below if in the northern hemisphere)  You want to track an
object inclined +/- 5 degrees to the equatorial plane, so that' quite
possible.
2)  Pointing is tighter due to the narrower beamwidth with a lrager dish,
but signals are as strong as you can achieve!
3)  Slight adjustment to the dish elevation may be needed for part of pass.
 This can be a nuisance if you stay with the manual system on a stock TV dish.
4)  Yes, eme on 1296 is std with this size and anything over 150w.
5)  The use for L-band uplink with a dual-feed is a real possibility.

I have an 8-foot (originally ku-band) dish that I have converted to radio
astronomy on 1420 MHz, and the small helix feed can work at 1296, so I am
considering its use for my mode-L uplink where I am limited to 15w.  Only
problem is getting the controllers working to drive the az-el system...yeh,
nice to have (but computerized but no software).

I think it would be fine for you if wind is not a problem...check out the
references others have given.

73, Ed - AL7EB


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