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Re: AO-40 dish



JoAnne,

Nice dish and I am sure it works real nice on AO-40.  I thought I would
respond to your comment about having to repoint it frequently.

If you were to use a 3-foot dish for AO-40 the gain is 25.7 dBi and the
beamwidth is 9.72 degrees.  Not too hard to keep pointed and only requires
repointing ocassionally (once per hour?).

Using your 2.4m (8-foot) dish the gain at 2400 MHz is 34.2 dBi (I think
your website lists 38.5 dBi but this is the gain for C-band TV not at the
lower freq of AO-40).  Your beamwidth is 3.65 degrees.  No wonder it has to
be pointed often.

I have an 8-foot dish that eventually will get set up for mode-LS with a
dual-band patch feed.

73, Ed - AL7EB
FT-847, MKU-232A, Drake, 85cm (33-in) offset feed dish with 5.25 turn
helix, 50w UHF PA at 436CP42 (16.5 dBdc)

At 07:53 AM 8/6/03 -0500, JoAnne Maenpaa wrote:
>Hi Glenn,
>
>> Any thoughts? Pointing might be a problem. Thought of building
>> a tripod mounted to the dish and manually point it for the 
>> major part of the pass.
>
>Since I just got my dish installed and the downconverter work-
>ing I've been doing the Armstrong Rotor on my AO-40 antenna.
>There's a picture at http://home.earthlink.net/~maenpaa/
>
>Sooner or later, time permitting, I'll figure out a mechanical
>way to rotate it.  I've been pointed towards C-band TVRO
>actuators as the best approach to automation.
>
>One thing that surprised me about the big dish was how critical
>aiming was.  Once centered on AO-40 (going by strongest signal
>received from the beacon) I lose the bird if I move the dish
>more than an inch or so left/right or up/down.
>
>I take the az/el info from the tracking program and translate
>it into my Armstrong Aiming Parameters (AAP's).  I started out
>using a compass for az and a plain 'ol protractor for el.  After
>a few weeks of practice I'm beginning to be able to eyeball 
>where I should point it.
>
>While AO-40 is reasonably far out I need to re-adjust its
>pointing about every 20 minutes.  I just keep the beacon freq.
>in the other VFO and use it to reposition the dish for best
>signal.
>
>Hope this helps ... go for it ... give your dish a try!
>
>73 de JoAnne WB9JEJ
>----
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> 

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