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RE: Direct TV offset dish -- best way to mount feed?



Bruce:

I just got home and measured the downconverter. It has 60 degree angle
off the rectangular arm.

If you take a piece of 1" wide by 1/8" aluminum, measure up about 8";
put a 60 degree bend there. Measure another 3" and put a 90 degree bend.
Cut that off at about 4". That should give you a 4" platform on which
you can mount a downconverter. The 8" piece gets bolted to the arm. As a
downconverter, I would recommend an AIDC 3731 from K5GNA. They are hot,
low noise, and 'relatively' inexpensive ($100). Then, make the patch
antenna described by K3TZ. I got some sheet brass from the hobby store
and cut it. It works great.

Spoke with Don earlier. He will take a digital picture of the
dish/mounting and send it to me. I'll then post it on my web site.

Hope this helps.

73,
Art N3OY


-----Original Message-----
From: Art Goldman [mailto:aegoldm@lts.ncsc.mil] 
Sent: Friday, February 21, 2003 4:57 PM
To: Bruce Bostwick
Cc: N3OY@comcast.net
Subject: Re: [amsat-bb] Direct TV offset dish -- best way to mount feed?

Bruce:

I have the same dish - obtained from a flea market. It did
have
the downconverter, so what I did was buy a stick of 1" x
1/8" aluminum at the hardware store, and bend it so the
angle matched that of the original downconverter. The final
bend had a flat area that I used to mount the downconverter.

Unfortunately, the "package", consisting of an AIDC 3731 and
the antenna, is at W4VQA's for testing. Don has a signal
source, a tripod on the (now heavily snow covered) deck, and
a second antenna/downconverter he uses for comparison. When
I gave it to him, the 3731 had a homemade patch antenna on
the end, and it was about 10" from the dish. I don't know if
Don moved it back or not, but he reported the combination
was working well, with minimal sidelobes, and about 3-5 dB
down from his 3' channelmaster dish.

As for the angles, well, I'll measure mine when I get home.

73,
Art N3OY

Bruce Bostwick wrote:
> 
> I've been toying with this project for a while and I think I need some
> help.  I have a Direct TV (?) offset Ku-band dish that I'd like to
> convert for other purposes, and I need some suggestions on how to
> quickly find the focal point of the dish.  It's missing the LNB -- I
> got it free from a relative -- and without getting a new LNB the only
> idea I can come up with is sticking some small mirrors on the edges
and
> one in the center and using sunlight, which may or may not give me the
> best angle for optimal focus.  If anyone's got better ideas I'm open
to
> suggestions.
> 
> Once I know where the focal point is, I think I can adapt various
feeds
> to this dish.  Thinking about using it mainly for analog Ku-band if I
> can get a sensitive enough LNB and feed, but also thinking about
> possibly picking up one or more AO-40 downlinks if I can.  Again, all
> suggestions are welcome.
> 
> AtDhVaAnNkCsE .. ;-)
> 
> "Go ahead and do it, you can apologize later." -- RADM Grace Hopper,
> 1906-1992
> "The sunset is an illusion, but the beauty is real." -- Richard Bach
> 
> ----
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