Re: [amsat-bb] G-5500

["Ben" <b-fisher@xxxxxxxx>]

Ok Jim
 I guess I should try it first. hi hi
Ben K9BF
----- Original Message -----
From: <Jim.Walls@sce.com>
To: "Ben" <b-fisher@uiuc.edu>
Cc: <amsat-bb@amsat.org>
Sent: Monday, December 09, 2002 10:06 AM
Subject: Re: [amsat-bb] G-5500


> "Ben" <b-fisher@uiuc.edu> said:
> > I just bought a G-5500. I don't have it up yet, but I did study the
> > schematic. There is no provision for speed control.
>
> Correct
>
> > I suspect these things are poor auto trackers. In order to stay fixed
> > on a moving target it would become necessary to pulse the motors.
> > I can see where these things would exhibit jerky motion.
>
> We're not trying to track airplanes overflying at 1000 feet.  Even low
> earth orbit satellites don't move across the sky fast enough to be a
> problem.  With the antennas that us hams are using for 2M and 430,
pointing
> only needs to be within about 10 degrees for really large arrays and with
> small yagis that figure is more like 30 to 45 degrees.  At S-band it
starts
> getting picky and the guys running big dishes need better directional
> control than the G-5500 will provide, but I can't imagine anyone trying to
> point a 10 foot dish with a G-5500 from a mechanical standpoint.  Most of
> the tracking programs will correct the antenna pointing when the satellite
> is more that some number of degrees from the antenna pointing.  So yes,
the
> antenna moves a few degrees and then stop for a while.
>
> > I've thought about designing a better system using servos or stepper
> > motors with optical encoders for position feed back. With the proper
> > software interface it would be easy to track a satellite with a
> > smooth motion of the antenna system. I'm sure its already be done but
> > by who?
>
> It's been done for larger arrays, but not worth the effort (especially
> since you already have the G-5500).  The G-5500 is generally considered to
> be the standard by which all other El/Az rotors are compared.
>
> 73
> -----------------------
> Jim Walls - K6CCC
> k6ccc@amsat.org
> Mobile Radio Operations
> Southern California Edison Co.
> Ofc:   626-302-8515   -   PAX   28-515
> FAX:   626-302-7501   -   PAX   27-501
>
>
>

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