Re: [amsat-bb] More Kansas City Tracker Questions

["Greg D." <ko6th_greg@xxxxxxxxxxx>]

Hi Joe,

With a 10' dish to aim, my guess is that you will need a
more precise position sensor than a pot with a weight on it.
That weight is going to swing a bit, and there is going to
be error introduced by the friction in the pot's shaft
bearing.  My limited experience with this sort of design
was moderately successful, but I was aiming a short yagi
at the time.

If you can anchor the "weight" end to something fixed,
that should help.  Also, pots don't like to get wet.

Just a suggestion,

Greg  KO6TH





>From: Joe Leikhim <jleikhim@nettally.com>
>To: "amsat-bb@AMSAT.Org" <amsat-bb@AMSAT.Org>
>Subject: [amsat-bb] More Kansas City Tracker Questions
>Date: Tue, 03 Dec 2002 23:21:17 -0500
>
>I have a KCT-T I would like to use to control a 10' dish antenna. What I
>have in mind is to use a potentiometer with a weighted pendulum to sense
>the elevation angle (0 to +90 degrees). Another pot will sense the
>rotation of the dish by direct mechanical connection. Finding a suitable
>360 degree rotation pot for the latter seems to be a problem. However 3
>turn and 10 turn pots exist.
>
>What drawbacks if any will I have if I use a 3 turn or 10 turn pot?
>Since I am using a 10 foot dish for the S-band downlink the pointing
>error (and pot resolution) will be critical.
>
>Is a carbon pot OK or should I be looking for wirewound?
>
>What value is recommended?
>
>Is there any drawback to using an externally regulated supply for the
>reference voltage?
>
>By the way, I have been using the "ultimate charger" site for reference
>but would appreciate links to other sites or suggestions about the
>mechanics of AZ/EL positioning of a 10 ft dish. If there are surplus or
>commercial sources for positioners I would like to hear about them as
>well.
>
>--
>Joe Leikhim K4SAT
>Jleikhim@nettally.com
>
>"Jazz is not dead.  It just smells funny." -F.Z.
>
>
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