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Re: Pointing large dishes



I am using 10' TVRO dish that come with AZ/EL actuator (polar mount).
Since the design is for geosync sat, the focus is more on the Elevation
(which cover Horizon to Horizon or at least  from horizon to 90 degree).
The Azimuth is the real problem, because the design is only for correcting
the inclination relative to QTH.
On my QTH (OI33lt) the west pass is around 270 degree (+/- 10 degree) and
the east past is around 95 degree (+/- 10 degree).
For that purpose, I am using a Kenpro KR-600 mounted to 3" pipe to rotate
the dish from 0 to 360 degree.
The only problem is the KR-600 resolution is only about 5 degree at best.
The 12' dish require at least 2 degree pointing error for optimum
performance. BUT considering the high dB gain achieved by the large dish,
the pointing error of 1 to 3 degree still have an acceptable performance.
The best solution is to use the actuator with speed reducer (60:1) and a
chain of 12:1 resulting  about 2 pulse per degree, which really have the
fine resolution for big dish.
For controlling the actuator, I am using Drake 600-A which has a dual
actuator capability.
Robert - W0LMD has a very nice website about large dish for AO-40.

Reinhard - YB0KTQ

----- Original Message -----
From: "Roger" <rogermj01@attbi.com>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, August 01, 2002 10:38 AM
Subject: [amsat-bb] Pointing large dishes


> have recently acquired a 10' TVRO dish and would like to use it for AO-40.
> I recall that when some folks were first trying to use the large dishes
the
> claim was made that AO-40 closely followed the ecliptic and that leaving
it
> set as a polar mounted system would work.
>
> I wonder if anyone actually made that  happen. I am willing to engineer an
> az el system but there will be a lot of adapting to do.
>
> Any help or ideas would be appreciated.
>
> Roger
> WB0GAI
>
>
> ----
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