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Re: Automatic AMSAT Antenna Rotators



At 07:30 PM 5/9/2003 -0400, Bob Bruninga wrote:
>On Fri, 9 May 2003 K5OE@aol.com wrote:
***snip***

>Wow, I hadnt thought of that.  Just mount the TV rotator tilted back to
>point at the North star, then the dish just moves along the AO-40 track
>and my interface could do that just fine.  Besides, AO-40 moves slow, so
>you just hit the "L" and "R" keys to peak Left and Right on the bird (if
>it is slightly off) and then it will track all day...

>Wow, Ill work on that soon.  Unfortunately I went to add a simple routine
>to let the automatic rotator follow any APRS object such as a
>balloon or aircraft and I broke the source code and it locks up.  I can't
>do anything new till I find out what I broke.  But now that I use a
>Windows PC, it takes 5 minues to re-boot for each test..  I hate it...
>
>Bob

This also applies to those who are looking to use a big TV dish (also known
as Big Ugly Dishes = BUD) (7.5-foot or larger) for AO-40.  A satellite
TV-dish is normally mounted on a modified "polar mount" (what it was meant
"above" by tilting the rotator mast to align with the north star).  So all
that is needed to use a standard TV dish, is to modify the setting screw
that adjusts declination angle*.  In the northern hemisphere, satellite
dishes point from dec=zero (at the equator) to dec= -8.6 (in the far north,
like Alaska).  For AO-40 you need dec range of around +/- 5-degrees (plus a
little if you are very far north/south of the equator).

Of course you need a tracking program that gives hour angle/declination
positions instead of az/el.

73, Ed - AL7EB
*Note: of course you must install a 2.4 GHz feedhorn and electronics. 



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