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Re: Rotor Problem



"Patrick Riggins" writes:

about elevation rotors:
> I know that there is no reason to really go past ninety 

As a matter of fact there is. Assume your azimuth rotor stops at north,
now assume theres a satellite who's path traverses from west to east via
north (KO-23 does this here). Track the pass; rotor moves clockwise until
it gets to north but then can't go further so it has to turn a full anti-
clockwise circle and start over from north until LOS. That anticlockwise
turn takes a minute or so (seems longer if you're waiting for it to end)
and so you miss a chunk of the pass. There are other passes which go from
west to east via south ... no theres no easy answer (so far); if you
disable the stops in the az rotator you end up with the cable snagged (or
worse) on the mount.

BUT ... if your elevation rotor goes to 180 degrees you just go there and
use (beam heading)-180. Lots of automatic antenna control software does
this; on my trakbox its called flip-mode.

> I cannot get a full scale reading on the control box. The most it will 
> go over is to ~135 degrees.

I'm presuming that is the meter reading rather than the actual elevation
that the rotor is pointing at. To do the following adjustments on the bench, 
rather than up on a tower, mount something in the rotor so you can *see*
how far it turns.

With power OFF, use the zero adjust screw under the center of the meter
so the needle points at zero degrees. Power ON and make sure that the
antennas (or the pointer) *are* horizontal visually when the needle points 
to zero on the "down" side.

Rotate in elevation through 90 degrees to zero elevation on the "up" side
(do this visually rather than watching the meter). There is a screwdriver
adjustment thru the back of the case, now adjust this so that the meter 
reads zero on the "up" side.

Go back to zero (down) and check again; this is mostly correct but worth
taking a look at if there was a large error (as in your case).

Done.

Regard the adjustment at the back as an fsd-gain control (it might even be
what its actually supposed to be used for).

73
Richard W L Limebear G3RWL
g3rwl@amsat.org
FOC # 1188

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