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Re: Antenna Aiming Calibration Using the Sun Question

At 06:03 AM 5/29/03 -0500, Ted Huf W4ZE wrote:
>I have not gotten my system on the air yet, waiting for all the parts to
>arrive.  I was wondering the best way to check that you have the rotator
>calibrated.  Does the Sun emit enough noise on S-Band to know that you are
>pointed at it?  Is that an acceptable way of checking you aim?  Any other
>ideas?  S-Band setup will be Kuhne down converter and James Miller's 60cm
>dish and patch feed.
>Ted Huf
>Hickory, PA


Yes, the sun, in fact, makes a good source to calibrate your rotator.  Even
if you cannot detect sun noise, you can point physically at the sun so the
feed's shadow falls in the center of the James Miller dish (don't look at
the sun to do this).  If you have your 2.4 GHz system connected, you should
also see about 1/2 s-unit rise when pointing at the sun vs. pointing at
cold sky (not at AO-40 or near the horizon).  Be sure that your view is
unrestricted by trees as they will both raise the system temp and attenuate
signals (solar noise in this case).  Use USB in the widest bandwidth your
radio is capable of.  If you have a good audio voltmeter you can connect it
to your speaker output to see an increase in noise level...it will be
offset by your AGC, so turn off the AGC if possible).

After you have the dish centered on the sun, compare your rotator read-outs
against computer predicts for sun position.  Make any corrections of the
rotator/dish accordingly until they agree.  You may have to adjust and
check several times since the sun will move during your adjusting ;-)

73, Ed - AL7EB

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