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RE: Primestar Dish



Sam,
Angle of incidence equals angle of refraction. Thus, if the feed is 23
degrees offset from the perpendicular of the dish center, the look angle is
offset to that straight line in exactly the same amount in the opposite
direction.. With other words, if the offset feed is on the bottom of the
dish, when the dish is pointed at the horizon, you are actually looking 23
degrees above the horizon.. For this reason, I mount an offset dish upside
down so I can receive the horizon without the dish trying to look down at
the ground beyond it's adjustment range.
Good Look,
Gunther Meisse
W8GSM
AMSAT LM#  594

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of SamThomasWalker@cs.com
Sent: Sunday, September 23, 2001 2:50 PM
To: AMSAT-BB@AMSAT.Org
Subject: [amsat-bb] Primestar Dish


Need help in understanding the Primestar Dish.
      I had it mounded in a fixed positiion on top of 2 inch thickwall pvc
and up 8 feet, was receiving AO-40 sigs weak and noisy but could hear it
plus
some QSOs. I tried to immprove the set up and used a 10 foot tv mast and
installed a horizontal rotor, which raised the dish to about 12 feet off the
ground.I have not heard anythink from the beacon nor any activity on the
band.
        My big question is how can one tell what the elevation angle is
using theis offset mount. I've tried perpindicular to the center of the
dish.
Also it looks like 60 degs is the offset angle but have no way to check this
for pointing to the satellite. I would like to hear any suggestions in how
to
make sure I have the dish pointed at the bird ocrectly in the vertical.
Thanks, Tom Walker, W4EWB, Samthomaswalker@cs.com
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