The only problem using Polaris, or most any star for that matter, is that the only time you're going to see it is when it's too dark to go climbing up the roof or tower to adjust the antenna. I use the one star that is always visible during the day, the Sun. Most satellite tracking programs can tell you where the sun is (Az/El), or you can look it up on-line. Aim the rotor controller to those coordinates, and then adjust the antenna so the shadow falls directly down the antenna boom. Done. I find it's best done later in the afternoon, when the Sun is closer to the horizon, but any time will do except when it's directly overhead.
And, with most practical 2m/70cm antenna systems, this adjustment doesn't need to be up to NASA standards. As I am sure you know, hand-holding the Elk, anywhere in the general direction of North works pretty well in practice.
Greg KO6TH
Date: Wed, 12 Aug 2009 11:22:16 -0500 From: n0jy@lavabit.com To: bhowell@mail.utexas.edu CC: amsat-bb@amsat.org Subject: [amsat-bb] Re: rotator questions
One can also use Polaris (the North Star) at least in most of the northern hemisphere where it is visible. A long time ago, I went outside after dark and looked at how my house lined up with Polaris. In my case, it was a dead sight along the front or back side and the peak of the roof to Polaris. If it's not, you could use a protractor to determine the difference. I have done that, relative to the E/W lines of the side of the house, to point the TV antenna to 125 degrees toward the transmitter site for this area.
Jerry N0JY
Joseph, Check out this page: http://www.thecompassstore.com/decvar.html# There's a link on that page to plug in your Zip code and figure declination, or you can use the handy map on the main page. For Austin, the magic number is 4 degrees.
If I recall correctly (it's been a few years), I set the rotor control box to North, went up on the roof and rotated the *mast* until the ants pointed to magnetic north (using a compass). Note that the compass will read inaccurately if held near a metal mast. Then I rotated the mast a bit more so the ants were pointing about 4 degrees *West of magnetic North*.
That's the way I remember doing it.
Bill N5AB
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