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
On Aug 12, 2009, at 10:28 AM, Joseph Armbruster wrote:
Hey everyone at the amtat-bb!
I spent a good portion of the day sick in bed yesterday and only naturally got to thinking about quite a few things. I figured i'd pop on here and start asking questions. Here's some background information on my sat experience; my rig consists of a TH-F6A (handheld, not full-duplex) and an arrow antenna. I have been successfull at manually trakcing the ISS and AO-51, but I have been unsuccessful at making a contact. I went out to field day (in Oviedo Florida) and was able to check out the rig the LMARS club uses. This got me wondering about sat tracking software, the internals and what definition of "North" that is used.
I'm familiar with the IGRF (from my day job as a GIS guy) and was wondering if any of these apps use the IGRF for calculating magnetic declination: http://www.ngdc.noaa.gov/IAGA/vmod/igrf.html
I've thought about creating my own rotator and started wondering about the configuration used. When you buy a rotator and put it out in the yard, i'm guessing you have to orient the base 'correctly'. How is the base of a rotator usually aligned? Do you get a compass out and use local magnetic north (without compensating for the declination from the IGRF).
I'm still in learning mode and very new to the world of sat, so if these are really dumb questions, my apologies!
I am open to any reading materials you can suggest on the matter.
Joseph Armrbuster, KJ4JIO _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb