[amsat-bb] Re: rotator questions

[Mark Lunday]

My 2 cents.

Use a handheld GPS to align, or refer to a map.  Reason: the Arrow is not a
small beamwidth antenna...don't put too much accuracy into alignment.  Like
tracking pennies on a million dollar contract.  Case in point:  I took a TV
rotor into the unfinished attic of my house, taped it to a cross beam on the
floor with duct tape, inserted a sawed off handle from a standard shovel,
and taped the Arrow at 30 degrees elevation to the handle.  Aligned the
Arrow to North by going outside and referencing the North Star after sunset
against the alignment of my roof longitudinal.  Works like a charm.


Mark Lunday
WD4ELG
Hillsborough, NC - FM06kb
wd4elg at arrl.net
http://wd4elg.net
http://wd4elg.blogspot.com


-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Joseph Armbruster
Sent: Wednesday, August 12, 2009 11:29 AM
To: amsat-bb at amsat.org
Subject: [amsat-bb] rotator questions

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
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