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[TowerTalk] Beam alignment

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Subject: [TowerTalk] Beam alignment
From: (
Date: Thu, 3 Jul 1997 13:39:00 -0500

You people wishing to split a gnat's eyelash with beam/rotor alignment
ought to also consider the following:

1) Where is your beam pattern really with respect to the physicial
antenna?  I've seen cases where imbalances in the design and feeding
have squinted patterns 15 degrees or more from where you'd expect it to
be.   Actually measure your pattern sometime with a local and find out.
You may be surprised.  You people with triband quads and a single
feedline may discover that your 10 meter pattern has two lobes about 45
degrees either side of the "true" peak with a depression at the position
of the "true" peak.

2) The popular Ham IV rotor has break stopping points only every 4.8
degress.  Couple a slight misalignement with this and you could easily
be off almost 10 degrees from where you wanted to point it.

3) Signals don't always come from the great circle direction.  If you
don't believe it, try aiming your 40 meter beam to Japan via great
circle in the morning.  Then aim it further at the equator and compare
the signal strenghts. K3KO's Theorem;  The strongest signal always comes
from the strongest signal direction.

4) If you have a globe, you can determine an accurate enough true
north/magnetic north variation by sticking a pin in Great Bear Lake in
VE8(an approximate location of the magnetic north pole, if memory
serves.  Correct me if you have a better geographical fix), the north
pole and your QTH.   Run a string from your QTH to the true north pole,
another string from your QTH to the VE8 pin and measiure the angle
between the two.  That's it.  There is no magic involved.    Oh, by the
way, the position of the magnetic North pole is constantly moving.
Enough so that the airports have to sometimes repaint the numbers of
their runways to keep up..

Bottom line, be practical.  The real world isn't neat and clean.  Don't
waste your time and energies on things that are really not important.
Not everything is known with absolute precision or ever will be.  Mother
nature is full of suprises.

Let's see, true north is 6.523 degrees East of magnetic north from here,
that means I have to ....

de Brian/K3KO
Vance Net Inc
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