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more azimuth indexing info

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Subject: more azimuth indexing info
From: al511@freenet.uchsc.EDU (Robert Neece)
Date: Wed, 8 Jan 1997 11:02:50 -0700

Chuck, KE5FI, and Fred, K1VR, have made intelligent
comments as to the use of landmarks to achieve compass
indexing of antennas.  

In my posting, I said that I always set the rotator dead north, 
and then orient my antenna elements by sighting them against a 
due-east landmark.

Chuck and Fred note that a more universal, and easier, method is to
determine the azimuth of a convenient landmark:  one at, say, 110 
degrees.  Then rotate the mast until the rotator indicator shows 110.
Aim the beam at the landmark, tighten the bolts, and you're done.

One might reasonably ask, therefore, why I suffer from a fixation 
that impells me to set my rotator on due north and then to proceed
from that beginning.  Chuck himself identified the reason when he
noted that his method depends upon the assumption that the
direction indicator in the rotator is linear.  

I am afraid that the Ham-M and Tail-Twister indicators I use are 
somewhat nonlinear.  I set my rotators so that the CW and CCW
limits are south.  North, therefore, is half way through the
rotation.  I reason that the north setting splits the effect
of the nonlinearity.

For me, there is an even more important reason to use north
as my point of beginning.  I don't do any serious VHF work.
HF DX matters most to me.  And my favorite targets are
the world's population centers:  Europe and Asia.  With 
typical propagation in the Rockies, those targets require beam
headings that are, respectively, a bit east and a bit west of north.  
By making the north heading my most accurate one, any nonlinearity
of the rotator indicator becomes inconsequential for short-path
circuits to Europe or Asia.  

Bob, K0KR and K7KU

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