Jim, Mike and Team
Thanks! It actually was probably about 25 years ago when I last checked the
magnetic declination here in Northern California and at 1 degree per 10
years rate of change in magnetic declination the 2.5 degree difference
tracks. :-) FYI Most of my rotor and antenna ensembles have at least +/- 5
degrees accuracy slop due to tolerances in the mechanics and electronics of
the self supporting towers, rotors and controllers and the 3dB width of the
main lobe of most of my antennas is large enough that I doubt that I would
ever actually be able to detect any difference in signal strength resulting
from a 2.5 degree difference in azimuth.
Realistically I could probably use the location of moss growing on trees in
the forest to determine initial antenna positioning and true north and be
close enough in positioning my yagis for most practical HF amateur antenna
positioning purposes :-) My 56 element 1.2 GHz antenna array on the other
hand is pretty directive and a few degrees error in azimuth would make a
difference for me on 1.2 GHz.....but otherwise I would have probably just
continued operating another 25 years (with any luck) in blissful ignorance
with a 2.5 degree (and slowly increasing) azimuth error vis a vis my HF
antennas.
73, Ted, K6XN
Ps I repositioned my HF antennas anyway this morning to correct for the 2.5
degree error :-)
-----Original Message-----
From: Jim Lux [mailto:jimlux@earthlink.net]
Sent: Sunday, August 27, 2006 8:54 AM
To: K6XN; 'Mike, K6BR'; towertalk@contesting.com
Subject: Re: [TowerTalk] THANKS MIKE! RE: something *really*
completelydifferent..andsimple... (True North)-
At 04:55 PM 8/26/2006, K6XN wrote:
>Mike
>
>I absolutely agree with your advice to those on the east coast and others
>having a negative magnetic declination. I apologize for the unintended
>possible confusion. Thanks also for the URL to find declination by zip code
>and date! I tried it and it turns out I have been off by 2.5 degrees all
>these years!!! :-) 73, Ted, K6XN
May not have been off "all those years", because the magnetic pole is
moving, and as a result, the declination is changing (especially in the
last 15 years). Here in Southern California, it's about a degree every 10
years, as I recall.
This also means it's something to be aware of when using "online" sources..
you need to check what the age of the data source is. The URL given
actually can tell you what the declination is for a given date, and is up
to date. I have seen some other declination sites that appear to be using
an old printed map as their data source.
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