[TowerTalk] And now for something completely different (TrueNorth)
mclarson at rcc.com
Mon Aug 28 10:26:44 EDT 2006
One should also be warned that sometimes a magnetic compass is useless also
due to declination anomalies. If one doesn't know about them, they can
really screw one up! See inserted info below. Sighting known geographic
features and comparing to a map is, for me, the simplest, most reliable
method for determining antenna directions.--Mike, WV2ZOW
Anomalous declination is the difference between the declination caused
by the Earth's outer core and the declination at the surface.
A few areas with magnetic anomalies:
-North of Kingston, Ontario; 90° of anomalous declination.
-Kingston Harbor, Ontario; 16.3° W to 15.5° E of anomalous declination
over two kilometers (1.2 miles); magnetite and ilmenite deposits.
-Near Timmins, Ontario, W of Porcupine.
-Savoff, Ontario (50.0 N, 85.0 W). Over 60° of anomalous declination.
-Michipicoten Island in Lake Superior (47.7 N, 85.8 W); iron deposits.
-Near the summit of Mt. Hale, New Hampshire (one of the 4000-footers,
near the Zealand Falls hut on the Appalachian Trail) ; old AMC Guides to the
White Mountains used to warn against it.
-Around Georgian Bay of Lake Huron.
-Ramapo Mountains, northeastern New Jersey; iron ore; compass rendered
useless in some areas.
-Near Grants, New Mexico north of the Gila Wilderness area; Malpais lava
flows; compass rendered useless.
They are not all in Canada. Some more:
Anomalous declination(degrees) Lat. Long. Location
46.4 W 40.2 106.2 75 km.(45 mi.) W Boulder,CO
24.2 E 40.7 75.3 20 km. (12 mi.) NE Allentown, PA
16.6 E to 12.0 W over 10km(6mi)46.7 95.4 250 km.(150 mi.)NW Mpls, MN
14.8 E 33.9 92.4 85 km.(50 mi.)S Little Rock,AR
14.2 E 45.5 82.7 In Lake Huron, Ontario
13.8 W 45.7 87.1 Escanaba, shore of Lake Michigan
13.7 E 48.4 86.6 In Lake Superior, Ontario
13.5 E 48.5 122.5 80 km. (50 mi.) N Seattle, WA
13.0 W 42.2 118.4 In Alvord Desert, Oregon
12.2 W 38.9 104.9 10 km(6 mi)W Colorado Springs,CO
11.5 E 47.8 92.3 120 km. (75 mi.) N Duluth, MN
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Keith Dutson
Sent: Monday, August 28, 2006 9:52 AM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] And now for something completely different
No. It is virtually useless to align an antenna on a tower, unless you like
climbing at night.
73, Keith NM5G
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