[Dx4win] Headings

[LY2CX]

To be very exact if use a compass to set a True NORTH, 
we have to take in to account 3 meanings of the "north"
1. True North  - the point what we rally need (Geographic North Pole)
2  Magnetic North - called declination (magnetic variation) and
explained by James 
3  Compass North - called deviation . 
compass deviation depends on the environment you make a measurement. 
e.g. the antenna  mast, or can of beer near by can make an impact. 
The only having those three figures it's possible to calculate a True
North.
 
The other way is to take a local map, or use Google map,  to point
antenna location on it
and find the right known point, check the heading on the map. Point the
antenna to it 
and make the right settings on the unit.

Rgds. Vigis LY2CX

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As a former naval navigator, I have been following this discussion with 
interest. I agree with Jim that it makes most sense to use true north.
The 
magnetic pole shifts each year, and the amount of shift is indicated on 
nautical charts as the "Variation".