----- Original Message -----
From: "AD5VJ Bob" <rtnmi@sbcglobal.net>
To: <towertalk@contesting.com>
Sent: Friday, December 02, 2005 1:00 AM
Subject: Re: [TowerTalk] Positoners Calibration to True North
> Also since you wanting precise measurement for sat work I
> just found out from reading that Mag north changes all the
Magnetic North wanders around in a rather large circle and changes between a
half and a full degree each year (in some areas) in others it may be quite
stable. In the NW US magnetic north is quite mobile and differes
considerably from true north (as much as 20 to 30 degrees in some areas).
We are also in an area where the isogonic lines are relatively close. Of
course that is true across the entire northern tier of states.
Be careful with using the following page as it does not take into account
such things as local anomalaties, and a number of variables that would
affect one area more than another. There are local spots around the globe
where the magnetic polarity is changing which confuses matters even more.
As they state, the information is to be considered as a guide only.
Good Luck,
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
> time so you might want to use this link for more accurate
> readings and subsequent periodic adjustments to your
> calibration mechanism:
>
> http://geomag.usgs.gov/observatories/data/realtime/
>
>
>
> 73 fer nw,
> Bob AD5VJ
>
> 10X# 37210, FP#-1141, SMIRK#-5177
> http://www.n5iet.com/
> Code may be taking a back seat for now,
> but the pioneering spirit that put the code
> there in the first place is out front of it all.
>
>
>
>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of
> Jim Lux
>> Sent: Thursday, December 01, 2005 10:54 PM
>> To: Tom McAlee; towertalk@contesting.com
>> Subject: Re: [TowerTalk] Positoners Calibration to True
> North
>>
>>
>> At 08:15 PM 12/1/2005, Tom McAlee wrote:
>> >Since the original question was posted by a VK station,
> it might be
>> >worth noting that using Polaris to locate north can
> only be
>> done in the
>> >northern hemisphere. It is not visible below the
> equator.
>> >
>> >Down there you'll need to locate south and flip that
> 180.
>> But, there
>> >is no "south star" such that the south end of the
> earth's
>> axis points
>> >almost directly at it. But, there is some bizarre
> combination of
>> >constellations/stars and drawing lines and following
> them
>> >perpendicularly to other stars, etc., that can be used
> to locate the
>> >south pole with enough accuracy for antenna work.
>> >
>> >But, never having been in the southern hemisphere, I
> don't know the
>> >details. I'm sure you can find info about it on the web
> though.
>> >
>> >And, by the way, Polaris isn't exactly north; it's
> about 1
>> degree off
>> >true north.
>>
>>
>> use the SUN.. at local solar noon, the shadow will
> either be
>> directly north
>> or directly south. The trick is figuring out when local
>
>> solar noon is.
>> Fortunately, you probably don't need to know to the
> gnat's
>> eyelash second
>> of arc accuracy.
>> Noon is when the shadow is shortest, but if you mark
> where
>> the shadow is
>> equal lengths, the north south line is exactly halfway
> between.
>>
>> Jim
>>
>> _______________________________________________
>>
>> See: http://www.mscomputer.com for "Self Supporting
> Towers",
>> "Wireless Weather Stations", and lot's more. Call Toll
> Free,
>> 1-800-333-9041 with any questions and ask for Sherman,
> W2FLA.
>>
>> _______________________________________________
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>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
>
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> any questions and ask for Sherman, W2FLA.
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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