Re: [TowerTalk] TowerTalk Digest, Vol 158, Issue 20

[jimlux <jimlux@earthlink.net>]

On 2/9/16 9:41 AM, Donald Chester wrote:
> > Also there is an averaging area dimension for the map - I don't remember
> > what it is - but any given soil in an area of less than that size,  can vary
> > quite a bit from the map values.
> > 73 John N5CQ
> Exactly.  Look at the map. Some adjacent sections jump abruptly from the lowest 
> conductivity to the highest.
> Santa Fe, N Mexico is a good example, where it's 15 on one side of the line, 
> and just to the north across
> the boundary, it's only 2. See section 15w.jpg on the FCC map.
>
> You know the actual contours would rarely, if ever, precisely follow the 
> boundaries shown on the map,
> jumping abruptly from low conductivity at one point, to high conductivity just 
> a few feet to the other side of the
> line.  Those maps, based on random samples, are virtually useless for 
> predicting the soil conductivity at any
> specific site location. They might be somewhat useful as a preliminary 
> guideline, but no substitute for actual
> measurement.

It's useful for deciding "are we building our AM transmitter in a good 
or bad conductivity location"


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