Thanks Dave,
I will look into it.
Bob
K6UJ
> On Jan 22, 2022, at 9:36 AM, Dave Sublette <k4to.dave@gmail.com> wrote:
>
> Do you have an agriculture extension office or a Farm Services Admin office
> in your area? You might try calling them and asking if they have that data.
> As much grape growing as there is in your area, one would think that all of
> the soil data is available.
>
> 73,
>
> Dave, K4TO
>
> On Sat, Jan 22, 2022 at 12:22 PM Robert Harmon <k6uj@pacbell.net
> <mailto:k6uj@pacbell.net>> wrote:
> I love your perfect QTH description. A hill of salt water, sloping gently
> in all directions. hihihi
>
> I am having trouble finding ground conductivity fro my area in the north San
> Francisco Bay Area. Napa county.
> Looks like my area shows a number 8. Where is he chart to find out what this
> means in conductivity ?
> Wish I could find a map that I could drill down closer to my QTH. I know it
> is pretty good right now, we have had
> lots of rain the last few weeks.
>
> Bob
> K6UJ
>
>
>
> > On Jan 22, 2022, at 3:58 AM, John Langdon <jlangdon1@austin.rr.com
> > <mailto:jlangdon1@austin.rr.com>> wrote:
> >
> > The other thing that K5IU was clear about is that the ground under the
> > antenna is the dominant factor in performance regardless of the radials you
> > use.
> >
> >
> >
> > If you have really low conductivity soil under the antenna, even if you
> > mount a vertical on a 1/4 wavelength radius copper disc, essentially an
> > infinite number of buried radials, you are going to get poor performance.
> > Elevated radials will be as good or better in that situation, and are less
> > work, but a high dipole, over poor soil, will be equal or better.
> >
> >
> >
> > If you have really high conductivity soil, a modest number of buried radials
> > or a set of 4 1/8 wavelength elevated radials tuned with an inductor will
> > probably give you good performance.
> >
> >
> >
> > If you are over salt water, a single resonant radial will work very well.
> >
> >
> >
> > BTW the ground conductivity maps most of us have access to, like
> > https://commons.wikimedia.org/wiki/File:United_States_Effective_Ground_Condu
> >
> > <https://commons.wikimedia.org/wiki/File:United_States_Effective_Ground_Condu>
> > ctivity_Map.png , are from data averaged over a large area and any given
> > location within an area on the map may vary widely from the average. The
> > perfect QTH is a hill of salt water, sloping gently in all directions.
> >
> >
> >
> > 73 John N5CQ
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> >
> >
> >
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