> The old inv L and on the ground non-uniform and erratic radial system
> did not cause this issue so do I conclude that the effective radiated
> field from the FCP Inv l is that much stronger?
Hi Frank,
When we confine a counterpoise to a small area, especially if we cancel the
magnetic induction field, voltage and resulting electric induction field
levels go way up. There just isn't any free lunch, no matter what the sign
on the door says.
When convenient, we often attribute increased problems to better performance
without regard to 20 other bad things that could be at work.
My wife does that with her occasional crispy blackened casseroles.
> Yesterday I also did
> some more work on the FCP ...when I initially built it I used 1/2inch
> pressure treated wooden spacers and tie wraps. Yesterday I replaced the
> those spacers with 1/2inch "PEX" (HDPE material) water pipe painted
> black. These spacers appeared to cause a slight shift in the SWR curve
> for the L...raising somewhat away from 1800khz. I am wondering about
> this material and whether its the right stuff to use?
Like the increased RFI, no one really knows what causes what without some
reasonable testing or evaluation. What we do know, without a doubt, is the
less spread out the counterpoise (or antenna) the more concentrated fields
become. I would expect any change in spacing or dielectric to have an
exaggerated effect on stub tuning (the folded counterpoise is a stub with
common mode current) compared to cases where there isn't such an intense
electric field.
It all makes sense for multiple reasons. The question is, how much of what.
If we took a big antenna and made it into a 20 foot long antenna, no matter
how we did it, we would expect more sensitive tuning and higher voltages
and/or currents. We would expect increased sensitivity to close
surroundings.
Why would we expect anything different in this case? The very fact it needs
an isolation transformer with high voltage insulation tells us we have very
large localized electric fields. Logically, we should expect all that comes
with those voltages.
73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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