> The consensus for grounding Beverages seems to be to use a "real
> transformer" and have isolated grounds for the antenna and the coax.
>
> Does the same apply to the K9AY antenna? Has anybody tried it both
> ways and seen a difference?
>
> Paul - KW7Y
Paul,
The commercial units we make do not have an isolated ground. In theory, an
isolated ground would minimize the potential of common-mode problems, but in
my experience, that potential is very small with moderate length, buried or
on-ground cables.
I would recommend feedline isolation in the following extreme
circumstances -- extremely poor ground (e.g. desert sand), very long
feedline and control line, feedline that must cross the TX radials, and
feedline that is elevated above ground for a portion of its length. That
isolation can be 1) transformer with separate primary and secondary, 2)
ferrite beads, 3) coiled feedline, perhaps through a toroid, or 4) feedline
buried for at least a portion of its length.
Finally, do no confuse re-radiation and common-mode -- signals re-radiated
by the TX antenna, other towers, or nearby metal are received directly by
the antenna. This is more likely to be an issue with a K9AY Loop, since it
may be installed near potential re-radiation sources.
73, Gary
K9AY
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