Topband: Coax Shield vs. Ground & elevated radials

[Björn Mohr]

Tom Rauch wrote:

>> With elevated radials near earth there can be a dB or more FS reduction
when the feedline shield is not decoupled.

This says nothing about the unwanted coupling of noise into the antenna, or
RF into other devices close to the feedline or operated from the power line.
<<

To decople my my inverted L I was using a RG213 coil made of 18 turns on a
11 cm plastic pipe. Would this arrangement be enough to decouple my top
loaded vertical with 2 elevated radials?

Where to best put the coil? I assume at the feed point but I read somewhere
that in some cases it might not be the best place. Just out of curiosity
what happens if I place it 1/4 wave down the feeder, will the feeder act as
a third radial?

Happy New Year!

Björn /SM0MDG