On Tue, 24 Jun 2008 17:41:31 -0700 (PDT), Nick
wrote:

On Jun 24, 3:30Â*pm, Cecil Moore wrote:
Nick wrote:
Â* Â*Thanks for all the great responses guys! Â*That is exactly what I
had thought, that since the outer coax braid is grounded at the
antenna, and at the shack, and (in my case) at the center with a
lightening protector, then I just couldn't figure out why some antenna
companies, such as reliable DX engineering with their DXE-VFCC H05-A
Vertical Feedline Current Choke, strongly recommend such a line
isolator for verticals.

Nick, think about it. If you ground the feedline at exactly a
common-mode standing wave voltage node, the ground accomplishes
absolutely nothing. You certainly don't want to use "plumber's
delight" techniques in your ground system.
--
73, Cecil Â*http://www.w5dxp.com


Thanks Richard and Cecil.
Cecil, I understand what you are saying, but still why not use the
outer shield of the coax as one of the radials, and simply choke off
the coax just before it enters the shack? I also don't want to add
what may be a useless choke at the antenna's feedpoint, since that
would decrease the antenna system's efficiency due to the choke's
resistive losses...

Thanks!

-Nick

When I was into 2-meters 40+ years ago, I preferred gamma-matched
verticals.

...Jim Thompson
--
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