Dear Dave D. (no call sign):

I have found it highly desirable with large and smaller HF LPDAs either to
decouple at the feed-point or to choke common mode right as the coax leaves
the boom to go down the mast. Of course, one could do both. Once you have
cleaned the transmission line, you need to attend to the termination at the
end of the boom. Your BW is small for a LPDA so design should be straight
forward.

Mac N8TT
--
J. McLaughlin; Michigan, USA
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"Richard Clark" wrote in message
...
On Wed, 29 Sep 2010 16:36:06 -0700 (PDT), Dave D
wrote:

Any ideas?

Inadequate decoupling of the transmission line at the feedpoint.

73's
Richard Clark, KB7QHC