[TowerTalk] Feed Point Choke Question
Jim Brown
jim at audiosystemsgroup.com
Sat Nov 7 14:15:26 EST 2020
On 11/7/2020 11:04 AM, Tom Osborne Sr. wrote:
> One thing I have wondered. I saw sometime back, that taping the coil of
> coax to the boom of the antenna hurts the function of the coil. Is it
> better to just let the coil hang down, maybe from a line or something,
> instead of taping it to the boom? 73
Hi Tom,
First, a coil of coax with no ferrite core is a lousy choke. Second,
yes, capacitive coupling between the coax and the boom on both sides of
the choke de-tunes and defeats the choke. There's a photo in
http://k9yc.com/ChokesVHF.pdf showing what I asked Hector, XE2K, to do
when he rigged my new 6M antenna. There are two half-sections of PVC
conduit between the chokes and the boom. The coax is a very low loss
PTFE version deigned for use in plenums. He developed a different method
to rig the choke on my SteppIR.
73, Jim K9YC
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