I got this same idea from Tom when he spoke at the Dayton antenna forum a
couple years ago, and I noticed the big chokes on the slides he was showing
of his tower.
In my case, I used 6-inch diameter PVC for the forms and about 75-100 feet
of cable wound on it for each choke. I did this for the rotor cable, and
also the feedlines (small hardline) for 6m, 2m and 220 mHz antennas that
are on my series-fed 100-ft Rohn 25 tower for 160. Each is on a separate
piece of PVC at the base of the tower. Now there is no difference in the
resonance point when I hook up these feedlines.
The 2m and 220 antennas are for my PacketCluster node; on the 220 feed I
was still getting some RFI from the 160m signal so I added a few big
toroids off old TV picture tubes around a few turns of the hardline at the
base, and that took care of it.
73/Jon AA1K
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