I've got a rope over a branch of a pine tree at 95
feet. This tree is in a forest with a bunch of other
trees, not very open at all. I previously was using
four elevated (about 10 feet) radials, base-tuning the
89 foot wire about four feet. Seeking to improve the
performance, I pulled that wire down, and pulled up a
pulley, and have something resembling an inverted L
(135' total wire, apex at about 75'). Base fed,
against four elevated 1/4 wl radials.
Adding two more radials causes very large changes in
the impedance of the overall system, as measured at
the base. The R component went from 58 ohms to 105
ohms (Can't remember the X, it was raining and getting
dark quickly). I was incredulous, checked all of my
connections, and sure enough, 58 to 108 (verified by
disconnecting, measuring, reconnecting). Presents
about 1.8:1 before tuner.
Does this mean:
1) I've got a crappy antenna, and I'm gamma matching
the fir tree, which is doing all of the work (no fires
yet), and should improve my system with a chain saw
2) This is normal behavior, expected when so few
radials are being used
3) I'm experiencing broadcast interference on the
meter
4) I should add more radials until I feel better, and
the impedance will reflect that
5) I should just tune it up and use it?
6) I should get the vertical wire farther away from
the trees
I did #5 -- The new inverted L worked well enough to
work about 9 stations last night... about the same as
the night before with the 89'. I felt like I had to
work less to get those contacts (in comparison with
the night before), however.
-Brian N9ADG/7 Preston, WA -
Exit 22 on the Massachusetts Pike
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