Jerry:
My Inverted L was ground-mounted, so I can't offer much in the way of
help for your elevated radial design. However, based on my experience with
my tree-supported L, I can offer this.
If possible, install your L so that the bend is supported on some type
of flexible lanyard. I say this because I ran my L's wire through an
insulator that I merely tied to a high tree branch. After a few months of
winter weather, the lanyard snapped and down came the wire.
I replaced the Dacron lanyard with an assembly that included a 5-inch
plastic clothesline pulley (I didn't want to $pring for a marine pulley),
and a rubber bungee cord. I wrapped the bungee around the tree branch and
hooked it on itself. I then crimped the pulley to the opposite end of the
bungee. I ran the L's wire through the pulley.
Since I installed this flexible joint (winter 2000) I haven't had to
climb the tree to replace the anchor point. The bungee is flexible enough
that it absorbs any shock a swaying limb might impart to the wire and anchor
point. You might even wish to install a second bungee and an insulator at
the far end of the wire to provide even more resiliency to the design.
BTW - with the pulley in place and some careful thought to the
mechanical design of subsequent antennas, I've been able to try different
versions of L's, as well as replace the L with a vertical wire for use on
the new 60M band. I merely attached the new wire or haul rope to the end
of the L and allowed the L wire to pull the new material through the pulley.
Welcome to the most challenging band in all of Hamdom!
73 de
Gene Smar AD3F
----- Original Message -----
From: "Jerry Keller" <k3bz@arrl.net>
To: <topband@contesting.com>
Sent: Monday, November 01, 2004 9:32 PM
Subject: Topband: Inverted ELL for 160M
> I've been wanting to try top band for a long time, and after scouring the
books on my shelf and a
> few internet sources, here's what I've come up with (tentative) that will
fit on my lot:
>
> The vertical section of about 60 feet would be supported by a tree, with
the horizontal component
> about 70 feet. (I could make the horizontal longer by 10 or 20 feet if
need be. I've read that
> lengthening the horizontal segment may increase the bandwidth?) I would be
able to raise and lower
> the far end of the horizontal segment for trimming as needed.
>
> The feed point would be about 8 feet off the ground (at the top of a 4x4)
with two elevated 1/4 wave
> radials 180 degrees apart, and 90 degrees to the horizontal segment. The
feed point support rises at
> the top of a mound so the ground slopes away rapidly putting the radials
about 12 feet off the
> ground for most of their length. The radials and the feedline shield would
be connected by #4 solid
> copper to a ground rod directly under the feedpoint.
>
> I had thought about feeding it direct with 50-ohm coax, but a friend tells
me I'll be much better
> off with two electrical 1/4-wave lengths of 75-ohm coax in parallel
between the feed point and the
> single point ground box at the house (just about the right length, too)
and connect there to the
> lightning arrestor, with about 25 feet of 50-ohm coax from the arrestor to
the rig. He says that
> should match pretty well.
>
> How does all this sound? Any suggestions? Any help or ideas or suggestions
you might offer will....I
> assure you.... be deeply appreciated.This will be my first attempt at top
band and I'd like to do
> the best wire antenna I can before the snow flies here in eastern PA.
>
> Thanks in advance, Jerry K3BZ
>
>
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