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[TowerTalk] Loading Coil - story

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Subject: [TowerTalk] Loading Coil - story
From: "Jim Miller" <JimMiller@STL-OnLine.Net>
Date: Tue, 5 Dec 2006 22:02:47 -0600
List-post: <>
> Best to check... spray some on paper and check it with an ohmmeter
> after it dries.

Something wrong with good tape?

EVERYBODY has a story, here is one from somebody that didn't know -

There was a QST article in early 90's about short 160 meter verticals that
showed the construction of a loading coil to allow the use of a 80 meter
length of wire on 160 meters.

Not know anything about calculating the required coil and wanting to build
to allow more than the 100w this was designed for, I plugged in the
specified construction and printed out the specs.  Then I played with the
build numbers until I had created a coil on a 4 inch dia PVC pipe using #12
instead of # 16 or 18 or whatever it was.  I figured this would take care of
considerably more power than the 100 watts.

I then used #12 THHN insulated wire (never considering the insulation) and
wrapped it tight around the PVC (not considering the dielectric of the PVC)
for the needed number of turns and sent them back through a hole in each end
of the PVC and taped the whole thing up with electrical tape to hold it all
in place and allow for handling (without considering any effect of the

I had a 21 ft guyed top rail from a chain link fence that stood on top of my
ranch style house supporting my 2 meter vertical and a 10 meter dipole (the
top end at above ground height of maybe 28 or 29 feet.  I installed a rope
through a pulley at the top of the pipe and connected the PVC to the rope
with the feedline coax attached.  The ground side of the coax was connected
to more of the #12 wire and also attached to the rope at the "same" point.
The rope hoisted and the antenna now hung at about 28 feet.  The coil center
wire side then sloped down to a tree in the backyard to a height of about 8
feet.  The other side, came down the pole then down the roof (under the
antenna) around the gutter and back to the house , down to the ground and
along the chain link fence (under than suspended antenna) for a length of
about a full 1/4 wavelength (it stretched out beyond the suspended leg).  I
had to cut off a few feet to get it tuned.  SWR came in nicely (I didn't
even have a tune at that point).  With my trusty TS120, I listened on 160
from Missouri and worked on phone 6 stations in the northeast in about 25
minutes all with good signals to me and to them (they said).

The moral of the story - Even if you don't know anything (but think you do),
try something, it might even work.

No, the tape didn't unwrap, nothing broke, it worked "fine" (with nothing to
compare it to), I never did run power into it, and I still have it even
after I moved and can't put it up now.

IF I could get permission to put it up, I am thinking about reversing the
leads at the connecting to the antenna so that the center went to the full
1/4 wave side and the shield side went to the side coming to the ground and
stretched out.  That would give me the longer wire connected to the center
lead.  Any advantage in doing this?

Thanks es 73, Jim


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