Topband: Inv-L joy
Gary at ka1j.com
Tue Jul 23 12:36:24 EDT 2013
Thanks for the many replies off and on list. I appreciate the
thoughts and the suggestions for wire and the liability of signal
loss and fragility of this kind of L.
While it might be possible to somehow get a pulley up via being
knotted to a rope, there's just no practical way for me to attach
both ends. There is a dense forest cover that is so thick I can not
see more than 30' in most directions. The only area I can get a clear
view of the the sky to send the "spud" through is very small, perhaps
8' at the widest. The wide open salt marsh offers no trees and I am
using what is for me, the best system I can make. The vertical
component has to be at an angle, maybe 75-80 degrees and none of the
surrounding trees are very tall. Being on the coast, tall trees do
not last long at the tree line thanks to Sandy like hurricane winds.
The Spud gun I have made was based on one in QST and the sprinkler
valve is a 3" one I found on Ebay. I added a larger open face fishing
reel and made an eye for the 50 pound test monofilament line to run
through. With no line attached I can get a 2.5" x 5" spud to
disappear from view, it has this much power. I use a spud that is
2.5" x 10" and has reflective tape so I can find it in the dense
foliage. With the line attached there is enough drag that the
distance is reduced. With 20 pumps of the tire pump it is perfect for
getting the 160 Inv L over the tops of the highest trees nearby and
in the air long enough to get it over the next few trees that it is
at least as high as it can be. I envy good antenna installations but
with my 60 130' radials on the salt marsh, I still do well. Better is
never enough though...
I have the 160 inv-L, an 80 Inv-L, and a 40, 30 and 20 meter
verticals all attached to the radial plate. A remote coax switch
allows me to select which I wish. I have no tuner and select the best
antenna based on the strength of the received signal. With the valid
antenna selections my worst SWR is 2-1 which the K3 & amp have no
160 works on 160, 15, 12, 10, and 6 meters.
80 works on 80, 17 and 12 meters.
40 works on 40 & 17 meters
30 only works on 30
20 only works on 20.
All considering, I need no tuner and though I don't beat the big
guns, with only a few exceptions I've been able to work every new DX
on 160 I could hear and I've only missed a few ATNO on other bands
that either couldn't hear me or responded to louder signals instead.
One thing I have but didn't think to use is flooded 75 ohm cable. I
bought a long length of it for the HI-Z Triangle array and have quite
a few hundred feet of it left. It has a smooth and rugged jacket and
the center is copperweld of sorts. If I were to affix a lug at the
end and short the cable/wire together it might be slippery enough to
handle the motion and strong enough to be break resistant. Not sure
how I would best attach the ring end but I need to think about this.
Thanks again for all the thoughtful replies.
> My Inv-l came down again. Went out to see what happened and another
> storm weakened tree came down & it's upper branches brought my
> antenna down with it. I really need to use a better wire than 8
> strand computer cable for the antenna. This CAT-8 wire comes down at
> least 2-3 times a year.
> Since I use a spud gun with fishing reel attached to get the antenna
> up through the trees I am limited in what wire I can use to get up
> there. I don't have pulleys available with what I have to do & the
> wire is subject to the constant friction of moving limbs & the
> insulation wears away soon enough. I hesitate to buy expensive wire
> as once the insulation wears away there will be arcing to a branch.
> Years ago I used to use old telephone wire, the heavily insulated
> solid conductor zip cord like drop wire but that's not available to
> me any more.
> Any suggestion as to a good rugged wire?
> Topband Reflector
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