I like that idea. I was concerned that I would have issues with changing
the loop. I really like the loop, especially for working local contacts.
It works very well for 80M and 40M on Sweepstakes.
The support I use for feeding the loop is approximately 560' tall - and I
have a nice tree about 75' tall (also supporting a corner of the loop. That
should make for a nice inverted L. The issue is radials. I need to figure
out something, or talk nice to my neighbor to allow me to establish a radial
field.
There might be another suitable tree I could use....need to figure that one
out - it is the radial issue that is causing me problems....
Scott
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Rob Atkinson
Sent: Saturday, December 06, 2008 9:55 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] 160M Antenna - Ideas
I am also on a small lot in a city with a 1 wavelength 80 m.
horizontal loop. Actually mine is 1 w/l at around 4 mhz so where I operate
it's really more like .8 or .9 w/l. my lot is 50 x 100 feet.
I found that the practice of feeding the end of the ladder line by tying
each side together and working against ground is at best a
compromise. Firstly, it only works if you have a pretty long
vertical run of line. 30 feet vertical with 10 or 15 running over
the ground to get under the feedpoint of the loop isn't enough.
Secondly, you also have to have some kind of counterpoise. A tuner
ground rod isn't enough. You say you have trees. If you have room
for a 1 w loop on 80 then you have room to get on 160. I'd take the tallest
loop support (I'll assume it is a tree) and use that to hold up a vertical
wire. You run the wire up and through a marine pulley on a dacron rope shot
over the tree to make an inverted L. The horizontal part of the L bisects
the loop and ends at the opposite corner, so for example if the vertical is
in the NW corner, then the L
ends at the SE corner. Don't worry about it messing up the loop's
performance, it won't. And the loop won't affect the L either. Run coax
feedline out to the base of the L, do the necessary counterweighting with
pulleys if you are using trees, spring-load the bottom insulator of the L if
necessary so it can move with the trees and put down a radial ring (don't
use aluminum) and as always, put down as many radials as you can with no. 14
solid, insulated that's sold in 500 foot spools at most hardware stores.
shop around for the best price, invest in a wire stripping tool, staple down
the radials
and they will eventually sink into the ground. don't worry if they
are only 10, 20, 50 feet long, just fit them in the corner of your lot as
best you can. If the horizontal part of the L is too long to fit in the
loop, you can bend it around like this > or this ) and it will work fine.
Does it sound like this is what I did? Bingo! and the horizontal part goes
right over my house and ends in a tree in my
front yard. Try this before you resort to loading, voyagers,
isotrons, etc.
73,
rob / k5uj
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