[TowerTalk] 160M Antenna - Ideas

[Rob Atkinson]

If you have a support for the loop that is 560 feet tall then you
don't need an inverted L; you can at the least put up a 1/4 w.
vertical with no horizontal part at all.  I am not sure what is
limiting your radial situation or why you need to involve a
neighbor--I have my inverted L feedpoint near one corner of my lot;
some radials are only about 10 feet long, there are 100 of any length
from 10 feet to 120 feet.  don't think you have to have 50 or 60 that
are 120 feet long; just fit as many as you can in your available space
and it will work okay.  Of course if you are able to put down 60 that
are all 1/4 wave then that's fine.   If you are planning to use this
antenna for a few years then no. 14 solid copper is a good investment.
  The insulation on it doesn't matter; solid goes down easier than
stranded which tends to spring up; that gauge will withstand some
physical wear without breaking.
Invest in good coax for the same reason--you can leave it out on the
ground and not worry about it.  1/2 inch heliax is practically
indestructible.

73

rob / k5uj


On Sat, Dec 6, 2008 at 10:21 PM, Scott MacKenzie <kb0fhp at comcast.net> wrote:
>  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 at contesting.com
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Rob Atkinson
> Sent: Saturday, December 06, 2008 9:55 PM
> To: towertalk at 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
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>