Hi Doug,
I home brewed a three band fan dipole that I just love. It consists of
a full size 160-m half wave dipole stretched from a thirty foot tree in
one corner of my property to a 65-ft tree in a corner of my neighbors
property... God Bless That Man.
Anyway, hanging about eight inches below the 160-m dipole is a full
size 80-m dipole and about 8-inches below the 80-m dipole is a full
size 40-m dipole.
The spacers are green fiberglass perfboard strips about ¾" wide spaced
every ten feet apart. Naturally all the dipoles are fed at a common
center connector with RG-8X which I try to bring away at close to a
right angle. The center of the antenna droops to about 23-ft off the
ground.
I start tuning the antenna on 160 and then continued to trim the 80 and
then the 40-m dipoles. I notice very little interaction between the
antennas.
I can work every station I can hear running only 100-watts into the
thing. Everyone says that at this low height this antenna is a "cloud
warmer." This is true but I've worked my share of clouds several
thousand miles away... which is OK by me. If you have the room I see
absolutely no reason to use traps on these bands... baluns add nothing
but weight and accomplish nothing. I'd dearly love to stick a 50'-ft
mast in the middle of my yard to support the center of this thing...
but then I'd end up with guy lines all over a beautiful Kentucky
Bluegrass lawn which even I'd object to. Love a self supporting
something there though.... but with the ends of the dipole in swaying
trees... I have my doubts about the wisdom of anchoring the center
somewhere. Would it contribute to a significant improvement in
performance? One never knows these things until they are tried.
Tuning dipoles is always fun. BTW...you don't need to solder the ends
around an insulator until you are finished trimming. Just start longer
than necessary and keep wrapping the excess back towards the center.
Solder later if you wish.
Good luck with your project.
73, Roger, K2JAS
<><><><><><><><><><><><><><><><><><><>
At 08:27 PM 11/21/97 +0000, you wrote:
>
>Has anyone figured out how to string an 80 and 160 meter inverted vee
off the same tower
>WITHOUT them interacting. Mine really tend to detune each other,
making length trimming
>near impossible. Are there any published notes on adding a trap in a
160 dipole to make it tune 80?
>I've tried various configurations -- and even tried loading my tower
as a vertical. I get
>a great SWR but it doesn't get out. Ideas?
> --Doug Brede, W3AS/7
>
>
>--
>FAQ on WWW: http://www.contesting.com/towertalkfaq.html
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>Search: http://www.contesting.com/km9p/search
>
Roger, K2JAS
Morganville, NJ
Just about half-way between NYC and Philly!
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search
|