[TowerTalk] Looking for 12M and 17M rotating Dipole ideas
Jim Martin - MM0BQI
MM0BQI at blueyonder.co.uk
Sat Apr 8 03:01:11 EDT 2006
I constructed a set of horizontal nested (fan) dipoles for 10/15/20 which
cost next to nothing and works perfectly. The longest element (20m) is
constructed out of aly tube and is a full size dipole (basically the
simplest form of rotatable dipole!). The centre is an aly plate with the
elements insulated by plastic pipe and secured with U bolts. Near the end
of the elements I fitted a vertical plastic rod to support wires which made
up the dipole legs for 10/15m. They are all fed from a common feed point
with a coax 1:1 balun. The 10/15m wires have very little interaction with
the 20m element.
The result is, low visual impact, strong, simple design and good bandwidth,
efficient and very easy on the pocket.
I also experimented by shortening the length of the 20m aly tube and used a
vertical end loading element. This worked to decrease the overall length and
supported the other two dipoles.
Works for me!
----- Original Message -----
From: "Mike Harris" <mike.harris at horizon.co.fk>
To: "James Sullivan" <jims at psws.com>; <towertalk at contesting.com>
Sent: Friday, April 07, 2006 10:19 PM
Subject: Re: [TowerTalk] Looking for 12M and 17M rotating Dipole ideas
> | I want to construct a rotating dipole for 24Mhz and 18Mhz with a single
> | line.
> | Does any one have any construction details, experience, ideas....
> | It could be made using traps or separate elements on a very short boom.
> | The one feedline and rotating capbility are the main requirements
> Sounds like a good case for an open sleeve arrangement like the Force 12
> driven element cluster. I believe the necessary details are in the ARRL
> Antenna Book.
> Failing that I guess some sort of matching network at the feed point,
> maybe relay switched or there is possibly some combination of element
> length and L or C that will auto-magically work on both bands.
> Mike VP8NO
> TowerTalk mailing list
> TowerTalk at contesting.com
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