[Antennas] DBJ-1 J-pole from Feb QST mag

[Tim Conway]

I bought some twinlead and a 12-foot BNC jumper from Radio Shack and
built 2.  One hangs in my shack and the other is rolled up in my pack.
As the author said, SWR isn't great on 440, but it's resonant, and works
well.  I've considered soldering a 17.5cm stub to it to try for better
match on 440, but that's just too much trouble.
I recommend the use of the soldering iron for the manipulation of the
insulator, as it's difficult to nip in there and whittle the wires clear
without popping a few.  Also stab a hole in the center near the top end,
which makes it easy to attach a length of light cordage (I use kite
string) to hang it with.
Using the aforementioned jumper makes it easy to make feedline... just
cut it in the center and you've got two 6-footers.
Oh, it improves a bit with a choke to keep the feedline out of the
radiating business.  A few turns of the coax will do it, but a ferrite
bead is nicer.
Arrow makes a nice aluminum 146/445 jpole.  Make that "really nice".  My
own needs are better served by the cheap little wire thing hanging from
my ceiling with the base of the radiating section at about 15 feet above
average terrain... the HOA nazis can't see it.

I love end-fed halfwave antennae.  No messing with groundplanes,
omnidirectional patterns, every watt that hits the feedpoint goes into
the ether.  The j-pole design does such an efficient job of matching,
and is so easy to build (even I can do it), that it's by far my favorite
design.

As far as it not coming up on the list... The J-pole is so
well-characterized , well-known, and widely-used, it doesn't come up
much in experimentation circles any more.  I'm sure you've noticed that
we also don't spend a lot of time on half-wave dipoles and quarter-wave
verticals.  Good new construction techniques on an old standby will
still get my attention, though.

73,
tim

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Message: 1
Date: Thu, 18 Sep 2003 11:49:44 -0400
From: Judy May <tandembike@worldnet.att.net>
Reply-To: tandembike@worldnet.att.net
Organization: South West Cycling
To: antennas@mailman.qth.net
Subject: [Antennas] DBJ-1 J-pole from Feb QST mag

I am interested in communicating with others who have experience
with the antenna project detailed in the February 2003 issue of QST
called the DBJ-1 dual-band twin-lead J pole for 2m and 70cm.  I bought a
completed model from the author and also built one from scratch, and am
interested in comparing notes with others that have used the antenna.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- 
Tim Conway
4853 Egret Dr.
Frederick, CO 80504

303.772.5120 H
303.641.4584 M

n9hmg@arrl.net
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