Thanks, you know I had these instructions a while back and forgot all about
them, I wonder what happened to them.
----- Original Message -----
From: "Kenneth Lee" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, January 26, 2005 8:57 PM
Subject: Re: TV twin lead antenna


>I did a google on "twin lead antenna" and found this.  There is nothing
> magic about this antenna, I've built many and they work great and it =
> doesn't
> really matter what kind of coax you use.
>
> Read on below - Regards -Ken -N5SWR
>
> http://hamgate.sunyerie.edu/races/antenna/pocket.htm
>
> Pocket J-Pole Antenna for 2 Meters
> The following is a description of a J-Pole antenna made from 300 ohm TV
> twin-lead. They have quite a few advantages which include improved
> performance for
> HTs, portability, and low cost.
>
> For a center frequency of 146 MHz:
>
> 1. Start with @54" of TV twin lead (flat, NOT foam core)
> 2. Strip 1/2" of insulation at bottom and solder wires together.
> 3. Measure 1 1/4" from soldered wires and strip insulation on both =
> sides.
> This is the solder point for a coax feedline.
> 4. Measure 16 3/4" from coax shield solder point and cut out 1/4" notch.
> 5. Measure 50 1/3" from coax center conductor solder point and trim off =
> twin
> lead at that point.
> 6. Feed with a length of RG58U coax. Tape coax at feedpoint to the twin =
> lead
> for strength and seal coax for weather protection.
>
> To get the best possible match, in step three above simply MARK the =
> "solder
> points" and measure from the mark for step 4 and 5. Now solder straight =
> pins
> to your conductor and your shield. Insert the pins at the marked point =
> and
> test for VSWR at the design frequency (146MHz).
>
> If necessary, probe up or down till you reach 1:1 (close as possible).
>
> Solder at the best points. To try this, you may want to start with the =
> twin
> lead a little long and trim down to resonant length - note: you'll need =
> to
> trim
> in a 3:1 ratio to maintain the 3/4 to 1/4 wave.
>
> It has been noted that this design can lead to rf coupling onto the
> feedline. To avoid, put ferrite beads on the coax at the feedpoint, or =
> use
> 3-5 turns
> of coax (1"-2") taped together at the feedpoint.
>
> You may attach an alligator clip to the plastic on the top of the =
> antenna in
> order to easily hang it. Alternately, punch a hole near the top and use =
> a
> length
> of fishing line to hang.
>
> This design appears on many BBSs, in club newsletters, and in books; the
> earliest reference that I know of is a Jan. 1984 D.A.R.C. antenna =
> article by
> James
> Burks, KA5QYV. This antenna is relatively broad-banded and will be more =
> than
> adequate if simply built as noted in steps above.
>
>
> ...artical continues ....
>
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