[TowerTalk] 80 M / 160 M dipole
jim at audiosystemsgroup.com
Sun Feb 19 05:45:27 EST 2006
On Sun, 19 Feb 2006 03:20:10 +0000, Ed Stallman wrote:
>Any problem with putting both 80 M / 160 M dipole on one feed
No problem at all -- in fact, it works quite well. I use 2-wire
and 3-wire dipoles extensively. I use spacers cut from 1/2" PVC
conduit that puts the dipoles about 7 inches apart. At W6BX, I
have a dipole for 20/15/10, another for 40/30/20, and one for
160/80/40. My standard Field Day setup includes two 20/15/10 3-
wire dipoles at 90 degrees to each other on separate feedlines.
The 160 antenna at W6BX is a full size two-wire dipole on 80 and
40, with loading coils added to make it resonate on 160 (total
length about 170 ft). Loading coils came from Barry at HyPower
Antenna Company. Google to find them. It works VERY well. This
particular antenna is the broadest antenna I have ever seen for
75/80 -- it's tuned for 3.55 MHz, stays below 3:1 from 3.5 - 4
MHz, and is below 2:1 for most of the band.
For a 3-wire dipole, cut spacers about 18 inches long, and drill
holes about 7.5 inches apart. You can lock the spacers in place by
soldering copper around them on one of the dipole conductors (that
conductor must be bare or stripped).
The ARRL Handbook says that the dipoles will interact slightly
with each other to modify their resonant frequency by a few
percent. I have not been able to see this effect.
Jim Brown K9YC
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