[OKDXA] Dipole Antenna Question

[kd5gho]

Nelson
I have $20 worth of wire and a 300 foot lot.
When would you like to start?
Oh the dreams we dream!
How bout a 80 and 40 double AC5UP zep and a Force 12 beam for the other
five, Dang all I need now is the cash.
Take good care all.
Jim   ad5kd
----- Original Message -----
From: "Nelson Derks" <ac5up@vei.net>
To: <okdxa@mailman.qth.net>
Sent: Thursday, October 31, 2002 7:41 PM
Subject: Re: [OKDXA] Dipole Antenna Question


> A flat top dipole at resonance will come in around 72 ohms with little to
no
> reactive components. You'll see an SWR minimum of 1.5:1 at the sweet spot.
> Droop the ends into an inverted vee and the impedance will drop down near
50
> ohms while the pattern goes toward a fatter figure-8 and becomes almost
> omnidirectional. One trick I've seen is pruning the dipole as a flat-top
> until the SWR dip is where you want it, then drop the ends until you hit
an
> angle that gives you a 1:1 SWR at resonance.
>
> But, being from Claremore, you want to go the other way...
>
> If it was me, I'd fix a horizontal pipe up on the tower that sticks out
> maybe 4' or so and hang a pulley on the end. Rig a rope so you can haul
the
> feedpoint up and down with minimal effort. Now... Here's the sneaky part:
> Instead of pruning the ends (like you've always done), cut the wire a foot
> longer on each side and let the extra wire hang from the center insulator
> like a short piece of ladder line. Add another insulator at the bottom to
> keep everything straight & pretty, then prune this wire section instead of
> the ends. It saves a bunch of time... This also allows you to put ropes on
> each end of the antenna that tie off to a pair of 10' pipes with eye-rings
> on the top so you can tweak the angle of the dangle just by adjusting your
> knots on the pipes. I've found you can wrap a rope around a pipe maybe six
> times, then loop it through itself, and it will cinch up tight enough to
> stay exactly where you want it. Play with this and you'll figure it out.
>
> Also... If you have the room... A 20 Meter Extended Double Zepp is 41'
each
> side of the center insulator and will load with a dead-flat 1:1 SWR across
> almost the entire band. They hear 'real good' and work damn near
everything
> they hear. You'll want to spread the ends out as far as you can, as it
> prefers a flat top, but can tolerate some doodling to fit your lot. I also
> had a 15 Meter Extended Double Zepp up for a month or so that was very
good
> on 15 and not bad at all on 40. A true EDZ on 40 is 170' tip-to-tip, and
if
> you can squeeze one into the antenna farm, you'll be tough to beat in a
> pile-up and will peg your S-Meter on more that an few SWL stations.
>
> I like to have at least one big wire for general purpose RX and a 20 Meter
> EDZ or Off-Center Fed Dipole (coaxial Windom at 136' tip-to-tip) can fill
> the bill. If I had the room, I'd go for the 40 Meter Extended Double Zepp
> just to see what it could do... I'd be looking at maybe $10.00 worth of
wire
> and a Saturday afternoon to find out.
>
> - AC5UP
>
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