[OKDXA] Dipole Antenna Question

[K5SIT BOB]

Hi ya guys,

Now for the most important info. on wire antennas.

I have seen just about every type of wire ant. for sale on E-bay. hi

Also if you go to your local farm supply store you can buy a quarter or half
mile
of shock fence wire for next to nothing when it's on sale. It's also on a
nifty
spool. The only problem is it is damn hard to see in the air.

Bob k5sit 73 es gl

----- Original Message -----
From: "kd5gho" <kd5gho@swbell.net>
To: <okdxa@mailman.qth.net>
Sent: Friday, November 01, 2002 04:57 AM
Subject: Re: [OKDXA] Dipole Antenna Question


> Okay I hafta ask.
> say our home brew ladder line hainging from the center insulater is
> pruneable, and it is.
> Would their be any way to tune the little bugger remotly?
> Say their are 2 pullys sort of like a block and tak, and the bottom pullys
> were able to roll the ends of our home brew ladder until we hit the sweet
> spot?
> Just sounds to simple.
> Q#2: a dipole should be about 75 ohms at the feed point?
> So changeing the spaceing of our spreaders will change the feed point
> resistance?
> Thies questions make the toss and tune method sound okay, but we all love
to
> play and learn.
> For sure wire lingth tuned for res freq = RX db.
> Ok now on to Daves Rombic farm.
> Jim   ad5kd
>
>
> -- Original Message -----
> From: "Nelson Derks" <ac5up@vei.net>
> To: <okdxa@mailman.qth.net>
> Sent: Thursday, October 31, 2002 9:15 PM
> Subject: Re: [OKDXA] Dipole Antenna Question
>
>
> > > I have $20 worth of wire and a 300 foot lot.
> >
> > Here's your plan for World Domination on 40 Meters...
> >
> > Buy a 500' spool of 10 gauge solid insulated THNN house wire from your
> > favorite hardware mega-store. That's about a $40 bill, but if you have
> 220'
> > of good sturdy antenna wire on hand, you can skip that part. Divide
1,500
> by
> > the absolute lowest frequency in MHz of the band you're interested in.
> Let's
> > say 1500 / 6.9 = 217.4' so you'll cut 220' of wire. Find the exact
center
> of
> > this wire and cut it again. That's your feed point. Then you'll divide
> 1,200
> > by the frequency in MHz of the band segment you're most interested in.
> Let's
> > say 1200 / 7.1 = 169', but since you don't like dealing with fractions
> (and
> > it really doesn't matter), you'll arrange the center insulator so you
have
> > 170' of wire across the horizontal top section. The balance of your wire
> > will hang from the center feed point and be arranged into something
> > resembling ladder line.
> >
> > A 10' length of 1/4" C-PEX plastic tubing (plumbing aisle, it's used to
> hook
> > up water coolers and such) runs about $4.00 and can be chopped up into
> 1.5"
> > spacers with a tubing cutter. Cut plenty of them. You'll also need a bag
> of
> > 6" black nylon Ty-Raps that you'll thread through the C-PEX spacers and
> > cinch around the two wires you're turning into a ladder line. Once you
> have
> > all of that done, haul the wire up to a comfortable working height with
> the
> > bottom of the feeder maybe 5' off the ground (4' if you're N5UW, OKDXA
Ham
> > Of The Year, 2002). Connect your 1:1 current Balun to the feeder
(Reisert
> or
> > Guanella type), then run any length of coax back to your rig.
> >
>
>
> > Key up at the absolute bottom of the band (or maybe a little lower if
you
> > dare) and take an SWR reading at the rig. It should be 1:1. Prune 2" or
so
> > off the bottom of the feeder and check your SWR. If it's still 1:1,
> repeat.
> > As soon as the bottom of the band shows any SWR rise, no matter how
> slight,
> > stop pruning and check the top of the band. If it's a little higher than
> you
> > like, prune just a hair more but keep a close eye on the bottom end.
> You'll
> > find the low end has a very steep SWR rise while the mid to top segment
> has
> > a much slower SWR rise. A slip of the cutters can ruin the CW section
> before
> > you realize it, so go slow and watch the bottom end 'real close'.
> >
> > Weatherproof your connections, haul the wire up to its final height,
then
> > wait for that magic moment when you hear K8FU trying to bust a pileup
for
> a
> > card he really, really wants...
> >
> > Feel free to key up and show Mr. Frogg exactly how it's done.
> >
> > As a bench project, you might consider whipping together a simple
battery
> > charger that connects to your antenna switch and tops off the HT NiCd
> > battery while you're not on the air. You'll have a volt or three to play
> > with at the PL-259 and a voltage tripler should get you there, so I say
> 'go
> > for it'. You'll also find the AM broadcast band has a bunch more
stations
> > than it used to, even during the day, and at night the weak ones will be
> 20
> > Over... Big wires are truly amazing.
> >
> > - AC5UP
> >
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>
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