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Re: [TowerTalk] Tuning Antennas with the MFJ-259

To: "'jimlux'" <jimlux@earthlink.net>, "'Richards'" <jruing@ameritech.net>
Subject: Re: [TowerTalk] Tuning Antennas with the MFJ-259
From: "AD5VJ Bob" <rtnmi@sbcglobal.net>
Date: Sat, 28 Mar 2009 23:59:49 -0500
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
Well one of the antennas I will be working on in the morning is going to be an 
80 Meter dipole, but I can only get it up here at abt
30' then I will be taking it and putting it up at around 60 feet, so it sounds 
like I want to tune it high and expect the dip to
move lower in frequency at the 60 foot level (maybe a few Khz per 10' in height 
or so).

If I am understanding all the input correctly, the swr curve will be less 
affected by the ground effects and therefore seem longer
(more inductive) as I raise it higher above ground (lessening the capacitance).

Bob AD5VJ 

> -----Original Message-----
> From: towertalk-bounces@contesting.com 
> [mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
> Sent: Saturday, March 28, 2009 10:24 PM
> To: Richards
> Cc: towertalk@contesting.com; K7LXC@aol.com; rtnmi@sbcglobal.net
> Subject: Re: [TowerTalk] Tuning Antennas with the MFJ-259
> 
> Richards wrote:
> > Gee...  that does not sound like you are tuning it on the work 
> > bench...  I think this is more of a vote for "no... you should hang 
> > your antenna to tune it" - than it does a Yes you can.
> > 
> > Or do I misinterpret your statement here?
> > 
> > ================   K8JHR  ======================
> > 
> > K7LXC@aol.com wrote:
> >>  
> >>         Once you see a dip, then  you can install the 
> antenna. Using 
> >> a tramline, you can run the antenna up  and take a 
> measurement. Then 
> >> you can lower it and make any adjustments to tune  it. Run 
> it up and 
> >> down as many times as you need and you're good to go.
> 
> 
> 
> 
> if you've got enough area around it, pointing it straight up, and 
> having it 6 feet or so off the ground, will give results very 
> close to 
> what it will read up on the tower.  Think of the "active 
> volume" of the 
> antenna as being everything within say, 1/4 wavelength.  For 
> a 20m band 
> antenna, that's around 15-20 feet.  It's pretty practical to 
> strap it to 
>   a 2x4 or or something and hold it up with a step ladder.
> 
> As others have pointed out, you're not looking to adjust to a gnat's 
> eyelash, you're really checking to see if it's close to what 
> you expect 
> (e.g. legions of stories about folks getting the traps in the wrong 
> order on trapped antennas, or forgetting to hook up a wire to 
> the balun, 
> etc.)
> _______________________________________________
> 
> 
> 
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