[TowerTalk] Tuning Antennas with the MFJ-259

[W0MU Mike Fatchett]

The antenna will appear longer closer to the ground.  If you cut it for 3800
it might dip low to the ground at 3600. 


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-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Dan Hearn
Sent: Sunday, March 29, 2009 9:43 AM
To: AD5VJ Bob; 'jimlux'; 'Richards'
Cc: towertalk at contesting.com; K7LXC at aol.com
Subject: Re: [TowerTalk] Tuning Antennas with the MFJ-259

I think you have it backwards Bob. My antenna resonant frequencies moved up
when I raised them.
73, Dan, N5AR

----- Original Message -----
From: "AD5VJ Bob" <rtnmi at sbcglobal.net>
To: "'jimlux'" <jimlux at earthlink.net>; "'Richards'" <jruing at ameritech.net>
Cc: <towertalk at contesting.com>; <K7LXC at aol.com>
Sent: Saturday, March 28, 2009 9:59 PM
Subject: Re: [TowerTalk] Tuning Antennas with the MFJ-259


> 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 at contesting.com
>> [mailto:towertalk-bounces at contesting.com] On Behalf Of jimlux
>> Sent: Saturday, March 28, 2009 10:24 PM
>> To: Richards
>> Cc: towertalk at contesting.com; K7LXC at aol.com; rtnmi at 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 at 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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>
> _______________________________________________
>
>
>
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