[Antennas] Using the AH-4 tuner on 80 meters

Wed Mar 2 10:30:56 EST 2005

I use an AH-4 with a half square antenna and it tunes to a near perfect
match from 160m to 10m... absolutely no problems.
Let me know if you wish more details.
Sean
W8OKN
----- Original Message ----- 
From: "Robert Lay" <w9dmk at crosslink.net>
To: <antennas at mailman.qth.net>; "DavidE Benedict" <iam at pmug.org>
Sent: Wednesday, March 02, 2005 9:51 AM
Subject: [Antennas] Using the AH-4 tuner on 80 meters
> Dear David,
>> In my original reply to your original posting, I assumed that the output
> interface of the tuner was for coax - bad assumption. I have many tuners,
but
> not an AH-4. Most of my tuners provide output for coax, for balanced line
and
> also to long wires.
>> I guess I should have asked you what you meant by a "resonant 80 m antenna
as if
> it were a whip".
>> If the wire that you want to use presents a moderate impedance to the
tuner,
> then it will tune it. Generally speaking, a moderate impedance will be
presented
> to the tuner when the end fed long wire (fed against ground) is an odd
number of
> quarter wavelengths. So, for 80 meters, that means your antenna should be
20
> meters in length (nominal quarter wave) or 60 meters in length (nominal
3/4
> wavelength) or 100 meters in length, etc.
>> Any time the length of the antenna becomes an even number of multiples of
a
> quarter wavelength, such as 40 meters in length (nominal half wavelength,
or 80
> meters in length (nominal full wavelength), etc., then the impedance
presented
> to the tuner will be extremely high and the tuner cannot transform it down
to 50
> ohms as needed by the rig.
>> Bob Lay (W9DMK), Dahlgren, VA
> w9dmk at crosslink.net
> http://www.qsl.net/w9dmk
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