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

[DavidE Benedict]

w9dmk at crosslink.net writes:
>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
>

Bob,...

OK, that's good info and education. Thanks. I have not gone to my other
computer yet which can read the pdf manual...there is a recommended
antenna wire-length for use with the AH-4... 23 or 26 feet or
thereabouts...I suppose they worked out the length to stay away from 1/2
wavelength on the amateur bands.
 
And I stll want to know opinions about trying this tuner with a resonated
antenna, for instance, on 80m with the likes of a HamStick.

Yea! Now another guy has posted... I am hoping to hear about Sean's
success with the AH-4 and a 1/2 square antenna, too. Maybe I can do that
for my mobile ant.

David
w7dbh
NW Oregon