[Elecraft] auto atu

Sun Dec 7 07:15:01 2003

Hi,

The W3EDP antenna electrically is equal to a 40 meter end fed Zepp:  67' 
radiator and one 17' twin lead feed line.  The counterpoise length of 17' 
with 17' of antenna act as the 17' of twin lead, except it radiates.  It is 
a random length wire on other bands but avoids 1/2 wave multiples except on 
10 where it doesn't work very well.  So, a regular 40 meter end fed Zepp 
should work about the same with a 17' open wire feed line, corrected for 
velocity factor that, which can be brought into the shack.  For the KX1 
with the 30 meter module, I think I will try a  20 meter end fed zepp fed 
(33') with 15' of 300 ohm ladder line (17' corrected for the velocity 
factor of .88) to get inside the shack and connect it directly to the KX1 
tuner or through a current balun and a short piece of coax.   It will be a 
random length of wire on 30 and 40 meters but will avoid the 1/2 wave 
length where the antenna will be high impedance at the tuner.  I will tie a 
string with a weight on it to the "business" end and just throw it over the 
nearest tree.  Let you know it works.

At 09:49 AM 12/4/2003, you wrote:
>Nigel-
>
>As Ron AC7AC has said to me on more than one occasion, there isn't anything
>magical about the W3EDP antenna. The theory behind it is interesting and it
>has certainly worked well enough for me, but essentially it is a random wire
>that works in conjunction with an rf ground wire to provide impedances that
>are purportedly easily matched on the major bands of interest with the use
>of a good transmatch.
>
>If you are leaning toward a simple wire antenna, what I advise is putting up
>the longest end fed wire you can manage, making an effort to stay away from
>lengths approaching 1/2 wl or multiples on your favorite frequencies. Get an
>MFJ Artificial Ground and put up as long a counterpoise as you can muster,
>and/or cut and try different lengths of wire until you find those that work
>the best for you as an rf ground.
>
>You shouldn't have any problem with a KAT1, and as David W1EUY mentioned,
>you can always adjust the antenna length as needed. You could also always
>experiment with adding a series capacitance or inductance to augment the
>tuner with the intention of manipulating the reactance of the antenna enough
>to get a good match on any problematic bands.
>
>Lots of options, and half of the fun is in the experimenting!
>
>Mychael AA3WF
>K2 #1025
>
>
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73, Chas,  W1CG
K2 462b, 3571 