[Elecraft] 80M on KX1

[Don Wilhelm]

Tom,

If you are not adverse to a separate antenna for 80 meters and you have 
the space, I highly recommend a full size 80 meter dipole.  About 136 ft 
long radiator and center fed with coax.  It should work (and feed 
easily) for 80 meters (but is a single band antenna).  Ideally, it 
should have a 1:1 choke balun at the feedpoint, but you will likely not 
notice any difference if you feed it directly with the coax.  It can be 
either horizontal or hung as an inverted vee.  Get it up as high as 
possible - I would say on 80 meters 30 feet is a minimum, 60 to 70 is 
much better.
If you want 80 and 40 meter coverage, you can install an additional set 
of antenna wires at the feedpoint each about 33 feet long - run these 
wires as close as possible at right angles to the 80 meter antenna wires 
to reduce interaction.  As the 80 and 40 wires are closer together they 
react more and more.  Tune the antenna lengths for the lowest SWR at the 
midpoint of your band segment of interest.  Tune the longer antenna 
wires first, then tune the shortest ones.
You could add more bands, but the tuning gets more cumbersome when more 
bands are added.  3 bands is practical, 4 is possible, but in my 
experience any more than that is a recipe for frusstration when tuning.  
The ends must be spread out as far as possible to keep things sane.

In this case the coax will closely match the feedpoint impedance of the 
antenna(s) which makes the feedline length unimportant.

73,
Don W3FPR

T W wrote:
> Hi, Group,
>
> Can anyone tell me what length of end-fed line works best on 80M using a KX1
> with ATU? I'm having a heck of a time trying to find a length that will work
> with 80M and 40, 30 and 20. I know the ATU is not really designed to tune
> 80M effectively. It would be nice to have one antenna to do all bands, but
> if not a separate wire for 80M is okay too.
>
> Cheers,
> Tom
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