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80M on KX1

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T Witherspoon

80M on KX1

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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Don Wilhelm-4

Re: 80M on KX1

Tom,

There is no single answer to your question. The real answer is that it
all depends...
The feedline is only part of the antenna system, and the rest of the
answer depends on the remaining parts of the antenna - length of the
radiator - orientation of the radiator - how the radiator is fed -
influence of surrounding objects. Those are the main factors.

Your transmission line acts as an impedance transformer unless it is
matched with its characteristic impedance at the antenna connection. If
the antenna feedpoint impedance is known, you can use a program like TLW
(available at the ARRL website) to figure the required feedline length
to give whatever desired impedance (near 50 ohms?) at the shack end of
the feedline.

If you do not know the feedpoint impedance of the antenna, then you may
be able to venture a guess by consulting the material in the ARRL
Handbook or ARRL Antenna book or other such sources. It is possible to
calculate the antenna feedpoint impedance by using an antenna modeling
program like EZNEC.

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.
>
>
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Don Wilhelm-4

Re: 80M on KX1

In reply to this post by T Witherspoon

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
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
>

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WILLIS COOKE

Re: 80M on KX1

I have used the 80/40 combo for over 40 years. It
works great for 80, 40 and 15 and not bad for 10. It
does not work very well for 20, 17 and 12 and I have
had poor results trying to add a third element for 20
meters. I have had good results with and without a
balun. It may make some difference, but I think
mostly to the pattern and it is not really noticeable.
I have used RG58, RG59, RG8X, RG8 and TV coax and all
work well.

Cookie, K5EWJ

--- Don Wilhelm <[hidden email]> wrote:

> 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
> > _______________________________________________
> > Elecraft mailing list
> > Post to: [hidden email]
> > You must be a subscriber to post to the list.
> > Subscriber Info (Addr. Change, sub, unsub etc.):
> > http://mailman.qth.net/mailman/listinfo/elecraft
>
> >
> > Help: http://mailman.qth.net/subscribers.htm
> > Elecraft web page: http://www.elecraft.com
> >
> >
> >
> _______________________________________________
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>

Alan Fryer-2

Re: 80M on KX1

In reply to this post by T Witherspoon

I have had good luck with a 51 FT radiator. Probably just as important is
to have a decent radial, about 66 FT...

Alan, N3BJ
Bent Mountain, VA

----- Original Message -----
From: "T W" <[hidden email]>
To: <[hidden email]>
Sent: Friday, May 02, 2008 7:40 AM
Subject: [Elecraft] 80M on KX1

> 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
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
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>

David Woolley (E.L)

Re: 80M on KX1

In reply to this post by T Witherspoon

T W wrote:
>
> Can anyone tell me what length of end-fed line works best on 80M using a KX1

The expression "end fed line" makes me confused as to what you are
actually talking about. The other replies have ignored the "end fed"
and read the "line" as "transmission line" (transmission lines in
amateur radio are generally always end fed (although that's not true of
Ethernet and Thinwire Ethernet).

I wondered if the "line" was the wrong term here and that you actually
meant antenna wire, in which case, if the transmitter is directly
connected to ground (no appreciable length of ground wire, the answer is
going to be an electrical quarter wave, which is of the order of 20.5
metres or slightly less.

> 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.

--
David Woolley
Emails are not formal business letters, whatever businesses may want.
RFC1855 says there should be an address here, but, in a world of spam,
that is no longer good advice, as archive address hiding may not work.
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Paul Huff-3

Re: 80M on KX1

In reply to this post by T Witherspoon

Hi Tom,

I assume that you are talking about an easily deployable field antenna. For
convenience it's hard to beat a simple length of wire with a few radials on
the ground. I don't have 80-meters on my KX1 but I use a 42-ft wire for 40,
30, and 20. Of course that length won't help you, but here's the idea...
Sometimes, because of the specific setup situation (angle of the antenna, a
dog-leg in the wire, nearby structures, etc.) I am not able to get a good
match with the ATU on all of the bands. So I used some hookup wire to wind
a coil on a plastic film canister and made taps about every-other turn. If
the ATU can't find a good match by itself I add in my coil between the rig
and the antenna wire. It doesn't take very long to find a tap that keeps
the rig happy. Something similar with a longer piece of wire might work for
you.

Good luck and 73,
Paul - N8XMS

> 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.

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Paul - VE1DY-2

Re: 80M on KX1

In reply to this post by T Witherspoon

I Tom,

I use the antenna suggested by Bruce Prior (N7RR) on QRP-L, which is
67' - 9" with a counterpoise of 33'.

Please have a look at my KX1-Canso Causeway web page for further details.
http://www3.ns.sympatico.ca/ppike/csway.html

Good luck,

73, Paul -ve1dy-

On Fri, May 2, 2008 at 8:40 AM, T W <[hidden email]> wrote:
> Hi, Group,
> Can anyone tell me what length of end-fed line works best on 80M using a KX1
> with ATU?
>
> Cheers,
> Tom

--
Paul - ve1dy - Halifax, NS
www3.ns.sympatico.ca/ppike
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