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K2 Tuner?

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Jim AB3CV

K2 Tuner?

My remote tuner bit the dust again and I'm going to actually use the K2
tuner for a while.

My setup is a dipole about 88ft long at about 50ft off the ground.

It's fed with a nominal 450ohm window line (thewireman) and it will take
about 75ft of this to reach my back porch where I will temporarily
operate...mosquitos permitting...

My question is do any of you find a balun necessary in such a situation or
do you just go with a BNC to banana jack adapter?

If you find a balun helpful which do you use: 4:1 or 9:1?

73

jim ab3cv

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Brett gazdzinski-2

RE: K2 Tuner?

I have a homebrew G5RV, with no balun.
That is sort of like what you are doing, just
with a 20 foot piece of coax between the feedline and rig.
It seems to work real well, at low power or high.

Not sure 88 feet of antenna and 75 feet of open wire
line is a good setup.
The antenna is to short for 80, to long for 40 meters,
and I don't know about the upper bands.
You will likely always have a high swr on it, which
most baluns don't like.

Good open wire line is almost lossless, even at high
swr's, but you might get a lot of loss in a balun.

I would not do the balun unless you have rf problems
at the rig.

Brett
N2DTS

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Jim Miller
> Sent: Tuesday, July 31, 2007 8:07 PM
> To: [hidden email]
> Subject: [Elecraft] K2 Tuner?
>
> My remote tuner bit the dust again and I'm going to actually
> use the K2
> tuner for a while.
>
> My setup is a dipole about 88ft long at about 50ft off the ground.
>
> It's fed with a nominal 450ohm window line (thewireman) and
> it will take
> about 75ft of this to reach my back porch where I will temporarily
> operate...mosquitos permitting...
>
> My question is do any of you find a balun necessary in such a
> situation or
> do you just go with a BNC to banana jack adapter?
>
> If you find a balun helpful which do you use: 4:1 or 9:1?
>
> 73
>
> jim ab3cv
>
> _______________________________________________
> 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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Don Wilhelm-3

Re: K2 Tuner?

In reply to this post by Jim AB3CV

Jim,

A 1:1 current balun (actually a choke) at the shack entry will work
wonders to keep RF out of the shack. See L B Cebik's recommendation at
the end of his website article on multiband antennas
http://www.cebik.com/wire/abd.html - I believe that article will help
your understanding of why using a 4:1 balun or a 9:1 balun would not be
a wise choice. Also take notice that the impedance seen at the tuner
has very little to do with the characteristic impedance of the feedline,
it can vary from quite high to quite low depending on the antenna feed
impedance at the frequency of operation and the length of the feedline
in wavelengths.

Jim Miller wrote:

Craig Smith

RE: K2 Tuner?

In reply to this post by Jim AB3CV

I don't have exactly the same setup, Jim, but I can describe what has worked
for me.

I use a 44 ft doublet fed with open wire line (homebrew) for 40 thru 10. I
bring the feedline down to my shack window and connect it to one of the
Elecraft switchable 4:1 and 1:1 baluns and then run a short (5 foot) piece
of RG-8X to the tuner/rig. Have also on occasion used an 88 ft doublet when
I wanted to operate 80. My feedline is much shorter than yours (30 feet or
so). Haven't bothered to go through the modeling and transmission line
length transformation type stuff, but with the Elecraft K2 tuner and the
switchable balun I can find a match on all bands. Some bands definitely
prefer one balun ratio over the other. The impedance seen at your shack
will vary over a WIDE range as a function of feedline length and operating
frequency. If you run into a situation that won't match, adding in a 5 ft
or so section of open wire line will no doubt fix things up.

73
... Craig AC0DS

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n6wg

Re: K2 Tuner?

In reply to this post by Jim AB3CV

Jim
I use the dual balun from Elecraft. I switch
between 1:1 and 4:1 to see which one gives
the lowest swr on the band I'm on. Then let
the ATU tune it for the final match. I do the
checking with the ATU in CAL S so I can
see the unmatched swr right from the balun.
Then I switch the ATU in and let'er rip.
Good luck and 73
Bob N6WG

----- Original Message -----
From: "Jim Miller" <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, July 31, 2007 5:07 PM
Subject: [Elecraft] K2 Tuner?

> My remote tuner bit the dust again and I'm going to actually use the K2
> tuner for a while.
>
> My setup is a dipole about 88ft long at about 50ft off the ground.
>
> It's fed with a nominal 450ohm window line (thewireman) and it will take
> about 75ft of this to reach my back porch where I will temporarily
> operate...mosquitos permitting...
>
> My question is do any of you find a balun necessary in such a situation or
> do you just go with a BNC to banana jack adapter?
>
> If you find a balun helpful which do you use: 4:1 or 9:1?
>
> 73
>
> jim ab3cv
>
> _______________________________________________
> 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