Open Line Feeder

Field Day is coming up and the K2 is going out.  I
have the KAT100 as well...and I want to put up a 130
foot dipole with that ladder line stuff.  Hey, its
only for 24 hours.  To use the KAT100, I have a 4:1
balun (a 4KW job).  Can I use that with the KAT100 and
the open line feeder?  What are all you guys doing?

Lee - K0WA


Common sense is in short supply - get some and use it  - Lee Buller
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[K5JAZ-2]

I use this same setup on a permanent basis. My doublets are 137' and fed with ladder line, tuned by the KAT100 on 80-10M. Works like a charm.
--
Regards,
Jim Brown, K5JAZ

 -------------- Original message ----------------------
From: Lee Buller <[hidden email]>

>
>
> Field Day is coming up and the K2 is going out.  I
> have the KAT100 as well...and I want to put up a 130
> foot dipole with that ladder line stuff.  Hey, its
> only for 24 hours.  To use the KAT100, I have a 4:1
> balun (a 4KW job).  Can I use that with the KAT100 and
> the open line feeder?  What are all you guys doing?
>
> Lee - K0WA
>

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[Don Wilhelm-3]

Lee,

The impedance at the end of an open wire transmission line depends on the
line length and the antenna, If you know the antenna feedpoint impedance and
the transmission line length, a program like TLW (from ARRL) can predict the
impedance that must be matched at the tuner.

In many cases, a 1:1 balun (or no balun at all) will serve better than a 4:1
balun.  The impedance that has to be matched by the tuner will almost always
be something quite different than the characteristic impedance of the
transmission line.  Feedpoint values ranging from only a few ohms to a few
thousand are not unusual for a multiband antenna.

Yes, you can use your 4:1 balun, but if you have trouble matching the
antenna system on some bands, just take the balun out and feed the
transmission line directly, one wire to the coax connector center and the
other wire to the ground terminal.  The transmission line will still be
balanced as long as the antenna is being fed at its electrical center - the
fact that the current at the ends of the antenna must be zero will assure
that the feedline will be balanced.  You may check out LB Cebik's info on
multiband antennas too if you have doubts, he states it in a different
manner than I do, but the end result is the same - you don't really need a
balun in all cases and connecting directly to an unbalanced tuner will do no
harm especially in a portable situation.

73,
Don W3FPR

> -----Original Message-----
>
>
> Field Day is coming up and the K2 is going out.  I
> have the KAT100 as well...and I want to put up a 130
> foot dipole with that ladder line stuff.  Hey, its
> only for 24 hours.  To use the KAT100, I have a 4:1
> balun (a 4KW job).  Can I use that with the KAT100 and
> the open line feeder?  What are all you guys doing?
>
> Lee - K0WA
>
>
> Common sense is in short supply - get some and use it  - Lee Buller
>

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[n6wg]

Lee
Here is something that works really well if you have the KAT2 ATU in your
K2.
Put a 4:1 balun on one antenna port and a 1:1 balun on the other.
Using something like banana plugs and jacks, you can quickly move the feeder
from one
balun to the other.
Now as you go from band to band, you can quickly pick the balun that gives
the best
match before tuning with the ATU.  That way it doesn't have to work as hard
to give
you a great match.

See you on the air for FD.
Good luck and 73
Bob N6WG

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Lee Buller
Sent: Tuesday, March 29, 2005 12:29 PM
To: Elecraft Reflector
Subject: [Elecraft] Open Line Feeder




Field Day is coming up and the K2 is going out.  I
have the KAT100 as well...and I want to put up a 130
foot dipole with that ladder line stuff.  Hey, its
only for 24 hours.  To use the KAT100, I have a 4:1
balun (a 4KW job).  Can I use that with the KAT100 and
the open line feeder?  What are all you guys doing?

Lee - K0WA


Common sense is in short supply - get some and use it  - Lee Buller
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