[Elecraft] Antenna question
Charles Greene
crgreene at cox.net
Sun Aug 21 07:09:00 EDT 2005
Tom,
While you can run the ladder line right to the shack and connect directly
to the K2, a balun mounted outside and a coax run to the rig works well and
you avoid having to run the ladder line inside which sometimes can be
problematic. There are several low cost 4:1 baluns on the market including
the Elecraft one, or you can use a BA-58 or BA-8 kit of ferrite beads over
the coax from Palomar. As my late friend George used to say, a 1:1 balun
works as well in this application as a 4:1. You need to avoid a length of
feed line such that the sum of the length of the feed line times its
velocity factor plus 1/2 the length of the dipole is 1/2 wave length. Then
keep the length of coax times its velocity factor unequal to a 1/2 wave
length too. Best to keep the coax run short. That is to avoid a current
node either at the position of the balun or at the K2.
73, Chas, W1CG
At 09:57 PM 8/20/2005, Tom McCulloch wrote:
>Hi all,
> I'm considering putting up a 40 meter dipole fed with a 450 ladder line.
> I have a K2 which I run at about 5 to watts (I do not have the 100 watt
> amp). The K2 also has the internal ATU.
>
> I have always used 50 ohm coax up until now. Is there anything I should
> know about using the K2 with 450 ohm feedline? (Will I need a balun, or
> can I just feed the ladderline directly to the K2's ATU and that will
> take care of the match.
>
>Thanks for your help.
>
>Tom, WB2QDG
>
>K2 1103
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