[Elecraft] Antenna question

[Rick Dettinger]

Hi Tom - I don't think you mentioned what bands you intend to use  the
antenna for.  If just 40M, then you may do as well with coax and not need
the tuner.  If you use it for an all band doublet, the tuner may have
difficulty on some bands depending on the impedence and the lenght of the
feedline.  Without the balun,  you may have radiation from the feedline,
which may not be a problem or it may cause problems in the shack with RF
getting into equipment or noise on receive if the source is near the rig.  I
use a doublet but I increased the lenght to 88 ft and the k2 handles it well
on most bands.  I plan to increase the lenght to 100 ft to get better
efficiency on 80 meters.  I use a 1 to 1 balun.  A 4 to 1 balun may work
better on some frequencies but would likely give less efficiency on 80
meters due to low radiation resistance.  Finally, changing the lenght of the
feed line can improve the match on some bands with a possible worse match on
others.  Multiband antennas are always a compromise and experimenting may be
required.    Rick - K7MW
Original Message -----
From: "Tom McCulloch" <thom2 at att.net>
To: <elecraft at mailman.qth.net>
Sent: Saturday, August 20, 2005 6:57 PM
Subject: [Elecraft] Antenna question


> 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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