[Elecraft] ATU vs. External Tuner

[Julian, G4ILO]

Frank MacDonell wrote:
> 
> I have a k3 with internal antenna tuner connected to a 40 meter dipole
> in the attic. Will the internal ATU work for me visiting other bands
> or would I be better off installing a tuner between the rig and the
> antenna? Is an auto tuner more preferred than automatic? Thanks to all
> for your time.
> 
That depends on what antennas you will be using on other bands and what the
SWR will be.

Although the KAT3 will match a wider range of loads than the internal ATUs
in most non-Elecraft radios, the SWR still exists between the output of the
tuner and the antenna, and and can result in considerable signal loss if
coaxial cable is used (see http://www.g4ilo.com/antenna.html).

I used a KAT2 to tune a non-resonant loop in my attic for several years, but
my shack is in the room directly below the attic and the length of the coax
was only about 8 feet. If you are a much longer distance from your antenna
feed point then you would be better off either using open wire feed and an
external balanced tuner, or else using a battery powered remote automatic
ATU in the attic at the feed point so you use a coax feeder without undue
loss.

If you will be trying to use your 40m dipole on other bands then the
mismatch will be quite considerable on most of them and you should consider
one or other of the options stated above. If on the other hand you add
resonant lengths for other bands to the same feed point, creating a fan
dipole, then you should be able to get a good match on those bands and you
will be able to use the KAT3 without worrying about feeder loss.

-----
Julian, G4ILO. K2 #392  K3 #222.
http://www.g4ilo.com/ G4ILO's Shack   http://www.ham-directory.com/ Ham
Directory    http://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 
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