Don Wilhelm wrote:
Kieth,
A dipole cut for 40 meters will provide a high feedpoint impedance on 20 -
and the L network used in the Elecraft tuners do not do high impedances very
well.
I find the T1 does very well with a very high impedance. I end feed
1/2 wave wire connected right to the T1 with a counterpoise and it
matches right up! I ran a test and the T1 can match a 4700 ohm resistor.
So it's not bad with high resistance.
73 Karl
Of course, all that does depend on your feedline length as well as the
flattop length - the feedline will act as an impedance transformer when it
has SWR on the feedline, so unless you can state the length and impedance
and velocity factor of your feedline, we cannot answer your question with
any degree of certainty.
I use an antenna cut at 22 feet each side of center with a 25 foot feedline
for portable use, and it works FB on all bands except that it is marginal on
30 meters - adding an additional 10 feet of feedline allows it to tune 30
meters just fine with the Elecraft L network tuners.
I deploy my portable antenna as a horizontal dipole, or and inverted VEE, or
as a vertical with a single radial, whichever is convenient for the location
I have at the moment - I do carry a 32 foot collapsible mast to deploy the
antenna if I have no other suitable supports.
73,
Don W3FPR
-----Original Message-----
Thanks for the quick response. For a field dipole I could use
that in an inverted V format I assume? I did purchase a
collapsable pole to try some of those out. If I used ladder line
or twinlead....would I need a balun in-line before connecting to
the T1?
If I understood you correctly, I could cut the dipole for 40M and
then use the T1 to use it on other bands. For my base setup I
use a dipole setup and it works well on multiple bands....I am
just not real clear on how to make this work on a portable
setup with the T1 ATU.
Is there any special twinlead or ladderline I should stock for
these projects? I hope to try a bunch of antenna designs for
different locations and learn from them...so I may as well stock
some wire.
I think a recent QRP Quaterly that had a plan for a portable
vertical...I will check it out.
Thanks again for all the advice.
73 de Keith KB3ILS
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