Jim, let's trade QTH's for one week, you operate here at my house under the
restrictions that I have, and then see if you still feel the OCFD is a
really bad idea.
It is working for me because I followed 'your' directions.
In addition to the dual-core balun at the feedpoint, I immediately inserted
a Maxwell choke, another choke half way to the house, and a third just
outside the house. I understand a Guanella would have been better but the
Maxwell is invisible (looks like part of the coax). As it turned out, the
Maxwell was good enough.
The result is, I run 600w to the antenna and have no problems with common
mode current at the house.
I can't measure any cmc on the line using my RF-Ammeter. I get no
significant distortion of the SWR curves (pattern across the bands) if I
measure at different points along the coax. When significant common mode
current is on the line, it is measureable and you see its nasty affects on
the shape of the SWR curve. They change as you take measurements at
different points because the amount of CMC is changing. I don't have this
occurring.
For me, with all of the restrictions placed on my antenna, this OCFD has
been a real blessing.
If I could have run openwire through the air, I would have center-fed the
antenna, but the landlord wouldn't allow it. The feedline would have been
right outside his big picture window in his living room. Instead, the coax
runs down the pole and along the ground, out of site.
The off-center-fed dipole, "under certain restricted conditions", and when
built right following Jim's recommendations in his cook book . . . is a
REALLY GREAT idea.
CAPS added for emphasis. :)
Most likely if I tried to run 1.5 kW I would get several problems, but
running 600w, it works fine on 7 bands.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Brown
In today's world, badly unbalanced antennas (off-center fed dipoles are the
most common) are a REALLY BAD idea.
Caps added for emphasis. :)
73, Jim K9YC
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