Hi Alex,
I ran a full length 160 dipole at less than nominal height for many years at
my old QTH. I fed my dipole (up at 100 feet suspended between Douglas Fir
trees on a mountain about 1000 feet above average terrain) with 450 ladder
line. This came to a homebrewed remote controlled "balanced balanced"
antenna tuner, aka a double L design, as published by Rich Measures in QST
back in February of 1990.
Here is a link to the article about the tuner:
http://www.somis.org/bbat.html
Another author, LB Cebik, writes about the same type of tuner in his
article:
http://www.cebik.com/link/l-bal.html
The beauty of this type of design is than ability to resonate the dipole on
just about any band, any frequency in the HF spectrum with a perfect match
every time. In addition, the system has excellent efficiency overall.
I used commercial "plastic window" 450 Ohm ladder line from the dipole to
the tuner. I found that the multi-strand Cu/Steel variety held up better
over the long run compared to the single strand CU/Steel stuff. Davis RF
and Wireman sell a good selection of the stuff. Commercial versions of the
double L tuner are available from Palstar and one or two other tuner
manufacturers, as well.
One of main design features of this matching system is use a balun to
convert the 50 Ohm coax unbalanced feed from your xcvr to the a balanced 50
Ohm input feed to the tuner. This avoids problems associated with trying to
use a balun on the output side of the tuner with less than optimum impedance
transformation ranges.
The design also allows a direct DC path to ground, which is most helpful
with large antennas on mountain tops.
Aside from all the above, keep in mind that a 160 meter dipole as low as
yours will send a significant amount of energy into a less than desired
launch angle for working DX. As said by other responders here, you may
benefit more by switching to a well designed vertical low angle radiator and
using one of the many available receiving antennas for your ears (K9AY Loop,
EWE, Flag, beverage etc) for top band use.
73
Paul WN7T
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