I had the same comment from W8ZD concerning 1/2" 75 ohm line and its
possible problems with 1 KW and some VSWR (2:1 or higher). I called
K8CC who has 1/2" 75 ohm line to many beams and he hasn't had any
feedline related problems with it. I think KS8S uses some 1/2" as
well. The manufacture specs do give a low voltage limit for this line
as it was intended for RX only purposes, but it must have some saftey
factor.
I installed two of the new W1WCR (2nd edition book) beverages last
year. I built them as per the book. They were 600 feet long. The
performance was poor considering the work involved. I found out that
running beverages within 1/2 to 1 wavelength of exsisting towers and
wires (250 to 500 feet on 1.8 MHz) causes severe pattern problems. I
had little if any front to back and no benefit over the 4 square
slopper system on 160 meters.
VE3EJ built a W1WCR system which works very well because it is far
away from anything else that might be resonant and cause problems. He
held the telephone up to his IC-765 and lat me listen to the front to
back in the AM broadcast band. On shared frequencies you could hear
two different stations each by themselves depending on the direction
selected.
I am starting to build a RX array using mobile antennas in a Five
Square array. It requires much less land and the computer models
indicate 30 db of front to back. WA3FET has a similiar system up on
40 and it really works! The antenna has the same idea as the paper
published in the ARRL antenna book volume 3 by K9UWA and W7EL.
I'll let you know how the mobile 5 square works this fall.
73,
Tim
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