A key issue is taking into account not only the distance from the tower, but
the tower distance + height of the antenna on the tower + length needed for
rotator cable loop + additional length from the outside panel of grounding box
to inside the shack + a few extra feet. Before you know it that 200’ away
tower with antenna up 120’ becomes ~ 350’+ of rotator cable. And you need to
take into account the voltage drop across the cable due. A rotator with
rotator cable that works fine on a 275’ length may not work at all on a 350’
length and you will need to go up several sizes in cable wire diameter which
can geometrically increase the cost per foot of the cable. Make sure that you
take this into account before you decide where to build your tower.
The voltage drop issue is also the same with control lines. Additional cable
distance costs additional $ in extra cable length + needing to use thicker
diameter wire to reduce the voltage drop at longer cable lengths.
73
Bob KQ2M
Keith Dutson NM5G wrote
About 20 years ago, after erecting a 150 foot tower (Rohn 45G equivalent), I
was inspired to continue toward a multi-multi station. I began to look for
and purchase other towers and antennas. So far, I have 320 feet of Rohn 55G
and 56 feet of Rohn HDBX. These sections have been stacked under an oak
tree for many years. I also acquired about 10,000 feet of used Phillystran,
and about 2000 feet of new old stock Andrew LDF50A coax, the longest piece
being 500 feet. Plans to erect got halted by heart arterial bypass surgery.
Well, 13 years after surgery I am still here, and in excellent shape. So, I
am thinking of putting up at least one more tower, and making do with a
multi-two station. The new tower may be a 200 footer, but I am also
thinking of a 120 footer, which would be easier to maintain, and may be
ideal to place my M2 40 meter 4el antenna (40M4LLDD). I have 16 acres, so
placement can be flexible. The existing tower is less than 30 feet from the
shack. I am thinking the second tower should be no more than 200 feet to
cut down on signal loss. I am wondering if this is a practical limit, and
how far from the existing tower it should be located. Suggestions and
recommendations are welcome. Thanks.
73, Keith NM5G
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