Thanks for the advice, Jim. Since I no longer climb (neither the XYL or
I want me to now and most likely won't be able to later) I really want
to go with a tower that allows me to maintain the antennas and rotator
from ground level. Unfortunately, that means a huge lump of concrete at
the base with a surrounding cleared space to lay it over on a tilt
plate. I'm undoubtedly looking at a situation that calls for some sort
of road to be bulldozed through the woods to reach the tower site.
I haven't yet come to grips with what I'll do for 160 and 80 meters yet.
It will probably be heavily influenced by where and how tall the tower
or towers turn out to be. I'm not sure just what critters we have in the
woods around here, but I know there are lots of deer. We're probably
down in the foothills of the Blue Ridge far enough that bears shouldn't
be a problem. I'm planning to install a BevFlex -4X receive antenna soon
and I plan to run it at least head high anchored to trees. We'll see if
that survives the local wildlife traffic.
73...
Randy, W8FN
On 8/18/2020 6:40 PM, Jim Brown wrote:
Hi Randy,
Several thoughts, based on my experience in a dense redwood forest.
These are very substantial trees, so all my guy-points are lagged into
the base of a different tree. It's 120 ft of Rohn 25, so that's 12 guy
points (30, 60, 90, 120 ft) and at the right vertical angle for each.
It took me a couple of years (and help from K7LXC) to find a place
where I could turn a 3-el straight SteppIR. Even at that, a couple of
dead ones had to come down, and upper branches around the antenna need
to get trimmed every few years.
The only reason for burying radials is to physically protect them or
prevent fall hazards for people or animals. We have no people, but do
have deer, coyotes, mountain lions, and assorted varmints. I have both
on-ground and elevated radials on three different 160M verticals.
In general, vertically polarized antennas don't work well in dense
forests. Horizontal antennas are less attenuated. 160 is the only band
where they are better than horizontal antennas. I've tried good tall
verticals on both 40 and 80, without success. The reason the verticals
are better on 160M is that any horizontal antenna for this band that
mere mortals can rig are very low as a fraction of a wavelength.
The bases for both of my towers were mixed in a relatively small
portable mixer at the side of the hole. No way a truck could have
poured either of them. Took a LOT of help from friends. Both towers
have bases over-sized for mfr recommendations. All my RF and control
lines are laying on the ground. All the TX coax is hard line, mostly
7/8-in. RX antennas are flooded Commscope RG6 like DX Eng sells. The
only failure in 12 years was the control line for my SteppIR, and that
occurred at a point where I'd had to re-route it under a newly built
deck where rabbits had moved in.
Experience with varmints varies with location, but before going nuts
with trenching, I'd tightly bundle everything, using more robust lines
like hard line to make control lines harder to munch. This assumes, of
course, that you don't need to trench to get under human traffic,
driveways, etc.
Rotator cable is a pair of 14-3 romex to the base of the more distant
tower, with something smaller going up the tower. Wire gauge was
chosen by translating the mfr recommendations using Ohm's Law.
I have no AC at either tower. All control lines are spliced at the
base of the tower, RF runs are continuous from just outside the shack
to the rotator loop. Short jumpers of RG8 tie them to the grounding
panel.
Hope this helps.
73, Jim K9YC
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