[TowerTalk] Tower in the woods?
Jim Brown
jim at audiosystemsgroup.com
Tue Aug 18 18:40:51 EDT 2020
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
On 8/18/2020 2:49 PM, Randy Farmer wrote:
> Now that I've relocated to semi-rural western North Carolina, I'm doing
> some planning for the new antenna system. I already have a US Towers
> TX-455 that will be going up soon, but I'd really like to put up another
> crankup / tilt-over tower with a somewhat bigger antenna. The good news
> is that we have a fair amount of land to work with. The bad news is that
> the available land for a second tower installation is almost completely
> heavily wooded. The XYL is willing to tolerate the TX-455 behind the
> detached garage, but not at all receptive to a tower in the cleared yard
> area.
>
> Even though I would really like to have the second tower I'm
> apprehensive about how big a project it would be to put up a serious
> tower in the woods. I'm especially worried about getting a proper base
> in, both because of remaining stumps and tree roots after land clearing
> and because of the logistical difficulty of hauling 10+ yards of
> concrete out into the woods. Trenching to install a proper ground system
> and to run feedlines and control lines would also seem to be another
> possible problem. Has anyone undertaken such a project? If so, would you
> be willing to share your experiences and advice? Off list would be fine.
>
> Thanks & 73...
> Randy, W8FN
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