Ditto. My 110' Rohn 55 tower is on a steep slope. The base is on a narrow
strip of relatively flat ground that's not much wider than the base in the
uphill/downhill direction, but stretches away from the base flat for about
80 feet in one direction and at least 300 feet in the other direction. The
long stretch of flat ground allowed one of the three sets of guys to be
approximately the Rohn-specified length for the tower height and attachment
levels, though very slightly shorter because the land rises a few feet at
the anchor. The uphill guys are quite a bit shorter than Rohn spec and the
downhill guys are quite a bit longer.
As W2XX/7 says below, try to maintain the same angels as guys over flat
ground. However, you may find, as I did, that you can't do that for multiple
guys terminating at the same anchor. To get the angles exactly right, you
need separate anchors for each guy. I didn't do that because the cost was
very high (9 anchors instead of three) and the angle differences were fairly
minimal. I ended up positioning the anchors so that the angle of the top
guys exactly meets Rohn spec. On the uphill and downhill guy sets, that
resulted in the middle guy being off from Rohn spec by about 2 degrees and
the bottom guy being off by about 5 degrees. I'm not an engineer, but this
amount of deviation doesn't worry me.
73, Dick WC1M
From: J.P. [mailto:firstname.lastname@example.org]
Sent: Monday, March 07, 2011 6:06 PM
Subject: Re: [TowerTalk] Tower for Challenging Terrain
Having done this myself, the answer is sure you can put up a guyed tower on
a slope. What's important to maintain are the angles of the guys to the
tower and the tension on them. If you maintain the same angles relative to
the tower, some will be shorter (uphill) and some will be longer (downhill)
but other than that there's not any magic besides basic geometry.
On Mar 7, 2011, at 2:35 PM, Jerry Gardner wrote:
> I recently moved to a new QTH and want to put up a 70' tower for a 20m
> monoband yagi and a 15/10 duoband yagi.
> I have 10 acres, but the terrain is challenging. Almost all of it is on a
> fairly steep slope (probably about a 12-15% grade). There are several
> relatively flat areas, but none larger than about 20' x 20'. There are
> telephone poles in the area carrying 13kV AC, so I need to avoid these.
> Under normal circumstances, my first choice would be a guyed tower using
> either Rohn 25G or 45G. Is a guyed tower even feasible with this kind of
> terrain? I assume that if it's possible at all, then the lengths of the
> three guys would not be equal and that this would affect the size and
> placement of the guy anchors. I have read several books describing the
> installation of guyed towers, but none of them address sloped terrain.
> Another option is a freestanding tower such as a crank-up or a Rohn SSV or
> an AN Wireless. No guys required, of course, but the trade-offs are higher
> cost and a larger concrete base.
> There is a semi-paved road leading to the site that will probably
> accommodate a cement truck and/or a crane.
> Any suggestions?
> 73, W6UV
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