My first question would be the diameter of the guy ropes. Nylon is rather
stretchy in smaller diameters, which is generally not good for towers. If
it was 3/8" or bigger and not springy when you pulled it tight and no one
had to climb the tower it would probably be ok. Manila rope is generally
not as stretchy, but also not as strong as nylon. You have to be sure it is
stored properly between uses or it will degrade rapidly. Again 3/8" or
bigger would be ok. A better rope is polyester, the type typically sold as
antenna rope in either 3/8" or 1/2" will keep a tower up nicely, doesn't
have the stretch of nylon, and is much more forgiving of bad handling and
storage than manila.
The other question is how long the pipe anchors are. I like 4', and drive
them in 3' of that at about a 45 degree angle slanted away from the tower...
and if the soil is soft then drive a second one 3' behind that and tie the
top of the first one to the bottom of the second one for extra holding
power... see an old boy scout handbook for details.
You would never want to use 1/4" ehs and tighten it to spec, you would pull
out the anchor stakes every time. one improvement might be aircraft cable,
but still pull it hand tight, don't try to use turn buckles or comealongs to
tighten it up or you'll pull out the stakes.
David Robbins K1TTT
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> -----Original Message-----
> From: Derek Cohn/WB0TUA [mailto:firstname.lastname@example.org]
> Sent: Sunday, August 10, 2008 00:12
> To: email@example.com
> Subject: [TowerTalk] Temporary guys for FD towers
> Hi Everyone,
> This year, our Field Day group put up two Rohn 25G towers. Towers were
> erected in the middle of a full size football field and separated by
> enough distance that if either one fell, it would not contact the other.
> Our stations were located about 200' from the towers to provide an extra
> measure of safety.
> My concern that I'd like to discuss is less about the tower and antennas
> and more about safety. While I hope the towers don't come down, my sole
> focus is making sure no one gets hurt/killed.
> Tower No. 1:
> 40' with 15' of mast sticking out the top with a 135' all band doublet
> hung from it. Tower base was a Rohn BPH25G bolted to an 8' automotive
> ramp made of angle iron (weighed about 150lbs.). Tower was pulled
> vertical with a truck mounted crane with truck sitting on the 8'
> automotive ramp and temporary guys made of nylon rope were attached and
> terminated in 2" pipe hammered into the ground at 120 degrees around the
> tower. Once guys were fixed, truck with crane was backed off the
> automotive ramp and headed for tower no. 2
> Tower No. 2:
> 40' and had a TA-33 tribander on it. Tower base was a Rohn BPH25G bolted
> to an identical 8' automotive ramp made of angle iron (weighed about
> 150lbs.). Tower was pulled vertical with a truck mounted crane and
> temporary guys made of manila rope were attached and terminated in 2" pipe
> hammered two feet into the ground at 120 degrees around the tower. Truck
> remained parked on the automotive ramp with crane attached to rigging on
> We had no issues with this installation. HOWEVER, I'm thinking we under-
> engineered the guy lines. My prime concern is with tower no. 1 that had
> only the guys for support (the second tower had the crane attached to the
> rigging the entire time). Eventhough this installation was designed to
> only be up for approximately 24 hours, I wonder if we should have used
> more substantial material for the guys. I'm concerned that if someone
> wandered into the tower area and tripped on a rope guy, the force might
> provide enough "pull" to start the tower crashing down. In addition, the
> guys were "hand tightened" with unknown tension. We used a level to make
> sure the tower was vertical as the crane pulled it into position and then
> snugged up the guys so that the tower remained vertical as the crane was
> removed from the rigging.
> In retrospect, I think this was a risky installation but I'm no engineer.
> Should I have bought a spool of 1/4" EHS and a LOOS tensioner and
> installed these for this temporary installation or am I being paranoid? I
> want to be sure that the fact we had no issue doesn't give me a false
> sense of security.
> What would be appropriate guy material for a Field Day installation such
> as I've described above?
> Thank you for your input & 73,
> Derek Cohn
> Morse Telegraph Club - Alton Chapter
> Office UD, Sine DJ
> Amateur Radio Station - WBØTUA
> 1969 Brunswick M274A5 Mechanical Mule
> TowerTalk mailing list
TowerTalk mailing list