Field Day (June 22and 23, 2019) is almost here and the planning is underway — for radios, tents, food, antennas—and how to keep them up! You may be lucky and have tall firs or high ridges to get your “skyhooks” in the clear but for many groups, a tower or mast is needed.
Being a veteran of many, many Field Days, I’ve seen a lot of putting-up and tearing-down—and even a falling-down or two—so here is some perspective on how to do the job safely and avoid damage to people and equipment.
It’s Not a Race
It shouldn’t have to be mentioned, but save the alcoholic beverages for after the work is done. Rule out the possibility of even partially inebriated rope handlers, tower lifters, or helpers! No exceptions!
Put an experienced person in charge of the whole tower or mast-raising process. Field Day brings a lot of enthusiastic volunteers, many helping raise an HF antenna for the first time. They will need instruction and guidance and possibly some safety gear. Get the whole team together and walk everyone through the process, including the use of tools and ropes. Make sure everyone knows what is supposed to happen and who is directing the work. Ensure that the most critical parts of the job are managed by someone who has done the job before.
Survey where the antenna is being put up. You may not be able to see hazards like power lines, especially in sites with trees. Be mindful of the potential footprint of the entire setup. Ask what might happen if things fall over or break or get out of control. Do not set up a station or any other facility within that footprint and keep bystanders out as well!
Finally, don’t let yourself or others be talked into doing something that isn’t safe. When the work isn’t going according to plan or starts going awry – STOP – and return to the last safe configuration if at all possible. Take time out to determine what went wrong and correct the situation before resuming. Make sure all crew members feel comfortable asking questions and don’t be shy about asking for help!
Erecting a Guyed Mast
Guyed fiberglass and metal masts are quite popular as Field Day antenna supports, ranging from multi-section military surplus to TV antenna push-up masts. The key to success is to have the guys pre-cut, all ground stakes or anchors in place, and all materials ready to go before starting. The figure below shows how AB-155 masts are walked up with all four of the guys attached and ground stakes in place. You can do something similar for any tall mast.
Be wary of walking up a mast with a beam and rotator at the top. There are some very high-load points during the walk-up process that most masts are not designed to withstand. If a mast fails during the walk-up process, either by breaking or bending, anyone near the mast is in serious danger of injury.
Walking Up a Tower
Short towers of 30-50 feet are another very popular Field Day antenna support. They can easily support an HF tribander, a rotator, and a wire antenna or two. They are also heavy and can be very unwieldy during the process of getting them vertical and then horizontal again.
Because the base of a temporary towers is not in concrete and the guy points are temporary, too, using a gin pole and climbing each section is fairly risky. Climbing any temporary tower is not a good idea! Put the tower up as a single assembly with antennas and rotators already installed.
Walking up a tower can also be hazardous. The drawing below illustrates the problem of walking up a tower consisting of four 40-pound sections of Rohn 25 topped with a 40-pound beam/mast/rotator. The total weight is 192 pounds at the center of gravity, 25 feet from the base. Assuming you have a crew that can lift 192 pounds to 7 feet, a horizontal pulling force of 658 pounds is required to lift the tower at its center of gravity and the same 658 pounds of force is pushing horizontally against whatever is holding the base to the ground. What do you think will happen if the base is not secure? Remember and account for this multiplication of force!
What if the crew walks toward the base to raise the tower further and reduce the pulling force? That will place the center of gravity behind them, enabling the tower to pivot around the crew lift point, and raising the base off the ground. This is not a good combination and many a tower-lifting operation has suddenly gone awry at this point.
The “secret” to tilting any tower into position is having a hinged base plate that is securely held in place. Without a hinged base, the lift will be risky. Make certain the base is secure by driving stakes through the base plate or having something very heavy holding it in place, like a vehicle. Avoid the temptation to rely on a shallow hole as a seat for the base or the dangerous practice of having someone stand on the base to hold it down. If the base begins to slip, you’ll have a lot of unwieldy tower and aluminum that is dangerously out of control.
The other secret is not to use weak guy anchors or unsuitable guy material. Make certain the guy anchors are strong enough to do their job, such as heavy pipes driven deep into the ground, or screwed-in earth anchors. Do not use brush or saplings as anchors. Only mature trees are safe enough to use as guy anchors and even then only attach guys near the base of the trunk. Vehicles? Forget about it!
If you guy with rope, use at least 3/8-inch diameter material without a lot of stretch, such as Kevlar or Dacron. Do not use nylon or manila rope. Once the guys are set properly, tie brightly colored surveyor’s tape to them up to and above head level. If possible, fence off the guy points to keep people from tripping over them or vehicles from backing into them.
The Falling Derrick
For larger masts and all towers, consider using the “falling derrick” method as illustrated on Rick Karlquist N6RK’s website http://www.n6rk.com/falling_derrick_gme/falling_derrick_gme.html. It’s a little more work up-front but the payback in safety and reliability is more than worth it. There are numerous videos online showing you just how to do this. For example, the Montgomery Amateur Radio Club has made a good video of their team putting up a tower this way at www.youtube.com/watch?v=psewv8s2v3E. Searching YouTube for “ham tower falling derrick” will turn up numerous examples of masts and towers being erected safely and quickly.
More How-Tos from the Experts
Every situation is different, so inform yourself and your team. Read the tower and antenna safety section in the ARRL Handbook, the more complete chapter in the ARRL Antenna Book, or the excellent books by K4ZA (Antenna Towers for Radio Amateurs) and K7LXC (Up The Tower). More tips and photos are included in the June 2013 QST article “Field Day Towers – Doing It Right” by me and Don Daso, K4ZA.
Don’t put anyone at risk by doing the job without the proper equipment or skills. A job done safely and properly usually takes less time in the long run, avoids accidents and equipment damage, and gets you on the air reliably. CQ Field Day!
