We decided to put up a third tower as part of our 2017 Field Day operation. The new tower will support a tri-band yagi and wire antenna for use by our Digital and GOTA stations this year. Our Field Day plans call for this tower to be located on the middle-level soccer field at the Hollis-Brookline High School. To overcome terrain limitations, we decided that our new tower should be a 60 ft setup.
The project began with some mechanical design and planning for a new, heavy-duty Falling Derrick System. Mike K1WVO, Dave N1RF and I secured the necessary materials and hardware to make the new Falling Derrick System.
The team in the two pictures above met at our QTH this past weekend to transport all of the equipment for the new tower to the high school for a test setup.
The first step in the test was to locate the tower base in the center of our test area and ensure that it was level. Steel stakes were driven and retainers added to secure the base to the ground.
Next, we assembled the falling derrick and the first section of the tower to the base.
With the Derrick in place, we assembled the remaining sections of our 60 ft tower on the ground.
WIth the tower, Derrick and base together; we carefully located and drove the steel stakes for guying the tower, the derrick and for anchoring the pulleys associated with the falling derrick system. With this done, we made up and attached two levels of guys between the tower and the anchor stakes.
The tower is lifted by two wire cables which run between the derrick and the tower. We made these cables up to length during our test session. Multiple cables are used to ensure that the tower is fully supported during the lift.
Here’s another view of the tower and Derrick prior to the lift. We supported the tower on a ladder to make the initial lifting easier. The ladder will also be needed on Field Day to allow our tri-band yagi to be installed on the tower prior to standing it up.
There is a considerable amount of rope that needs to be pulled through several pulleys to lift the Tower/Derrick system. The pulleys provide mechanical advantage and slow the lift rate to a safe level. We used a heavy-duty gasoline powered capstan winch to pull the considerable length of rope required to lift our tower into the full upright position
With our crew fully briefed on the process and safety procedures, it was time to lift our tower. The picture above shows the lift in progress. Our setup ensures that no one needs to be in the tower’s fall zone during the lift.
Here’s a picture of the tower after it was up and fully guyed. Our new heavy-duty Derrick system worked very well and lifting the tower was completed smoothly and safely with very modest effort.
After a few pictures, we took the tower down and disassembled it. We had quite a few members turn out to help us with our new tower test. Thank you to everyone who pitched in to make our third tower project a success! We are looking forward to using it during Field Day 2017!
Notice: falling derrick tower systems can be dangerous if they are not engineered, built and used properly by a well-trained team. The tower system described here is unique and is not a standard falling derrick system. Significant steps and material choices were taken to ensure the safe use of the system described here to put up our tower Time was spent to train the team who used the Derrick system to use it correctly and safely. We do not recommend the system here to others as the engineering, materials, and training required for its safe construction and use may not be readily available.
Fred, AB1OC
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