WB2FKO Tower Project


I started thinking about putting up a backyard tower shortly after I bought my house in July 2002. The goals were to get up 40 feet and keep the whole project under $3000, including antennas, low loss coax cable, and hardware. Brand new, each 10-foot section of Rohn-25 is $90 less shipping! Freight would actually double the cost, so that meant I was looking for used tower sections. Bobby Smith (N5XZM) saved the day here -- he had a contact who sold me three tower sections (two main sections and a top) plus a Ham-IV rotor for 300 bucks. These were located in nearby Los Lunas, NM and I purchased them in November 2002; they were hauled back to Albuquerque in Bob's truck. For what I had planned, I didn't need the top section, but it was a package deal. I was still short two straight sections. Bob found these for me via a friend in west Albuquerque and I bought a package of two straight pieces and another top in January 2003. Bob's truck was again pressed into service hauling the load back to my place. I gave Bob one of the tops and sold the other one to Owen (KB5XE).

Now I could start planning the installation. In the first deal, I got a hinged baseplate that would allow me to assemble the tower on the ground and walk it up into place. One can use a gin-pole to build a tower vertically, but I wanted to take advantage of the pivot on my tower base. I determined that the tower would comfortably fit in my backyard lying horizontal. What I didn't anticipate is how hard it would be to push it vertical (more on that later).

I spent most of the spring running through red tape with the city, trying to get a permit. It was a nightmare and I'll leave it at that.

In May 2003, I started digging. The hole for the base was located near the back corner of the house. This gave me the most space to lay down the tower. I also liked being close to the back bedroom to minimize the cable run. This cuts down on cable cost and rf loss. As per the instructions at Texas Towers, I dug a 2 x 2 x 4 feet deep hole. This took me two days with a shovel and was real hard work. All the excavated dirt wound up scattered around the garden.

The concrete pour took place in June 2003. I got the help of my friend Gary who has been in the construction business for something like 30 years. He knows what he's doing. I, of course, do not. Gary built the rebar reinforcing cage, shown here with the tower bottom hinge plate attached. He used saddle ties at all the joints. This photo shows the rebar cage in the hole to see how things would fit. The plate is attached to threaded J-bolts that are saddle tied to the cage. The plate was removed and we were ready for concrete. Gary built the wooden frame from 2 x 4 lumber to give the finished concrete block a clean, professional looking appearance.

It took twenty 80-lb bags of Quickcrete to fill up the hole. These were obtained at Home Depot for a little less than three bucks per bag. We had to make two trips in Gary's pickup. Damn those bags were heavy. This photo shows Gary mixing the first bag with water in a wheelbarrow. There were 19 bags to go. Despite the hard work and scorching temperatures, I really enjoyed this part because it was the first time I had ever mixed concrete. Less than two hours later, it was all in. Here Gary is stirring up the concrete to get it homogeneous. The board directly in front of him was used as a ramp for the wheelbarrow. The last step was smoothing out the top surface. I really wanted to do this, but saw that it was tricky and a bit delicate so I was happy to let Gary finish it professionally.

I let the base cure for several weeks and started assembling the tower in July 2003. The antennas are raised and lowered using a tram system called "The Hazer". I'll have more to say about that on the next page. This photo shows the assembled tower lying on its side in the backyard, ready to be walked-up into position. The tree branches above it would have to be pulled out of the way with a series of ropes. You can barely see the pulley on the silver crossbar at the the top. At the base of the tower is The Hazer, with no payload. A cable runs from The Hazer on the outside of the tower, through the pulley, down through the center of the tower to a hand winch mounted at ground level. The tower sections are "swaged" together and secured with high-grade bolts. I was unable to mate the 3rd and 4th sections, but once again Bob came to the rescue. It was a simple matter of bending the frame very slightly with a long lever. Then everything fit together nicely.

The tower sections weigh 40 pounds each and I was able to push up a two-section "test tower" quite easily by myself. Four sections was a different story altogether. My friend Woody and I were unable to get the complete tower past 30 degrees. We enlisted the help of another friend Mark who provided the final push. Even that was right at the limit of our combined strength and there were a few anxious seconds when I didn't think we were gonna make it...but we did. This picture shows the tower in the air, waiting for the mast and antennas.

I estimated that the maximum force we encountered in the push-up was in excess of 900 pounds! This was really a four man job and I should have known better. I strongly doubt it can be lowered using the walk-down method. It needs to be tethered and winched from the other side. Either that, or at least one if not two sections should be removed while it's vertical. So I hope I'm not disassembling it for a while.

When the tower first went up, there were no guy wires. I and others were quite sure it was plenty strong enough to stand up by itself, even in a good wind, but I couldn't help but feel nervous. The following weekend, the guy wires went on, which are barely visible in the last photo. These are 3/16" stranded EHS cable, often called aircraft cable. I bought a 30 inch bolt cutters at the Albuquerque flea market ($12) to snip it into proper lengths. Each end is dressed with eyelets to form loops for attachment. As per manufacturer's suggestion, guys are attached directly to The Hazer at about the 35' level. Two anchor points are in the ground and the third attaches to a chimney bracket.

I couldn't resist the temptation to climb up and have a look. Perched just below the Hazer at about 35 feet, here's the view to Four Corners in the northwest and Arizona to the southwest. The Sandia Mountains are to the immediate east, but the photos didn't come out. Note that I'm well above the power lines and the antennas will be still higher. Here's what you see looking straight down.

Next: Antenna installation.

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