A 40′ Tilt-Tower for VHF Beams
This is the first tower I built. After moving here, the idea occurred to me that trees can save a lot of money and work when it comes to towers. Trees are already firmly rooted, eliminating the digging and concrete work, which to me are the hardest parts of doing a tower.
This tower was my first effort at utilizing a tree. The branches on this oak were already dead all down one side, and it was located right off the corner of my shop/shack, so it was a natural for a tower.
And here’s the result….
The hinge point is about 19′ off the ground. Added to the 20′ of EMT, this gives a rotor mount point of about 40′. The 2m yagi is another 8′ over that. (2m yagi details are on another page)
My thanks to Al Goshy and Mark Hager for help with the welder, and other valuable advice.
Making a Tilt Tower:
Step #1, Cut Off Top of Tree…
I went up the ladder and lopped off the top at about the 22′ level. This gave me the first 20′ of “tower” plus the “digging and concrete work”, for free. I left the still-living branches on the tree, to help keep the trunk alive for as long as possible. I expect to get a good 5 years or more from this tree before rot weakens it too badly. This oak is about 12″ diameter at the butt.
Step #2, Cutting the Materials….wheeee!!
Step #3, Figure Out the Mount and Tilt Mechanism:
I came up with a pretty simple tree-mount and ‘hinge’ assembly, using steel angle, channel, and square tubing stock, and a TIG welder. A single 3/4″ bolt is the hinge-pin. I bored the holes on a mill, producing a snug fit on the pin, which gives a very stable tilting mechanism.
It doesn’t rattle around at all, even in the strongest winds. The bottom section of tower tubing slides into a “sleeve” of EMT nestled into the angle stock, which is firmly held with two steel straps. Finished parts, ready for mounting and tower-hanging….
Also mounted to the hinge assembly is 16′ of 4×4″ lumber, hanging downward, which counterbalances the tower almost perfectly, and also provides a convenient place to attach a tilting-rope. With the rope 16′ below the hinge point, I also get plenty of leverage, so the pull required for tilting up the tower is very light. The top end of this 4×4″ counterweight is visible in the picture above.
Materials for Tower:
For this first effort, I decided on EMT, i.e. electrical metal tubing, i.e conduit. It was cheap, readily available, and is already galvanized for corrosion protection. Unfortunately, it’s not very strong, so I can’t tilt up a very large load.
At first I had two 10′ sections of 2″, with a 10′ section of 1.5″ on top of that, giving me 50′ total height. Unfortunately, during a tilt-down event, the rope slipped a bit and when the rope caught again, the ‘jerk’ bent the bottom section right over. Sigh….
Oh well. I removed the bent bottom section and then had a 40′ tower instead of a 50′ one. One of these days I’ll get a piece of 2.5″ structural tubing to add to the bottom, and get back up to 50′.
PS: two weeks ago, this 40′ tower, with the rotor, 8′ mast, and 2m yagi on it, survived a long night of 70+ mph winds. I think it’s a keeper…
On the mill, I slit a piece of 1.5″ PVC sched-40 pipe to make a sleeve which fits perfectly between the 1.5″ EMT (1.75″ approx OD) and the 2″ EMT (2.1″ approx ID). A couple of muffler clamps and a 1″ metal strap for electrical connection completes this joint. The 2″ to 2″ joint was made with a 1 foot piece of 2″ EMT slit on the mill and spread a bit to slip over the two sections. A couple more muffler clamps completed this joint as well.
The 2″ to 1.75″ joint… (electrical strap out of view, underneath tubing)