Last week the postwoman delivered an interesting QSL card from Leroy N7EIE. A brief note on the card indicates that Leroy had been using a triband Yagi suspended from trees for our QSO. I had to know more!
I’ve had a similar idea myself and was therefore pleased to know that someone out there had the actual fortitude to put such an idea into practice.
A few emails later…what can I say – amazing! Not as convenient to rotate but Yagi performance without the hassles and expense of a tower.
Leroy was kind enough to not only answer my questions and provide photos of the initial installation but to allow me to post them here as well.
What gave you the idea to install a Yagi this way?
When we put in a bid for this house in 2002, a LARGE reason was the veritable mini-forest of (6) fir trees in the back yard. They were 100+ feet then and are even bigger now.
In the fall of 2006 I paid Mac the Tree Guy $1200 to bring in his 80′ bucket and install 3/8″ eye-bolts in the side of each of those trees at a height of 80′, with nylon ropes through the eye-bolts.
Three of those trees are about 20′ south of the house, and in a triangular arrangement, about 15′ to a side, which JUST happens to be the turning radius of a TH3DX Mark 4 tri-band beam. My son James dubbed it Jupiter 2 because it looks like it belongs in outer space, and I already had a VHF beam, which he also dubbed Jupiter 1. 8-)
As you can see from the photos, I ran 3 3/8″ ropes up through pulleys at those eye-bolts at 80 feet then down to clevises on a 3″ washer underneath a pipe-cap on the top of the mast onto which the beam is attached. Last summer I built my J2J (Jupiter 2 Jig) in which to store the beam for maintenance and between major contests.
Are you able to rotate the antenna from the ground?
Yes, I have a rope attached to a steering bar pointing in the direction of the beam. I usually just leave it pointing SE for stateside contests, but for DX contests I swing it around to Europe in the morning, then Japan in the evenings.
How high is it?
That can vary, of course, as to how many times I hoist up the ropes – one at a time – in a series of upper-body-strength-building-exercises (each rope has about 75 lbs of weight on it) the week before each contest. Usually I get it up to 30-40′ and quit. Performance is quite satisfactory on EVERY contest! Beats the hell out of my G5RV! Much higher than that I would run the risk of popping the eye-bolts during a wind-storm.
I’ve even pondered putting a Yagi in a tree, rotator and all.
Me too, at first. But the rotator thrust bearings would have to have the weight of the beam ABOVE the rotator. If you can figure out a way of hoisting the rotator up by ropes without getting the ropes caught in the rotated beam, let me know. Possibly a rather large (20′ square) platform underneath with a much larger support tree set-up than I have.
We have about a dozen tall pine & oaks in our yard around 100 feet tall.
They should work, John. Just bear in mind that trees are living (breathing(sort of)) life-forms that grow, sway in the wind, imbed themselves in dirt, and catch diseases. And, as James says, where you have trees, you have limbs. Indeed! The first winter I left it up a 50 lb. limb came down and crashed into the active element, bending it badly. He bent it back later, but it is still a little mis-shapen.
If you have any photos you could email, I’d sure be interested in seeing them.
These were taken last summer right after I build my J2J, and hoisted up the beam from the jig.