I bought a tower! It was something I always wanted and when the chance of a tilt over wind up tower came along at the right price I jumped at the chance. It is a 30 foot (10 metre) lattice tower with a full rotator cage. When fitted with a mast support pole it makes it 45 feet (15 metre) tall.
How do you bring a lattice tower home? You put it on the roof of your car!! As it is a post mount and not a plate mount tower I managed to fit the base post, sleeve and rotator cage inside the car and the rest on the two roof bars. A nice gentle 100 mile drive back and it was home.
Installing a tower is easy..... it just means digging a hole and filling it with concrete... Not quite!
First I had to decide where it was going to go. The layout of my garden made that easy. I have a long and fairly narrow garden so the far end was the perfect location for it. I could then use it to support a wire antenna as well as beams so it needed to be as far from the house as possible.
Digging a hole isn't easy. The first foot down was easy. After that my garden is clay soil but not ordinary clay. It is more like a gypsum, greay and rocklike when dry and sticky when wet. I took to digging in stages and it went well, eventually getting to the required 3 foot cube. I actually made the hole slightly bigger to accommodate a bigger tower should one arive at a later date.
I then made up a rebar cage to give extra strength to the concrete form, making three square loops and tying them to four vertical bars. The vertical bars are actually embedded into the clay at the bottom of the hole and also tied to horizontal bars embedded into the surrounding clay. In the middle of the cage went the sleeve itself. The sleve was not an original item but one that had been made from heavy duty steel angle, welded on the two edges. A standard sleve is only made from 3mm plate or box section steel, this angle has a thickness of 10mm!! There were also extra bits of rebar welded to the outside to add to the rigidity in the concrete.
Finally it came to the concrete. I ordered 900kg of ballast and 250kg of cement. Now in true british style, deliveries are made at the front of the house and it is up to yourself to move it somewhere else. So I thought to myself.... I'll put it in a 'wheelie bin', roll it up the garden and then tip it out ready. The cement bags were easy..... I got the empty bin, made steps up the steps in the garden and filled the bin about half full. That was a bit heavy but hey, a bit of exercise never hurt.... oh yes it did... I got the bin to the top of the garden. tipped it on its side and as I was lifting it up to empty it my old back injury kicked in, woke up and said no. Like a fool, I ignored it and got a fair ammount of the ballast to the top end of the garden.
A week later, my back had got to the stage where I could walk reasonably well...
I was going to rent a mixer and have it turned mechanically but in the end a quick phone call to the resident club concrete expert Rob, M6YDX meant that there were two of us mixing the lot by hand in a wheelbarrow. So. all in all we mixed all of the ballast and 200kg of cement together and poured it round the sleeve and cage. A quick smoothing off and it was time to relax. All in, 5 hours to mix and pour over 1000kg of concrete.
A week later it was ready to slide the post into the sleeve. Along came Rob again and we greased the post thoroughly before dropping it into the sleeve. Once that was in place we carried the tower to the post and lifted it into position. Once the bar was in place and the split pin in place it was time to cable up the luffing winch. The cable was released from the winch drum and attached to the base of the tower. As the tension was taken up on the winch more grease was applied to the cable. Before raising the tower vertically the rotator cage was bolted to the the top of the mast, complete with rotator and antenna pole. All of the cable showing was greased some more and the tower was raised vertically. It was at this point both myself and Rob were puzzled. It looked like it was leaning over and not vertical. We walked around it, we checked that it was located in the sleeve properly, we checked the safety pin at the base... still it looked wrong. Out with the measure and the spirit level. It was spot on. It only looked out of alignment because we were on the slope of the garden and the fence panels actually slope. It was all an illusion..
We then greased the cable of the vertical winch as we wound the cables up and down and luffed the tower ready to take the antenna.
For details of the antenna follow this link.