Tower Install – Day 6 “Erection”

After the concrete base had enough time to cure to the designed strength, the next step was to call in the crane and lift it into place on the base. We used a 95′ boom crane, and it barely make it up the hill, which is not for the faint of heart (or QRPers). We had to do some quick pruning to remove some overhanging branches that were blocking the driveway.

Pruning Pruning

Once the crane was in place, the operator lowered his outriggers (to give the crane greater stability) and had me sign a waiver in case the crane cracked the driveway. Steve connected two steel cables to the top of the tower and the driver started to lift.

ReadyToLift Ready to Lift

To the unpracticed eye, it looked like there was no way to lift the tower and clear all of the obstacles, but the crane operator made it look easy. He had the tower vertical and lifted over the garages and hanging over the tower base in less than a minute. Steve guided the tower down to the base where we connected the base to the first section of the tower using 1/2″ bolts and steel plates.

Touchdown Houston, Tranquility Base Here, the Eagle Has Landed

The next photo shows the overall view from the front of the house. 3900′ Mt. Diablo is the peak in the background on the right. In the right foreground is Mt. Wanda, named after Wanda Muir, the oldest daughter of John Muir, which is part of the John Muir National Historic Site. To the left of Mt. Wanda is Eastbay Regional Park land.

OverallView Overall View

Steve climbed the tower to detach the cables connecting it to the crane. I’m sure the view up there must be great!

DetachinCrane Detaching the Cables

The next step was the raising of the mast and inserting it through the thrust bearing at the top of the tower and connecting it to the AlfaSpid rotator sitting on the rotator bracket 8′ feet below the top of the tower. Steve rigged a sling around the mast, which the crane lifted while he waited at the top of the tower to receive it.

MastComingOver Mast on its Way

Once Steve wrestled the mast through the thrust bearing, which seemed like threading a needle to those of us on the ground, the rest was easy. With everything securely fastened, Steve removed the sling from the mast and climbed back down.

OverallViewMast Mischief Managed

By this point, the wind started to pick up and we decided to leave the raising of the TH-7DX antenna to tomorrow. I spent the rest of the evening assembling the major components of the antenna, which I had pre-built in the garage over the last month. Final assembly had to be done outside as the garage door wasn’t big enough to get it out. I also built the coax rotator loop and the section that comes down the tower. The DX Engineering cable prep tool certainly made this task easier, as did the crimp on connectors.

The last work done today was driving the ground rods. There are three 8′ ground rods at the base of the tower, one for each leg. There’s another rod right outside the shack where the coax and control cables enter the house. Although Northern California has one of the lowest frequencies of thunderstorms in the entire country, it’s still prudent to plan for the unexpected. When I’ve driven ground rods in the past, I’ve done it with a sledge hammer standing on a ladder. It’s hard work and the end of the rod usually ends up mushroomed. The solution is a rotary impact hammer with a ground rod bit, like the one shown below. This baby drives an 8′ ground rod home in about ten seconds with almost no effort and leaves the end nice and round.

Hammer Impact Hammer

Next update will be after we raise the antenna.

Leave a Reply