Tower Install – Day 7 “Aluminium Overcast”

Today was a long, tiring, but very productive day. It started out with a mad dash to the local equipment rental place in Pleasant Hill to return the impact driver (see Day 6) before they charged me for a second day. Then a quick stop at a bagel place to get breakfast before heading home.

The first order of business was to do the final prep of the TH-7DX yagi before sending it up to the top of the tower. This mostly consisted of tightening all of the hardware again, attaching the coax pigtail to the balun, and riveting one element that wouldn’t remain in place no matter how tight I tightened the hose clamp.

TH7DX TH-7DX Completed and Ready to Go Up

Steve then climbed the tower and attached a steel cable about half way up the mast. Steve attached the other end of the cable to the bumper of his truck parked on the other side of the garages and tightened it with a come-along. He attached two slings to the yagi on opposite sides of the mast clamp and attached the sling to a pulley. The pulley went onto the steel cable and was attached to a rope to pull the antenna up the cable. This technique is called a tram line and is a common way to get large yagis to the top of a tower.

TramLine Going Up the Tram Line

Steve waited at the top of the tower while Steve’s assistant and myself pulled on the rope attached to the pulley, which pulled the antenna up the cable towards the tower.

GettingThere Getting Close

Once the antenna was at the top of the tower, Steve grabbed it, wrestled it to the mast, and attached the mast clamp and securely bolted it to the tower. Once that was done, he attached the truss (used to reduce sag in the boom) and connected the coax and rotator control cables. While coming back down the tower, Steve fastened the coax and control cable to a tower leg. Once down, all that was left was to test the rotator to see if the antenna would rotate (it did), connect the antenna analyzer and verify the tuning of the antenna.

An antenna tuner is the best thing since sliced bread to a ham, because it’s a small, handheld device that lets you check an antenna’s SWR without a transmitter. It works by generating a low power signal (milliwatts) and analyzing the reflected power. Since the power is so low, it can even work outside the ham bands, useful if your antenna is resonating well outside one of the ham bands. The analyzer revealed that the tuning was spot on — close to 1:1 100 kHz up from the bottom edges of 20, 15, and 10 meters.

After cleaning up and gathering all his tools, Steve took his leave for the last time. It was a great pleasure to work with Steve throughout this project. His professionalism and skill made this project go smoothly.

A big yagi on a tower is a beautiful sight to any ham. I’m sure drivers on the local highway (about 1-1/2 miles from my QTH) will notice it.

Beautiful What a Sight!

The next step was getting coax and control cable to the shack. Last weekend I installed 160 feet of 2″ PVC conduit from the tower site to the wall outside the shack. This is mainly to prevent the wide variety of critters we share the land with from chewing through the cables. The first step in the process was to get a rope through the conduit that would be used to pull the coax and control cable. This was done by tying a plastic grocery bag to a spool of twine and shoving it into one end of the conduit. I then used a shop vac at the other end of the conduit to suck the bag and attached line through. The total transit time of the bag and line was about three seconds from end to end. I then used the twine to pull a larger 1/2″ poly line through the conduit. This larger line was needed to provide the strength needed to pull the cables themselves.

After attaching the coax, rotator control cable, and another piece of twine (to use in the future if any more cables needed to be pulled through the conduit) to the pull rope, I went to the other end of the conduit and pulled while Julie feed the cable bundle into the conduit on her end. Five minutes of pulling later, the cables emerged at my end. Piece of cake..

Cables W6JLG Feeding Cables into Conduit

Then it was just a matter of installing connectors, lightning arrestors, and plugging everything together. I finished all of the outside work this evening (with the aid of a clamp-on light), with the exception of drilling a hole in the wall of the shack and installing a piece of 2″ conduit to route the cables inside. That’ll have to wait until tomorrow as I’m zonked.

Then comes the real fun part — connecting the coax to the rig and firing it up. After 32 years of compromise antennas (ground-mounted verticals and low wire dipoles), this is an experience I’m really looking forward to. I hope the bands cooperate.


Leave a Reply