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A Dolphin We Did Not Want to See

On May 15, 2015, Typhoon Dolphin made its unwelcome and widely reported visit to Guam, and KTWR lost power for three days and mangled an antenna.

KTWR is a powerful shortwave station on Guam, a great island for snorkeling and diving. Much of the island�s reputation is due to the clean water and abundant marine life. The spinner dolphins, in particular, are quite an attraction and are fun to watch as they surf the tour-boat wakes. Recently, however, we at KTWR were visited by a dolphin no one wanted to see.

KTWR is a facility of the global Christian media ministry TWR (also known as Trans World Radio) and maintains one 100 kW transmitter and two 250 kW units on the Pacific island. The transmitters are connected to six antennas via an antenna switch matrix, giving them the capability of beaming signals toward Australia and New Zealand, Northeast Asia, Southeast Asia, and South Asia.

On May 15, 2015, Typhoon Dolphin made its unwelcome and widely reported visit to Guam. Most of Guam lost power and some areas lost water service. Even telephone service was problematic in many areas. The utility crews worked hard to get things back to normal. KTWR did not have commercial power for three days, so we had to run our generators. The generator used for broadcast shifts consumes approximately 50 gallons of diesel an hour, so this was an expensive way to operate.

Dolphin managed to mangle one of our antennas (ANT1) during its visit. We were grateful that the antenna switch matrix allowed us to use other antennas so that nearly all the programs could continue to be aired. There was some minor damage to another antenna (ANT2A), but we could still use it.

ANT1 had to be rebuilt. It would take a week to lower the antenna, rebuild it and raise it back up. Safety was a concern, especially with all the volunteers we had. The antenna field is definitely a hard-hat area. It was really hard work, and the weather was quite hot and sticky.

KTWR�s staff is too small to rebuild an antenna relatively quickly. We contacted local churches to assemble crews of volunteers to come out and help with the repairs. We also had a former KTWR staff member, now stationed in Cary, N.C., fly here to help with the antenna rigging � especially the tower work.

It was encouraging and exciting to see so many people sacrifice time and energy to help with the difficult task of getting the antenna back up and running!

The first major task was to lower the broken antenna. Two men climbed the antenna towers to attach clamps to the top support cable of the antenna. They disconnected the broken antenna and reflector screen from the towers. Then the team used a system of cables and pulleys to slowly lower the antenna safely to the ground using a tractor, a road grader and a dual-spool winch.

Once the antenna reached the ground, our crew of volunteers worked to separate the screen from the antenna. The act of lowering everything at once, while the safer option, caused the screen and the antenna to get tangled. It took a few hours of careful puzzle-solving to separate the two.

After we separated the antenna and the reflector screen, our crew went to work checking the antenna dipoles and replacing any broken pieces (see photo above). Next, we patched the antenna dipoles back together and slowly raised the antenna row by row (right).

Now that the most pressing problems had been addressed, we focused on a longer-term solution. One of the causes for the damage to ANT1 was that the anchor for the support cable on the side of the antenna was ripped out of the ground. This anchor was hooked into a reinforced concrete block buried under approximately 6 feet of earth. After years of oxidation and corrosion, spots on the anchor became thinner and thinner until the anchor broke in half during the strong gusts of the typhoon. This break increased the stress on the other support cables and resulted in broken drop lines and the tangled web of metal and ceramic insulators evident in the first photo.

To prevent this from occurring on all the other anchors, we had poured a cylindrical concrete form to protect the anchor from corrosion and add additional stability and strength. However, this had not been done to the anchors on ANT1 before the typhoon.

To fix the anchors, we temporarily connected the side support cables to two vehicles to hold the antenna in place while we worked. Next, we dug holes to get to the buried concrete blocks and chipped away concrete to expose the steel rebar so we could attach the new anchors. Once we attached the anchors and set them at the proper angle and direction, we poured the concrete into cylindrical forms around the anchors.�

The next-to-last step was to backfill the holes we had dug and to wait two weeks for the new anchors to set. Finally, we reattached the side support cables to the new anchors and tensioned the cables to the proper load.

And with that, ANT1 was completely repaired. Thanks to lots of selfless volunteers, adaptable staff members and strategic planning, Dolphin�s visit disrupted less than an hour of TWR international broadcasts each night for a week and, ironically, resulted in upgraded facilities.