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Thursday, April 12, 2012

Repairs atop 1,100-foot-tall tower complicate WBZ’s return to the air

BOSTON – Imagine doing tests and repair work on a dinner-plate-sized component weighing perhaps 50 pounds. Now imagine doing it while you’re attached to a slightly swaying, wind-blown tower, and you’re 1,100 feet above the ground.

“Tall-tower work is a very specialized field, requiring a lot of expertise and knowledge. Plus, those people are crazy,” said Robert Yankowitz, chief engineer for WBZ-TV in Boston, in an interview Wednesday.

WBZ knows all about the need for tall-tower work these days. Since Sunday, the CBS affiliate has been trying to fix its main antenna, which sits on a 100-foot pole that’s on top of a 1,100-foot antenna in Needham, Mass.

Over-the-air signals for Channel 4 went out Sunday afternoon, right at the end of the Masters golf tournament, and returned Tuesday night only because the station is using Channel 2’s antenna. Channel 2 has switched to a less-powerful backup antenna, Yankowitz said.

Channel 38 and Channel 5, which use antennas atop the tower, also are affected.

People who watch over cable TV didn’t notice anything because cable systems grab the signal before it gets to the tower. Some customers of satellite television were affected, because they use the over-the-air signal.

It’s not entirely clear what the problem is, Yankowitz said, although it’s probably an electrical component that connects the antenna pole to the tower.

In other words, it’s an indefinite complication more than one-fifth of a mile off the ground.

“It’s not like pulling the starter out of the car engine to check it,” said Yankowitz.

As Yankowitz explained it, three transmission lines run up the tower, which is owned by a separate company. They are in 20-foot-long, 8.4-inch-diameter copper pipes, which contain an inner copper pipe, 3 inches in diameter. The sections are joined by bolted flanges.

As he wrote in a posting on the technical discussion group AVSforum:

“Connecting, moving, and mounting these lines is heavy, exacting work. Now think about doing it when the pipe is vertical and you are balanced on a tower 1,100 feet in the air. It’s slow. Real slow.

“Working on the antenna is especially difficult, as the panels that surround the problematic part must be removed and the part tested and brought to the ground, all while hanging from rigging almost a quarter of a mile up,”

“We do have an elevator on the tower, but it only goes up to the 850-foot level. At that point, the tower reduces in width from 12 feet across to 7 feet, so tower workers have to climb the top 250 feet,” he wrote.

Free, over-the-air signals have become a minor part of television. WBZ said in a statement that the signals are used by only 7 percent of its audience.

Still, said Yankowitz, the company takes the problem seriously.

“Every transmitter engineer and his immediate superior (and I) reported to the site Easter Sunday evening as quickly as they could, and didn’t leave until late that night. Yesterday I was at the site from 6:30 a.m. until 11 p.m., and then back again early this morning,” he noted on the forum. “This was a very big deal to every station involved.”

And by the way, he added in the phone interview, tall-tower workers aren’t really crazy.

“They’re actually very calm. They have to be. You only get to make one mistake up there.”

David Brooks can be reached at 594-6531 or dbrooks@nashuatelegraph.com.