Sights Unseen: MPBN’s Litchfield transmitting station

The squat brick building on top of a tree-covered hill in Litchfield doesn’t give any hint of the complex transfers happening inside.

Seven microwave radio transmitters and receivers inside the Roland A. Desjardins Technical Center gather a microwave signal — generally originating in either Portland or Bangor — and relay it to other tower sites over the entire state of Maine.

Litchfield, one of 15 sites maintained by the Maine Public Broadcasting Network, is a critical connection in MPBN’s complex network stretching from Kittery to Fort Kent.

“It’s a junction; like a major interstate crossroad. It (the signal) comes into one location and we send it out where it needs to go,” said Bob Mullane, transmission manager for the southern system at MPBN.

Roughly every 30 miles, from Kittery to Fort Kent, there is a tower site, taking the signal and leap-frogging it across the state of Maine.

“A microwave signal can only travel about 30 miles before it becomes so weak that we can’t decode it properly,” Mullane said.

On top of relaying the microwave signal to the next receiver, the Litchfield site is also a television transmission site for MPBN’s Channel 10.

“On top of the tower is a tall stick that weights several tons. That is the antenna to broadcast television,” explained Mullane.

During the day, Channel 10 offers children’s programming and educational shows. In the evening, Masterpiece Theater and news are among the programs that hit the airwaves.

: The Roland A. Desjardins Technical Center sits on a hilltop in Litchfield and is home to microwave radio receivers and transmitters, as well as a television broadcasting antenna for the Maine Public Broadcasting Network. “This site is one of the easier sites to get to,” said Bob Mullane, MPBN’s transmission manager for the southern system. “Some of them don’t have roads and we have to use an ATV or a snowmobile to get to them.”

: The convex dishes on the tower at MPBN’s Litchfield site send and receive microwave signals to other sites across the state of Maine. Also, because regulations make it hard to build new tower sites, other agencies and broadcast television stations rent space on the tower for their dishes and communication devices.

: “This is our maintenance area,” said Bob Mullane. “The field crews do everything from work on the generators to mow the lawns.”

: Bob Mullane, MPBN’s transmission manager for the southern system, shows how to test the signal strength of the microwaves received at the Litchfeild tower site.

: Back in the early 1980s, technicians lived at the various stations 24 hours a day, 7 days a week. From the late 1980s to mid 1990s all of the systems transitioned to remote monitoring. Now the tower sites have security systems to protect the expensive equipment and are physically checked at least once a month.

: “We have various ways we can see the television signal strength coming in,” said Bob Mullane while giving a tour of the MPBN Litchfield tower site.

: A complex filter attached to the television transmitter ensures that the signal sent out by MPBN stays within the designated frequency alloted to the station by the Federal Communications Commission.

: A bank of seven microwave radio transmitters and receivers at the Litchfield tower site leapfrog MPBN’s signal from Kittery to Fort Kent.

: “Honestly, the easiest and quickest way to see if there is a problem with the television broadcast is to turn on the television,” said Bob Mullane.