Copyright ©1997 RF Specialties Group.
It was a chief engineer’s
worst nightmare come true.
I was a thousand miles from Barrow, Alaska, installing a remote studio when our general manager called and said that the AM transmitter site had burned down. Investigators eventually traced the probable origin of the fire to an unused outlet box in the AC distribution system.
It was the middle of October with the Arctic winter coming. We could expect darkness and temperatures with windchills approaching 75 degrees below zero. It was hardly a good time of year for a complete site rebuild. KBRW is the northernmost broadcast station on the North American continent. We knew we were facing a big job.
Of all the decisions that had to be made, the choice of a new transmitter was simple. Our Nautel 10 KW AM transmitter had given excellent service for five years. It had needed only one air filter cleaning. The boxes containing spare parts and a spare power module had never been opened.
John Schneider of RF Specialties of Washington in Seattle told us that Nautel had begun production of a new 12 kW AM transmitter, the XL12. He made a quick call to Nautel and we were in luck. Nautel had an XL12 in final test. The customer was willing to wait for another one.
Within a week, the transmitter was on a truck bound for Seattle. Then it was shipped air freight to Barrow. The compact dimensions of the transmitter simplified shipment. I know from 20 years’ experience just how large a traditional AM transmitter can be. The dimensions of the XL12 would also allow it to be placed in the small temporary building on site.
Getting the transmitter from the airport to the site and then into the building was the most difficult part of the installation. Sometimes it seems I have spent most of my life contorted into strange positions trying to get to a terminal strip. Not so with the Nautel XL12. Open the front door and all connection points are on a panel at eye level. For the utmost in reliability, we use dual remote control systems at our site. One path is via STL and TSL. The other is through an Optiphone telephone link. Therefore, there are many connections and a lot of cable. The XL12 has plenty of room for all of it.
Thirty-four
days after the fire, General Manager Don Rinker threw the circuit breaker and
we began testing. Among the reasons we chose the XL12 are the dual exciters.
In case of failure, the transmitter will automatically switch to the spare.
Both exciters tested well.
Our service area is more than 89,000 square miles. To cover this area we need to get as much power as possible into the sidebands. We use heavy audio processing and achieve a high level of average modulation.
We conducted an informal listening test by calling some of our listeners near Prudoe Bay, 200 miles from the AM site. They reported improved reception.
As of yet, I have been unable to conduct field strength measurements. Who wants to stand on the tundra with temperatures well below zero and the wind screaming in your face? Field strength measurement is definitely a summer-time project north of the Arctic Circle.
Thirty-seven days after the fire I noted in the transmitter log, “service restored and all systems normal.” But, as with all new models of electronic equipment, there were a few teething problems.
The B+ voltage protection circuits showed a high voltage and shut the transmitter down. The voltage was okay; the problem was in the protection circuit. A coil in a relay failed and put us off the air. It was replaced with a coil from a locally procured relay.
This happened within the first few weeks of operation. Since then the XL12 has purred away happily 24 hours a day. It sounds great and is easy on the power bill. We expect that we will get the same sort of reliability with the XL12 that we did with our former Nautel.
(Editor’s note: This article was written in March of 1997, and appeared
in the April 30 issue of Radio World Newspaper. The installation described was
a temporary one, and plans were made for a permanent installation. In the summer
of 1997, KBRW ordered and received a second XL12, and plans to operate the two
transmitters as alternate mains. However, the harsh environmental conditions in
Barrow have dragged out this project. KBRW does not expect to complete construction
until the summer of 1998.)
Photos:
1. Transmitter building damage, taken one day after the October 16, 1996, fire.
2. Chuck Lakaytis shows off his new Nautel XL12, on the air just 36 days after
the fire.