The broadcast engineering merit badge idea we discussed in July is generating a lot of positive responses, as you will see in future columns.
A story from retired chief engineer Ron Joseph gives insight into what broadcast engineers may endure. This one involves a white and orange lightning rod.
It was a dark and dreary September night in Lynchburg, Va., in the 1970s. Thunderstorms had been predicted all day; now the lightning was popping and the thunder rolling and booming.
Photo by Dan Slentz Several minutes after the last flash, Ron’s telephone rang. It was the station, off the air. Ron headed to the site, arranging for an associate to meet him for safety’s sake.
As he drove to the site, he speculated about what may have happened and what might be necessary to get the station back up. The site sat on a mostly flat piece of land, with a slight downhill to the transmitter building and fenced-in tower. As he crested the rise and stared at his unlit stick outlined in the nighttime sky, he thought power failure must be the culprit.
Ron entered the building, expecting silence, but was greeted by a strong hissing sound, and it wasn’t a snake. The hiss was pressurized dry nitrogen escaping from the FM antenna coax.
The coax and the AM antenna feed both exited the building and ran on supports about 30 inches above the ground. Lightning, seeking a path to earth, had followed the coax down and made its way to ground by exiting and leaving a nickel-sized hole in the corrugated shield. With this discovery, Ron suspected it would be a long night. In fact, fixing the problems would take the better part of a month — and raise the hair on the back of his neck several times.
First, he had to try to get the tower lights back into operation.
Ron instructed the operator/announcer on duty at the station to inform the airport tower that all of the tower lights were out due to the storm.
Then he replaced the tower light cartridge fuses and turned the switch on. Pop! The fuses blew out, so he went to the tower base for a continuity check on the other side of the lighting choke and found a heart-dropping confirmation: The side marker light and top-of-tower beacon wiring all indicated a short. Furthermore, the wiring also shorted to the angle frame of the tower itself!
How much more damage could one lightning strike cause?
By that time one of his contract engineers had arrived, with a propane torch and some large-diameter solder. While his associate cleaned and closed the hole in the FM feed line, Ron attempted to fire up the FM transmitter. The errant lightning had managed to do damage even here; it had shorted out power supply diodes that took an hour to replace. Thankfully, this was the extent of the damage to the FM transmitter.
Even though the AM transmitter had not been on during the storm, Ron wanted to be sure it was okay for the next morning. It wouldn’t come on. His investigation showed that the many top-hat diodes comprising the LV power supply had shorted. How did lightning get in there?
Fortunately, Ron had purchased spare plug-in legs for this bridge power supply unit, so it was quick work to swap out the diode bridge. He tried the AM again; it worked and made full power.
As strange luck would have it, all of that lightning jumping around in those transmitter cabinets had not found its way into the equipment racks; hence the audio processing remained operational. Telco audio circuits from the studios to the transmitters also were undamaged.
The hole having been repaired in the FM feed line, Ron opened the valve on the dry nitrogen tank and pressurized the line, having no idea if there were additional holes along the “run” up the tower. As he and his associate cleaned up and rebuilt the blown diode stacks, they closed the valve and kept check on the pressure gauge. Over a couple of hours, it did not move even a half division.
The next morning, you would never have known that a storm had blown through. A bright, sunny, cool day greeted Ron’s trusty tower contractor, a one-man operation like many at the time; he headed up for an inspection.
Returning to the ground a couple of hours later, he reported seeing a couple of places where the lighting cable looked burned and “welded” to the tower. He had pulled it away from the tower in one place and it had come in half, so the lighting power cable would have to be replaced. Even though the tower was equipped with a rod to take lightning hits and protect the beacon, lightning had completely destroyed the beacon and cracked all of its clear glass, blown the metal top off and smashed the top red filter.
For reasons of both aviation safety and liability, Ron opted first to have the contractor replace the lighting wiring and get the side marker lights working.
The day to install the new beacon dawned sunny, with just a slight breeze. The contractor had the beacon ready to hoist. Pulling it up seemed to take forever. Eventually, the new beacon reached the top; but now the climber was shouting something from his perch. It was difficult to make out words coming from 320 feet in the air. (It later occurred to Ron that they should have had two-way radios.)
Ron saw the climber pointing and waving and shouting. After about a half hour of this pantomime, Ron made out that the climber was pointing to a cloud that Ron could not see from the ground. The climber was worried about a storm coming.
Now he stopped waving and shouted down “I’m scared!” The hair on the back of Ron’s neck rose up. Ron shouted back: “You want to come down?” The climber shouted back, “I can’t. I’m scared!”
What do you do when you have a frightened climber atop a big lightning rod, a storm approaching, a beacon that has begun to swing in the breeze and nobody else around to grab on to it? You might call the fire and rescue department, but that didn’t occur to Ron at the time; and now the tower guy was shouting: “Get me some help!”
Ron remembered that another tower contractor had stopped by the station looking for business a couple of months earlier, and had said if Ron ever found themselves in need of a new tower company, he would like to be considered. Ron called and was relieved when the contractor answered the telephone.
“Calm down,” the man told him. “He’s frozen from fear on that tower. He probably has his safety belt attached and out of fear he’s holding on tight. There’s no chance he will turn loose. You will be able to find his finger prints in the metal. I’ll come get him off the tower, if you want.”
The second contractor came, checked the tied-off rope, declared it fine and headed up the tower. When he reached the top, the new man began assuring the first that he would get him down safely.
The next day, the first tower climber headed back up the tower to install the new beacon.
About half way up he paused for an unusually long time. From the side of the tower between the level of the first and second level obstruction lights, he called out: “I see clouds.” He stayed there for a few minutes and then headed back down, apologized, saying he was afraid the same fear might overcome him again and he just couldn’t do it.
Sadly, as Ron understands it, the contractor never climbed again.
In the ensuing years, Ron left the radio broadcast business and has since retired from a second career. But his first love, radio, remains with him today in retirement. A broadcast engineer never knows what curve Mother Nature will throw.
Among the lessons in the above, for all troubleshooting situations: Think clearly. Don’t jump to conclusions. Handle problems one at a time. And buy some two-way radios.
Find many useful tips in our archive. Click on Workbench under the Columns tab at radioworld.com.
Contribute to Workbench. You’ll help your fellow engineers and qualify for SBE recertification credit. Send Workbench tips to email@example.com. Fax to (603) 472-4944.
Author John Bisset has spent 46 years in the broadcasting industry and is still learning. He handles West Coast sales for the Telos Alliance. He is SBE certified and is a past recipient of the SBE’s Educator of the Year Award.