RADIO REDUX—A SAFETY PRIMER FOR TRANSMITTER VISITORS
As the years wear on, I’m beginning to feel more and more like an old-timer. When I started out in this business, there was a lot of mentoring going on, with chief engineers passing on safe operating practices to their newer colleagues. Nowadays, we more often work alone, by necessity, which makes proper safety procedure even more important. Since transmitting tubes aren’t even discussed in school anymore, let’s start with a trip to a tube transmitter site:
BEFORE YOU SET OUT…
Does anyone know where you’re going, and when you should be checking back in? You should always alert someone, whether from work or home, that can come looking for you, if you have a nocturnal encounter with a moose, for instance!
WHEN YOU ARRIVE…
Take a quick glance around the site as you approach. I always like to count the guy wires on each tower to make sure that they’re all still connected. I got in the practice after arriving at a site and tripping over a downed guy wire. While you’re looking up there, you might as well check that all the beacon bulbs are working. And are there any signs of vandalism or forced entry at the building?
IN YOU GO…
We’ll assume that it’s a routine visit, and not an emergency call. Everything in its place? Transmitter visiting is such a sensory experience: does the blower sound normal, or are belts or bearings wearing? Do you smell anything you shouldn’t? Part of troubleshooting is developing your nasal skills, so that you can tell a burnt resistor from a transformer or coil. And if you ever smell a selenium rectifier that has gone to meet its maker, you will never forget the stench! How do the air filters look? And roughly what’s the inside temperature? Any signs that water has leaked in anywhere?
IF YOU MUST…
Open the transmitter door, well, let’s hope that you checked the interlock switches are working. Lock the transmitter off by opening circuit breakers and switches—make sure that the remote control cannot reenergize the transmitter. Of course you’ve removed all rings and jewellry. Make sure you use that shorting bar on anything you’re likely to be touching. If you don’t have a shorting bar, use a big screwdriver and touch those contacts to ground. When you’re reaching around inside, develop the habit of placing your other hand in your pants pocket. The tendency to use that hand to lean on the grounded cabinet should be avoided, as any voltage that you encounter would likely travel from hand to hand across your heart, making the experience much more lethal.
Connections all clean and tight? Insulators all clean and dry? Any sign of arcing, or leaks or bulges on capacitors? Belts in good shape? Bearings all lubed? Well let’s get out of here then! Close up the transmitter carefully, turn on those breakers and switches. Listen when you power up—often worn blowers will choose this time to complain. Did the air switch take a moment to close—if it didn’t, maybe it’s stuck closed—it’s not protecting your transmitter! Make a quick note in the maintenance log of what you’ve done.
That’s it for this month. On your way out, put your hand on the generator block to see if the block heater’s still warming it. Next trip, you’ll exercise that genset for sure!
Dan Roach works at S.W.Davis
Broadcast Technical Services Ltd., a contract engineering firm based in