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