This is the War Stories Section of
The Broadcast Archive
Maintained by:
Barry Mishkind - The Eclectic Engineer
WHEN ANTENNAS ATTACK!
by Tom Bosscher
I've heard of transmitter fires, but how many
folks have been attacked by their antennas ? Pull
up a chair and let grandpa tell you this story.
It was around 1977, or so. The station, WLAV-FM. Grandpa
Tom had installed a new 400 foot tower, with a brand new McMartin BF-25
transmitter and a brand new 5 bay antenna in them thar' fancy white radomes.
Now keep in mind that the owner ordered the equipment
first, then hired the engineer. Grandpa Tom would prefer other equipment. (In
fact, I begged to get a Collins FM transmitter.)
Everything was fine for a few months. Then I get a call
from the friendly neighbor that the top tower light is all white, no red. Great,
someone shot out the lens. Back in those days, the FCC actually mattered so I
drove out to the site. From 3 miles away I see the white light from the tower.
But it's on all the time ! Great Guns, the flasher shorted out ! I get to the
bottom of the road leading to the tower, and walk to the gate to unlock it, and
then it struck me. I CAN see a flashing red globe, maybe 20 feet above the white
spot!
Getting to the building, it was pretty obvious that I had
one bay arcing.
The transmitter shows 1.2 VSWR, up from the dead flat. I
turned the transmitter off, then back on ( thank you for the stories about the
500 kW WLW transmitter that did that). The arc stopped. VSWR was normal. I suick
around and then left.
Next day, the transmitter dumps, and stays down. I went out
to the site, and found the VSWR lamp tripped. I reset it, and fired up the
transmitter. I figure, I'm going to sit around for a bit and watch this. So I
started some needed house cleaning. 30 minutes later, as I was sweeping dust out
the door, I heard the transmitter cycle on and off. A quick glance across the
room showed the VSWR lamp lit up. The last recycle holds the transmitter on the
air.
As I started walking out the door. I heard a whining,
shrieking sound. Suddenly, ten feet from me a smoking piece of brass and copper
lands. I glanced up, and I saw not one, but two white radomes ON FIRE floating
down! I was under attack from my antenna! I dove back into the "thank God
it's concrete" building, and waited. Two bays worth of copper and brass and
two burned up radomes were sitting just a few feet from my truck. I waited. I
waited some more. I waited even longer. With my eyes up towards heaven, finally
I walked out the building.
I ordered out an exact replacement antenna, except that I
specified no radomes. When the replacement arrived, its helix spacing was twice
that of the burned up antenna. I'm convinced that I was shipped a low power
antenna, and was running my full 21 kW TPO into it. Happily, the replacement
antenna held up.
And somewhere I have some Polaroids of the two antennas
side by side.
Tom, shouldn't this be worth 100 points in the SBE
real-life stories special achievement award?, Bosscher
Copyright 2000. Reproduction without permission is not only
disrespectful, it is illegal.
| 
