FPS-27 Transmitter Explosion

contributed by Dave Roepke

I was a 30352 on the search RADAR (FPS-27) at the 786th from Sep. 71 to Sep 72.

Besides the weather, one memory that sticks in my mind was a mid shift surprise the RADAR thru at me once. This incident concerned the left side transmitter. As I recall we had just switched transmitters and it kicked off right away. After messing with it for awhile I opened the transmitter room door and as I recall, bypassed an interlock so I could see what was going on. I was supposed to be watching the thyratron to see if it turned blue (gas lighting up). My shift partner powered up and threw on the high voltage. There was a curious buzzing sound for about two seconds the on hell of an explosion!!!!. I jumped about ten feet away from the door and saw red hot bits of something laying on the floor and equipment racks. We put the other transmitter back on line and went into blast zone. Since neither of us wanted to deal with this little episode by ourselves, we called in the standby crew. The standby guys all lived in the limited housing at the site so they arrived in a hurry. As it turned out, a vacuum switch that was supposed to kick in for about 1/2 of a second to prevent high voltage spikes out of the transmitter at start-up welded itself closed and dumped the high voltage thru some 100 watt dropping resistors WAY too long. The resistors blew into about 500 pieces and took mounting clips with them. There wasn`t a piece bigger than a penny left which was remarkable since the resistor was the size a stick of dynamite ( oddly enough). Everyone agreed that they had never seen anything like it before.