button to projects menu

I SAW BALL LIGHTNING !

In 1962 I was hired as a transmitter engineer with radio station WAEB in Allentown, Pa. The transmitter site was several miles remote from the studios in Allentown and the site covered a rather large, clear area to accommodate five tall towers. My job was to take meter readings to satisfy FCC requirements and keep the AM and FM transmitters on the air.

One evening, during a violent thunderstorm, I heard a very loud crack outside the transmitter building.  This sound was indicative of a close lightning strike. Instantly my eyes were drawn to the AM transmitter window, which exposed the tubes and final amplifier wiring. I was amazed because there, in the window, was a very bright, very white ball, about the size of a golf ball, lightly dancing on the high voltage buss attached to the top of one of the final tubes. The floating/slightly dancing motion reminded me of a Karaoke bouncing ball. There was a distinct "hissing" sound which accompanied the ball. The ball very slowly "walked" across the horizontal voltage buss feeding the right hand Machlett ML-357B tube and after approximately 4 seconds it instantly dropped or got sucked, 3 feet down into the high voltage power supply compartment at the bottom of the transmitter. There was a bright flash inside the power supply compartment and the transmitter went off the air. My first impressions were fascination with the generation of the ball itself and of how slowly it walked across the buss by the tubes, and how very quickly it dropped into the power supply cabinet and why did it take that route.

I didn't have much time to dwell on what I had just experienced, because my job was to put the transmitter back on the air. Since the transmitter was so very reliable, it was my first time to actually work on it and I could feel the pressure to fix an unknown problem.

To shorten the story, I removed the mercury vapor rectifiers and replaced them with two from a special rack that were previously pre-warmed (to get the mercury to the bottom of the tubes) and fortunately the transmitter came back up.  Days later, during maintenance, the removed tubes were found to be good.  I realized that I could have merely reset the breakers and the transmitter would have come back up.

It was one of the most interesting things I have ever seen and to this day I don't know how the ball was created. I was at the transmitter site many times during strong thunderstorms and why it happened this particular night, I can not provide an explanation.

Below is a cropped photo from the old WPIC transmitter in Sharon, PA, which is an exact duplicate of the old WAEB transmitter.  Original photo made by Charles Ring W3NU.


 

73,

Ken W2DTC

button to projects menu       button to send ken email