The other tracker "fire"

By Gene McManus

This occurred sometime in early 1962, when the tracker had been online for only a few months. We were in the TRAM (Tracking Radar Automatic Monitoring) room, doing absolutely nothing, and wishing for some excitement. Well, we got some, alright.

The TRAM console suddenly went from all green to a bunch of yellow, and alarm bells going off. Most of the yellow lights were transmitter lights. After some scrambling around, talking to the transmitter guys, somebody finally went up into the radome for a look. What they saw resembled a huge thunderstorm - right in the antenna`s feed horn. Fire arcing all over the place. We shut down the transmitters, and began both a diagnostic for the cause of the problem, and a damage assessment.

The damage wasn`t limited to the feed horn, which had large burns in the silver plating inside. The connectors in the rigid coax, upon which the feed horn was mounted was also badly burned, and a considerable amount of waveguide was damaged as well. The feedhorn couldn`t be repaired, and a call was made back to Moorestown, NJ for guidance. One of the feedhorns being readied for the RAF Fylingdales site (Site 3) was prepared to be shipped to Thule.

We at J-Site erected scaffolding the reached from the floor to the feedhorn - some 45 feet high, and began the task of unbolting it - at least a zillion bolts it seemed. After the feedhorn was loosened, and removed, the antenna was pointed straight up to facilitate removing the four rigid coax center conductors (3" aluminum tubing). This is where I got over my fear of heights, having to work out on the backside curve of the antenna, about sixty feet off the floor, with a double strap safety belt holding me up while I unbolted the 90 degree corner of the coax to get to the center conductors. Doing this silliness was like taking a drug. For a while, I`d find any excuse to climb the antenna. There were many trips up and down before the antenna was reassembled. Seems like they had to bring the feed horn in thru the side of the radome, removing several pieces to pass the unit thru - can`t really remember any more, though.

The cause of the problem was found to be a crack in the separator in a water-cooled dummy load, which allowed coolant to run into the waveguide.

We were down for over a week getting this back in shape. This was the equivalent of several years worth of scheduled P.M. downtime, and Colorado Springs was very nervous about the excess downtime. (I hope nobody told "Ivan").

A memorable scene is that of working on the feedhorn on top of the scaffolding, with engineers in yellow hard hats lined up around the radome floor watching. Periodically, someone (no names here) would "accidentally" kick a bolt or two off the scaffold, and we`d laugh watching the engineers scatter.