Winter 2003 Issue

Photo 2. Assembling the support for the dish.

Most of us take our hobby seriously. Some, like KL6M, take it to a serious extreme. There is something about “Build it and they will work you.” What can you expect, however, from the biggest state in the Union?

By Mike Melum,* KL6M

Obsessed! That’s what my wife calls me. It all started in early 1999 when I decided to put up four 12-element Yagis on 2 meters with a 160-watt brick just to make one or two QSOs with a couple of the “big guns” on 144-MHz EME. I only wanted to make one or two QSOs so I could say I worked EME.

After many hours of studying operating procedures and how to interpret Moon propagation data, the contacts came fairly easily. By that time I was so hooked that there was no escape. Two months later I had 16 ¥ 12-element Yagis on 432 MHz. This was mounted on a flimsy 10-foot TV-antenna-type tripod, using a light-duty Alliance HD-73 for azimuth and a U-100 for elevation. Very careful balancing of the array and good tie-downs for high winds yielded an antenna that stayed up for over a year, which brought in 57 QSOs on 432 EME (photo 1).

This was still not enough. I needed to delve deeper into the depths of EME. I had asked a friend who works for a local telecommunications company to let me know if he ever came across a surplus dish, maybe a 15 footer. A few weeks later I was invited to tour the company’s excess lot, where my friend said I could have my choice of a 16- or a 30-foot transportable dish on a trailer. There was no choice!

I got the 30-foot dish and trailer in September 1999, all 17,000 pounds of it. One note about safety: Don’t let your enthusiasm get the best of you and do anything stupid! I tried to pull 17,000 pounds of antenna and trailer with my half-ton Suburban. I got almost all the way home before the trailer tried to outrun my truck on a small hill. I jack-knifed and had the scare of my life. Somehow I managed to survive without tipping over (thank heaven there was no traffic), but the Suburban received some permanent scars. I was very lucky. That little mishap brought me back down to earth, and I spent the rest of my time on the project aware that this was no ordinary monster I was playing with.

The Planning Stages
I spent all winter engineering a way to mount and rotate the dish, and on tower designs, az/el positioning designs, feed designs, and many other things. The transportable dish was not made to move freely. It was designed to point at one satellite for special applications of wide-band satellite communications. Consequently, all the azimuth and elevation positioning had to be fabricated. I might add that I had never undertaken anything quite like this before. I realized that I had to keep everything as simple as possible. I needed to re-use as much of the existing design and hardware as possible. I needed to retain the heavy steel structure if I planned to put together a system that would survive the extreme environment of Alaska. This meant I needed to support and rotate a mass of steel and aluminum weighing 7000–8000 pounds.

I immediately started searching for surplus materials for the project. The best find of all was in a junk yard behind a crane repair shop. I found a 30-inch, 300-pound bearing that had been removed from a crane because of failure to meet tolerance. Two cases of beer later, it was in the back of my truck. This bearing was the key to pulling off this whole project.

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