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No More Calls, I Think We Have a Winner!!

 

Previous articles on Tower-pro dot net chronicle the installation of the first Dialight LED beacon in the Nashville Tennessee area and the subsequent history of that beacon. The first article, "LED Beacons, My experience Thusfar, Article 1" which appeared on Tower-pro dot net in December of 2002 and spoke of the characteristics of the beacon , its construction, the methods my crew used installing the beacon and the designed access for servicing the unit on the tower.

The second article, "Our First Dialight LED Beacon, 18 Months Later" appeared on Tower-pro dot net in June of 2003 and described our amazement at finding the unit virtually destroyed by lightning. The article described what I perceived as design flaws, which provided poor to non-existent lightning protection.

Now I hope I'm reporting the end of problems encountered in the original effort resulting from a complete design change in the Dialight LED Beacon.

The Story Continues

Upon discovering that the original Dialight beacon couldn't easily be repaired we decided to completely replace it. I could have gotten an exact replacement but I'd heard that Dialight had come up with a new design. I had my contact at Harris Broadcasting scrambling for a few days but finally he found what I wanted and shipped it overnight for free due to a couple of problems on their end. My crew was already on the tower when the beacon arrived at my shop, thirty miles distant from the tower. Not wanting to be surprised I removed the new unit from its well appointed shipping box and was astounded by the change in design.

With the new design the metallic top cover was gone, replaced by a "fish bowl" design of a clear acrylic lens. No metal to conduct lightning was an immediately evident plus.

Next I was aware that the beacon had far fewer individual LED's than its predecessor's 720. I'd been told that LED technology had changed and now this new unit had approximately half as many diodes producing the same amount of light.

A previous design problem provided poor electrical conduction between the metallic top cover and the tower. The top cover was attached by screws to a telescoping two part rod which was designed to allow easy access to the interior of the beacon for servicing. The second part of the two-part telescoping rod was then attached with screws to the base of the beacon. The base of the housing was then attached with screws to what can only be described as a piece of pipe about four inches in diameter which was subsequently attached with screws to the mounting plate. When the previous beacon received a big lightning strike these mechanical joints created a considerable impedance which allowed the strike to vaporize screws and pieces of alloy. The new beacon's base is made of a single piece of cast aluminum thus eliminating mechanical joints. One last thing to mention is the new beacon's weight. The old beacon weighed in at 84 pounds. The new unit weighs only 50 pounds.

The Beacon was extremely easy to install along with the ERI Spur lightning dissipators which we were prevented from installing originally. The only problems were caused by poor placement on the hoisting line, caused by me. We rigged the 1280 foot tower rather quickly with our 2600 foot 3/8 inch Stablebraid By Samson ropes and within 30 minutes had the entire load to the top of the tower. The beacon wired into the existing circuit with absolutely no problems and our guys descended with the end of the rope. Soon the combined ten bay ERI antenna was hot again and the radio stations were happy to get off the standby antennas. It was at this point my lead man realized he'd forgotten one of our good alloy blocks and had left it at the top of the tower.

An LED beacon at the top of a well protected and very hot tower pretty much insures we won't be in a position to retrieve the block any time soon. Perhaps some day an archeologist will discover it hanging there and wonder what manner of ancient man left it.

 

John Hettish
Middle Tennessee Two-way Inc
615-890-6685

 

 

 

 

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