As the CE of a TV station in South Florida we had to contend with lightning during about 4 to 6 months a year (spring & fall thunderstorm seasons) in the highest lightning strike area of North America. We did not ever shut down but did go to generator power during lightning within 25 miles; as seen on the radar display with lightning strikes superimposed.
We had a 1,049' main tower, 2-500' microwave receive towers and a 185' tower at the studio not to mention 2 bureaus with antennas on the 3rd floors. The towers had massive ring ground systems. The rings varied from 20' diameter to 30' diameter. each ring had 10' & 20' alternating 100% copper rods cad welded to a 4-0 bare copper wire. The ring was attached to the tower leg's 20' ground rod with 2 or 3 radials per leg. The tower ground rod was set in the foundation to be next to the leg and connected to the leg with the least angle. (remember a right angle from the leg is a 1/4 turn inductor!). The guyed towers also had a ring ground system around the anchor. All RF, video, audio & data signals going to the tower at the site were protected with commercial protectors except the studio tower which was replaced with fiber to carry those signals. We probably took between 6 and 10 direct hits on a good year and many many more on a bad year. The new studio & one of the bureaus had a ground system constructed to reduce lightning damage. The building had a perimeter ground system with a single point power & phone and the exit panel for RF, video, audio, data and dc control. The ground systems was 4-0 copper with ground rods about 10' apart. We did find that our damage was reduced but not eliminated. We never went off the air; but we did have periods where we were using redundant (back-up) equipment for a while until the main equipment could be repaired. Our largest reduction in damage occurred once we deployed dissipation arrays! These reduce the space charge in the immediate area in hopes the lightning choses another location (competitor's tower). My experience with towers, satellite antennas & ENG microwave antennas on 50' masts on trucks is that the dissipation array is #1 then a ground system followed with surge protectors. I would not chose one but all three. We had a saying at work about lightning protection after repairing extensive damage after a bad hit - Lightning protection is akin to elephant repellant - just because you don't see an elephant does not indicate the repellent actually works. I spent over 30 years in South Florida and would never come close to guaranteeing that we had finally done everything to eliminate the risk! Not sure at what point you should stop spending money on lightning protection for a hobby should go. For me at my new QTH it will probably be a few surge protectors, grounding each mast & tiny tower and a simple ground improvement to the house. 73 George AI4VZ -----Original Message----- From: Rich - K1HTV Subject: Re: [Elecraft] Unhook *ALL* connections before Lightning storm ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
