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metal fence vs wood fence around AM towers

A

andydallas

Ok, I am not an engineer, so forgive my lack of knowledge.

I have had AM towers with chain link type fencinig around them before, but now i have someone saying you can't have that around an AM tower,,,,I'm sure wood is better, but is it that important to replace a chain link fence with wood?

Thanks for your help!

andy
 
"It Depends" If you are talking about a single tower, kilowatt station, I don't see a problem. Of course the fence should be built far enough out to meet public RF exposure limits (keeping people far enough away). The fence should be grounded at periodic intervals (ground rod driven into the ground, #4 wire clamped to posts), but shouldn't be a problem.

Higher powered stations probably should consider non-metalic options. There are ( somewhat expensive but durable) plastic materials that look like wood which may be more durable. Of course, any fence must be maintained.
 
Simply put, no, you can use chain link. If you have a directional AM, you need to be careful to not disturb your pattern after replacing it. That means check your monitor points before and after the fence gets replaced. Just do document stuff. On a 50kw, we had the fence grounded to the chain link every so many feed to keep it from singing and creating noise (RF). That would be a good idea.
 
We used 6' high chain link with a 1' barbed wire riser at the top around each tower of a 4 tower, 5kW, DA. The fence was there for years before I ever saw it and it's still there 30 years later. Never had a problem. Was sure fun to poke 4' flourescent tubes through the mesh and watch them light up, though! The reason this works is because the fence is too short to be electrically significant at AM frequencies. As long as the fence is bonded to the ground, it's no problem. Chain link fences tend to last longer than wood.
 
For some 25 years I maintained 6' high wood fences that circled each of four towers 40 feet out. A real pain in the a## to maintain even though they were redwood! Several times they gave trespassers a place to hide.

Chain link replaced them when three tower were taken down and five new ones went up. 14 years and no problems. The chain link and metal posts are grounded. The bonding between copper and the fencing shows no deterioration again after 14 years.

This on a 50 kw DA.
 
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also keep in mind that many stations have been fined for fence repair issues

Wooden fences to me seem like a potential for issues with the FCC as they must be watched for deterioration and parts replaced more regularly. I'd rather go with chain link because history of NALs have proven any defect in your fence around the tower that lets some little bastard in will immediately run their register with your check to the treasury lockbox.
 
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