On 7/8/2013 10:45 AM, K8RI wrote:
On 7/8/2013 8:06 AM, Jim Thomson wrote:
Ok, I’ll bite. What do AM /FM /TV broadcast folks do or use for
lightning protection ??
Esp with real high towers involved in some cases. They don’t shut
things off and toss cables
out the window. And ditto with cell sites and microwave sites.
They are all left on 24-7-365.
IE: what do the big boys use ? Why not copy their procedures ?
They do nothing magical, but they carry the grounding system, and single
point ground to an extreme. IE: the transmitter "house is usually laid
out to take advantage of the SPG. I have over 600 feet of bare #2 run
in a star pattern from the towers and most everything goes point.
I was in a hurry and missed the point where I have 32 or 33 8' ground
rods CadWelded to that 600 feet of bare #2
All coax has the shield grounded at the top and bottom of the 100' tower
as wrll.
73
Roger (K8RI)
Unfortunately through the grounding panel at the entrance is on the
opposite side of the house from the power entrance.
So the commercial station would "probably" have several thousand feet of
grounding cable, duplicates/back ups for everything possible and a spare
tube on hand. They use "spark gap" devices on the coax which I've seen
as large as 4". Also, they have a rugged transmitter and no receivers.
As others have said, It's most likely well beyond cost effective for a
ham station so many of us really do as much as we can afford to emulate
the commercial installation.
Judt do remember it's not uncommon for them to get knocked off the air.
Then the delay is usually the time it takes maintenance to drive out
to the site, turn the breakers back on and let the transmitter(S) warm
up. Some have back up transmitters.
73
Roger (K8RI)
Jim VE7RF
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