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Author Topic: Grounding Rod.  (Read 1174 times)
W3LK
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Posts: 5639




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« Reply #15 on: February 26, 2009, 01:55:18 PM »

<< 1) A DIRECT lightning hit can and will take out everything it directly hits. Tower, Antenna, Mast. >>

HOGWASH!

Cell towers, commercial radio towers, TV stations, law enforcement and fire systems all take direct hits and keep on ticking. Nothing is destroyed.

73,

Lon - W3LK
Naugatuck, Connecticut
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
KB9CRY
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« Reply #16 on: February 26, 2009, 01:59:37 PM »

Mine too.  My three towers and extensive antenna systems and equipment take hits all the time.  I never disconnect and nothing is ever damaged.  And my keyboard has capital letters too.
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W5WSS
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Posts: 1782




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« Reply #17 on: February 26, 2009, 02:47:43 PM »

There is still on going debate about the lightning arrester rods above the antennas at commercial or ham installations....suffice to say there are two main issues 1)dc earthing or grounding 2)common mode currents deterents via a REAL RF ground. I suggested recently that a lightning rod be installed above the antennas then connected directly via a wide diameter strip or wire like 2" or greater(for the purpose of minimising the inductance(Note* the tower may provide less inductance because of surface area it depends) down to a Stainless Steel rod or more that is at least 8' long or longer there are couplers available for deeper depth if one so designs demands. This system is self contained and NOT connected together with transceivers ect. This is the DC ground or earthing system at it's most basic form entire faraday systems can be designed to protect buildings etc...But there are limitations. The Real Rf ground can best be understood simply stated..No loops should be read between the two systems and best to use wide diameter copper strips for equipment bonding and same goes for a short wide diameter strip or radial copper wire to a dedicated earthing rod that again is Stainless steel. The copper clad steel rods will eventually deteriorate and the resistance will increase. anyway Do not connect the lightning system to the rf earthing system keep plenty of distance between the two. All The connections should be weatherproofed up at the top and bottom take a reading with the multi meter and remember it double check it occasionally. Do not install the lightning rods in the tower base concrete. Mobile installs frequently need common mode deterence...There is nothing wrong when mobile hill topping/rv etc. to drive one into the ground but most do not because you cant retrieve it afterward. 73 hope this helps some
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K9KJM
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Posts: 2415




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« Reply #18 on: February 26, 2009, 09:22:46 PM »

There is no "debate" on proper lightning protection among professionals who design systems for commercial use.
As already pointed out by CRY and others, Tall radio towers, Including my own, Repeaters, Broadcast, Cellular, etc all take DIRECT lightning hits with NO damage to equipment most every storm.

"Disconnecting" coax is like handling a stick of dynamite.  If you do decide to disconnect, DO somehow connect that coax to a good ground! To just leave it "lay" is dangerous.

I much prefer to just use a high quality coax switch that puts unused antennas to ground. Alpha Delta makes good ones for VHF.

For some good info on proper lightning protection:

http://members.cox.net/pc-usa/station/ground0.htm

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W5WSS
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Posts: 1782




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« Reply #19 on: February 27, 2009, 06:11:50 PM »

There is debate pertaining to lightning rods above where the rods are pointed or blunt and/or have many points. The debate centers around whether or not the rods offer an umbrella of protection, a cone shaped dome as related to trickling down the potentials of Static electricity as preventative. Meaning that the trickling will divert a stroke before it gets large enough to use air as it's dialectric medium.(ground to air or vice versa) But ehhh I would recommend installing a lightning rod that is pointed above the beams or whatever. So even though there is no debate in my opinion..there is amongst many (those whom do the standarding)just not you and I.
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W5WSS
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« Reply #20 on: February 27, 2009, 06:18:35 PM »

K9kjy Nice station great work on the layout design functional I am certain 73
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KC5UUS
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Posts: 103




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« Reply #21 on: February 28, 2009, 09:06:23 AM »

well this will sound elementary elmers.. ha but i really havent figured out yet , how to ground my g5rv.
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W6RMK
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Posts: 669




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« Reply #22 on: March 01, 2009, 09:42:02 AM »

why 8 feet?
Because the electrical code requires 8 feet of rod in the soil (if the rod sticks up above the surface, one uses a 10 foot rod)

Nothing special about 8 feet though, from an electrical standpoint. It's not like 7.5 or 8.5 feet would be noticeably different.  6 feet is getting pretty short, though (and that's the next "standard" length for things like rods, pipes, lumber, etc.)

Bear in mind that a rods are for grounding your electrical system or your lightning dissipation system. They make a terrible RF ground.  And a rod's not legal as the sole electrode for an electrical system any more. Look for a Ufer ground (Concrete Encased Grounding Electrode in code-speak)

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KC5UUS
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Posts: 103




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« Reply #23 on: March 01, 2009, 10:33:43 AM »

ok guess im just not quiet getting it. i have decided against a ground for lightening. because i will unhook everything after each use.
 now how do i rf ground the rig and or antenna? its a g5rv .. thank you.
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K9KJM
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Posts: 2415




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« Reply #24 on: March 01, 2009, 11:53:06 AM »

DID you read the link I provided about good lightning protection?Huh

http://members.cox.net/pc-usa/station/ground0.htm

IF you disconnect when not operating you would need to remove the coax FROM the building!  To be safe it should be taken outdoors far from the building. Leave it lay right under the antenna.

And the radio would need to be also disconnected from your power supply. Not connected to ANYTHING.
(If you take this route, I suppose you could have some kind of coax bulkhead connector where the coax enters the building so you could just "disconnect" it outdoors, And have some kind of plug on your power supply wires, Or pull the plug out of the wall on the power supply, To make it fast and easy)

Far more work than I want to do on a daily basis.
Not to mention dangerous if you are handling that coax when a storm is in the area.
I would much rather spend the effort ONCE and have a safe system I can operate during storms

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