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Author Topic: Where to connect my lightening arrestor  (Read 897 times)
WB1AAT
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« on: October 08, 2007, 12:03:36 PM »

I've just picked up a couple lightening arrestors to put in my feedline. They have SO239s in and out and a wire lug to attach the ground. But I'm not 100% sure what to connect that lug to. My primary concern is static discharges. I doubt anythibng I can "afford" to do with protect my radio from a direct strike.

I have a ground rod just outside the shack entracce (I know it has to be bonded) to which all my radios are grounded via an SPG. I also have a MFJ1704 antenna switch on some of the antennas that grounds unused antennas as well as having soem internal protection.

Shoudl I just connect the lugs to that same SPG that goes outside, do I run a separate wire to the ground rod for these arrestors, or do I need a separate rod for them?

I've read and been confused by the monstrous amount information on grounding and its not clear to me the way to go. It seems too complex for me and alos seems you can spoend a fortune protecting a $700 radio.

Mike WB1AAT
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KB9CRY
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« Reply #1 on: October 08, 2007, 12:29:58 PM »

Well, it's actually more than your radio that you're protecting.

That ground rod outside your shack IS your SPG.  Your shack equipment should be bonded to that.  Your arrestors should be installed outdoors right at the ground rod and bonded to that rod directly.  And, bond that rod to your service entrance ground rod.

Your tower grounds or your mast ground should also be bonded to this SPG ground rod.


Not all the complicated and not that expensive.

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N5YPJ
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« Reply #2 on: October 08, 2007, 09:03:56 PM »

"I doubt anythibng I can "afford" to do with protect my radio from a direct strike. "

One thing that you can do that will give you a good degree of protection and costs only 30 seconds of your time - disconnect your antenna from your rig when not operating.
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K9KJM
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« Reply #3 on: October 08, 2007, 11:21:29 PM »

About the best place for your "Single Point Ground Panel" (Where all lightning arrestors and coax switches are mounted to is at the point right where the coax enters the building.
Good quality lightning arrestors (Polyphaser, I.C.E. etc) are made to mount directly to the flat copper strap at that point, Just like your coax switch.
Flat copper strap is the best material to use, Get it from a home supply store (Copper roof flashing, Or an upscale roofer)
A coax switch that puts unused antennas to ground is MUCH safer than "disconnecting" your coax!  Think about it!  Lightning that has just jumped several miles through the air to your antenna will have NO problem jumping that final few feet to your grounded radio if you "disconnect"  A local ham in town here found this out the hard way this summer! PLUS it is very dangerous to be "disconnecting" and handling that coax when a storm is approaching.
http://www.comm-omni.com/polyprod2.htm
(Scroll down to the installation instructions)

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

(A long read but well worth your time to follow all the links)

It does NOT have to break the bank to properly protect your station from direct lightning strikes.
Get to know your local utility line crews (Used pull out ground rods have no scrap value and can be yours for a few beers)
Old used copper tubing works well for grounding material.  Old used factory or house entrance wire works great. Just strip off the insulation with a handy knife, etc etc.
Proper bonding of all grounds is most important. The actual arrestors used is way down on the importance list.

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WB1AAT
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« Reply #4 on: October 10, 2007, 10:03:57 AM »

Ok, so let me see if I got that right. I currently ground my rig, tuner, etc to a SPG ( copper bus bar ) and I have that connected to the ground rod outside via a short 5 ft or so heavy cable.  Are you suggesting I run a separate lead from the arrestor directly to that ground rod, or can I just connect the arrestor to the same "SPG"/busbar, etc I connect my rig and tuner to? It does, after all, go to the ground rod from there.
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KB9CRY
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« Reply #5 on: October 10, 2007, 10:19:07 AM »

Ok, so let me see if I got that right. I currently ground my rig, tuner, etc to a SPG ( copper bus bar )

No you've got the terms wrong.  Your copper bus bar and the connections to the equipment inside of the shack is your Shack Ground.  

This of course is connected to that ground rod outside.  See below.



 and I have that connected to the ground rod outside

This ground rod is your SPG.


via a short 5 ft or so heavy cable.


Good


 Are you suggesting I run a separate lead from the arrestor directly to that ground rod, or can I just connect the arrestor to the same "SPG"/busbar, etc I connect my rig and tuner to? It does, after all, go to the ground rod from there.


Yes you're right about the connection BUT that arrestor MUST be outside or else you'll be allowing lightning energy into your shack prior to it reaching the arrestor.  Make sense?

The arrestor should be mounted in line in your coax, located outdoors, and preferably right at your yoru SPG (that outdooer ground rod).

Finally you must also bond that SPG rod to your electrical service entrance ground rod.

QSL?
 
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K9KJM
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« Reply #6 on: October 10, 2007, 11:58:45 PM »

In your case, Your "ground buss bar" would be your "Single Point Ground" panel. So your arrestors and coax switches would be mounted to that panel.
Flat copper strap is simply better than a heavy wire to provide a nice low inductance conductor to your outdoor ground system. (A single rod is really not enough for any normal soils, Usually several  are required, Spaced twice the distance apart as the rod depth)
ALL commercial radio communications tower sites have the lightning arrestors mounted just inside the building where the coax enters.
(But do make sure your heavy copper wire, Or better yet flat copper strap has no sharp bends leading out to your ground system)

http://www.comm-omni.com/polyweb/hamradio5.htm
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KB9CRY
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« Reply #7 on: October 11, 2007, 03:34:27 AM »

I'll stand corrected by Ken but would like to add that that buss bar which can be called your SPG can't be called that unless it's properly routed to that outdoor ground rod and properly attached to the rod.

If this is the case, then your SPG would consist of the combination of the buss bar and the rod together.

If so, then I agree that you can bond your arrestor anywhere to that, but if your arrestor is indoors, as stated, it must be right at the entrance to the indoors and bonded very directly and quickly (short length) to the bar.

I know a many installations where the ops have a copper panel mounted to the inside of the wall and route their cables and coaxes right away to arrestors mounted on this panel which of course is properly bonded to outdoor ground rod(s) just back outside of this location.
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K1KAA
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« Reply #8 on: October 11, 2007, 09:46:42 AM »

Oh boy...

In all reality, go ahead, ground your arresters to your common station ground.  You shouldn't notice a difference.

What we do here is run all the coax out a steel patch panel.  Bonded to the panel are the arresters (after switch relays) and the adapters (the RG8 becomes thicker stuff for the antennas further away).  The ground from the station also goes through this panel and into the ground rod.  Most hams, at some point in their station evolution, will go to this method and I recommend it.

Its different for listening antennas and other stuff (you can see more specifically what we do here at http://k1kaa.413ma.org).

You won't notice a difference.  One ground point won't hurt you.  We did that for a number of years.  Good luck.
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K7AAT
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« Reply #9 on: October 16, 2007, 01:23:29 PM »


  Most of the hams responding to your question have it right.  Mount your lightning arrestor OUTSIDE and ground it directly to your ground rod.

   The main point,  which hasn't been clearly presented here yet,  is to keep any potential lightning strike OUTSIDE your home.  

    Ed K7AAT
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KE5OKQ
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« Reply #10 on: November 06, 2007, 06:40:23 PM »

Can you mount the arrestor at the feedpoint of a ground mounted antenna and run  a wire to a ground rod located at the antenna?
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K9KJM
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« Reply #11 on: November 06, 2007, 08:50:43 PM »

Sure you can mount the arrestor at the base of the antenna outdoors, But dont expect it to protect your radio from that location!
The correct location for your arrestor is on your "Single Point ground" panel, Right at the point where the feedline enters the building.

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