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Author Topic: Best practice for ground and surge protection  (Read 3137 times)
KG6OMK
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Posts: 107




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« on: February 05, 2007, 12:48:38 PM »

Summary:  What's best practice for ground and surge/lightening protection.



I'm installing a new VHF antenna on a roof mast and running a coax line down.  My goal is the best quality installation possible.  Current project is a dual band   vertical but a smallish yagi and a 6M vertical are to follow.  HF later.

This weekend I got the mast up and a 10ft ground rod driven.  Mast is connected to rod by large diameter coper wire.

I figure I need to place some kind of lightening/surge protection between the antenna and the radio.  Looking at Alpha Delta's products I see the same "Arc-Plug" device inside both their surge protector and their coax switch.  So I'm thinking I don't need this in two places.  If I want a switch having it there should be enough.

But then I'm thinking about location.  The switch would be right at the operating location near the radio(s) and operator.  Wouldn't it be best to place the surge protection near where the cable enters the house (about 12 feet from the radio(s)?

This may be moot anyways.  lightening is rare in So. California and even if it weren't it is obvious that lightening can arc over a 1,000 foot airgap so what's the point of a surge protector?  non-direct hits I guess?

BTW the location I have is great.  For you locals... on a clear day I can see the Hollywood sign, Mt Wilson, all the building in down town LA and clear into Orange County and the inland facing side of PV.  The Antenna is 45ft above ground level, which in turn is 150ft hill.
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AA4PB
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« Reply #1 on: February 05, 2007, 02:40:51 PM »

Check out http://www.polyphaser.com/  Lots of good material there.
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Bob  AA4PB
Garrisonville, VA
KB9CRY
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« Reply #2 on: February 05, 2007, 04:51:28 PM »

Go to the main forums page and type Grounding in the search window.  All your answers are there.
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KB9CRY
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« Reply #3 on: February 05, 2007, 06:36:50 PM »

What's best practice for ground and surge/lightening protection.

Tnx for asking Chris.  Please do a search as directed and the Polyphaser and ICE (Industrial Communications Engineers) websites have tons of info on their technical articles.


All grounding requirements apply regardless of band/frequency.


This weekend I got the mast up and a 10ft ground rod driven. Mast is connected to rod by large diameter coper wire.

Good


I figure I need to place some kind of lightening/surge protection between the antenna and the radio.

Just trying to jab you, it's lightning.  Lightening is something like bleach that you use to lighten something, even though I guess lightning will lighten most things instantaeously but afterwards they get darkened!!!


Looking at Alpha Delta's products I see the same "Arc-Plug" device inside both their surge protector and their coax switch. So I'm thinking I don't need this in two places. If I want a switch having it there should be enough.

These arc plugs aren't enough protection. I'd avoid them.

 where the cable enters the house (about 12 feet from the radio(s)?


Correcto mundo


 it weren't it is obvious that lightening can arc over a 1,000 foot airgap so what's the point of a surge protector?

Yes but the purpose of a properly designed and installed grounding system is to shunt all that energy to ground and not into the expensive equipment.  I can be done and doesn't need to be very expensive.

non-direct hits I guess?

Yes.  You got it.

You're going to want to purchase good lightning arrestors (I use ICE products.), install them at your SPG, that ground rod just outside the shack, connect your equipment grounds to that rod, and then connect, via outdoors, that rod to the electrical service entrance ground rod.  Then you'll have your entire grounding system all tied together such that in an energy surge event, all the grounds will rise and fall together and not take any paths through your equipment.  Read the references and it should all come together.  Ask away if you need.  Phil  KB9CRY
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WB2WIK
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« Reply #4 on: February 05, 2007, 06:52:44 PM »

For a VHF antenna installation in Redondo Beach, all you *really* need to do is ground the antenna mast itself using a large conductor following the shortest possible path to earth ground and an 8' ground rod, and be sure to use:

1.  Longer run of coax than that ground cable is.  If the ground wire (above) is 50' long, then your coax needs to be longer - maybe 70' or 80', or whatever.  The important thing is, the ground cable length should have lower impedance (resistance + inductance) than the coax outer conductor has.

2.  A coaxial lightning arrestor, which installs in-line (usually between a pair of UHF or N connectors) with the coax, and should be installed at ground level, OUTSIDE the house, and be grounded via the shortest possible conductor to earth, using an 8' ground rod.  In my experience, the shortest possible conductor can be about two inches long, if you mount the arrestor right on the ground rod and route the coaxial cable through it.

Using those two methods of protection is about all you can do in most cases, and in R.B. should be more than adequate, considering our lightning incidence locally is close to zero.

WB2WIK/6
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K9KJM
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« Reply #5 on: February 05, 2007, 11:11:13 PM »

For good overall information about lightning protection read:
http://members.cox.net/pc-usa/station/ground0.htm
I use Alpha-Delta (and other brands as well) stripline coax switches, Mostly to be able to switch antennas AND put unused antennas to ground when not in use. For protection I agree that I.C.E. (Industrial Communications Engineers) has good products for typical ham use, At a fair price.
The "single point" ground system is the way to go, And your protectors and switchs would best be mounted on that panel, Ideally right where the coax enters the building. All commercial systems mount the protectors right INSIDE the building, NOT outside.
If you do mount protectors outside, You have connector sealing problems.........  
Flat copper strap is the best ground conductor, and do not have any sharp bends!
As pointed out in the link I provided, BONDING all grounds together is very important.
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W6GF
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Posts: 168




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« Reply #6 on: February 16, 2007, 05:11:49 PM »

The best protection is to disconnect all antennae when not in use.  Also careful, some protectors may cause attenuation at VHF frequencies so pick carefully if you are going to use them

George, W6GF
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