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Lightning Arrestors

Jun 2nd 2012, 13:48

KapAceHigh

Joined: Sep 24th 2010, 13:12
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When I was WB2MHI from 1963 to 1968, the only type of coax lightning arrestor was the gap type, which I installed on my coax transmission line right ouside the entrance to the shack.

after about 42 years, I'm again a licensed ham,KC2ZDT, but still have vintage vacuum tube gear. My question is this: is a gas discharge tube type arrestor necessary with vintage tube equipment.
Thanks,
Bob K
KC2ZDT
Jun 5th 2012, 18:55

WA0CBW

Joined: Apr 4th 1998, 00:00
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Bob,
Tube type equipment may offer a little more protection against lightning damage through the antenna than today's solid state equipment. The purpose of the coax cable lightning arrestor is to attenuate the surge voltage that comes down the coax because of a nearby lightning strike. Most lightning damage is usually caused by flash over between things that are at different ground potentials. It is probably more important to connect all of your equipment to a single point ground. Along with the phone, internet, cable tv and any other wires that come in or out of your house.

Bill
ARRL Technical Coordinator - Kansas Section
Jun 6th 2012, 22:28

KapAceHigh

Joined: Sep 24th 2010, 13:12
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Bill,
Thanks for the information and the importance of grounding everything.
Guess the best precaution is to disconnect the antenna and power from all the equipment ahead any approaching thunderstorm.

Bob
KC2ZDT
Jun 7th 2012, 15:39

WA0CBW

Joined: Apr 4th 1998, 00:00
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Bob,

Yes, grounding is your friend. But don't be be fooled by thinking that that after lightning has traveled several miles through the atmosphere that it will be stopped by the two feet of distance between the coax connector and something in your shack that is at ground potential.

Bill
Jul 24th 2012, 21:50

dksac2

Joined: May 24th 2012, 23:18
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Excellent point, I have seen the electricty and static a while after the lightning has gone by.

I have a board covered with copper on one side that all of my adapters are in to bring my coaxes into the house, the copper plate on the board is grounded as are the outside of the adapters. Will making fittings with the center conductor from each adapter grounded to the same grounded copper plate on the window entry help stop voltage from jumping to equipment at other ground potential?

Sounds like it may be best to unplug all equipment as well as remove the grn wire from the common connection point at the equipment and the through bolt on the entry board in the window to protect the equipment, just leave the ground from the outside connected to the copper plate on the window board. Is that a workable solution ???

73's, John
Jul 25th 2012, 15:27

WA0CBW

Joined: Apr 4th 1998, 00:00
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John,

Good lightning protection begins with the principle of "single point" grounding. That is all grounds go to a single copper bus located near the entrance of all coax cables. The buss should be at least 1/4 inch thick and sized length/width to accommodate all the ground wires. This bus should connect to your outside ground and the electrical panel ground. Connected to this bus would be all your equipment and all your surge protectors. Each device should be a "home run" from the device to the ground bus. In addition it would be a good idea to connect the cold water pipe to this same bus along with any telephone, cable vision, or satellite cable ground.

The idea is during a voltage surge you want EVERY piece of equipment to rise with the voltage. If one piece of equipment is at a different potential then the chance of an arc-over can occur. Most lightning damage occurs because of arcing between pieces of equipment or wiring or piping.

Bill
Jul 29th 2012, 22:26

dksac2

Joined: May 24th 2012, 23:18
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Thanks for the reply Bill. My grn to the radio and buss bar runs a very short distance to the main grn to the electrical panel. 2 more grn rods, 8' long have been driven into the ground and also connected to the main grn for the electrical panel. My equipment each has a seperate grn which is run to a thick copper buss bar behind the equipment which runs to the mains and the coax is grounded with a Diamond 3000 lightning arrester, connected to the same grn wire that comes from my station.
All equipment has the 3rd grn terminal on the plugs.
My window board also has a sheet of copper on it that the through fittings are bolted to and it is grounded to the same ground wire that runs from my equipment to the mains grn. I don't think I can do too much better. Have some tall electrical poles about 150 yds away, with any luck, lightning would hit them and I would be left to deal with the electrical pulse, with everything grounded to the common mains, I should be OK, but never say never.
Does this sound about right?

My Best, John
Sep 26th 2012, 02:44

JMWinPR

Joined: Aug 12th 2010, 11:37
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I would recommend PolyPhasers on the coax, and use coax grounding straps at each right angle bend, and at the entrance to the shack. I would also disconnect everything when storms approach and connect the antenna feeds to a "cantenna" or equivalent. This will help to keep it from bouncing around the shack. Don't count on objects 150 yds away to take the hit. After you've been hit a couple of times, it sort of comes natural.

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