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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Tue 02, 2018 5:25 pm 
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Joined: Sep Thu 23, 2010 6:37 am
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Location: Powell River BC Canada
Lightning hits on telephone outside plant installations can travel down buried
cables and do a lot of damage. A solution is to bury a ground cable along side.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Tue 02, 2018 7:38 pm 
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Joined: Mar Sat 15, 2014 9:22 pm
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Considering that lightning is a dirty great spark traveling from the sky to earth, as has been said, a little knife switch won't help a lot. Some way to earth the aerial outside the house, and disconnect it from any lead in if there is a real danger, surely.


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Wed 03, 2018 4:14 pm 
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Location: Leo, IN or Zellwood, FL
Leigh wrote:
Paul wrote:
Using an ohm meter, there is no DC continuity through the Polyphaser.

What does you ohmmeter say about the 2000-foot air gap that the bolt just jumped ?

Absolutely and totally useless...
And dangerous because it brings the antenna line into the house before any lightning arrestor.

- Leigh


Does your local TV station go off air when their tower it hit?
Does your local Radio Station go off the air when their towers are hit?
Does Ham Radio Station K9UWA go off the air when the towers are hit?

The answers to all the above are Only Momentarily they go off air until the power is reset after the event. Then the station is back on the air as if nothing had ever happened. My Hit Counter on the 180 foot tower says it has been hit 180 times as of last summer when I last looked at it. Damage to house, radio, computers and other electronics. ZERO The system has been place since 1989. The key here is properly designed Ground System. Mine has 100 ground rods and over 1200 feet of connecting copper tubing. That solves 90% of the hit being bled off to ground. The other 10% is taken care of nicely by Polyphaser devices. The Key here is don't miss anything that connects to anything else in the whole house. Any small relay wire rotor wire coax power line telephone line or antenna wire has to have some sort of proper protection device that takes whatever the line is directly to the common ground. In my system nothing is ever disconnected. The equipment isn't even turned off. It would difficult for me to reconnect or turn some of it back on from 1200 miles away from the home ranch. Yes I remotely operate the station.

Polyphaser turn BLITZ into BLISS
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John k9uwa

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Wed 03, 2018 4:28 pm 
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Location: Leo, IN or Zellwood, FL
Chas wrote:
Poyphaser?

It is believed that the extensive damage is not from the hit itself but from a pulse that extends out and induces high voltage in metal objects, both above and below ground.
Chas


Chas a local small time example of this happened to a friend of ours. His place had a small 60 foot tower with antennas and he thought a complete proper ground system and protection devices. One time his tower was hit and the damage was to an Unplugged TV set that was setting on top of a 5 foot tall metal filing cabinet. After that happened he added a nice heavy wire from the filing cabinet to the common ground system and never had more damage to items left on or in the filing cabinet.
It would probably be impossible to do that with the are your describing.
John k9uwa

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Thu 04, 2018 2:35 am 
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Location: Austin, Texas
I was always under the impression that lightning would strike the tallest object in the area and lower items would not take a direct hit. I am fairly sure I have seen drawings showing how something like an overhead power line will protect a large area near it. Unfortunately lightning must not have been well educated. It struck my neighbors driveway knocking out a sizable piece of concrete. The driveway is next to a two story house and surrounded by tall trees. There is also an overhead power line behind the house.

Tall buildings use something the size of a welding cable to ground their lightning rods and I suspect anything smaller is a waste of time.


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Fri 05, 2018 7:35 am 
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JnTX wrote:
I was always under the impression that lightning would strike the tallest object in the area and lower items would not take a direct hit. I am fairly sure I have seen drawings showing how something like an overhead power line will protect a large area near it. Unfortunately lightning must not have been well educated. It struck my neighbors driveway knocking out a sizable piece of concrete. The driveway is next to a two story house and surrounded by tall trees. There is also an overhead power line behind the house.

That used to be the theory, but, as you noticed, it isn't correct.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Sat 06, 2018 12:43 am 
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Location: Hamilton, Ontario
I have picked up all of the materials for the aerial but I just need the weather to break first; it's too cold for even a Canadian to be standing outside for too long! :wink:

I do have one final question though:

I found a good deal on some 14ga. stranded wire. $30 Canadian (about $25 US) for 1000 feet. Needless to say I now have lots.

Would there be any improvement in reception if, rather than one 70 foot run of wire, I ran two runs of 70 feet and soldered each of the ends together and braided them?

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Sat 06, 2018 12:47 am 
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Jim Mueller wrote:
JnTX wrote:
I was always under the impression that lightning would strike the tallest object in the area and lower items would not take a direct hit. I am fairly sure I have seen drawings showing how something like an overhead power line will protect a large area near it. Unfortunately lightning must not have been well educated. It struck my neighbors driveway knocking out a sizable piece of concrete. The driveway is next to a two story house and surrounded by tall trees. There is also an overhead power line behind the house.

That used to be the theory, but, as you noticed, it isn't correct.

Whatever you think lightning will hit Well I think it follows Murphy's Laws

jason


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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Sat 06, 2018 2:26 am 
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jrs wrote:
I have picked up all of the materials for the aerial but I just need the weather to break first; it's too cold for even a Canadian to be standing outside for too long! :wink:

I do have one final question though:

I found a good deal on some 14ga. stranded wire. $30 Canadian (about $25 US) for 1000 feet. Needless to say I now have lots.

Would there be any improvement in reception if, rather than one 70 foot run of wire, I ran two runs of 70 feet and soldered each of the ends together and braided them?

I assume you mean connecting the wires in parallel. If so, it won't make any difference. A single 28 AWG wire will work as well. The only reason to use heavy wire for a receiving antenna is to have enough mechanical strength to withstand the weather. For a transmitting antenna, the wire has to be heavy enough to carry the current and to not have excessive losses. Even here, mechanical strength usually is the limiting factor.

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 Post subject: Re: Another Long Wire Antenna Question
PostPosted: Jan Sun 21, 2018 9:55 pm 
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Location: Hamilton, Ontario
Well the weather finally broke up here so I installed my long wire antenna this weekend and all I can say is WOW what a difference!!!!!! It's like sex for the first time....well that's an exaggeration but you get the idea.

I am easily and clearly pulling in not just local AM stations but clear signals from Buffalo, Pittsburg, Cleveland and Detroit. I am also getting lots of SW stations but I haven't figured out where they are from yet.

This was on a GE M51 that I redid but haven't even aligned yet.

Thanks for the help.

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 Post subject: Re: Another Long Wire Antenna Question - UPDATE
PostPosted: Jan Mon 22, 2018 1:02 am 
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Quote:
I am also getting lots of SW stations but I haven't figured out where they are from yet.

That can be hard. It's common for broadcasters to buy time on other stations that are closer to their target audience. So just because you are hearing something identified as from some country doesn't mean that it is transmitted there.

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 Post subject: Re: Another Long Wire Antenna Question - UPDATE
PostPosted: Jan Mon 22, 2018 3:13 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 500
Location: Effingham, IL
Ben Franklin invented the lightning arresters and it was presumed to protect the structure from lightning by directing bolt to ground through a heavy woven copper wire. To me , just would seem to attract lightning. Phone company would use "protectors" or carbon blocks with narrow air gap at the central office and residence. The carbons will short to ground on high voltage surge. High voltage can be induced in a wire without a direct hit, like EMP, so I think this is what antenna wire grounding is all about. If the air ionizes around the conductor from a direct lightning hit ; I don't see that lighting protector doing much. Millions of volts at thousands of amps traveling thousands of feet at the speed of light could care less about that piece of wire with a lightning protector. Its the ionized air that carries current , and it doesn't go around corners or right angles. My random thoughts only so correct me if I need enlightened.


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 Post subject: Re: Another Long Wire Antenna Question - UPDATE
PostPosted: Jan Mon 22, 2018 5:20 am 
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Joined: Dec Sun 21, 2014 5:03 am
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Location: Traverse City, MI 49684
I've got a sailboat, which means I have a stick poking up toward the sky. On the subject of mast grounding, opinions run all over the place. I opted to ground it to the ballast keel, a big chunk of cast iron hanging under the boat. The mast is wood but it has a heavy bronze cover plate, about 1-1/4" x 3/16" running tip to bottom over a wire chase. It has a bronze sail track over that. It has 4 stainless steel stays running top to bottom. The bronze strip and three stays are grounded via stranded copper, a big wire (can't recall the gauge). I tried to minimize the bends and maximize the radius of them because lightning doesn't like to change course and will derail on a sharp turn.

At the top of the mast I have placed a stainless steel spike with a sharp point. There is a theory that a sharp point is more effective at equalizing voltage differentials and at least minimizing static discharges. You can buy stainless devices that look like toilet brushes to maximize that effect.

If an ungrounded sailboat mast is hit, the lightning tends to travel down the mast and then get all confused, exiting to the water through the hull and leaving lots of pinholes. My theory was that a careful grounding scheme might at least guide it safely to the water with minimal physical damage, even if all the electronics were fried. And of course, if I'm out sailing when the lightning encounter takes place, it would give some sense of safety (perhaps false, but all we need is something to encourage).

I've been aboard a replica schooner with big wooden masts and a big iron wheel in a couple thunder storms when the flash and the boom were simultaneous. Scary. The last time I kept thinking that you sometimes feel static electricity before a lightning strike. I was ready to let go of that big iron wheel, duty or no duty, and jump below at the first tingle on the arm airs. But then, it was pouring rain and I was soaked under my rain gear so the arm hairs were probably disabled.

Chris Campbell


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 Post subject: Re: Another Long Wire Antenna Question - UPDATE
PostPosted: Jan Thu 25, 2018 10:33 pm 
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Joined: Aug Sat 06, 2011 10:46 pm
Posts: 96
Location: Kurri Kurri, N.S.W., Australia
I cannot add much to this conversation, but here it goes.

First, my own lightning protection consists of a Siemens lightning arrestor that probably came from the local phone company. A simple neon discharge device with an adjustable gap to deal with over-voltages. It's mounted on my mast in a clear acrylic box and the ground lead goes down from there.

This is where I made my sets nearly lightning-proof: Hanging down from the box is the end of my antenna lead. EIGHT INCHES of number 12 single strand, the end. Since I do not listen every day, I use an old style battery clip attached to my lead-in. When I want to listen, I open the window and attach the clip to the bottom of the antenna. If a storm gets close, a quick jerk disconnects the antenna and removes any connection to the radio. No link at all. Since a small capacitance is often used in many radio circuits (which is what would be the result of an imperfect connection to the antenna at the clip) I have suffered no detectable decrease in performance.

I suspect however that a direct strike might create enough inductive energy in the area to damage some sensitive electronic devices not even connected to anything.

I have seen some older lightning rod systems that used braided aluminum wire to shunt the strike to ground. I have heard of these disintegrating at the time of a strike and saw one that had been melted on an old house. This was BIG wire, 3/4 of an inch total. I believe what happens is that when a big strike hits a system like this, the system guides the initial charge to the ground setting the path of the strike. Even as the ground lead disintegrates there will be conductive particulates to maintain the path for a while. Remember- that spark has already jumped a few thousand feet, a few more feet won't change much. But, by that time the lightning has discharged and the threat is gone.... for a few minutes.

Those are my thoughts, take them for what they are worth but I hope this helps someone.

Lindsey


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 Post subject: Re: Another Long Wire Antenna Question - UPDATE
PostPosted: Jan Thu 25, 2018 10:39 pm 
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High Tension wrote:
I suspect however that a direct strike might create enough inductive energy in the area to damage some sensitive electronic devices not even connected to anything.

Several years ago a mountain-top site at which we had some equipment took a hit. The lightning hit the tower itself, not our antenna which was 10 to 20 feet below the tower top.

It created a very noticeable problem, which I was dispatched to investigate.

When I arrived, I found one 8-foot relay rack full of equipment that had been blown through the wall of the metal building and all the way across the parking lot.

Lightning does whatever it wants to do.

- Leigh

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