Lightning

[Cheech]

Well this has been buging me so Im going to ask :roll: We were talking about this on the radio before the storm rolled in, we were talking about lightning and antennas. Yeah this might lead on for while. How is it that all the antenna towers mostly comercial dont get hit by lightning? There is towers in town all over with fiberglass antennas on them. we have lots of lightning and some how they never get hit? All these antenna are grounded very well odviously. So is this what is protecting them or is it luck. I have alway heard lightning takes the quickest path to ground. most of these antenna are higher than anything and they survive the storms. I also no someone who did not have ther antenna grounded and it got fried along with his radio and power supply. One of my other friends said it might be becouse lightning goes from the ground up, That dont seem right to me but maybe its true? Dont realy know anything for sure but it interest the hell out of me!

 

[parkair]

Boy you started a good one ! There is a lot of theorys, and here's mine. Commercail towers get struck more than you might think, but they are grounded so good the path goes to ground instead of the feed line. I have a 50 foot rohn 25 tower and eight years ago it took a direct hit, it blew up a fiber glass antenna I had on the very top ! Since then I have had many different antennas ( now I have three fiber glass antennas )and have not been hit again. If a tower is grounded good and there is a electric charge build up the lighting will most likely make the jump to a tower, also I think if a small tower like what I have is NOT grounded well it is most likely NOT to get struck. I think Ham and CB'ers are better off not having a well ground tower or push-up poll. Yes lighting can come from the ground.

 

[Captain Kilowatt]

The minute you connect your feedline to your antenna you have a path to ground whether your tower is grounded or not.That path is down the coax and through your radio.Having a well grounded tower is definately the best as it offers a MUCH lower resistance to ground than your feedline and radio and will shunt most of the strike to ground.I can attest to the fact that commercial towers do in fact get hit a lot more than people think.I spent 22 years as a commercial broadcast engineer with a total of 14 towers in the air that I was responsible for.Trust me they get hit.When they are grounded properly you get lucky with just needing a TX reset or replacing a power supply component or maybe a capacitor in the AM tower tuning unit.If they were not grounded,well let's just say it would be a whole lot worse. :shock: :shock: :shock:

BTW the majority of lightning strikes do start at the ground and move upwards to the clouds.That is because electron flow is from minus (the ground) to plus,the charged cloud.Rarely do you get a cloud that is more negative than the earth.

 

[KingCobra_CDX882]

QRN

Most of what you said is right..

However the more we learn about the different types of lightning there is...the more we re-write the book on them..

there indeed are clouds thast have minis charging..
those i believe do not strike (or rarly strike the ground)
but rather strike upper atmosphere
(this has only recently been learned about but is actually very common happening)

Later

 

[Captain Kilowatt]

BTW the majority of lightning strikes do start at the ground and move upwards to the clouds.That is because electron flow is from minus (the ground) to plus,the charged cloud.Rarely do you get a cloud that is more negative than the earth.

Like I said,rarely do you get a cloud that is more negative than the earth.They do occur but rarely.Also such clouds are,as you pointed out,mostly involved in cloud-cloud discharges but there is the rare earth strike from a "more minus" cloud.I find lightning fascinating.I get glued to the window every time there is a good light show.

 

[Chong]

radio

hey you get your radio fixed yet cheech?

 

[Cheech]

There is alot of towers around town here with the fibeglass antennas on the very top. Can these antennas take strikes?

 

[PLUTO]

I just wanted to add, if you don't already know, don't beleve the old "put the end of the coax in a glass jar and you will be protected" thing. Lightning+glass jar=Lightining+glass exploding in your room. I cringe every time I hear someone say they're putting thier coax in a "pickle jar" :roll:

 

[Captain Kilowatt]

I agree with Pluto! I knew a guy that installed a PL259 in a jar lid and screwed his coax into it whenever a storm approached.Lightning struck his A99 and started a house fire in the kitchen where the radio and pickle jar were.It blew slabs of wood out of the kitchen countertop where the jar used to be. :shock: Don't ever try to store lightning in a mason jar unless it is white lightning.

 

[LoneWolf TN]

"unless it is white lightning." LOL That was funny.

Why is it, anytime I am driving down the road in the big truck, when I see lightning, it always appears to strike from the clouds then to earth? Not ground first then to sky. Surely it's not an optical illusion. Well, in my case it just might be. You know, many past years of mass consumption of magic mushrooms. LOL

Have a great day, LoneWolf TN

 

[EDUK8TR]

"unless it is white lightning." LOL That was funny.

Why is it, anytime I am driving down the road in the big truck, when I see lightning, it always appears to strike from the clouds then to earth? Not ground first then to sky. Surely it's not an optical illusion. Well, in my case it just might be. You know, many past years of mass consumption of magic mushrooms. LOL

Have a great day, LoneWolf TN

LW,
I guess it is kinda an optical illusion. The event happens so fast that you don't see the initial discharge but do see the main discharge. I have a neat video at work I use, produced by the the PBS show NOVA that has a time lapsed video of a strike and you can actually see the small first discharge followed by the main bolt. I too like to watch it as well, but now I worry about it hitting my antenna.

I have a separate run of coax that is connected to a different ground that I hook the main line from my antenna to when I'm not home or when storms are in the area.

As for the white lighting in a jar. Its really good with some blackberries or cherries soaked in it. Then of course there are the "Jello Jigglers" made with it that can make for some interesting conversations. :shock: Alas, I digress from the topic at hand.

73's :!:

Wayne C.

 

[Captain Kilowatt]

What you do not see is the stepped leader that the lightning follows upwards. Check this link out.Lightning Explained

 

[C W Morse]

The minute you connect your feedline to your antenna you have a path to ground whether your tower is grounded or not.That path is down the coax and through your radio.Having a well grounded tower is definately the best as it offers a MUCH lower resistance to ground than your feedline and radio and will shunt most of the strike to ground.I can attest to the fact that commercial towers do in fact get hit a lot more than people think.I spent 22 years as a commercial broadcast engineer with a total of 14 towers in the air that I was responsible for.Trust me they get hit.When they are grounded properly you get lucky with just needing a TX reset or replacing a power supply component or maybe a capacitor in the AM tower tuning unit.If they were not grounded,well let's just say it would be a whole lot worse. :shock: :shock: :shock:

BTW the majority of lightning strikes do start at the ground and move upwards to the clouds.That is because electron flow is from minus (the ground) to plus,the charged cloud.Rarely do you get a cloud that is more negative than the earth.

Well, durn, QRN! I was going to respond, but you stole my thunder!!! :twisted: 8)

Sorry, I couldn't resist!!!


CWM

 

[Captain Kilowatt]

Nope,it weren't me. I don't steal. Anybody see Jerry's thunder rolling around anywhere??

 

[Cheech]

Lots a good info at the link QRN especially the lightning safety link at the bottom of that page. Found some interesting info on station and tower grounding!