Dipole questions, cont'd

[IronGuts]

Thanks to everyone for the help with my previous questions about dipoles for cb. On the subject of lightning protection, I think I've just about reached the end of the internet, and im still unclear on what to do. Lots opinions from fancy expensive protection systems to very simple advice to just disconnect the antenna.

Setup will be simple: Uniden grant ssb with 10 amp power source in garage. Dipole will be in yard strung up between two trees. Coax run back to cb in garage. Here are a few questions.

1. As far as lightning protection goes, it seems the best thing is just to disconnect the darn coax OUTSIDE when not in use. If so, should i ground the shield of the coax to a grounding rod near where the coax comes down from the dipole, away from the house? Not sure if this is necesary, or if it would do any good anyways if hit by lightning. Wondering if grounding it might help prevent damage to the coax if hit, or if grounding would help eliminate any noise from static, etc.

2. In order to disconnect the coax outside, i'd need to do some sort of connector. Id run one section of coax from the radio out through the garage wall to connect to the coax outside running to the dipole. Any special connector needed? What woudl you recommend.

3. As far as the coax lead running from the dipole to the garage, does the lead need to be raised above ground, or can it run on the ground to the garage, or even underground in a pvc pipe. Stringing it up would be a pain. Thinking of just coiling it up and hanging it on a tree under the dipole when not in use, so having it lay on the ground when in use is no big deal. Just want to make sure this didn't reduce performance. Thanks again!!!

 

[The DB]

When it comes to lightening protection, there is the right way to do it, then there is the various things that many people do instead, sometimes thinking what was done is adequate. Often times people get away with such measures, but use at your own risk.

The first thing you need to realize when dealing with lightening is that it is unlike any other electricity you have ever dealt with. It has a much higher voltage, and much higher current than anything else you will ever deal with. The extreme voltage levels allow it to jump from one circuit to another with ease. Insulators like air, wire covering, or the glass of a mason jar doesn't stand a chance next to that kind of power.

The first step in protection from an antenna hit is intercept it and direct it to ground before it enters the house with a coax surge arrestor. The ground rod should be 8 feet long if possible, and in addition to the coax surge arrestor it should be connected to the electrical ground system in the house using 4 awg wire and clamps (not solder).

Disconnecting the coax from the radio is generally not needed at this point but it never hurts.

If you live in an older house it is a good idea to make sure all of the house grounds are connected together.

A proper ground system doesn't generally cost a ton. Generally some 4 awg wire, some grounding clamps, and a coax surge arrestor is generally all you need. It is possible to go overboard, but taking more steps never hurts.

If you want to make your system better than that you should research what broadcast radio stations do, they don't stop transmitting during lightening storms, and definitely don't unplug their antennas, and yet rarely if every do they have trouble. That isn't to say they are immune, I have heard of them lowering power to fix lightening damage to an antenna, but have never heard of them going down, at least not locally.

EDIT: Forgot to mention, coax is very forgiving when it comes to where you run it. Running it on the ground will not hurt anything. The same goes for underground in a PVC pipe, although I would make sure the openings of that PVC pipe are sealed.


The DB

 

[QROdx]

1a) you're correct. you could spend a fortune on polyphasers and the like on protection but you are better off disconnecting the coax and getting the end away from the gear.

1b) personally I would not ground the coax because lightning loves a good path to ground and you might actually encourage it to strike the antenna. while not doing any harm to your gear, you would more than likely have to replace the coax if not the coax & antenna.

2) so239 barrel connectors are available in various lengths. you could even drill through a wall and use one long enough to be able to secure each end with washers and nuts and weatherproof it so no moisture can get inside the walls... then all you have to do is go outside and unscrew the coax when you're worried about lightning.
there are many other ways to make even simpler disconnects such as banana plugs and the like, options are up to your imagination.

3) as long as the coax is at a right angle from the dipole for a few meters your options are limitless. you can lay coax on the ground, bury it, run it through pvc, string it up on supports etc.

3a) coiled up and laying on the ground is where my coax lives until i get ready to use it

 

[RADIOOMAN]

1a) you're correct. you could spend a fortune on polyphasers and the like on protection but you are better off disconnecting the coax and getting the end away from the gear.

1b) personally I would not ground the coax because lightning loves a good path to ground and you might actually encourage it to strike the antenna. while not doing any harm to your gear, you would more than likely have to replace the coax if not the coax & antenna.

2) so239 barrel connectors are available in various lengths. you could even drill through a wall and use one long enough to be able to secure each end with washers and nuts and weatherproof it so no moisture can get inside the walls... then all you have to do is go outside and unscrew the coax when you're worried about lightning.
there are many other ways to make even simpler disconnects such as banana plugs and the like, options are up to your imagination.

3) as long as the coax is at a right angle from the dipole for a few meters your options are limitless. you can lay coax on the ground, bury it, run it through pvc, string it up on supports etc.

3a) coiled up and laying on the ground is where my coax lives until i get ready to use it

Number 1 conern is to divert the energy imparted to the antenna/coax from the lightning strike from being delivered to the house so as to preserve life and property.
Number 2 is to preserve equipment.

And QROdx's recommendation per "1a" does both of those.

Cheap, simple, and very effective if done properly.

 

[W5LZ]

Good lightning protection isn't 'simple' in that a lot of things have to be taken into consideration, at least checked. 'Correct' the goofs that were made in the original construction (maybe) and then providing that 'path' so that lightning doesn't go where you don't want it to go. That requires some knowledge of what constitutes a good 'path' and that can get really 'odd' at times. Not that I'm trying to 'drum up' business for someone, but the average person can't cover all the 'bases' that should be covered. Get competent help is the best thing you can do. Or, you make your self 'competent' and do it your self.
Good luck.
- 'Doc

 

[IronGuts]

Thanks guys, So the bottom line is that if you are unsure in any way (or can't spend the $) whether you have good lightning protection, then just disconnect the antenna lead and get it far from the house? That's about the best lightning insurance you can have?

 

[binrat]

Thanks guys, So the bottom line is that if you are unsure in any way (or can't spend the $) whether you have good lightning protection, then just disconnect the antenna lead and get it far from the house? That's about the best lightning insurance you can have?

Its about the simplest along with disconnecting the equipment from everything as well.

 

[vo1ks]

Your best lightning insurance is to have no antenna or radio gear. Tear down the house, dig a hole, and live underground.

Read the documents referred to in the other message thread. Properly bond your antenna and AC grounds together and there is very little reason for concern. The likelihood of a direct hit in reality is low. If you build the station properly the vast majority of any surge current can be diverted around the equipment, greatly reducing or eliminating any damage. Having to disconnect antenna lines and bring them outside is utter nonsense and for clueless people who don't know how to install things.

Nothing will protect you against all perils. What about if there is a flood, hurricane, tornado, or major snow or ice storm? You have to deal with hazards regardless.

 

[Lil'Yeshua]

Bonding

One of the concrete plants I work at has ground bonding on everything. Reason why? That particular area is prone to lightning strikes. We don't batch concrete by reading scales and pulling levers anymore. We have computers with batch programs on them. Just type in a particular mix code and amount and let the computer batch the concrete. We also have moisture probes($3000+one probe)in the overhead bins that tell us the moisture content of the sand. Lightning can ruin your day price wise and productivity wise. So,bonding and proper grounding is a big plus.

 

[northern35s]

Your best lightning insurance is to have no antenna or radio gear. Tear down the house, dig a hole, and live underground.

Read the documents referred to in the other message thread. Properly bond your antenna and AC grounds together and there is very little reason for concern. The likelihood of a direct hit in reality is low. If you build the station properly the vast majority of any surge current can be diverted around the equipment, greatly reducing or eliminating any damage. Having to disconnect antenna lines and bring them outside is utter nonsense and for clueless people who don't know how to install things.

Nothing will protect you against all perils. What about if there is a flood, hurricane, tornado, or major snow or ice storm? You have to deal with hazards regardless.

That's a bit rich old chap, the guy wants to install a wire dipole, this being the CB section I'm guessing it's for the 27MHz band, want to know the cheapest form of lightning protection, disconnect the feed, now why is that nonsense and clueless?
It's effective and at zero cost, that in my books = win win if he chooses to investigate the subject more closely, and finds disconnecting the coax a bit of a chore, then I'm sure he'll put some effort into creating a lightning / surge protection system in place, until then his BEST choice is to disconnect, wouldn't you agree?

 

[vo1ks]

No I don't agree. There isn't much effort or expense required to do it properly the first time. If he's going to invest funds into equipment, he should have the resources and knowledge to do it right. Do some study, learn how to do things, and then proceed. Following half assed advice from those spouting nonsense is the wrong approach to take.

 

[northern35s]

Disagreeing is fine I'm cool with that, however stating that disconnecting the coax is half assed nonsense is a nonsense in itself it's a certainty that a strike to the antenna will not hit the radio if the coax is disconnected, unless of course you know different, in which case I'm willing to learn from someone else's experience

 

[The DB]

At least he is disconnecting it outside to try and keep a direct hit out of his house, that being said that can lead to problems on its own.

Lightening storms tend to happen just before or during thunderstorms. I hope that coax end is well made or well protected as, even if it isn't laying in the rain, it will be in a very humid environment, and this can cause damage in and of itself.

I side with vo1ks in concept and practice. Also, to put a connector outside isn't exactly free, you will have to put ends on the coax to use that barrel connector and get a barrel connector. If your going to put ends on anyway why not go ahead and get a coax lightening arrestor and some wire and do it properly to begin with. They don't cost that much, but an arrestor does cost more than the barrel connector.

Many arrestors screw right into the coax line, so if you want to go cheap with a barrel connector outside that you manually disconnect, and intend to upgrade later, you can simply screw those connectors into an arrestor and run the ground wire later.

You don't need to spend hundreds of dollars to have a proper setup, my complete setup cost me less than it cost for the coax to run from the radio to the antenna, a lot less. I have never had an issue, and I don't unplug my radios.


The DB

 

[gamegetter]

greetings: i will throw this out.

disconnecting the coax is a certainty that lightning won't come in the shack, but in the event of a strike where will the lightening that might travel down the coax go?

Perhaps right outside your window and onto the house and start a fire. Perhaps redirected to a person just happening to pass by the area?

Grounding sounds like a better solution to me. Best of luck all, nice discussion.

 

[W5LZ]

And just a reminder, lightning can also get into the house/equipment from the ground side. No antenna connected and there's still the probability that there can be enough 'charge' entering by way of the grounds to do damage. Grounding or throwing that feed line out the window is not a sure way of preventing lightning damage.
- 'Doc