Antenna Grounding

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BaLa

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I see this has been asked a few times.


Although I have a bit of a different idea.

My House doesn't have a mast, so I was wondering If I could just nail a small steel plate to the roof and put a magnet mount antenna on top of it.
Call me crazy. :lol:
But I do not want to install a mast.

Do I need to ground the antenna if I do that?
If so how would I go about doing that?

In another thread, it was suggested to ground the mast. Not the antenna itself.

http://www.radioreference.com/modules.php?name=Forums&file=viewtopic&t=15349
I wont be using a mast....
 

DXKW

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antenna grounding

as far as a direct hit by lighting on your antenna no amount of grounding
is going to save it. three years ago lighting hit my fifty foot tower and you should have seen the amount of damage it did im glad it did not burn the house down. what kind of antenna are you going to install ? also i am not trying to imply not to use a proper ground.









thank you
 

BaLa

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Re: antenna grounding

DXKW said:
what kind of antenna are you going to install ?

this is the antenna I have

http://www.universal-radio.com/catalog/scanants/1581.html

As of now I just put it on the A/C Unit outside.
Having this antenna outside just on top of the AC works much better.

Before that I just had my RH77CA attached to my scanner, it worked pretty good. But I had a lot of interference inside the house.


I would have gotten a 'regular' antenna but I do not want to go through the trouble of installing a mast just for that purpose.
And my Dad said I needed to look into grounding it if I do that (put it on the roof)
 

DXKW

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antenna grounding

you realize that mobile antennas like the mag mount your going to use
make use of the car body as a gound. also i have tried some scanner antennas on my car and at 800 mhz the rg58u causes a lot of line lose.
i did not check the database for your area but i will take a look.










thanks
 

BaLa

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Re: antenna grounding

DXKW said:
you realize that mobile antennas like the mag mount your going to use
make use of the car body as a gound. also i have tried some scanner antennas on my car and at 800 mhz the rg58u causes a lot of line lose.
i did not check the database for your area but i will take a look.
well it works great on top of the A/C so I don't think it will be a prob.

Most of the freqs programmed in my scanner are in the 153-160mhz range.
The Higwhay Patrol Rolla uses 42.58, .24 and .00 for Car 2 Car Traffic.
I'm mainly interested in improving or actually picking up some more HP traffic.


I don't expect anybody to switch to 800mhz anytime too soon either.
 

jim202

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Re: antenna grounding

DXKW said:
as far as a direct hit by lighting on your antenna no amount of grounding
is going to save it. three years ago lighting hit my fifty foot tower and you should have seen the amount of damage it did im glad it did not burn the house down. what kind of antenna are you going to install ? also i am not trying to imply not to use a proper ground.

I take extreem exception to this statement. Grounding does work and does protect a radio site from lightning hits. You may sustain some damage, but it won't be anything major. If you hear someone saying you can't do anything about a direct hit, your so far from wrong.

The stories you hear about and the one that DXKW is giving us all probably are lacking a good grounding system. You notice I used the term "SYSTEM" because that is what it takes.

Do you think any of the cellular companies or the TV stations would still be in business if they couldn't make their facilities survive? A good grounding system will survive a direct hit any day. I have seen a tower take a direct hit. The tower steel will steam in the rain from the heat that was generated, but it will survive. As one of the people that maintained the radio equipment at this tower, I went inside the building to check on the equipment status. Everything was operating normal except one of the ham repeaters. It kind of smelled inside the cabinet.

We had been after the ham club to improve the grounding on their equipment and they just took the stand that it wasn't needed. They too felt that there was nothing that could be done to protect the radios and antennas. Kind of funny that their equipment was the only gear that sustained damage.

If I was a betting person, the tower of DXKW that was described above that took all the damage had a poor ground or no ground at all. Even a Rohn 6 or 25 style tower can be made to survive a direct hit. It just takes some care and an investment of time and materials to do the job. I will say that a single ground rod on a tower is by no means enough.

Jim







thank you
 

W4KRR

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BaLa said:
My House doesn't have a mast, so I was wondering If I could just nail a small steel plate to the roof and put a magnet mount antenna on top of it.
Call me crazy. :lol:
But I do not want to install a mast.

Why don't you want to install a mast? It's no big deal to install a simple 20 foot mast such as what you can buy at Radio Shack or Home Depot. If you want to nail a steel plate to the roof and use a magnet mount, remember that most magnet mounts use RG-58 coax cable, and you will probably have to extend the cable to reach from the roof to where your radio is, since most mag mounts only come with 10 to 20 feet of cable. RG-58 is a poor cable to use for a base installation, there's too much signal loss. You will notice a better improvement if you do the mast with a base station antenna and a better coax cable, like RG-6 or LMR-400.

Remember, if you're going to go swimming, you have to get your feet wet! :wink:
 

coolblueneon

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Re: antenna grounding

If you can hear the MHP dispatch out of Rolla with your current set up, stick with it, if you're trying to hear more mobile to base traffic, good luck, the mobile units are very low powered and use a repeater inside the car. I used to live less than a mile from Troop H HQ on I-29 and heard very little traffic from the mobile units even from my 3rd floor apartment. I suggest you try mounting your mobile antenna on the roof and post your results.

Good Luck!

Greg
 

BaLa

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Re: antenna grounding

coolblueneon said:
If you can hear the MHP dispatch out of Rolla with your current set up, stick with it, if you're trying to hear more mobile to base traffic, good luck, the mobile units are very low powered and use a repeater inside the car. I used to live less than a mile from Troop H HQ on I-29 and heard very little traffic from the mobile units even from my 3rd floor apartment. I suggest you try mounting your mobile antenna on the roof and post your results.

Good Luck!

Greg

I don't know what kind of power output the stations use....but they seem to be quite powerful..
I can pick up Troops C and E also. Of course NO mobile traffic there whatsoever. :lol:

The other 'problem' is I still live with my parents and I don't know for how much longer, just another reason not to go with a permanent install.
The Mag Mount wouldn't be much trouble to take off the roof.
I could take the cable/wire for the ground
Depending on how I do the grounding thing that shouldn't be too much trouble to get rid of either.


I'd hate to money on an antenna and mast, only to move out in a few months, or in a year at the latest.
 

Raccon

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My House doesn't have a mast, so I was wondering If I could just nail a small steel plate to the roof and put a magnet mount antenna on top of it.
This would be asking for trouble if there is no ground and the antenna marks the highest point in the immediate area - it will be very attractive to a lightning and you may in fact guide the lightning straight into your room/house (via the antenna cable).
If it works great on the A/C I would just leave it there but take it indoors when the weather get's bad.

Working in the cellular industry for years I can only concur to what jim202 says - a good grounding system does help.
However the effort spend on commercial sites would probably exceed what a private person would be willing to invest, in particular in terms of money.


Actually I got a question: is it permitted in the US to connect equipment ground and lightning protection ground together (equipotential bonding)?
 

jim202

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Actually I got a question: is it permitted in the US to connect equipment ground and lightning protection ground together (equipotential bonding)?[/quote]

That all depends on a couple of things. First and foremost, some insurance companies won't allow it. They want a certified lightning protection system. Connecting non approved devices to it could invalidate the insurance.

Second in working over the years with some of the lightning protection companies, they too get a little testy about people connecting to their wiring. They have a hard time certifying a protection system with unknown connections to it. Kind of goes along with the insurance company stand.

However, if you go look through the NFPA 70 aticle 250 I think, they talk about antennas on building roofs needing to be connected to the lightning protection system. Your in a catch 22 here.

Jim
 

Cribbage

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If I may..

The mobile mount on the AC unit sounds like a great idea. As long as, like was noted above, it isn't the highest thing around.

I'm going to get a Diamond 2m/440/1.2 mobile (N2000xx) and their 4" mag mount for it. I have 50' of 9913 I've never used (still in the roll with caps) and use that to bring it the rest of the way down.

Grounding shouldn't be an issue, it's a single-story house, and if the wind speed got to high, the mag mount would give way long before the AC did.

Plus, the size of the AC unit will give a good groung plane to the mobile mount.

If I can figure out a way to ground the whole thing, I will.

Great, low cost, stealthy antenna.

Thanks for the idea!

Cribbage
 

Al42

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Re: antenna grounding

DXKW said:
as far as a direct hit by lighting on your antenna no amount of grounding is going to save it. three years ago lighting hit my fifty foot tower and you should have seen the amount of damage it did
Damage?

I shudder whenever I see someone (not you, BaLa and jim) even hint that an antenna can be "protected" from a direct lightning strike. Many years ago I was working as an engineer at an AM broadcast station. The 3 antennas were 4-legged towers - with 12" diameter static discharge balls (one ball solidly grounded, the other connected to a 6"X6" tower leg, with a gap close to a foot). The towers were mounted in concrete "piers", about 4 feet on a side and about 12 feet deep. One night, during a particularly nasty thunderstorm, one of the towers suffered a direct hit. The next morning, when I arrived at work, we had a 2-antenna array, and a block of concrete in the ground where the third antenna used to be. The tower vaporized, if it didn't turn to plasma. A few hundred thousand degrees will do a bit of "damage".

I disconnect my outdoor antennas when they're not in use and connect them to a ground block. (My scanner mag mount sits on a tool chest in the radio room.) Not to protect the antennas, but to protect the house. If one of the antennas gets hit, I'll buy a new antenna and cable. I don't want to have to have the house rebuilt and, even though I know how to (theoretically) protect the house from even a direct strike, I'd rather not put that knowledge to the test.

Never underestimate lightning. Those who do usually get the title "The late" added in front of their names.
 

kb2vxa

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Hi all,

"My House doesn't have a mast, so I was wondering If I could just nail a small steel plate to the roof and put a magnet mount antenna on top of it.
Call me crazy.
But I do not want to install a mast."

OK, you're crazy. That's about the worst hair brained scheme I've seen yet, your parents will KILL you when the rust sets in and streaks permanently stain the roof. That is if dad doesn't catch you pounding nails and causing leaks, he'll get his shotgun and drop you like a squirrel before you can climb down and say "I'm sorry."! You're much better off putting a discone in the attic, it will save your life and you can take it with you when you move. The little hole in the ceiling inside the closet will never be noticed.

Here comes the hard part, your parents may be a lot more amicable than the landlord. One of two things happen to apartment dwellers, they get lucky and can mount an antenna somewhere provided that it's unobtrusive or they go antennaless. It's not for broadcast reception so federal preemption doesn't apply and it's not for Amateur Radio so the PRB-1 guidelines and limited state preemption (if any in your state) doesn't apply either. Bottom line, scanner buffs are at the mercy of the landlord or the Neighborhood Association Nazis and it's not limited to antennas.
 
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