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Message |
    
Jameslarson
New member
Username: Jameslarson
Post Number: 1
Registered: 4-2006
| | Posted on Saturday, April 08, 2006 - 5:06 pm: | 
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Hi all. I've run many omni antennas and such in the past when i was younger. Example. I would put an antron 99 on a 10 foot pole, tripod roof mount, run the coax to my station, and run a ground from the u clamps to an 8 foot rod in the ground. But now I see all this complex grounding stuff that may need to be done. Central ground point from the radio, polyphasers, etc...Can someone please help me out here step by step on how to properly ground my entire system, model numbers, where to buy them etc???? AAlso, the polyphasers that copper sells looks like there is a so-239 on one end, but something different on the other. Sorry for the long post, but my IMAX 2000 will be here soon, and I want to do it right. Thanks.
PS,,,I plan on mounting the antenna in a tree, so I probably cannot use the Ground plane kit, unless of course you have ideas. Please help. thanks. |
Tech833
Moderator
Username: Tech833
Post Number: 1302
Registered: 8-2002
| | Posted on Saturday, April 08, 2006 - 6:44 pm: |
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There is a ton of great reading here. Just do a search for 'grounding' and let er rip. Reading what has already been written saves my arthritic hands from retyping the answers again and again. Sorry, it really hurts to type. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1393
Registered: 9-2004
| | Posted on Saturday, April 08, 2006 - 10:13 pm: |
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also, searching will lead you towards very specific questions, that are individual to your installation.
get the basics first, and then let 833, and everyone else help make it work at your house.
when you do post the inevitable questions, remember to give as much detail about your installation and as you can.
good luck,
matt |
Jameslarson
New member
Username: Jameslarson
Post Number: 3
Registered: 4-2006
| | Posted on Saturday, April 08, 2006 - 10:17 pm: |
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Hi. Yes, I did some searching, but some of it was confusing. I was hoping I could get a step by step on how to properly do it, model numbers, where to buy, etcc..Thanks |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1396
Registered: 9-2004
| | Posted on Sunday, April 09, 2006 - 3:04 am: |
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i'll try and give you some basics, but like 833 said, when you've typed the same thing over and over, it gets tiring.
as for model numbers, if you know what things you need to have, you can determine which model is right for you.
ok, single point ground means that all your ground rods, and the house AC ground, are tied together. (connected)
here's an example:
your radio room is on the west side of the house, on the first floor. your antenna is on a metal mast going up from the ground, on the south side of the house. the breaker panel is on the east side of the house.
you are using a radio, a power supply, a linear amp, and a low pass filter.
you are going to need two 8' ground rods, a big roll of 8ga. solid copper wire (or braid if you can afford it) grounding clamps, a polyphaser, a grounding buss bar, and some short lengths of copper wire 10-14ga.
each piece of radio gear inline gets a short length of wire attached to its metal case.
the length of this wire should be just enough to reach your grounding buss bar with some slack in the wires. (should be 2-3 feet, not much more)
all those wires are connected to the buss, which has a length of 8ga. solid copper wire attached to it. the 8ga. wire gets attached to the ground rod that will be located right outside the radio room.
drill a hole in the wall and attach the 8ga. wire from the buss to the ground rod using the proper clamp. (brass) the total length of wire should not exceed about 7 feet. this means that if any of the wires going from the radio, linear, supply, or filter, is 3 feet long, then the 8ga. wire going to the ground rod cant be any longer than 4 feet.
now, attach the polyphaser to the ground rod we just talked about.
run the coax from the antenna to the polyphaser, and then a jumper from the polyphaser to the low pass filter. (it should be the last thing in line)
now go to the antenna mast and pound in the other ground rod right near the base of the mast.
attatch the rod to the mast using the proper clamp.
now run the big roll of solid copper wire (8ga. or bigger) from the antenna ground rod, to the station ground rod, and then to the ground wire of the AC system at the breaker box. (be careful around there!)
you can bury the wire, and insulated wire will last a bit longer.
that's it, now you have a single point ground.
hope this helps,
matt |
Jameslarson
New member
Username: Jameslarson
Post Number: 4
Registered: 4-2006
| | Posted on Sunday, April 09, 2006 - 11:15 am: |
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That helped alot. Thanks. How do I actually attatch the cable to my equipment? Do i just simply find a screw on rach piece and attactch it there? Do I need some type of crimped cable end and then attatch that end to my euipment? Thanks. |
Tech833
Moderator
Username: Tech833
Post Number: 1303
Registered: 8-2002
| | Posted on Sunday, April 09, 2006 - 4:04 pm: |
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Excellent job, KV!
James, yes, you just find a screw on the equipment that is bonded (electrically) to the equipment chassis and connect there. Using the crimp spade lugs works great, just be sure to solder the wire in the connector after you crimp it.
BTW, solid copper wire works better than braid for a ground connection. Braid is handy when you need to run a ground wire from something that moves a lot (like from a mast pipe past a rotor to the tower or mast below). |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1162
Registered: 6-2004
| | Posted on Sunday, April 09, 2006 - 3:44 pm: |
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The point (pardon the pun) of a single point grounding system is to prevent ground loops. It accomplishes that by connecting to the grounding system with only a single point. If there is only a single point connected to that system, there is much less of a chance for ground loops. Generally a bar, a sheet of copper, or even a copper pipe is used to centrally connect the equipment, and then that is connected with (as wide as possible) copper strap to the ground system. Hopefully that connection has more surface area than the coaxial shield so any RF travels on the copper strap instead of the coaxial cable's shield.
Grounding systems should be as large as possible. Ideally your entire house's perimeter would be surrounded by copper strap with ground rods at every corner and every 8' in between. The multiple interconnected ground rods share the job of grounding and present a better path to ground than a single ground rod can. It should connect to your home's electrical system ground if allowed, and also the ground for your tower/antenna if it's located away from the perimeter of the house. The strap used should be as wide as possible, and should be connected to the ground rods with both physical connections such as clamps, and also some kind of bonding like soldering to provide the lowest possible resistance.
Tech 833 adds- Amen!! This is EXACTLY the way it 'should' be. At the very least, go for ground rods at each corner of the building. |
Jameslarson
New member
Username: Jameslarson
Post Number: 5
Registered: 4-2006
| | Posted on Sunday, April 09, 2006 - 10:00 pm: |
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Where does one get wide straps? what type? This has been very helpful. Thanks. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1400
Registered: 9-2004
| | Posted on Sunday, April 09, 2006 - 10:18 pm: |
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hey paul (833),
a quick question.
i have some stranded copper wire with an O.D. of about 1". the insulation is about 1/16", so the O.D. of the copper is about 7/8". each strand looks to be about 30ga. wire. maybe even smaller.
i would really like to use this in my upcoming antenna installation, to run around the house perimeter interconnecting the ground rods.
i have about 100' of it, and the insulation is awesome. (got it from a theatre show load out)
what is your opinion on using this?
thanks,
matt |
Marconi
Advanced Member
Username: Marconi
Post Number: 640
Registered: 11-2001
| | Posted on Monday, April 10, 2006 - 7:14 am: |
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Kid I have seen others post that encircling the house with a ground is a good idea. I read your post above, and I believe if you are going to ground for safety then plenty of copper in the ground is important. But, in your mind, what is the idea behind this additional effort?
Due to some reading on Coppers I am begining to rethink my ideas about grounding and the use of the Polyphaser in particular. I used to "phoofa" the use of the PP, because I did not think it would hold up to a lightning strike. After rethinking, I believe it is a good idea and regardless of how it ends up, it is the only way to make a ground connection at the base of your antenna support. If you get a hit, then the low impedance of your coax is going to be the path the current follows to earth and if the PP can redirect this to ground at that point, then we have something. It might be a prudent move to place another PP at the entrance into the shack with it attached to another ground rod right outside however. You know, just in case. |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1163
Registered: 6-2004
| | Posted on Monday, April 10, 2006 - 11:19 am: |
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It puts more copper in the ground and then the entire ground system shares the burden. The point of ground rods in the corners is because turns present impedance to RF at higher frequencies, so hopefully the ground rod at the corner will dissipate the energy at the corner.
Services that enter your home at different points should have their ground interconnected to the ground(s) of other services such as cable, telephone, electrical services, etc. A perimeter ground handles that very well.
It also adds flexibilty for future expansion of your radio hobby should you choose to move your station, add an additional station, or add additional towers/poles. You have only a very short distance to connect it to ground.
I've read that a perimeter ground is standard practice in the broadcast/recording industries and I believe it originated in the military as did Ufer grounds. Perhaps someone in the business can confirm this is true, but even if it isn't it still makes sense if you have the time and resources. There is no such thing as overkill when it comes to grounding for safety or lightning protection. |
Road_warrior
Senior Member
Username: Road_warrior
Post Number: 1327
Registered: 7-2004
| | Posted on Monday, April 10, 2006 - 2:41 pm: |
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I know what you mean Marconi. The more i learned,
the more things started making sense.
I also agree with Hollowpoint on using Copper Strap. More surface area then round copper
wire.
I would think though that only 1 polyphaser would be needed in a system. |
Tech833
Moderator
Username: Tech833
Post Number: 1304
Registered: 8-2002
| | Posted on Monday, April 10, 2006 - 10:40 pm: |
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KV- That wire will probably work just fine. However, I would suggest removing the insulation if possible. It is not mandatory, but it would make your system slightly more effective.
Using more than 1 Polyphaser will not hurt anything, but I am not sure of the benefits. A Polyphaser isolated the coax center conductor (there is NO continuity through a Polyphaser). Insulating it twice may have some benefit in a direct strike situation, but I have not tried it. One Polyphaser always seems to do the trick.
Yes, it is stadard in professional broadcast and communications installations to do a perimeter ground. Some also install a 'halo ground' inside the building to bond all the racks and equipment to. |
Chad
Advanced Member
Username: Chad
Post Number: 778
Registered: 11-2004
| | Posted on Tuesday, April 11, 2006 - 8:48 am: |
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We recently did a halo ground in the last shack build and it seems to be working out better for us. Although the whole thing was gutted and rebuilt we have NO, None, Zilch, signs of AM rectification in the plant be it on phones, computers, or consumer electronic equipment! Made me a believer!
Chad |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1413
Registered: 9-2004
| | Posted on Tuesday, April 11, 2006 - 11:53 pm: |
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thanks for all the input guys,
yes, i am considering this to be a "safety" ground.
while i like the idea of doing a perimeter ground, and will end up doing one at my next location, (hopefully very long term), the only reason i mentioned using so much of the wire was that i would need a lot to get all the way around a house, and i was just considering that i would have to for logistical reasons.
the real question was about whether a HUGE stranded copper wire (this stuff looks like a garden hose!) would be an effective ground path in the case of a strike.
everything i have read says that lightning likes a solid conductor better than a stranded one, but i have so much of this stuff that i want to use it.
833, i thought about removing the insulation, (that would be one stinky fire!) but i am wighing the gains against having to replace it sooner due to corrosion. or will it corrode underground just as fast with the insulation on?
good thread here guys!
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1306
Registered: 8-2002
| | Posted on Wednesday, April 12, 2006 - 10:42 am: |
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KV,
First of all, I do not recommend removing insulation with fire. A knife works way better and leaves the copper clean.
Your copper will not corrode under ground if the insulation is left on, but that is not the point. You WANT the copper to mend with the ground. If your copper is garden hose size, it will outlive you in almost any ground acidity.
I have some AM's that are almost 60 years old and the #10 bare copper radials still look good. Of course the copper is no longer shiny, but the wire size is unchanged and it is still very strong and conductive.
Now, if your copper ring-around-the-house is not in contact with the ground at all, then it does not matter if it is bare or not. If it is laying on the ground, then you would benefit from having it naked. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1418
Registered: 9-2004
| | Posted on Wednesday, April 12, 2006 - 10:33 pm: |
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good deal 833!
thats what i needed to know, what kind of time frame we are dealing with as far as the corrosion goes.
that cinches it; i'll be stripping the insulation off.
im already thinking about how i would build some sort of jig that i could attach a razor knife to, and then just pull the wire through, since i have such a long run to do.
thanks for the input.
matt |
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