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Message |
    
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 251
Registered: 7-2004
| | Posted on Tuesday, August 24, 2004 - 5:51 pm: | 
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I read that a ground wire over 9 feet was not a good thing. I just want to be sure because if it is I might have to figure out some other way to ground my base equipment.
Thanks in advance
Bob |
Pig040
Advanced Member
Username: Pig040
Post Number: 561
Registered: 7-2003
| | Posted on Wednesday, August 25, 2004 - 10:05 am: |
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From what I have read, the ground wire can become resonant if it is too long, but most people cannot cut it with 9ft, mine is about12 ft, and works well. |
Bob_p
Intermediate Member
Username: Bob_p
Post Number: 254
Registered: 7-2004
| | Posted on Wednesday, August 25, 2004 - 12:20 pm: |
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What I read was basically if it's over 9 feet long it begins to become less effective and begins to put out RF and can become source of TVI.
I think what Rich said is more or less it. By the way mine is about 12 feet as well. I have a #14 solid core copper wire attatched to eveery thing in the shop, and 12 feet is about as short as I can get it unless I begin to move things around which wuold be a bear. |
Gonzo
Junior Member
Username: Gonzo
Post Number: 23
Registered: 9-2004
| | Posted on Wednesday, September 29, 2004 - 9:33 am: |
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Under 9 feet is the general rule, however you can use coax, the thicker the better (RG142 I think). Use the center conductor only and make ground wire as short as possible, and attach to a 8 foot copper rod or copper clad rod buried in the ground. Before burying and after placing the rod, spread rock salt in and around the hole and around the rod.
Your not done: You need at least 2 other copper rods sunk 8 feet down and spread them at least 6 feet from the first sunk rod in a triangle configuration if possible. Attach all 3 rods with 8-10 gauge wire buried at least 2" below the grounds surface. As an alternative you can use 20-40 feet of flexible copper tubing and create your own circle around the first sunk copper rod, and attach to that rod with 8-10 wire similar to the 3 rod arrangement. be sure to bury the copper tubing & wire attached at least 2" below the surface so that it doesn't not radiate RF.
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You are accomplishing 3 things here.
1. Grounding your antenna system and radio to protect from lightning strikes
2. Eliminate stray RF like TVI, and RF running back down the cable from the antenna. This can also eliminate alot of mike squeel and other weird SWR and Linear amp problems.
3. You also will make the alot of noise & garbage that your antenna picks up disappear.
The coax will not radiate, unlike a straight copper wire over 9 feet in lenght. DO NOT connect the shield of the coax ground wire to anything! This is very important. Just use the center conductor.
Connect any outside metal case parts of ALL of your equipment to this ground, including the base of your microphone. This means: microphones, TVI filters, Radio's, Amps. Anything that has a possiblilty itself of radiating RF. |
Tech833
Moderator
Username: Tech833
Post Number: 868
Registered: 8-2002
| | Posted on Tuesday, October 05, 2004 - 1:31 am: |
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Bob,
No sweat really.
Gonzo,
Let me correct a few things.
1. If you use coax as a ground wire, you use BOTH the inner and outer conductors together. If you just use the inside, the cable will not provide lightning protection. It will become a bazooke choke at most frequencies and a baun on a few.
2. Using a pair of 8 foot ground rods is a great idea, but they must be more than 8 feet apart or they will cancel each other out.
3. All the rock salt will do is corrode the copper rod much faster. Fine sand is a better choice. |
Gonzo
Junior Member
Username: Gonzo
Post Number: 43
Registered: 9-2004
| | Posted on Sunday, October 10, 2004 - 5:03 pm: |
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Tech883
1. I am connecting the inside of the "ground wire" coax to the outside of the active coax (shield) and chassis of rig and microphone. The outside (shield)of the "ground wire" coax then Indeed does become a Bazooka Choke! It prevents any RF from the inside from being radiated outside. This is what you want. This bleeds off any static rf buildup, and will prevent most strikes.
2. Whether the ground rods are 6 feet or 8 feet apart makes no difference actually, the idea to to get a solid ground connection. Actually more than 2 rods spaced apart as such would be even better.
3. Yes you are correct rock salt WILL EVENTUALLY corrode the copper rod, in fact faster then not using it. However rock salt guarantees that the area around the Ground rod is in fact bleeding off any electrical charges. In effect you are giving yourself a perfect ground in the area around the copper rod. So Yes you are correct.
You could mix the rock salt with the dirt to try to give the surrounding dirt better conductivity. This will not corrode the rods so fast.
Another alternative (now this is getting silly) is too water the ground rods before going on the air!! This will also ensure that the area around the rods is capable of conducting electrical current.
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Botoom Line ....a good ground however you do it is important. |
Gonzo
Junior Member
Username: Gonzo
Post Number: 44
Registered: 9-2004
| | Posted on Sunday, October 10, 2004 - 7:15 pm: |
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I just happened upon another user who posted similar information as I did, possibly his explanation is better than mine. This is the thread. Warlock's answer is essentially a duplicate of mine, possibly he has a better command of the english language than me.
Copper Talk » Product Reviews » Amplifiers » X-Force Base Amplifiers
Although the set-up is NOT a exact bazooka antenna set up,it is similar. In the bazooka antenna the shield is also connected to another piece of coax. This is NOT the case here. |
