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2nd Story Grounding Solutions ?

Discussion in 'General Technical Questions and Answers' started by N9ALS, May 18, 2008.

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  1. N9ALS

    N9ALS Ham Member QRZ Page

    My shack must be set up on the second story of my house. I understand that long grounding wires can become resonant and cause all kinds of problems(?). What solutions are there for this scenario?
    Also, is it necessary to keep the feedline away from the ground-line conductor- I am curious if I can run them out through the same wall opening.

    73,

    Al
     
  2. W9TTW

    W9TTW Ham Member QRZ Page

    Ground problems

    I have the same situation but have never had any problems. My antennas are far away from the house so that may have something to do with it. My ground wire runs throught the same pass through also. I have 3, 8 foot ground rods that are all bonded together. All antennas and radio equipment are all on the same grounds. I have never had any problems. Send me an email and I can send you some pictures of my setup. Thx and 73
     
  3. AG3Y

    AG3Y Ham Member QRZ Page

    What type of antenna are you planning to use ? You do NOT need an RF ground on your radio/tuner/etc. in most cases. IF you are feeding an unbalanced antenna, then you will need a good RF ground system ( counterpoise or ground plane ) located as close as possible to the FEEDPOINT of that antenna . The feedpoint is defined as the place where the feedline ( coax or twin feeder lines ) attaches to the antenna .

    There are untold numbers of posts on this forum about hooking up grounds to the rig. I have NEVER used an RF ground on the chassis of my radio, or tuner in over 25 years of operating a ham station. But of course, all of my antennas have had balanced feeds or a counterpoise/ground plane at the feedpoint!

    Check out Glen's web page for thorough information about safety grounds, RF grounds, the differences, and what is needed for your station.

    73, Jim
     
  4. WA8RTI

    WA8RTI Ham Member QRZ Page

    Some people report good results when using the MFJ artificial ground. As I understand it was designed for people in your situation. You might look for reviews of it on various ham web sites.
     
  5. N9ALS

    N9ALS Ham Member QRZ Page

    The grounding connector on the rear of my radio's chassis... is that for RF or electrical/safety ground? Don't I need to have it grounded for safety?

    It was my understanding that most all radios have an unbalanced feed (so-239 for coax?), but then you must use a blaun for a balanced feed (i.e. I want to convert the coax to ladder line for my wire dipole). Where should the balun be located (near radio or near antenna feed point)? Would this situation require an RF ground (and where/how do I actually ground this setup)?

    I don't think it's practical to run a braid wire all the way from the second story(?)
    Do I have to use that type of wire, or will 14 or 16 gauge electrical wire work ?
     
  6. KK5NL

    KK5NL XML Subscriber QRZ Page

    I am in a similar situation, second story shack, currently just using the ground plug as my electrical ground, and I have no RF ground.

    From what i have read, if you install a bus bar, and just ground your power supply, rig, etc to it, thats better than no ground at all. As this makes sure each of your equipment is at same ground potential. Ideally you would want that bus bar grounded too, but from what I read its better than nothing.

    I have conduit in my attic, that goes down to my power panel. I could run a ground from my bus bar up into my attic and down into my power panel, to ground against a earth ground at my breaker box. My concern is that now I end up with a 25-30' ground wire and maybe its a better antenna than it is a ground!

    Truth is, long grounds are everywhere. Look at high rises, office buildings, skyscrapers. They have radio equipment on the roof alot of times to minimize transmission line loss. They may be 100's of feet from the earths ground, so obviously they run some sort of ground system which is not a short path to true ground, but things work...........
     
  7. W8JI

    W8JI Ham Member QRZ Page

    Al,

    There are only two times when you need an RF ground in the shack.

    1. When you intentionally feed an antenna directly from the shack that requires a ground to function, like a random wire or any other single conductor feedline.

    2. When you accidentally bring RF into the shack from a poor antenna design, poor antenna system components, or poor antenna layout.

    Both of these cases obviously mean you have something bad in the antenna design, so it is fair to say the only time you need an RF ground is when you have an antenna or hardware problem.

    Often amateur gear does not meet the same consumer safety standards as common appliances, so it requires an electrical safety ground independent of the house wiring path to the safety ground, BUT ALWAYS bonded to that ground. This safety ground is required because our equipment normally uses an outside or external antenna, and our equipment sometimes even has high voltage transformers. It is possible for example for a linear amplifier with a 3000 volt supply to have more than 3000 volts on the chassis if the chassis is not grounded and the power transformer develops a primary to secondary short. It is also possible during a power mains fault or lightning event for a surge to flow from the power mains into the antenna (or less commonly the other way around), so you would want everything (especially the antenna entrance) to be well-bonded to the power mains ground OUTSIDE the house wiring path.

    The safety ground is always required but the RF ground clearly is a band-aid or patch for an antenna system problem. It is better to fix the real problem than to patch it.

    The safety ground MUST be bonded to the power mains entrance ground. Adding a shack ground that does not tie the mains ground into the system outside the house actually increases the chances of lightning or power line fault damage or hazzard.

    Nearly all of the lightning protection you get from a shack ground and ALL of the electrical fault safety will be from bonding the power mains ground to the feedline entrance and shack grounds. If you fail to bond into the mains ground properly you actually increase some risks.

    As for resonant ground leads, resonance is not an issue. The impedance is an issue. The ground will not radiate no matter how long it is if the antenna system is proper. If the antenna is improper any ground lead and even the wiring inside the house will be radiating, and nothing you do to the ground will eliminate the problem. You might change what you notice by changing the ground lead length or using an artificial ground, but you cannot stop the overall unwanted radiation. You can just move it around a little, perhaps to a place where it is less noticable.

    We can have a terrible ground with a terrible antenna and not notice problems in the shack if everything entering the shack is at the same potential. If everything in the room is bonded together with short heavy leads even considerable unwanted RF current in the shack would not be noticable. We shouldn't confuse the fact we don't notice a problem with the fact we don't have a problem.

    I have some stuff at:
    Staion Grounds
    73 Tom
     
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