[TowerTalk] Rooftop vertical grounding
Thu, 10 Feb 2000 16:30:58 -0800
Jeff: You have come to the right place to find answers to your
Welcome to ham radio. We could use many more like you. You showed by
questions that you have searched the archives and learned all that you
before asking intelligent questions on topics of importance to you. I
will comment on a couple of things.
I believe that you have selected an antenna which is considered by many
one of the best of the multiband trap verticals.
There is no better way to protect your equipment from lightning damage
than disconnecting all external wires from it. This includes coax feed
rotator cables,antenna selector switch wiring, and power cable. There is
nothing wrong with disconnecting the grounding cable when you are not
operating but it must be in place when you are using the station. Most
hams leave the ground cable connected when the station is not in use.
Your other questions can be best answered by one of the several
Good luck with your station installation.
73, Dan, N5AR
> Hello everyone.
> My name is Jeff and I'm a new ham. I received my general class
> license approximately two weeks ago. Call sign is KC0HEP. I
> live in Colorado. I'm not putting up a tower (yet), so if this
> not the appropriate forum for my questions, please chastise
> me and I'll be on my way.
> My first antenna is going to be a vertical. The Butternut HF9V
> to be exact. I'm planning on mounting it the roof of my house
> with the counterpoise kit on a tripod. The antenna is about
> 26 feet in height.
> I'm trying to figure out the best way to ground this thing in
> case Mother Nature decides to zap it.
> The antenna needs to be mounted in the middle of the roof because
> there will be four rope guys going to the corners of the roof.
> So the down conductor(s) will have to take a turn when it gets
> to the edge of roof. I understand from reading messages in
> the towertalk archive that the turn should be as small as
> possible. Does anyone know how tight I can go? If I did get
> a lightning strike and the bolt reaches the turn, I don't
> know where it else it could go (other than down the coaxial
> cable). All the fences around here are wood and there aren't
> any above ground utilities. So wouldn't it continue down
> the conductor to ground in spite of the turn?
> I'm thinking about two down conductors of #1/0 gauge going down
> adjacent corners of the house into separate ground rods tied
> together. Is this enough? Can I get away with only one down
> conductor? It is my understanding that the down conductor
> surface area should be at least equal to or larger than the
> total surface of the coax. I'd like to use insulated conductors
> if possible. Any reason why I should use bare conductors?
> Since my shack will be in the basement, I'm looking at
> installing an entrance panel at the top of the wall of the
> shack (have to see how much room I have between the top of
> the foundation and the floor above to see if I can squeeze
> one in there). So the outside of the entrance panel would
> be tied into earth ground and the inside would be tied
> into the equipment bus bar. I have a electrician coming
> over to see about moving my service ground (which currently
> resides under a concrete patio) somewhere else so I can
> tie into it.
> The part that scares the hell out of me is tying my shack
> bus bar into the antenna ground.
> Let's say I've done everything by the book with respect
> to lightning protection. What if the energy from the
> strike isn't dissipated by ground quickly enough? What's
> to stop the energy from finding it's way to my equipment?
> I'd like to have a good RF ground for sure, but I'm worried
> about protecting my equipment. I'd like to set something
> up where I could not only disconnect the antenna feed
> from the shack, but also disconnect the bus bar from
> ground when not operating. I'm thinking that this way,
> if a lightning strike does occur (when I'm not operating)
> the equipment is isolated. Of course *all* connections
> would be severed (power, etc.)
> Is this a good idea? Comments? Flames?
> Thanks for reading this far.
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