WA Radio Scanner Users' Group

Hi all,

I have some dumb questions that I hope noone minds me asking, and I figured others may have questions about setting their shacks up too.

My question...

I have an HF base rig, a rather long dipole antenna and I need to ground the antenna. How do I do this??? Run coax from rig -> earth spike -> antenna, but how to connect them all together? Just put a cut in the coax partway along and run copper from that to the spike?

Apologies for the dumbness of the question... at least I'm asking before I blow something (or someone - probably myself) up

Cheers
Meg

I don't think it is a dumb question, it's something that's you need to know!

Is this in the Foundation manual? I have a feeling I read it there... I can't check any more because somebody stole mine

Check this powerpoint out. It might help

http://www.aksarbenarc.org/main/media/H ... unding.ppt

A "complete" antenna like a dipole or a ground plane does not need a RF ground, as long as you keep common-mode currents off your feedline. A "current" or "choke" balun is most commonly used for this.

Ground your rig and any other devices to the same point and not from one to the next.

Choke balun at HamUniverse.. easy to make, no cutting etc

http://www.hamuniverse.com/balun.html

I use this on a couple of 2m antennae

robbage wrote:Is this in the Foundation manual? I have a feeling I read it there... I can't check any more because somebody stole mine

Check this powerpoint out. It might help

http://www.aksarbenarc.org/main/media/H ... unding.ppt

The powerpoint is perfect - the foundation manual mentions grounding, but doesn't talk about how to do it.

Thanks Robbage

That PowerPoint slide is brilliant!

Page 53 of the first edition Foundation manual (I haven't got my hands on the new one yet), does have a small section on RF Earth:

Earthing or Grounding

Your amateur station should have a 'signal earth' consisting of a thick and short wire connected to a ground rod, water pipe or/and a series of buried wires. The thick earth wire is connected to the rear of your antenna tuner or if you don't use a tuner to your transceiver.

A suitable earth can be made using 6 square mm earth wire connected to a ground stake or water pipe. If your station is in a multi-storey building, or more than a few metres above ground, then such earthing is not practical and the methods are mroe difficult. Seek advice from a more experienced person at a local radio club.

The photo that goes with the text shows some thick earth wire clamped to a copper rod buried in the ground. One thing I remember being told about connecting the wire to the ground stake is to use a clamp rather than solder.

Also, even though the book mentions a water pipe, I think I'd much rather use a dedicated earth stake.

The problem with using a water pipe is that they are sometimes not a proper ground, with the risk that anybody touching a tap or having a shower can get zapped. This happens occasionally with mains power grounded to water pipe.

Yes - and that's the kind of excitement I could do without

robbage wrote:The problem with using a water pipe is that they are sometimes not a proper ground, with the risk that anybody touching a tap or having a shower can get zapped. This happens occasionally with mains power grounded to water pipe.

Copper water pipe is required to be bonded to the earth stake so doesn't matter what you use they are all connected.

FoxtrotZu;u wrote:Copper water pipe is required to be bonded to the earth stake so doesn't matter what you use they are all connected.

I'm not sure what you're trying to say there, would you mind elaborating?

AS/NZS3000:2008 states that all copper water pipe (amongst others) in an installation is required to be bonded to the protective earthing system of the installation at the main earth stake. This joint is known as the equipotential bond. Clear enough?

FoxtrotZu;u wrote: Copper water pipe is required to be bonded to the earth stake so doesn't matter what you use they are all connected.

Most of us drive in our own independent RF earth stake that's not linked to anything else

FoxtrotZu;u wrote:Copper water pipe is required to be bonded to the earth stake so doesn't matter what you use they are all connected.

Yes. Unfortunately people disconnect them, plummers don't have them redone after work, they get knocked off, they corrode and some electricians don't do what they are supposed to in the first place.

Zebedee wrote:

Earthing or Grounding

Your amateur station should have a 'signal earth' consisting of a thick and short wire connected to a ground rod, water pipe or/and a series of buried wires. The thick earth wire is connected to the rear of your antenna tuner or if you don't use a tuner to your transceiver.

The photo that goes with the text shows some thick earth wire clamped to a copper rod buried in the ground. One thing I remember being told about connecting the wire to the ground stake is to use a clamp rather than solder.

Yep, the station earth isn't a problem - there's a lug on the back of my rig and I have some copper pipe - just a matter of drilling a hole in the floor to feed the wire through and digging some kind of hole in this gravel!

I'm trying to figure out how (and looking at that powerpoint doc - IF) to earth the dipole antenna also.

Either way, I think the antenna goes into the trees tomorrow and we'll start on the earthing system, but I'd like to get everything *right* before I switch on and irradiate everything within a 5km radius - the firies are likely to scold me alot if that happens

Cheeers
Meg

meg wrote:I'm trying to figure out how (and looking at that powerpoint doc - IF) to earth the dipole antenna also

I'm pretty sure you don't need to for a dipole. Does it have a balun on it already or is it a plain coax cable with a wire from the shield and another from the centre? That link I posted about making a balun is easy and doesn't require cutting or soldering the existing antenna. I made mine with about 100mm of PVC pipe with a notch in each end where the coax could be slotted into the notch, wind some turns and slotted into the other notch. If you do it right, you don't need to tape it (tape will perish). The PVC pipe should be UV-stabilised type so it doesn't kark it either.

robbage wrote:I'm pretty sure you don't need to for a dipole. Does it have a balun on it already.

Thanks Robbage - yep, it's got a balun already. So, this means I might be able to get this rig fired up by the end of the long weekend, which would be fantastic!

Thanks again, and particularly for not laughing at the dumb question! I'm sure I'll have more...

Cheers
Meg