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Topic Title: Amateur Radio Grounding Opinions RFI/TVI
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Created On: 17 November 2013 03:03 PM
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 17 November 2013 03:03 PM
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g7jwr

Posts: 20
Joined: 28 June 2013

Hi All,
I am looking for opinions on grounding of Amateur Radio equipment, i.e. Transceivers, Linear Amps, Power Supply chassis and coaxial cable to independent earth (earth spikes)
Particularly interested in the use of such an earth system to combat or reduce the effects of RFI/TVI.
I would also be interested if anyone has used commercial built line isolator for coax such has the MFJ 915 or the W2DU
Martin
 17 November 2013 09:02 PM
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kengreen

Posts: 400
Joined: 15 April 2013

Hello Martin,

Yes, I am mildly surprised that accidents of this kind seem to be rare in the amateur realm.

Thinking, except in the VHF bands, needs to start with the aerial (or in English-US, the antenna); the efficiency of physically large radiators is critically dependent on a good solid earth and there exists a (perceived) risk - in the event of a break in an Earth connection to the mains supply - of the amateur rig carrying earth currents from the locality. It is important therefore to establish a good and reliable Earth connection to which all the amateur equipment must be connected and then disconnecting entirely the AR equipment from an incoming mains earth.

I have written elsewhere on this forum of my earthing problems which are exacerbated by the excellent drainage from which I suffer - seasonal and short-term variations in the weather figure largely. We live in a very narrow valley from which the sole "escape" is due west and, of course, upward. I built a long-wire aerial close on 500-feet as high as I could get it which was the only position in which it could be built which meant that for most of its length it paralleled an 11-kV overhead feeder which was much too close for comfort. I erected a 42-foot mast of two 21-foot scaffold poles which was designed so that, in the event of any failure, it must collapse rather than fall. That long wire began with an Earth point which I created from the bottom of a defunct copper hot-water tank to which I attached a heavy tail by both bolt and solder and also ran a counterpoise wire from there under the aerial.

It worked into Australia but never made contact in the Home Counties! The only problem was that when it rained the entire rig was blotted out by a raucous mains hum caused undoubtedly by corona off that 11-kV which otherwise (I believe) acted as a nationwide coupled aerial? We also built several experimental aerials for all bands; only one problem arose from the AR equipment when somebody complained that his battery-operated domestic receiver was plagued by Morse over its entire range - he had it standing on the cooker hotplate, because that was where it worked best, and the "fault" was cured by the application of a small mechanic force!

I must admit however that much of this success probably arose from our isolation and can envisage every kind of problem had we been in a residential area. Even kindly and friendly neighbours can be a pain for the amateur!

Ken Green
 18 November 2013 07:58 AM
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g7jwr

Posts: 20
Joined: 28 June 2013

Alan Thanks for the info, I have started the task a few days ago of grounding the station (Earth)
My Mast is an ex military pump mast so it is only possible to earth the whole mast only the bottom section which I have done, I have also grounded the outer coax. The earth points at the moment comprise of three earth spikes linked together but I intend to increase this number in the near future.
This takes me the entry point into the shack, my intention here is ground every bit of kit I have in the shack even the computer, I am also considering the use of line isolators but have no experience of them in the past. My idea is to use independent earth straps on each piece of equipment going back to one central point which will then exit the shack to the earth spikes, by using separate straps going to one central point instead of daisy chaining each piece of equipment together, I hope to reduce the chances of ground loops.
So this is where I am as of today and will making a start inside the shack today
Any views on this subject welcome

Martin G7JWR
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