Howdy,
I am currently building up my station. This weekend I have been installing the station earth. I have posted some photies here:
http://60.242.149.195/e107/e107_plugins ... ?3729.last
The stake is driven about one metre into the ground - clay then shale - so I ended up having to cut about a foot off the stake when I thought I had hit rock. The cable will then go up to the second storey where my office is located.
Earth Steak
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VK5PJ
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Re: Earth Steak
Hi, did not get to look at your photo's but if you have had problems getting one earth stake to full depth you should consider adding multiple earth stakes and hook them together via a heavy copper cable or copper strip.
Relying on one stake that is partially in the ground is a bit like having a condom with a hole in it.
and thinking your safe.
You should always consider what sort of soil the stake is going into when planning your earthing system and if you have a tower near by, you should give consideration to connecting the base of the tower to the shack earth stake through a trench to help with lightning srikes
Peter
Relying on one stake that is partially in the ground is a bit like having a condom with a hole in it.
and thinking your safe.You should always consider what sort of soil the stake is going into when planning your earthing system and if you have a tower near by, you should give consideration to connecting the base of the tower to the shack earth stake through a trench to help with lightning srikes
Peter
VK2FANG wrote:Howdy,
I am currently building up my station. This weekend I have been installing the station earth. I have posted some photies here:
http://60.242.149.195/e107/e107_plugins ... ?3729.last
The stake is driven about one metre into the ground - clay then shale - so I ended up having to cut about a foot off the stake when I thought I had hit rock. The cable will then go up to the second storey where my office is located.
Peter Sumner, vk5pj
You have enemies? Good. That means you've stood up for something, sometime in your life.
- Winston Churchill
You have enemies? Good. That means you've stood up for something, sometime in your life.
- Winston Churchill
Re: Earth Steak
I have found the best way to get earth stakes in is to use something like a Kanga (electric) jack hammer. Just use the Kanga, without any tool attached on top of the earth stake. You'll be surprise how the stake disappears into the ground.VK2FANG wrote:
The stake is driven about one metre into the ground - clay then shale - so I ended up having to cut about a foot off the stake when I thought I had hit rock. The cable will then go up to the second storey where my office is located.
73 Brian
VK5BC
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VK4QB
Re: Earth Steak
Hi All,
Just recently I was given a pre-loved earth stake and, as in the past I have been worried about lightning strikes, I have made moves to belt this one into the ground and as I live in the city of ROCKhampton I only got about 1/2 way down. Thanks for the way to get more power into the sledge hammer Brian 5BC. I will check it out tomorrow !!! However, interesting measurements have shown that there is a 10k ohm connection between this earth stake and the steel house stumps which are imbeded in concrete. ???? Is concrete a conductor ? Evidently it is !!! This is measured with a digital ohmmeter. I also measured the connection between the power earth and the new earth stake and got 300 mv AC between the two earth stakes, but no AC between the steel house stumps or the new earth stake. Mmmmmmm. Possibly some coupling somewhere. We've got the summer storms coming up in a couple of months so I thought I should go around and check a few earths.
Posted for interested earth connectors
Brian 4QB
.
Just recently I was given a pre-loved earth stake and, as in the past I have been worried about lightning strikes, I have made moves to belt this one into the ground and as I live in the city of ROCKhampton I only got about 1/2 way down. Thanks for the way to get more power into the sledge hammer Brian 5BC. I will check it out tomorrow !!! However, interesting measurements have shown that there is a 10k ohm connection between this earth stake and the steel house stumps which are imbeded in concrete. ???? Is concrete a conductor ? Evidently it is !!! This is measured with a digital ohmmeter. I also measured the connection between the power earth and the new earth stake and got 300 mv AC between the two earth stakes, but no AC between the steel house stumps or the new earth stake. Mmmmmmm. Possibly some coupling somewhere. We've got the summer storms coming up in a couple of months so I thought I should go around and check a few earths.
Posted for interested earth connectors
Brian 4QB
.Re: Earth Steak
Learning heaps. Thanks.
Re: Earth Steak
Just to add a bit of technical knowledge to the discussion, a few years ago I had a long discussion with an engineer in the USA from one of our suppliers. My job involves working with licenced (6-70 GHz) and unlicenced (2.4 and 5.8 GHz) links on rooftops etc.
We had a bit of a problem with a certain model of gear dying on us after a couple of years on the ethernet side. So after a call I was a bit more enlightened about the physics of it all.
A typical lightning strike has a rise time in level about equivalent to 100 MHz, then dies off more slowly. A good building or tower earth will measure pretty much zero ohms resistance as you would expect. But unfortunately for us the earth cable exhibits an impedance at 100 MHz, which can equate to about 10k resistance.
So despite having good lightning arrestors and a good earth, the cable down the side of the building or tower represents a stopping point. The induced voltage from a nearby strike could well be enough to cause minor damage to the silicon interface in the radio's ethernet port before it bleeds off, that would gradually show up as current leaking through. Eventually this would build up to a stage where the transistors would latch on and it would stop working. A power cycle fixed it for another month or so before the leakage again caused the problem.
Slightly different with radios feeding RF up the cable as opposed to ethernet, but it shows the limitations of even a good earth system. And I agree with all the comments before about how to belt the earth stake in or use of multiples. We had one a few years ago in Adelaide (not installed by us orignally) where the 20m tower was on a concrete block and not earthed. A direct hit took out the radio and about 75m of coax cable - we had to replace the whole run (indoor unit feeding IF at a few hundred MHZ to the tower radio that was 23 GHz).
Had one a few months ago where a direct hit took out the ethernet port of our radio and one of the switch ports, on top of an 8 story block of flats - as well as blowing the inlne fuse we had. But it also knocked out their TV system and security in the block. Very hard to protect against a direct hit - except pull the plug if you can! That's why during storm season the radios and antennas are not plugged in when I'm not here, I figure that 9 metre mast out the back is a nice lightning rod, even though it is well earthed I don't want any residual current flowing down the wires!
We had a bit of a problem with a certain model of gear dying on us after a couple of years on the ethernet side. So after a call I was a bit more enlightened about the physics of it all.
A typical lightning strike has a rise time in level about equivalent to 100 MHz, then dies off more slowly. A good building or tower earth will measure pretty much zero ohms resistance as you would expect. But unfortunately for us the earth cable exhibits an impedance at 100 MHz, which can equate to about 10k resistance.
So despite having good lightning arrestors and a good earth, the cable down the side of the building or tower represents a stopping point. The induced voltage from a nearby strike could well be enough to cause minor damage to the silicon interface in the radio's ethernet port before it bleeds off, that would gradually show up as current leaking through. Eventually this would build up to a stage where the transistors would latch on and it would stop working. A power cycle fixed it for another month or so before the leakage again caused the problem.
Slightly different with radios feeding RF up the cable as opposed to ethernet, but it shows the limitations of even a good earth system. And I agree with all the comments before about how to belt the earth stake in or use of multiples. We had one a few years ago in Adelaide (not installed by us orignally) where the 20m tower was on a concrete block and not earthed. A direct hit took out the radio and about 75m of coax cable - we had to replace the whole run (indoor unit feeding IF at a few hundred MHZ to the tower radio that was 23 GHz).
Had one a few months ago where a direct hit took out the ethernet port of our radio and one of the switch ports, on top of an 8 story block of flats - as well as blowing the inlne fuse we had. But it also knocked out their TV system and security in the block. Very hard to protect against a direct hit - except pull the plug if you can! That's why during storm season the radios and antennas are not plugged in when I'm not here, I figure that 9 metre mast out the back is a nice lightning rod, even though it is well earthed I don't want any residual current flowing down the wires!