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 earthing braid 
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Hi folks I keep reading posts about people looking for suppliers of earthing braid the best place and cheapest is a car breakers all cars vans etc have earth straps from the engine to the body etc


Thu May 02, 2013 9:36 pm
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 earthing braid 
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Post Re: earthing braid
Earth straps for engines are good for DC but not good for RF. Flattened RG213 braid works better.


Thu May 02, 2013 9:46 pm
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 earthing braid 
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m6tee wrote:
Earth straps for engines are good for DC but not good for RF. Flattened RG213 braid works better.

For what reason?

Cheers

Tony

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Thu May 02, 2013 9:49 pm
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 earthing braid 
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m6tee I have used them and they stop rf in the shack I was on the second floor of the house


Thu May 02, 2013 10:08 pm
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 earthing braid 
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mi0hgn wrote:
m6tee I have used them and they stop rf in the shack I was on the second floor of the house



that's a long engine strap!

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Fri May 03, 2013 5:56 am
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 earthing braid 
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gw8asd wrote:
m6tee wrote:
Earth straps for engines are good for DC but not good for RF. Flattened RG213 braid works better.

For what reason?

Cheers

Tony


Got me baffled too :scratch:

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Fri May 03, 2013 6:49 am
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 earthing braid 
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bonehead the straps were used to connect radio to atu etc then I had to use wire down to a copper pipes I had buried


Fri May 03, 2013 7:22 am
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 earthing braid 
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What antenna are you using? What is the length from the equipment to the buried copper pipes? And what are trying to achieve? Is it RF bonding or electrical safety bonding? Sorry about all the questions, but you might not have to go to all that extent if it's not needed.

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Fri May 03, 2013 7:31 am
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 earthing braid 
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Hi Paul sorry that was in 2006 I was getting rf thru the radios speaker and getting rf burns from the atu when I added the straps wire and pipes it cured it


Fri May 03, 2013 7:37 am
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 earthing braid 
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mi0hgn wrote:
Hi Paul sorry that was in 2006 I was getting rf thru the radios speaker and getting rf burns from the atu when I added the straps wire and pipes it cured it


I understand, you might have found just by adding a counterpoise would have had the same affect with less work. That is probably all you were doing anyway. Unless you can make the connection between the equipment and ground less than 6 feet then you are going to end up with a length that is going to be a significant portion of a wavelength long, hence the reason I would use a counterpoise, it is more predictable than a variably lossy ground connection.

There are safety implications of adding an addition earth connection as well, which has been discussed on the forum before.

That is why I was asking about the antenna because there must have been a reason why you had all that RF around the shack.

I am not avoiding answering the question about earthing braid, as you can see by my previous comments I think braid is a waste of money when there are other ways to achieve the same or better results.

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Fri May 03, 2013 8:15 am
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 earthing braid 
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Hi Paul the antenna at that time was a home 80m dipole fed with coax no balun etc


Fri May 03, 2013 8:22 am
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mi0hgn wrote:
Hi Paul the antenna at that time was a home 80m dipole fed with coax no balun etc


That sounds like you were getting RF back down the coaxial cable, an easy fix without going to the extent of burying pipes :thumbsup:

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Fri May 03, 2013 8:33 am
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 earthing braid 
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Strip form copper or brass is better for RF conduction because high frequencies are carried on the skin of the conductor. A flattened form of conductor has a greater surface area than a round conductor. That's why high power RF amplifiers often use strip to connect RF components, rather than wire, and why high power RF coils are often wound in tubular material, rather than solid. As RF is only flowing on the skin the lack of material in the centre of the conductor is irrelevant. I hope I have this right, my Elmer was drumming it into me the other day!


As a person who works in the motor trade, I haven't seen braid used for earthing engines or batteries to the chassis in many years, most if not all cars use normal insulated cable these days. I too would like a source of heavy copper braid, at a decent price, here in the UK.


Fri May 03, 2013 9:28 am
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Basil wrote:
Strip form copper or brass is better for RF conduction because high frequencies are carried on the skin of the conductor. A flattened form of conductor has a greater surface area than a round conductor. That's why high power RF amplifiers often use strip to connect RF components, rather than wire, and why high power RF coils are often wound in tubular material, rather than solid. As RF is only flowing on the skin the lack of material in the centre of the conductor is irrelevant. I hope I have this right, my Elmer was drumming it into me the other day!


As a person who works in the motor trade, I haven't seen braid used for earthing engines or batteries to the chassis in many years, most if not all cars use normal insulated cable these days. I too would like a source of heavy copper braid, at a decent price, here in the UK.

One problem with braid is that the surface current needs to conduct readily from one strand to the next in order to exploit the potentially large surface area. If the braid is outdoors and begins to "weather", conduction from strand to strand may suffer and the effective impedance increases.

Steve G3TXQ


Fri May 03, 2013 11:05 am
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 earthing braid 
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G3TXQ wrote:
One problem with braid is that the surface current needs to conduct readily from one strand to the next in order to exploit the potentially large surface area. If the braid is outdoors and begins to "weather", conduction from strand to strand may suffer and the effective impedance increases.

Steve G3TXQ

I've almost always used solid, for outside, but often braid for internals where solid has been a problem to fit.
Braid, obviously, for anything moving.

I've still not seen a response to the "straps are no good for RF statement.

I can't see any reason myself. :scratch:
Other than the possible corrosion problem but, externally, I've always wrapped it anyway.

Cheers

Tony

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Fri May 03, 2013 11:41 am
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