At 08:20 AM 7/12/2006, Martin Ewing wrote:
>JC Smith wrote:
>>Gary's right although copper strap can be overpriced depending on where you
>>find it. Copper tubing is such a common commodity it's hard to overprice
>>it. One other advantage tubing has is it's easy to protect from
>>weedwackers, lawnmowers (not the blades), etc. Just run it inside a length
>>of thick hose.
>If you are running strap in order to make a ground, you don't want to
>insulate it -- at least when it's running underground. Maybe you are
>referring to runs above ground.
>>I wonder... if you roll (the long way) copper strap you could put it inside
>>hose. As long as the inside circumference of the hose was greater than the
>>width of the strap you wouldn't be forming a tube with the strap. What if
>>you slit the copper tube before using it, would that be enough to allow both
>>the inside and outside to conduct high frequency current?
>You get minimum impedance when the strap is flat. If you roll it up, it
>is no better than thin wall tubing - i.e., there is no current on the
>inside. Impedance per foot is roughly doubled. A narrow slit on tubing
>won't change things at all, since all the current flow is
>longitudinal. Pound for pound of copper, you get the best ground with a
>wide flat strap, maybe 10 skin depths thick. You get the least effective
>ground by compressing it into a circular rod (wire). Hollow tubing is a
>Basically all the interior copper (below the skin depth) is wasted for AC
>current flow. Of course, it does give you better physical strength and
>thermal mass. (A low impedance ground isn't much help if it gets
>vaporized. Has anyone done a thermal analysis for very thin strap in a
Wouldn't it be better than a round wire? greater surface area to volume
ratio and all that.
>>Just some thoughts.
>>73 - JC, K0HPS
>73 Martin AA6E
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