Question on grounding (at the rig) - longish.

[Charles W. Morehouse]

John, 
You forgot to mention grounding.  I live in central Florida which is the 
lightning capitol of the US.  Have been zapped several times and lost 
some solid state gear.
Went to some seminars by a Dr. Uuman of the U of F.  He is a lightning 
specialist.  Learned. a lot.  Now have five ground rods at the base of 
the tower.  EVERYTHING in the house is
connected to that point.  Single point ground.  If struck, everything in 
the house is at the same potential.  If you have ground rods several 
meters apart, there can be several thousand volts difference when 
struck.  So watch out.  73.
Wayne,
W4GBW,

JF wrote:

> On 7/9/06 Robert Myers wrote on the Heath List:
>
>> I want to ground my SB-401/SB-303 'properly.'  Everyone seems to have
>> there preferred method.  I have 100 feet of 0.5 inch braid (when flat)
>> to play with.
>
>
>
> My 2 cents worth:
>
> Even tinned braid is really only good for shielding and DC grounds - 
> don't
> use it for RF grounds because braids become increasingly inductive as
> frequency rises and so can radiate. Untinned braid is worse and can soon
> corrode, become more resistive, and eventually disintegrate if exposed to
> the weather. Instead, look around in sheet metal shops and on the web for
> flat copper strips about 2-4 inches (5-10 cm) wide:  the longer the run,
> the wider it should be. Some sheet metal and gutter/roof repair places 
> may
> have scraps left over from commercial building repairs. You can cut and
> solder them to desired lengths, or buy small rolls in various widths.
>
> In the shack, make a common ground point for all the various rig chassis
> (xcvr, linear, tuner, filter, etc) and run that to a verified earth 
> ground
> by a short a route as possible - don't rely on the shields in the pieces
> of interconnecting coax for an RF common.  RF in the shack is not fun.
> The best RF grounds for HF are radials and multiple counterpoises.
>
> A 1/4 wave or odd multiple lead to an earth ground can be an inductive
> reactance and so radiate. Artificial ground tuners can be used, but bear
> in mind that the ends of their counterpoise wires can arc at higher power
> levels, so they could cause a fire if they are close to something that
> will burn. If you have 1/4 wave ground lead or poor soil conductivity
> problems, these can be reduced by using multiple ground rods and leads
> in parallel.
>
> About putting a ferrite over a water pipe:  I'm not sure I understand
> what you're saying:  a ferrite big enough to put over a water pipe ground
> would be counterproductive because it would reduce or eliminate its
> effectiveness as an RF ground, although it would not interfere with its
> being a DC or low-frequency AC ground.
>
> You should not presume a metal water pipe is well grounded: test the
> resistance of metal pipes to earth ground because some homes have metal
> interior pipes that connect to an outside buried PVC delivery pipe, which
> invisibly ends the usefulness of that route as a good ground.
>
> You can look at several web sites like
> http://www.radioworks.com/nbgnd.html
> for suggestions about grounding, including the parts about line isolators
> and ground loops. The author says not to use a long copper strap for a
> common ground along the back of your rig desk because of the possibility
> of making ground loops, but if the chassis are close together and the
> strap is wide that should not be a problem.
>
> And you asked:
>
>> Finally, does it really matter all that much how I do it?
>
>
> Yes. A correct system can eliminate RF bite, fire hazards and reduce
> interference to other household electronic devices and neighbors via
> the power lines. The combination of antenna height, type, ground and
> nearby objects can change the radiation angle of an antenna, so an
> incorrect setup could make a system into a cloud warmer instead of a
> DX-getter, even though you might be able to load it to a low SWR. Of
> course, sometimes operators have no way to set up an ideal system.
>
> Finally, do some reading and Google searches about lightning protection.
>
> 73
>
> John   KE5ZB
>

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