Question on grounding (at the rig) - longish.

[JF]

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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