North American Network Operators Group

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Re: Presumed RF Interference

  • From: David Lesher
  • Date: Sun Mar 05 18:06:37 2006

> That is already half of a solution:
> Go for fiber. That is imune to both ground and RF problems. Avoid
> ground connections between the equipment.
> Replace ethernet with fiber. Break serial lines with optical isolators.

Yes, fiber will solve ground loop problems. And this smells like
a ground loop issue. But at this juncture, I don't have enough
specifics to recommend ma$$ive changes.

> Cut the ground wire in your power cords but ground the equipment directly
> to a metal frame.

I would NEVER tell a client to do this. 
That could easily kill someone.

> Avoid ground loops: Between two computers you have a ground connection
> via the powerline ground. Connect them via RS-232 and you have a second
> connection via the RS-232 ground. If your power ground is bad then you
> might run amperes through the RS-232 ground that results in Volts, more
> than your signal level, maybe.

I don't recall mention of RS-232,. but yes, this is the classic
example of ground loops.

A host is a host from coast to [email protected]
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Unless the host (that isn't close).........................pob 1433
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