[TowerTalk] Back of desk grounding buss

[K4SAV]

On 3/25/2014 10:42 AM, Stan Labinsky Jr. wrote:
> One point the instructor made was to look at your whole system setup 
> from a top down attitude (like you were the ceiling) and make sure 
> that all of the interconnections came from a common hub, like an old 
> wagon wheel.  But, there should ONLY be spokes... NO WHEEL-RIM.  No 
> cross connections from one spoke to another which would create a 
> magnetic loop capable of coupling both in and out.
>

It's difficult to make a rule that fits all situations, and that one 
doesn't work all the time.

Every time I hear that rule I'm reminded of the time I was called in to 
debug a noise problem on a piece of equipment some guys had built.  It 
was a combination digital plus analog system.  The guys had heard that 
rule and applied it.  They ran separate ground wires for each on-card 
ground area, off each card and back to a common point 2 ft away where 
all the grounds tied together.  The system was a total disaster.  All 
the cards had to be redesigned.

Hams also misapply this rule by running separate ground wires from each 
piece of equipment back to the ground rod outside.

If you want a rule that works try this.  Draw a diagram of your system, 
which includes all the ground wires, and analyze where the currents go 
and what the effect of those current will be.

If you generate specific rules, it has to apply to very specific 
situations.  That's one of the main problems people have wih grounding.  
They have heard a bunch of rules but don't know when or where to apply 
them or even if they are significant for the situation.

Jerry, K4SAV