[Elecraft] K3 RFI in transmitted audio

[Don Wilhelm]

  Joe,

For elimination of DC and AF problems, no ground is required.  The real 
requirement is that all equipment be at the same potential.  Connecting 
the chassis of all equipment together with heavy gauge wire or strapping 
material will provide that low resistance path.  Potential differences 
of a few millivolts matter here.  As Jim has pointed out, divorcing the 
power supply V- from the power supply chassis (and AC supply neutral) is 
often needed to solve hum and modulation of the V- line.

If we were discussing RF, then your single point ground connected to a 
low impedance ground for RF would be correct - keep the path to RF 
Ground the same distance for each piece of equipment. will achieve what 
is needed for lightning protection.

In difficult situations, both may be necessary.  DC and audio grounding 
requirements are different from RF grounding requirements.

73,
Don W3FPR

On 9/13/2010 1:26 AM, Joe Subich, W4TV wrote:
>   >  This is a common misconception that results from muddy thinking. It
>   >  is the big lie, repeated over and over again until somehow everyone
>   >  believes it. DC and low frequency currents follow Ohm's Law -- that
>   >  is, the path with the lowest DC resistance.
>
> And the proper low impedance ground fits that requirement but the
> common point must be proper - not just a couple of ground rods.
>