[Elecraft] K3 RFI in transmitted audio

[Jim Brown]

On Mon, 13 Sep 2010 09:40:00 -0400, Don Wilhelm wrote:

>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.

I disagree with that concept as well. The notion that a separate wire 
is required for each piece of gear to a point that is often at a fair 
distance from a closely arranged collection of gear in a typical ham 
shack when that gear is already well bonded together does not make 
sense. How, for example, do we insure that each wire is the same 
length, follows the same or a similar path, and thus has the same 
inductance? 

There is NO CONFLICT between bonding all equipment chassis together by 
the shortest practical path, as I've outlined, and making one or more 
bonds between that equipment and the earth electrode system (ground 
rods). 

Indeed, both IEEE Standards on Grounding and most building codes either 
recommend or require multiple paths to ground for lightning protection. 
A large part of the thinking behind that is that the inductance is 
reduced by having multiple wires in parallel. 

As hams, we tend to think of our antennas as the only source of 
lightning ingress to our homes, but that is FAR from reality. It's like 
looking at the circus elephant through a tiny hole in the tent. EVERY 
CONDUCTOR that enters the house, and every conductor INSIDE the house, 
is a receiver for energy from lightning. That's why IEEE Standards and 
nearly all building codes call for ALL non-powered metal to be bonded 
together, and to one or more earth connections, and for all earth 
connections to be bonded togther. 

One other thought on this. In thinking about how all this fuzzy 
thinking about so-called single point grounding came about, one source 
of it might be equipment with a pin 1 problem. If, for example, the 
bonds to the equipment are improperly made to some point OTHER THAN THE 
CHASSIS, then yes, lightning current WOULD go through equipment if it 
was daisy-chained. But that's not a GROUNDING problem, it's an 
EQUIPMENT problem, and it's IMPROPER bonding. 

The good news is that I don't recall ever seeing ANTENNA connections in 
ham gear with pin 1 problems (except, perhaps, for an occasional RX 
antenna). It's only the audio and control wiring, and an occasional IF 
output. 

73, Jim Brown K9YC