[Elecraft] OT A/C RFI

[Jim Brown]

On 7/19/2017 7:52 AM, Clay Autery wrote:
> Hmmmm....  Jim...  I have a variable speed down-hole pump on my water
> well...  reckon that could cause RFI via the AC wiring?
> The down-hole pump is 220VDC on dedicated circuit, and shack is on a
> separate dedicated circuit from same service with separate sub-panel.

This is a complex question with no simple answer. Current flows in 
loops, the loops produce magnetic fields which couple into other loops, 
and the current also produces radiation. Radiation from the parts of the 
loop that are under ground are certainly less than if they were above 
ground. Those currents also produce IR drops.

Another mechanism that is often overlooked is leakage current on the 
"green wire" as a result of capacitive coupling from the phase (hot) 
conductor(s). This creates potential differences for that trash between 
one equipment chassis and another. This is most often an issue at 
baseband (harmonics of 50/60 Hz) but could also be a factor at RF.

73, Jim K9YC