[RFI] RFI from variable speed swimming pool pumps

[Jim Brown]

On 6/30/2018 9:49 PM, Randy Standke wrote:
> In addition, some type of filtering on the ground wire may also be needed because the line filters don't filter the ground wire.  A large clamp on ferrite over all the power wires will also filter the ground.

WRONG -- sort of. The solution is multiple turns of the line cable wound 
through a large #31 ferrite core, NOT the ground wire only. In general, 
commercial line filters are effective ONLY if they are integral to the 
equipment, so that they are properly bonded to the shielding enclosure 
of the equipment. Simply clamping a ferrite onto the cable (a single 
turn) works only at VHF, and multiple clamps will be required.

In general, variable speed motors should be assumed to be noisy until 
proven otherwise.

73, Jim K9YC