[RFI] Multi-Stage High Efficiency Air Conditioner Units

[Jim Brown]

On 2/7/2020 10:39 AM, r55stan at gmail.com wrote:
> The lesson for me on that project was RFI can get out of a piece of equipment on EVERY conductor that comes out of it. 

RIGHT.

  I think we tend to only focus on the power cord because for most 
appliances those are the only wires connected to it.  My only other 
comment is a single pass through a ferrite probably won't reduce a 
strong RFI source enough.

Also correct, but there is MUCH more to it. Study k9yc.com/RFI-Ham.pdf 
and http://k9yc.com/KillingReceiveNoise.pdf

The culprit in these units is the variable speed motor controller, which 
is a generator of rectangular waves, the pulse width and/or frequency of 
which is varied to control the speed. Better mfrs of these units MAY 
have optional filters/mods for RFI.

73, Jim K9YC