[RFI] Multi-Stage High Efficiency Air Conditioner Units

[Jim Brown]

On 2/8/2020 4:15 AM, Rob Atkinson wrote:
> Why do hams mindlessly use ferrite on everything, including lines that
> only have DC on them?  What happened to RF chokes and bypass
> capacitors, which when the correct component values and specifications
> are used (value, current handling and voltage rating), will work
> better and cost much less?

You may be confusing differential mode with common mode. And with modern 
electronics, DC often has a strong AC component. That's what's going on 
with variable speed motor controllers and switch mode power supplies. 
And, sadly, lots of equipment is poorly designed, with common mode 
emissions and common mode susceptibility. Ferrite chokes solve common 
mode problems. Traditional RF chokes and bypass caps solve differential 
mode problems.

73, Jim K9YC