Re: [RFI] Blower noise from Carrier Furnace

[Jim Brown <jim@audiosystemsgroup.com>]

On Wed,1/27/2016 11:54 AM, Jim Netwal via RFI wrote:
> Does anyone have any advice or a fix for this?
Call the vendor. Many have optional line filters. Variable speed drives 
are inherently noisy -- they start with a Switch Mode Power Supply, and 
then they pulse-width modulate what's left to control the motor. The 
vast majority are unfiltered, and wiring is spread out so that they 
generate strong magnetic fields by virtue of their large loop area. This 
combines to make them terrible noise sources.
73, Jim K9YC


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