[LCC] RFI problem from our Texas connection

[Dan Edward Dba East edwards]

hey randy
thats interesting. i thought PWM's (pulse width modulation) were just used for  d.c. motors....they're putting d.c. motors in washing machines now ??
they ( pwm's ) DO make a nasty looking square wave, which contain manymany many frequencies...
curious......or maybe i'm just stupid and dont know about PWM's & ac motors...
73, w5xz, dan


--- On Mon, 8/2/10, Randy Prewitt <ranprew at foxsale.com> wrote:

From: Randy Prewitt <ranprew at foxsale.com>
Subject: [LCC] RFI problem from our Texas connection
To: lcc at louisianacontestclub.org
Date: Monday, August 2, 2010, 7:14 AM

Forwarded from our Texas friends. Two separate exchanges.

randy  K4LJA in Monroe, LA

----- Original Message ----- Sent: Sunday, August 01, 2010 9:16 PM
Subject: Re: FW: RFI problem


> I also monitor the RFI reflector and that sounds correct to me.  If your rfi is low level or can be worked around count yourself lucky.  I would think your machine would have a low usage.  It will be interesting to hear what Whirlpool has to say.  I've worked with Mike Gruber  at ARRL when I was involved with Vectren Energy.  Good man.....
> 
> Skip
> 
> On 8/1/2010 20:45, Randy Farmer wrote:
>> 
>>> I contacted ARRL about my washing machine RFI problem and received the following response.  My RFI isn't all that bad, so I'm not sure I'm going to do all of this stuff, but I thought it might be of interest to some of you.
>> 
>> I'm subscribed to the RFI reflector, and there have been numerous messages regarding washing machine RFI complaints. Most the newer "high efficiency" models use DC motors with variable speed controls. The designers know how to make PWM motor controls cheap, but they don't know squat about EMI. The haphazard wiring, with no common ground point (if there's one at all) make them dandy radiators. Seems that one of the Korean brands, maybe Samsung or LG, has a reputation of being pretty clean. Whirlpool is reputed to be the worst.
>> 
>> As I recall, the consensus of the experts on the RFI reflector is that the FCC doesn't regulate "appliances" at all. If they don't now, they're not likely to start any time soon. Welcome to the 21st century.
>> 
>> 73...
>> Randy, W8FN



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