[RFI] Whirlpool Duet Washing Machine RFI update

[Leigh L Klotz, Jr.]

Thank you Pete and Tyler.

It is not in warranty -- I got a few levels up on the phone and thry 
said as a "goodwill gesture" they would send me new parts.  They also 
said that the front panel is unshielded (which is where I pick up the 
noise from) and that they had nothing else to do if this didn't fix it.

On the other hand, since Tyler K3MM's Duet is quiet so maybe I will give 
it a go.  Mine interferes with an FM broadcast boombox running in 
batteries as well as my K2 and FT-817 on a doublet, and I have messed 
around with grounding to no avail.  I am not hopeful though...

73,
Leigh / WA5ZNU.

On Fri, 11 Feb 2005 7:18 am, Pete Smith wrote:
> Leigh, do I understand correctly that these parts haven't yet been 
> installed?  If so, my suggestion would be to let them install them in 
> the stock fashion and see what happens to your noise problem.  If they 
> went to this much trouble to fix it, the new control system may be 
> clean.  By all means DON'T mess around with shielding or beads until 
> you know -- I suspect doing anything like that could void your 
> warranty.
>
> 73, Pete N4ZR
>
> At 08:40 PM 2/10/2005, Leigh L. Klotz, Jr. wrote:
>
>> Here is an update on my Whirlpool Duet problem.
>>
>> I have a Whirlpool Duet front-loading washer, which I think uses a 
>> variable-frequency AC motor and a fairly complicated mpu control 
>> system.
>> I've reported this here before, and also have talked to the Whirlpool 
>> people.  I now have a new set of innards, and the new news here is 
>> pictures of them at http://wa5znu.org/2005/01/duet/parts/
>>
>> I am seeking advice as to whether I should try shielding them with 
>> copper tape or foil, or at the very least putting some ferrite beads 
>> on the control cables, or if I should just let nature take its course 
>> and let the service people put in the new parts as is.
>>
>> Also, if anybody has recommendations for RF-quiet front-loading 
>> washers, my wife has fortunately agreed that if the problem can be 
>> solved by selling this unit and buying a new one, we can do that.  (If 
>> you would like to buy a slightly used Whirlpool Duet spark gap 
>> transmitter, works on all bands, please contact me offlist, hi hi.)
>>
>> Details below.
>>
>> 73,
>> Leigh WA5ZNU
>>
>> *Kinds of Noise*
>>
>> The washer makes at least 3 kinds of noise.
>> 1. When it's off or on, there's some hash.
>> I assume this is from a switching power supply, or possibly the MPU.
>> I don't have images of this noise off and on.
>>
>> 2. When the drum is spinning, it makes both broad noise and discrete 
>> noise about every 17KHz
>> The noise extends up well past 20M.  I have audio spectrum images at
>> http://wa5znu.org/2005/01/duet/noise/
>>
>> You can see the discrete noise clearly in the 4th and 7th images.  To 
>> the left of the blue line is foreign BCB.  To the right is the 
>> discrete noise starting.
>>
>>
>> The broad noise "washes out" everything for me, and the discrete noise 
>> is maybe 10dB above that.
>> You can see the effect of the broad noise effect in the 3rd and 5th 
>> images on the web page.  The weak PSK signal disappears when the noise 
>> starts.  The rolloff below 500 and above 2500Hz is system audio 
>> response.
>>
>> 3. It makes other discrete noise when the water pump is running.
>>
>> *Sources of noise*
>> I took my Elecraft KX1 with a short piece of wire as an antenna and 
>> found that little noise came from the power cable.
>> However, tremendous noise came from the front panel.  In fact, I can 
>> pick it up there on a cheap FM broadcast radio with no antenna.
>> There is much less noise to the sides of the washer, where metal is 
>> between it and the front panel.
>>
>> *What I've done so far
>> *A Radio Shack AC line filter did nothing but it did show me that the 
>> 3rd prong is grounded.
>> An ohmeter shows <1 Ohm between the 3rd prong and the water pipes.
>> Bonding the washer 3rd prong to the water pipe did nothing.
>>
>> *What Whirlpool did
>> *Whirlpool said that their Part 15 data was proprietary.
>> I checked and appliances (except microwaves) are not required to be 
>> submitted for certification.
>> Sure enough, Whirlpool has FCC Part 15 data filed with the FCC only 
>> for microwaves.
>>
>> Whirlpool said that the control board and front panel are unshielded.
>> They spent a bit of time talking to me on the phone, and their 
>> engineers looked at my audio spectra.  They sent me a new set of 
>> innards -- motor, control board, AC line filter, and front panel, for 
>> free (out of warranty) and said that if that didn't fix it they didn't 
>> know what to do.  They said the controller is made in Germany, but 
>> that it is not sold in the EU (I thought maybe they'd designed it for 
>> CE but removed parts not required.)  They said this is their 3rd 
>> product with an MPU instead of a mechanical controller.  They also 
>> said they have no other RFI reports so far.
>>
>> I have pictures of the parts at http://wa5znu.org/2005/01/duet/parts/
>>
>> *What do I do now?*
>> So I think the service call is going to be on my dime, and I don't 
>> know what to do next.
>>
>> 1. Call and have the new parts installed and probably get no result.
>> 2. Try to retrofit copper shielding into the control board box and 
>> front panel and hope the service installer doesn't notice.
>> 3. Clamp a few ferrites on the wires in the front panel and hope for 
>> the best.
>> 4. Do #1, but if there is no result, try to get the ARRL or the FCC 
>> involved.
>> 5. Sell the washer and buy a different brand that might or might not 
>> generate RFI.
>>
>>
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