[RFI] Mr. Carlson's Lab: coffee maker RFI

[Hare, Ed, W1RFI]

Thanks, Charles.  I didn't look all the way to the end,  I will admit. We are running shorthanded in the Lab, so I am doing lots of things quickly.

I did get another report that several Keurigs did cause RFI problems, but none that have ever been sent to me as a complaint. I have 3 at home, one still working, that I can do some testing on, as well as the ARR: Lab coffee pot\, which is now a Keurig.

________________________________
From: Charles Coldwell <coldwell at gmail.com>
Sent: Friday, January 14, 2022 7:56 AM
To: Hare, Ed, W1RFI <w1rfi at arrl.org>
Cc: rfi at contesting.com <rfi at contesting.com>
Subject: Re: [RFI] Mr. Carlson's Lab: coffee maker RFI

If you watch the whole video (spoiler alert!), at the end he kills the RFI by shunting the AC with some capacitors and increasing the value of a cap coupling the AC ground with the DC ground on the other side of the SMPS. He mentioned that he has about three of these coffee machines and only one of them is misbehaving.

However the troubleshooting is less satisfactory than is usual for Paul Carlson, VE7ZWZ (he is usually restoring antique radios). Essentially the problem is (spoiler alert!) in the microcontroller firmware which appears to have flipped a bit somewhere in the motor control/PWM code path.

On Fri, Jan 14, 2022 at 6:22 AM Hare, Ed, W1RFI <w1rfi at arrl.org<mailto:w1rfi at arrl.org>> wrote:
This is very interesting.  I do note that the unit in question is defective, with a motor that seems to be running very slowly.  This could be the reason for the RFI problem. ARRL has zero reports of KRFI (Keurig RFI), but I am sure many a ham has a Keurig.  If any of you do experience this problem, send an email to rfi at arrl.org<mailto:rfi at arrl.org> with the details.

It is worth noting that under FCC rules, this would be classified as an appliance (used in heating, cooling, cleaning or the preparation of food).  As such, it is categorically exempt from the specific emissions limits that apply to other unintentional radiators.  Appliances are subject only to the requirement that the operator use them in a way that does not cause harmful interference.

Ed, W1RFI

________________________________
From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com<mailto:arrl.org at contesting.com>> on behalf of Charles Coldwell <coldwell at gmail.com<mailto:coldwell at gmail.com>>
Sent: Friday, January 14, 2022 1:24 AM
To: rfi at contesting.com<mailto:rfi at contesting.com> <rfi at contesting.com<mailto:rfi at contesting.com>>
Subject: [RFI] Mr. Carlson's Lab: coffee maker RFI

Pretty interesting

https://youtu.be/f3dGStQuI7c <https://youtu.be/f3dGStQuI7c>

--
Charles M. Coldwell, W1CMC
"Turn on, log in, tune out"
Belmont, Massachusetts, New England (FN42jj)


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--
Charles M. Coldwell, W1CMC
Belmont, Massachusetts, New England
"Turn on, log in, tune out"