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[RFI] 3" ID core for RFI suppression

To: rfi@contesting.com
Subject: [RFI] 3" ID core for RFI suppression
From: Howard Lester <howard220@gmail.com>
Date: Tue, 29 Dec 2020 20:07:17 -0500
List-post: <mailto:rfi@contesting.com>
Very long story short: A particular circuit card (I am guessing so) of my 2-1/2 
year-old Maytag HE washing machine is susceptible to RFI from… my 
propane-fueled furnace! The symptom is occasional: A loud 2-step snapping sound 
that emanates from parts of the back of the machine’s control panel when the 
furnace first gets the signal from the thermostat, and then begins its cycling 
on. It happens just once in a while, and I can prevent it from happening at all 
simply by unplugging the washer from the AC outlet. What could be easier? 

When the snapping recently occurred when my 16KW Generac generator kicked on 
for its weekly 5-minute exercising, I got even more suspicious. And when 
yesterday I transmitted with 75 watts on 20 m SSB, using my MFJ Hi-Q Loop up in 
the attic about 15-20 feet away from the washer, and I heard the snapping 
multiple times, I then said, “This means war!”  ;-) (That was the first time I 
ever heard the washer do that from me transmitting on any band. I rarely use 
more than 50 watts.)

The flat AC cord is a bit under 1/2” across and has a large plug. The plug size 
requires about a 2” I.D. core, but I cannot find anything specifically of Type 
31 or 77 or, really, anything — except this:

https://palomar-engineers.com/ferrite-products/AC-Cable-Noise-Filter-for-Large-Plugs-3-ID-p75172171
 
<https://palomar-engineers.com/ferrite-products/AC-Cable-Noise-Filter-for-Large-Plugs-3-ID-p75172171>

But it’s $40+, and I don’t want to spend that kind of money if it’s not the 
right tool for the job. No, I will not cut the AC cord. The washer is past its 
1 year full parts and labor warranty, so I’m out of luck there. (Until last 
November, well past the 1 year, I thought all along it was the furnace making 
the snapping sounds.)

Thanks for any ideas. No, I’m not going to replace the washer. As I said, I can 
just unplug the thing except for the few times a week I use it. 

Howard N7SO

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