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RFI from Electric Stove




 
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Author Topic: RFI from Electric Stove  (Read 326 times)
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W2JBL
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« on: March 15, 2019, 06:41:31 PM »

Moved into a new house last fall and have been having trouble with pretty bad RFI on the AM broadcast  and above. The other day I finally identified the main culprit: A Maytag Performa Advanced Cooking System electric stove. I makes RFI even when turned off. The stove is in perfect condition and looks almost new. Anbody run into this before? I'd rather not try to put an external EMI/RFI filter on it carrying the full operating current as good ones seem to be rather expensive. 
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W1ITT
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« Reply #1 on: March 15, 2019, 08:35:00 PM »

This seems to go both ways.  Over on the RFI Mailing List, there is a fellow in 7-land who is getting into his neighbor's GE Signature Cafe electric cook stove and making it do crazy things.  It seems that the FCC didn't specifically address the possibility that appliances like these would not only make noise, but also be susceptible in the Part 15 considerations.  They are trying to go after GE to solve the problem. Apparently there is is no  FCC protection for the neighbor with the stove, but it's difficult for them to accept the fact that this new ham in the next yard is mucking up the works.
I don't understand why a cook stove needs to have all this electronic foolishness on it.  I like our gas stove more every day.  We turn it on and it makes fire and cooks.
As an attempt at a cheap and cheerful fix, have you tried running a ground wire from the stove chassis to something that is
grounded, other than relying on the long run of the 240 volt wire back to the box?  Perhaps a ground between the electronics package  (and space-age display} might help.
KF7P sells a big honking  4 inch Mix 31 ferrite toroid ($20 each) that might help if you wrapped a few turns of the 240 volt stove cable onto it.  Usually those electric stove cables disconnect with ring lugs at the back of the stove so you should be able to get a few wraps, if your fingers are really strong!
GL de Norm W1ITT

link to KF7P...

http://kf7p.com/KF7P/Ferrite_chokes.html
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #2 on: March 15, 2019, 08:52:50 PM »

 50 amp schaffner RF filter is less than 100 $  Screw it to the metal box of the stove (the shield) and connect SHORT to the stove,
In Spain I had an induccion plate with 4 places from Phillips, here in Costa Rica I have one from Whirlpool. From both no RFI at all. They have common mode RFI filters incorporated.
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KK4YY
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Gol’ na vydumku khitra


« Reply #3 on: March 15, 2019, 09:09:58 PM »

If it's making RFI all the time it wouldn't seem to be the heating elements. Maybe it's just the control circuitry. If you can isolate the source within the unit, you'll have a better chance of cleaning it up with, perhaps, just a few well-placed small ferrite chokes around the wires leading to the control board. Even a few properly rated bypass capacitors on the line might do the trick. Check for the usual things too, proper grounding and shielding.

A visit to the Maytag website might get you a service manual or give them a call about the problem. Also, you local appliance parts/repair guys may have experienced this before. It couldn't hurt to ask.


Good luck,
Don


Edit: I've had good results with #77 mix ferrite on BC and 160m.
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W2JBL
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« Reply #4 on: March 18, 2019, 06:58:50 PM »

Yes the noise is always there. I have played with ferrite cores on other noise sources in the past and find it's nearly impossible to get enough inductance to work on the BC band to do any good. Same for 75 meters as well. In fact in one case I hit the correct number of turns and had a core actually resonate on 40 meters, which made the proble (Rf in my audio) worse. if I can get somebody to help move the stove I'll see if I can get into the control circuitry. Meanwhile I identified another very nasty source of noise here: My two brand new Harman P43 pellet stoves. The distribution blower speed control interferes everything from
200KC to about 5 MHZ. I contacted Harman about it and they did not reply. 
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #5 on: March 18, 2019, 08:25:18 PM »

Maytag seems to have online support to solve problems. Try it, doesn't cost anything

https://www.justanswer.com/sip/maytag-repair1?r=ppc|ga|21|ROW%20-%20HI%20-%20Maytag%20-%20Google%20-%20Alpha%20-%20Desktop%20-%20Broad|maytag%20troubl
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KD6VXI
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Making AM GREAT Again!


« Reply #6 on: March 18, 2019, 08:52:41 PM »

Maybe you had the wrong mix?  If you didn't use type 75, I don't know if you could get enough wraps.

Charts taken from:

https://palomar-engineers.com/ferrite-products/ferrite-cores/ferrite-mix-selection

Powdered iron may be better that low in frequency too.

--Shane
KD6VXI


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* Screenshot_2019-03-18-17-50-01.png (147.23 KB, 1440x720 - viewed 2 times.)
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KK4YY
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Gol’ na vydumku khitra


« Reply #7 on: March 18, 2019, 09:54:39 PM »

Best, of course, to eliminate the source. But, using coax as my feedline, I was able to very significantly reduce noise from sources that I didn't have access to, coming from inside my apartment building by using ferrite chokes on the feedline. The noise was riding the outside of the coax cable up to the antenna. I used an FT-240-77 at the feedpoint and an FT-240-43 at the other end of a quarter-wave matching section feeding a fullwave loop on 75M. The matching section was RG-59 and I was able to get a good number of turns (12 iirc) around each of those cores. It worked like a charm.

In another case, on the second floor, a ceiling fan which was about 20' from my antenna was tearing things up until I put an FT-140-43 core right at the fan. I had to extend the power wires to get enough turns through the core. This too, worked very well.


Don
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WD8BIL
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« Reply #8 on: Yesterday at 12:53:24 PM »

Quote
Yes the noise is always there. I have played with ferrite cores on other noise sources in the past and find it's nearly impossible to get enough inductance to work on the BC band to do any good.


Hey Chris...……. I have some 75 mix ferrite clamp cores that are rated 150kHz to 10MHz. If you want I'll box'em up and send them out.
Just need a valid address. PM me here or email; wd8bil at yahoo dot com.
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W3RSW
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Rick & "Roosevelt"


« Reply #9 on: Yesterday at 02:16:41 PM »

Boy I guess we’re really in for it. Can’t wait for fully implemented ‘internet of things.’

 As Kk4yy mentioned, Also might try going back to the breaker box where the stove usually has its own 40 or 50 amp 240 v breaker.  Turn it off and pull it and install .01uf at say 3kv caps to ground.  I don’t think adding ferrites at his point would be easy or meet code, the caps possibly too for that matter, but far easier to install.

If there’s room in the main breaker panel, ferrites and add’l caps might be feasible in a parallel PI circuit, but a separate NEMA outboard enclosure close by should meet code.
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RICK  *W3RSW*
WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #10 on: Yesterday at 03:09:49 PM »

Chris,

If all else fails, this may be the ultimate solution!!


* JACKSON HAMMER.jpg (24.35 KB, 650x650 - viewed 1 times.)
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_-_- bear WB2GCR                   http://www.bearlabs.com
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