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eHam Forums => Elmers => Topic started by: KD0ZGW on November 10, 2017, 01:26:45 PM



Title: How to alleviate new washer interference on 17M?
Post by: KD0ZGW on November 10, 2017, 01:26:45 PM
New kenmore washer is in room adjacent to shack.  RF noise actually sounds like the washer when it is reciprocating the tub.  Easily identified and went away when I shut down the washer.  Is there a simple way to block the interference?  Station and devices are all grounded according to recommended practices.

thx in advance for suggestions.

KD0ZGW


Title: RE: How to alleviate new washer interference on 17M?
Post by: K5LXP on November 10, 2017, 05:40:02 PM
Usually this will involve more than one remedy, as just one may reduce but not eliminate it.

You can try ferrites on the power cord.  Plugging it into a different circuit might help.  But something that stands out here is you're picking up an emitter that's next to your equipment, not next to your antenna unless your antenna is in the laundry room.  That implies you have a common mode path into your reciever, so improving the isolation between your shack and your antenna might help too.  How exactly you do that will depend on what you're using for an antenna feed system.

Mark K5LXP
Albuquerque, NM


Title: RE: How to alleviate new washer interference on 17M?
Post by: KC1BMD on November 10, 2017, 06:31:26 PM
Same problem here with GE washer. Ferrites on the power cord didn't help... but I'm in a condo and my antennas are in the attic. The solution for me was to not operate when the washer is on, or ask my wife to do the laundry at a more convenient (for me) time. :)


Title: RE: How to alleviate new washer interference on 17M?
Post by: K8AXW on November 10, 2017, 10:12:23 PM
Can it be determined if the problem is radiated or coming in on the AC line?

What happens when you unhook your antenna and raise the RF gain control?

It seems to me that in any case the manufacturer of the washer bears some responsibility for this problem.


Title: RE: How to alleviate new washer interference on 17M?
Post by: W9IQ on November 10, 2017, 10:29:15 PM
Quote
It seems to me that in any case the manufacturer of the washer bears some responsibility for this problem.

You would think so but they are specifically excluded from complying with Part 15 regulations:

Part 15.103(d)  A digital device utilized exclusively in an appliance, e.g., microwave oven, dishwasher, clothes dryer, air conditioner (central or window), etc.

In any case, it is the operator/owner of the offending device that bears the responsibility to correct the RFI problem. The only redress the owner has against the manufacturer is a civil case:

15.103 ...The operator of the exempted device shall be required to stop operating the device upon a finding by the Commission or its representative that the device is causing harmful interference. Operation shall not resume until the condition causing the harmful interference has been corrected....

In some cases, the manufacturer has stepped up to the plate to correct the problem. A major line of home furnaces is one recent example.

- Glenn W9IQ


Title: RE: How to alleviate new washer interference on 17M?
Post by: K8AXW on November 10, 2017, 10:41:15 PM
Copy that Glenn.  Now is the time to ask if this is frequency related...across the spectrum, etc. (Since he says the problem is RF related on 17m alone this should throw it into the Part 15 area?)

If it's AC line related only then perhaps bypassing the AC line of the appliance with caps......(since ferrite cores are ineffective.) Or, is the interference on all the AC circuits? 


Title: RE: How to alleviate new washer interference on 17M?
Post by: WB4SPT on November 11, 2017, 05:16:56 AM
I think you will need to get closer to the source, that is the motor drive circuit.   Once the genie is out of the bag, it will couple to much of the wiring, including the AC mains.  

Like modern furnace motors, these variable speed 3 ph motors have sharp edge waveforms driving them.  You want to get ferrite very close to the connector on the PCB, driving the motor power wires.  Preferably, a ferrite, multi turn, for each of the 3 drive phases.  You can likely ignore (not treat) any speed measurement wiring.  
 
Note that the drive circuit is a very low Z circuit.  I would tend to think bypas caps are not the correct path for a fix in this area.  You want to slow down the current waveform, using series Xl and R, just what the correct ferrite offers.  

Depending on the effectiveness of the ferrite at the right spots, you may STILL need a AC mains filter, most conveniently done with a  10A corcom metal box filter at mains inlet, or even easier, a Trip lite Iso bar power strip, with surge too.  I use a small iso bar on my clothes washer currently for surge control. 


Title: RE: How to alleviate new washer interference on 17M?
Post by: K8AXW on November 11, 2017, 09:26:31 AM
Then there is the warranty....which will be voided if any mods are made.

I still think it's time to rattle the manufacturer's cage. 


Title: RE: How to alleviate new washer interference on 17M?
Post by: ND6M on November 11, 2017, 10:17:38 AM
>>>>>>THIS<<<<< is the type of issues that the ARRL should become a player in.

flame suit on


Title: RE: How to alleviate new washer interference on 17M?
Post by: WA3SKN on November 11, 2017, 02:19:35 PM
Back to the issue.
Is the interference incoming via the antenna, power leads, or some other way?  Replace the antenna with a known good dummy load and see if you still hear a problem.  If not, it is via the antenna.  If yes, it is probably via the power line.  Direct radiation and via the ground connection is rarely the case.
And what band(s) are being affected?

-Mike.


Title: RE: How to alleviate new washer interference on 17M?
Post by: KD0ZGW on November 11, 2017, 08:10:51 PM
Everyone,thx for suggestions.  I'll test into a dummy load.  Antenna is over 150' away so I'm suspecting the A.C. line.   I can power the radio from battery for another check.


Title: RE: How to alleviate new washer interference on 17M?
Post by: KM1H on November 12, 2017, 06:53:39 AM
The first place Id go is the manufacturers web page under "Support" and ask a question if our problem isnt listed.

Another option is to Google for others who have/had the problem.

Carl


Title: RE: How to alleviate new washer interference on 17M?
Post by: K8AXW on November 12, 2017, 10:29:05 AM
Lesson learned:  I've used phone calls and email to get problems resolved with less than optimum results.

I eventually found out that a well written letter using logic, attention to detail without writing a book, to one of the customer support SUPERVISORS or higher.  It will take a great deal longer but this gets the best results. 

Most companies like happy customers/clients; don't want any governmental agency involved with their business and for the most part like to resolve any problems they have with their product.

While most companies test their product the best they can, they can't cover ALL potential problems so when they find out that they indeed do have a problem, they will try to solve it.  Or not.

That's when you go to Plan B.


Title: RE: How to alleviate new washer interference on 17M?
Post by: WE6C on November 13, 2017, 06:10:08 PM
I also have problems with a washing machine. So far no clothes washing during radio time. I'll make note on the type of noise, frequencies etc and report back here in a few days.
Bob


Title: RE: How to alleviate new washer interference on 17M?
Post by: WB4SPT on November 13, 2017, 06:34:53 PM
To further insult us,  dishwashing and clothing washing cycles seemed to have doubled over the years.


Title: RE: How to alleviate new washer interference on 17M?
Post by: N8CBX on November 14, 2017, 02:49:29 PM
I have 20db over S9, washing machine noise that is strongest on 80M. It's a Maytag washer with the 3-phase motor. In the beginning I had NO idea where the RF interference was coming from. So, I homebrewed a hand held 80M Directional Finder (w/loop & whip antennas). My hand held DF directed me to the house (my shack is in the back yard in another building) and I found the washing machine was the source. Not only that discovery, but the noise followed the power line into the house.
I think it needs an AC power line filter to the washer, as WB4SPT has mentioned, but just don't have the time yet to try it.
Jan N8CBX