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Author Topic: Oddness with home appliance  (Read 1178 times)
K5TED
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Posts: 243




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« on: September 07, 2018, 07:30:01 PM »

Typically we deal with home appliances interfering with ham radio. In this instance, it's ham radio interfering with a home appliance.

Recently revamp of the washer/dryer situation resulted in a Kenmore washer that is apparently susceptible to RF that no other device in the house has problems with.

When operating on HF, the washer flips out and makes weird humming noise. This is, by the way, the third washer replacement in so many months. The first two had other issues. We thought this one was good but it works 100% til I transmit on HF on a random wire. Then the washer either flips out while in standby and has to be 'rebooted' or if in mid-cycle, has to start over.

This does not happen with my magloop.

Installed a transformer based SmartPower filter on the washer outlet, same results. I suspect something is coming over the ground lug of the power supply for my SG-230 auto-coupler. Everything is grounded to building steel to dirt.

Kenmore = no Ham operation, apparently. I'm sure there is an electrical solution, but for now, unplugging the offending washer is the cure.

We didn't have this problem with the old washer that didn't have all the 'smart' features. New dryer with 'smart' functions is OK.
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W9IQ
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Posts: 3553




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« Reply #1 on: September 08, 2018, 12:08:31 AM »

Since the problem is associated with your random wire antenna, make certain you have tamed its common mode current with ferrite current mode balun(s), a good counterpoise, etc.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
K6BRN
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« Reply #2 on: September 10, 2018, 10:06:28 PM »

Ted:

Tough problem to diagnose remotely - but here are some thoughts...

First, I agree with Glenn's advice.  A nonresonant wire antenna can generate some pretty significant RF current on the outer shield of a coaxial feedline that can cause all sorts of radiated RFI/EMI, as well as feeding back into the equipment in your shack.  Installing a good feedline RF choke before the coax enters your home or runs near the washer would be a good preventive measure and is VERY easy to do.  You might start there.  An exterior coax ground block and very good shack ground (which is more difficult to do) can also help.

Second,, what model and year of washer is it?  Does the washer have a touch control panel whose buttons have a metalized surface for touch control?  Is the problem worse on lower bands (40M, 80M)?

The problem almost sounds reminiscent of the pervasive touch lamp issues encountered by hams over the years - hence my questions above.  If the washer buttons are mechanical or capacitive (plastic membrane), this would be less likely to be the cause.  But in recent shopping I've also seen some Samsung (or might have been LG) washers with what appear to be metallic touch controls which might be MUCH more sensitive to RFI. I'm not sure who is making Kenmore washers now.  It USED to be Whirlpool, but I've heard that has changed.

I have two new (less than a year old) Whilpool "smart" WFW85HEFW front loader washers at two different QTHs.  In addition to working well, neither has ever been bothered by my transmissions on any band, even at power levels of 500W (average) or 1 KW PEP/SSB. Neither have their companion dryers.  They use non-metallic capacitive touch buttons.  The washer DOES generate some obvious interference from its PWM controlled direct-drive drum motor, though.

Both QTHs have resonant end fed wire antennas (EFHW-8010s) with feedline chokes.  At both QTHs the feedline runs within 10-15 feet of the washer.  The antennas are much further away.

Is it possible that your wire antenna is too close to the washer (say, closer than 10 feet)?  That could cause all sorts of issues, too.

Brian - K6BRN
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W9IQ
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Posts: 3553




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« Reply #3 on: September 10, 2018, 11:26:15 PM »

First, I agree with Glenn's advice.  A nonresonant wire antenna can generate some pretty significant RF current on the outer shield of a coaxial feedline that can cause all sorts of radiated RFI/EMI...

Just to be clear as possible since some people get this point mixed up regularly on eHam - the fact that the antenna is non-resonant is not the cause common mode current. It is that an end fed wire antenna is often highly unbalanced and this promotes common mode current.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
KC4ZGP
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Posts: 1961




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« Reply #4 on: September 11, 2018, 04:48:38 AM »


I believe it. Consumer devices are not RF proofed.

Kraus
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K6BRN
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Posts: 1350




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« Reply #5 on: September 11, 2018, 06:31:05 AM »

Glenn:

Quote
  Just to be clear as possible since some people get this point mixed up regularly on eHam - the fact that the antenna is non-resonant is not the cause common mode current. It is that an end fed wire antenna is often highly unbalanced and this promotes common mode current.

If you say so it must be so.

 However, after some comments to that effect regarding an EFHW-8010, I placed a clamp-on Rf wattmeter over the coax feedline at various points from feed to antenna end and measured negligible current on the outer shield.  AFTER removing the feedline choke.

I will not try to explain this other than to say that Danny's antennas, with their 49:1 feedpoint transformers, seem to minimize this effect.  So not all end feds are created equal.

Brian - K6BRN
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WB4SPT
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Posts: 784




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« Reply #6 on: September 11, 2018, 10:06:19 AM »


Installed a transformer based SmartPower filter on the washer outlet, same results. I suspect something is coming over the ground lug of the power supply for my SG-230 auto-coupler. Everything is grounded to building steel to dirt.


I read a few SmartPower spec sheets and see nothing about RF "suppression".   Just surge let thru.
Their use of this "differential transformer" is interesting.   Like... What is it?   Most of their boxes are far too small to hold a 800W isolation transformer. 

 My Whirlpool washer has a triplite surge box, and it is speced for RF isolation.

First step is line choke the antenna.... 

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KD0REQ
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Posts: 2404




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« Reply #7 on: September 11, 2018, 01:59:10 PM »

agree, current chokes on the coax to start (snap-over ferrites.)

next, same to the washer power cord. meter the ground connection at the chassis to the ground pin of the line cord, correct if not near the lower limit of the meter. flip the breaker, make sure that ground wire is really connected to the outlet and goes into the wall.

check the ground of the hood over the control box to the cabinet, and the same for the back panel to the cabinet.

you might have to choke the motor and any spin detector leads inside the washer cabinet as well.  hopefully you won't have to tip it on the back, like I had to with my Kenmore/Whirlpool unit to replace the spin detector, they leak like Washington DC when you do that.
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