[RFI] Washing machine RFI question
Leigh L Klotz, Jr.
Leigh at WA5ZNU.org
Tue Jan 11 17:14:00 EST 2005
Dale and all,
The high bit is that now someone at Whirlpool is talking to me instead of
reading a script.
Here are the details:
Changing the ground type (removing bonding, switching to solid instead of
braid, etc.) didn't make a difference.
I did, however, switch to using battery-operated consumer radios to
better locate the noise, and to show there was no issue with my amateur
There are three types of noise:
1. Fairly broad noise coming from the switching power supply in the
2. Discrete noise coming from the switching power supply, eminating from
the plastic control panel.
3. Bands of discrete frequencies every 17Khz or so, tighly spaced there,
when the motor is running, which change based on motor speed.
I have images of #1 and #2 at http://wa5znu.org/2005/01/duet/noise/
I used a Sony AM/FM Boombox and found that the majority of the noise is
coming from tthe control panel, both front and on top. Little, if any,
noise comes from the power cord. In fact, it's pretty quiet right next
to the sides of the washer.
So I called Whirlpool and they assured me that they would send someone
who was capable of dealing with the problem.
Whirlpool's service people were scheduled to come out yesterday between 1
and 5pm but called at 3:30 when the caller ID said "SEARS" I got a
At least the guy was honest enough to say he couldn't deal with it.
So I called today and waited on hold about 45 minutes. I explained the
problem again and they said "Our technical support people say that the
control panel and washer will just do that and even changing a new
control board and motor won't help." So I asked for the FCC ID number
for its Part 15B unintentional radiator and in response I got "Dave," a
supervisor. Dave and I talked for a while and he said he would go back
to the engineering group with the data I have and try to find out what's
up. I told him I thought that their control panel was unshielded and
perhaps they had overlooked Part 15(b) compliance. I sent him the
http://wa5znu.org/2005/01/duet/noise/ and told him that I would like
their help in finding out whether their design or my unit is meeting the
regulations or not. He said that they have only three products with
electronic controls and that this unit is designed in "North America" but
manufactured in Germany. "This particular SKU is not sold in Germany" he
said, when I asked if perhaps it was supposed to be CE compliant as well
as FCC compliant and they'd removed CE required filtering.
More news as it develops.
More information about the RFI