[RFI] LG Range RFI

[Dave Cole (NK7Z)]

When you buy the range, take a portable SW radio, and ask that things be 
connected first...  Our local sales point for that sort of thing will do 
that, not sure if yours will.

73s and thanks,
Dave (NK7Z/NNR0DC)
https://www.nk7z.net
ARRL Technical Specialist
ARRL Volunteer Examiner
ARRL OOC for Oregon

On 12/6/18 8:23 AM, Jim Miller wrote:
> Service techs just left after spending about an hour trying to determine
> the source of the RFI from the LG range. It appears the RFI is generated by
> the switching power supply. Not clear at all why turning on the lower oven
> squashes the RFI. One thought is that the lead from the heavy 220 power
> cord to the PSU that supplies it with 110v may also be conducting back into
> the house wiring. Turning on the oven would create quite a hefty "short"
> across that path and internal to the metal shielding provided by the oven
> structure.
> 
> I've asked for a cost to replace the PSU as well as asking them to inquire
> about a RFI mitigation kit. If PSU replacement is not effective I could try
> a choke on the 110v line to the PSU. I'd have to splice in some additional
> wire to accommodate creating enough turns to be effective.
> 
> This range will be replaced in a few months with an induction cook-top and
> separate wall oven so I might just live with workarounds of turning on the
> oven (a single piece of DX being chased) or throwing the breaker to the
> oven (contesting on 80m).
> 
> 73
> jim ab3cv
> 
> On Thu, Nov 29, 2018 at 2:38 PM Jim Miller <jim at jtmiller.com> wrote:
> 
>> After doing a whole house shutdown I've identified our LG electric range
>> (LDE3017ST) as the culprit producing strong RFI on 80m across the whole
>> band. My antennas are 100ft or more away from the house so this isn't
>> subtle. This is not causing a similar pattern on 160m.
>>
>> This range was produced in 2013 and came with the house we recently
>> purchased. It has a touch panel which likely is the source of the problem.
>> I'll need to have my wife play with the "buttons" while I'm listening to
>> see if there is anything obvious.
>>
>> Short term cure is to flip the breaker in the electric service panel when
>> operating on 80m unless there is a kit for RFI. I'm not going to attempt a
>> home-brew repair on something like this.
>>
>> As expected calls to LG haven't produced any useful response yet. If they
>> come up with a kit I'll report. We're planning a complete kitchen remodel
>> so this range won't last more than 6 months anyway.
>>
>> Picture attached but may not make it thru the list. The strong ocean waves
>> every 200khz or so are from the range. The finer grained stuff isn't coming
>> from our house and will require some DF work. I've sent the pic to Dave,
>> NK7Z for his compendium.
>>
>>
>> EDIT: I've since discovered that an alternative to switching power at the
>> breaker panel is to turn on the bottom oven. The result of doing so
>> completely knocks down the RFI signature. The upper over has some effect,
>> burners seem to have no effect.
>>
>> 73
>>
>> jim ab3cv
>>
>>
>>
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