Forgot to add the link to the treadmill youtube video I mentioned. Here it
is: https://www.youtube.com/watch?v=VO5DcVSw3M0
73,
Don (wd8dsb)
On Fri, Jun 26, 2020 at 7:12 PM Don Kirk <wd8dsb@gmail.com> wrote:
> Hi Grant,
>
> Treadmills are notorious RFI generators due to their variable speed
> drives. I suspect you are onto something regarding what outlet it's
> plugged into versus how long the run is relative to resonance. On my wifes
> treadmill I had to add a choke on the power cord for common mode rejection,
> as well as a commercial input power filter for differential mode
> suppression. Here is a link to a youtube video showing my treadmill RFI
> and the two filters I used.
>
> I always knew when my old neighbor was on her treadmill, and had a lot of
> fun telling her so.
>
> 73,
> Don (wd98dsb)
>
> On Fri, Jun 26, 2020 at 3:35 PM Grant Saviers <grants2@pacbell.net> wrote:
>
>> Any surge protectors on the problem circuit? Degraded MOV's can cause
>> problems. GFI outlets also.
>>
>> Grant KZ1W
>>
>> On 6/26/2020 10:30, Gary Peterson wrote:
>> > Periodically, I have been plagued with RFI from an unknown source. It
>> sounds like a washing machine, as far as the cadence is concerned, with a
>> swish, swish, swish sound. It will show several tracks on the 80 meter
>> waterfall. It will end abruptly. Every previous time it has come on, it
>> has quit before I could get to my gear together and DF it. I had my
>> equipment ready to go and when it came on and I dropped what I was doing
>> and went outside. My loop gave me a beautiful, deep null toward the
>> neighbors house, about 300 feet away.
>> >
>> > I gave my neighbor a call and told him what I discovered and asked him
>> if he had been running any appliances a few minutes earlier. He told me
>> his main squeeze had been on the treadmill. My neighbor is a ham, who has
>> not been active for about a decade. He turned on the treadmill and there
>> it was! Source found. The treadmill is a PowerTread, I was told.
>> >
>> > I gave him an EMI filter to try, that I had found in a box of assorted
>> electronic parts purchased some time ago. The filter is a TDK, model
>> ANF-106U. My neighbor plugged it into the outlet and plugged the treadmill
>> into the EMI filter. The filter knocked the RFI down by a couple of S
>> units, but I could still hear the swishing. Next, he plugged the
>> treadmill, via an extension cord, into a different outlet, without the EMI
>> filter. No interference whatsoever was heard or seen on the waterfall.
>> >
>> > Is it possible that the wiring from the nearest outlet, back to the
>> service panel, is resonant on 80 meters? Or, is it more likely that a
>> connection might need tightening in the outlet box or breaker panel? He
>> does not know whether the troublesome outlet and the good outlet are on the
>> same circuit or not. I had him check both outlets with an outlet tester,
>> thinking that he might have a mis-wired outlet. Both checked OK. He is
>> afraid to get into the troublesome outlet box or his electrical panel. I
>> volunteered, but he doesn’t want me to take the risk. When I was in
>> broadcasting full time, I was inside more electrical panels than I can
>> count, but I respect his wishes. Before I hire a licensed electrician to
>> check my neighbor’s wiring, I would like to have a better handle on the
>> probable cause.
>> >
>> > Any thoughts as to the explanation for this rather odd behavior will be
>> most appreciated.
>> >
>> > Gary, K0CX
>> >
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>> >
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>
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