Yeah, sorry about that. I didn't make clear that the image was the
waterfall from WSJT-X, so it's audio frequencies. At RF, it's right around
21.074 MHz. It looks like it could be something that is
temperature-sensitive. It appears that it reaches its highest frequencies
pretty consistently in the afternoon.
I found a couple of potential culprits (including a touch lamp), but no
success yet.
Time to start hunting. Thanks for the ideas, though!
73, Matt, N0EYE
On Wed, Apr 15, 2020 at 1:52 PM K9MA <k9ma@sdellington.us> wrote:
> I may have misinterpreted the frequency scale, as I thought it was RF.
> It appears it is audio, Hz, not kHz, in which case I agree, it doesn't
> look like a switcher, but something modulated at 55 Hz.
>
> 73,
> Scott K9MA
>
> On 4/15/2020 13:03, Hare, Ed W1RFI wrote:
> > Most of those switchers do drift with temperature. They also show
> > little jumps in frequency with voltage changes, so that, too, can be
> > diagnostic.
> >
> > The real question is not usually the one hams always ask: What is it?
> >
> > You need to know where it is, and it is easy from there to narrow it
> down.
> >
> > ------------------------------------------------------------------------
> > *From:* RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of
> > K9MA <k9ma@sdellington.us>
> > *Sent:* Wednesday, April 15, 2020 12:48 PM
> > *To:* rfi@contesting.com <rfi@contesting.com>
> > *Subject:* Re: [RFI] Does anyone recognize this RFI?
> > Looks like a switching power supply running at 55 kHz. If you zoom in on
> > one of the spikes, you'll probably see an asymmetrical spectrum, with a
> > longer tail on one side. And it will probably be drifting around a lot.
> >
> > 73,
> >
> > Scott K9MA
> >
> > On 4/15/2020 11:02, Eddie Edwards wrote:
> > > Without seeing the motion, hard to tell what it's really doing.
> > Anything with a free-running oscillator might cause that. Those old
> > touch controlled lamps use to make multiple drifting spikes like that
> > and lots of noise as well with clumps of noise every so many KHz.
> > >
> > > Only way to know for sure what kind of device is to DF or track it
> down.
> > >
> > > 73, de ed -K0iL
> > >
> > > -----Original Message-----
> > > From: RFI <rfi-bounces+eddieedwards=centurylink.net@contesting.com>
> > On Behalf Of Matt Foster
> > >
> > > The linked image shows interference that, as far as I know, is
> > always present for me on 15m. I’m talking primarily about what is
> > appearing between about 1400 and 2100 on the waterfall. If you look
> > closely, you’ll see that the lines are leaning slightly to the right.
> > They VERY slowly progress up in frequency and then back down in
> > frequency. It appears to me that there is a spike about every 55 Hz. I
> > have no idea what this might be.
> > > I thought someone on here might recognize it.
> > >
> > >
> >
> https://drive.google.com/file/d/1FthSrYNX1ogF9IGJAYA_TeeHWFF7qrch/view?usp=sharing
> > >
> > > Thanks and 73,
> > > Matt, N0EYE
> > > _______________________________________________
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> > > RFI@contesting.com
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> > >
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> >
> >
> > --
> > Scott K9MA
> >
> > k9ma@sdellington.us
> >
> > _______________________________________________
> > RFI mailing list
> > RFI@contesting.com
> > http://lists.contesting.com/mailman/listinfo/rfi
>
>
> --
> Scott K9MA
>
> k9ma@sdellington.us
>
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