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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--
Scott K9MA
k9ma@sdellington.us
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