[RFI] Does anyone recognize this RFI?

Hare, Ed W1RFI w1rfi at arrl.org
Wed Apr 15 14:03:00 EDT 2020


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 at contesting.com> on behalf of K9MA <k9ma at sdellington.us>
Sent: Wednesday, April 15, 2020 12:48 PM
To: rfi at contesting.com <rfi at 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 at 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 at sdellington.us

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