[RFI] Mystery noise

[Hare, Ed, W1RFI]

Switching regulators make noise ever N kHz, with N being the free running frequency of the internal circuitry.  The noise can be almost a carrier to just broadband buzz every N kHz, with a 120- or maybe 60-Hz component.
They are also drifty with temperature, change frequency with load changes and when there is a voltage dip or surge, they do a little burble or change in frequency to match.

-----Original Message-----
From: RFI <rfi-bounces+w1rfi=arrl.org at contesting.com> On Behalf Of Mike Martin
Sent: Wednesday, August 11, 2021 1:45 PM
To: Pete Smith N4ZR <pete.n4zr at gmail.com>
Cc: AA5CT via RFI <rfi at contesting.com>
Subject: Re: [RFI] Mystery noise

Hey Pete can you send that to me please

⁣Be safe,
Mike Martin
RFI Services
51 W Bay Front Rd
Lothian, MD 20711
240-508-3760​

On Aug 11, 2021, 10:39 AM, at 10:39 AM, Pete Smith N4ZR <pete.n4zr at gmail.com> wrote:
>I don't know if the reflector will allow this image, but thought it was
>
>worth a try.
>
>   This thing shows up periodically - happily not often.  The 
>periodicity makes me think switching power supply, but aren't they 
>normally discrete , sometimes noisy, sometimes drifty but fairly narrow
>
>critters? This has a substantial 120-Hz component, but why every 19 
>KHz?
>
>--
>73, Pete N4ZR
>Check out the new Reverse Beacon Network web server at 
><http://beta.reversebeacon.net>.
>For spots, please use your favorite
>"retail" DX cluster.
>
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