[RFI] Powerline noise humps?

David Winarsky david at winarsky.com
Wed May 11 16:42:06 EDT 2016

Thanks to everyone who responded (on and off list).  As always, incredible knowledge and experience here.  It’s very helpful to know powerline noise doesn’t normally represent itself with these types of humps spaced ~50 kHz apart.  I can then focus more on my loop and Tecsun 660, without being distracted by the active dirty poles. 

73 David NY6W

> On May 11, 2016, at 9:27 AM, JW via RFI <rfi at contesting.com> wrote:
> Yup.Many returns on 'clock dithering' too. This could have saved us some blood and sweat at a critical time (EMI pre-screening) a few years back on a new product but the digi-whizes had not incorporated that feature in their design ...
> https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=clock%20dithering%20emi
> de Jim WB5WPA
>      From: Charles Coldwell <coldwell at gmail.com>
> To: JW <jwin95 at yahoo.com> 
> Cc: Mike Ryan <mryan001 at tampabay.rr.com>; "rfi at contesting.com" <rfi at contesting.com>
> Sent: Wednesday, May 11, 2016 10:24 AM
> Subject: Re: [RFI] Powerline noise humps?
> On Wed, May 11, 2016 at 8:40 AM, JW via RFI <rfi at contesting.com> wrote:
>> ... manufacturers today are employing 'clock dithering techniques' to avoid any specific, individual, high amplitude single-frequency emissions
> Also known as "spread spectrum clocking" (a nice search-engine term).
> Lots of PLLs on the market advertise this feature.  USB 3.0 uses it on
> the high-speed conductors to avoid the need for shielded cables.
> -- 
> Charles M. Coldwell, W1CMC
> Belmont, Massachusetts, New England
> "Turn on, log in, tune out"
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