Hi Dan,
Traces like this are common to switch mode power supplies (SMPS) that
are switched on. They are free-running, and frequency drift is their
warmup. If the waterfall is opened up to show greater bandwidth (100-200
kHz), you'll see the trace repeated every 40-80 kHz, depending on the
frequency at which the SMPS is operating.
The thing that's different about these data is that one of them is
drifting up in frequency -- most that I've seen drift down. This
suggests that it might be another power handling controller, like the
controller for a variable speed motor or something totally un-related.
73, Jim K9YC
On 2/20/2020 9:03 AM, Dan K2YWE wrote:
I noticed this linear sweep EMI running through 80m two nights ago. A bit
of research found it on 160 and on 40 as well. The signal is not clean and
sounds like it has some FM on it as it runs through the listening
frequency. As you can see, the sweep rate varies.
I have no clue as to it's origin. There is so much crud in our neighborhood
.
https://drive.google.com/open?id=1Y1KX8mpE2Ufg8pAztgVEuxBqM24OnV_t
https://drive.google.com/open?id=1K-mhTYa1DJix0kB7cgn4CeWt7FQTx5nR
Dan Zeitlin - K2YWE
South Shore ARC - K3AU
Annapolis, Maryland
dan z website <http://danzee.org>
On Thu, Feb 20, 2020 at 11:43 AM Wes Stewart via RFI <rfi@contesting.com>
wrote:
Last night I noted a drifting birdie sweeping up and down the 160 meter
band. To make a long story short, I recently installed one of these to
archive some VHS tapes:
https://www.amazon.com/HDML-Cloner-Supported-Schedule-capturing-Supported/dp/B01LX22X2T?ref_=ast_sto_dp
I figured the wall wart, but the signal persists slightly after unplugging
it then dies, so it looks like something internal. Easy fix is to plug it
in only when necessary.
FWIW
Wes N7WS
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