[RFI] A new RFI source

[Jim Brown]

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 at 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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