[RFI] Fwd: 20 Meter Interference

[K9MA]

No. "Safeguard Supply"

It was very cheap.

73,
Scott K9MA

  On 2/26/2021 12:21 PM, Michael Aust wrote:
> Interesting.
> Was it a Ring Doorbell Extender ?
> 73
> Mike
> WB6DJI
>
>
>
> Sent from the all new Aol app for iOS 
> <https://apps.apple.com/us/app/aol-news-email-weather-video/id646100661>
>
> On Friday, February 26, 2021, 10:05 AM, K9MA <k9ma at sdellington.us> wrote:
>
>     It turned out to be a wireless doorbell extender, right in the shack.
>     Once again proving that one should check your own home first. I'm not
>     sure if it's the wall wart or the device itself. It seems to have
>     magically fixed itself after power cycling, but I'm sure it will
>     be back.
>
>     I suspect the 1.1 second interval between noise pulses is the polling
>     period of the device, when it draws current from the wall wart. If a
>     ferrite core on the power lead doesn't fix it, I'll just unplug it
>     when
>     operating.  Who wants to be disturbed by the doorbell then, anyway?
>
>     73,
>
>     Scott K9MA
>
>
>
>     -------- Forwarded Message --------
>     Subject:     Re: [RFI] 20 Meter Interference
>     Date:     Tue, 23 Feb 2021 20:25:09 -0600
>     From:     K9MA <k9ma at sdellington.us <mailto:k9ma at sdellington.us>>
>     To: rfi at contesting.com <mailto:rfi at contesting.com>
>
>
>
>     The spectra images didn't come through, so here are the links:
>
>     http://sdellington.us/hr/RFI/20m_K9MA.jpg
>     <http://sdellington.us/hr/RFI/20m_K9MA.jpg >
>     <http://sdellington.us/hr/RFI/20m_K9MA.jpg
>     <http://sdellington.us/hr/RFI/20m_K9MA.jpg>>
>
>     http://sdellington.us/hr/RFI/20m1_K9MA.jpg
>     <http://sdellington.us/hr/RFI/20m1_K9MA.jpg >
>     <http://sdellington.us/hr/RFI/20m1_K9MA.jpg
>     <http://sdellington.us/hr/RFI/20m1_K9MA.jpg>>
>
>     73,
>     Scott K9MA
>
>
>
>     On 2/23/2021 7:46 PM, K9MA wrote:
>     > I've recently started seeing this signal on 20 meters, probably
>     local,
>     > as it is present late at night when the band is dead. It is a swept
>     > signal, typically starting at about 13.625, sweeping upward to a
>     sharp
>     > cutoff at about 14.125. The total sweep seems to be about 500
>     kHz. The
>     > sweep slows down near the upper limit and seems to dwell there.
>     Sweep
>     > repeats about once per second. It seems to be amplitude modulated
>     > during the sweep, so it shows up as a series of pulses on the
>     > waterfall display. While the frequency range seems fairly
>     stable, it
>     > does move around a bit. I can't tell whether the frequency
>     change is
>     > systematic or random.
>     >
>     > In the attached images, the blue trace is the peak signal,
>     accumulated
>     > over many sweeps. The yellow one is the actual signal, without
>     > averaging, which I caught near the upper end of the sweep. The
>     > waterfall shows the pulsed modulation. Resolution bandwidth is
>     about
>     > 440 Hz.
>     >
>     > Any idea what this might be?
>     >
>     > 73,
>     >
>     > Scott K9MA
>     >
>
>     -- 
>     Scott  K9MA
>
>     k9ma at sdellington.us <mailto:k9ma at sdellington.us>
>
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>

-- 
Scott  K9MA

k9ma at sdellington.us