Sure sounds like a power grid discharge! Connect your audio captures to an
o'scope and look for 60 Hz and harmonics. I could do the same, but the
o'scope is on the other side of the room from the PC.
If you connect your o'scope directly to your 160-meter antenna, I'm willing
to bet you'll see 60-Hz with an exponentially decaying discharge envelope
of each pulse.
Dave - WØLEV
On Tue, Mar 5, 2024 at 8:01 PM Wes Stewart via RFI <rfi@contesting.com>
wrote:
> Not letting a good thread die, here is some more info.
> Here is a link to a Dropbox folder where, if it works, there are six
> files.
>
> https://www.dropbox.com/scl/fo/3c95ijqs0bs11i1mtveyc/h?rlkey=2wsbz4jkjo86a45n8fkjsy5lm&dl=0
> Two of them are baseline plots taken from a Perseus SDR with the 160-meter
> antenna disconnected. There is a spectrum plot and a waterfall plot. Two
> others are the same setup with the antenna connected. These are centered
> on 1840 kHz with a span of 320 kHz. There are two audio files recorded at
> two different frequencies using my Kenwood TS-890 in AM with a 10 kHz BW.
> There is a fair amount of FFT averaging and smoothing on the spectrum plots
> but the waterfall shows the multiple frequencies in this mess.
>
> Some, but not all, of the frequency shaping can probably be attributed to
> the antenna but this is definitely not what I would expect from powerline
> noise. Has anyone seen anything like this?
> Wes N7WS
>
> On Monday, January 29, 2024 at 05:39:55 PM MST, Hare, Ed, W1RFI <
> w1rfi@arrl.org> wrote:
>
> I agree; with no change, the noise is probably external, but do keep in
> mind that some UPS devices or devices connected to them may still be
> powered on, although in that case, I'd expect to see some change.
>
> And no need for an apology. Tracking down RFI can be darn tricky. If
> anything, you can be proud of having a mind open enough to backtrack and
> find what really is a minor misstep. When I worked in the ARRL Lab, many
> hams with RFI problems would not go back and look again at things they were
> "sure" they tested right.
>
> You are going to find this.
>
>
> From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> on behalf of Wes
> Stewart via RFI <rfi@contesting.com>
> Sent: Monday, January 29, 2024 4:55 PM
> To: rfi@contesting.com <rfi@contesting.com>; dave@nk7z.net <dave@nk7z.net>
> Subject: Re: [RFI] Mystery Noise (Aren't they all) Sadly, no. A mea culpa
> and apologies to all who replied. When I removed power to the shack, of
> course the KAT500 antenna tuner turned off. I had put it in bypass mode,
> however, that wasn't good enough since it defaults to port one and my
> vertical was on port three. So effectively, I disconnected the antenna
> when I removed power. When I reran the test today with a jumper around the
> tuner, there is no change in the noise with the house un-powered.
> I am satisfied that the noise is external.
>
> I don't know whether I can make attachments on this site. If so, I have
> some screen shots.
>
> On Monday, January 29, 2024 at 09:10:35 AM MST, Dave (NK7Z) <
> dave@nk7z.net> wrote:
>
> Hello,
>
> This indicates that the RFI is in your home. This is great news, it
> means you can fix it as fast as you want, and you don't have to wait on
> people... Take a look at:
>
> https://www.nk7z.net/i-have-rfi-now-what-locating-it/
>
> I have a handy flow chart there that may help you locate the RFI...
>
> Please report back on what you find it to be...
>
> 73, and thanks,
> Dave (NK7Z)
> https://www.nk7z.net
> ARRL Volunteer Examiner
> ARRL Technical Specialist, RFI
> ARRL Asst. Director, NW Division, Technical Resources
>
> On 1/28/24 19:50, Wes Stewart via RFI wrote:
> > In conversation with the tech a few days ago I offered to battery power
> > my TS-890 and turn off the whole house breaker. When I did the noise
> > went from S9+10 dB down to about S4, but it was still there!
>
>
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--
*Dave - WØLEV*
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