It does look like a amp of some sort.
TV, a blue-tooth speaker bar, etc or like a cellphone BDA.. chased a few in my
day.
When you find it, please let us know what is was.
KA1FFO
AL
On Saturday, December 23, 2023 at 06:49:16 PM EST,
rfi-request@contesting.com <rfi-request@contesting.com> wrote:
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Today's Topics:
1. Re: Peculiar Noise (Jim Brown)
2. Re: Peculiar Noise (k1ttt.dave@gmail.com)
3. Re: Peculiar Noise (Jim Brown)
4. Re: Peculiar Noise (David Eckhardt)
5. Re: Sources of wideband hiss (AA5CT)
6. Re: Sources of wideband hiss (David Eckhardt)
----------------------------------------------------------------------
Message: 1
Date: Sat, 23 Dec 2023 11:46:47 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
To: rfi@contesting.com
Subject: Re: [RFI] Peculiar Noise
Message-ID:
<c8294032-b2ba-4396-8ecc-0c49efc24712@audiosystemsgroup.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 12/23/2023 11:34 AM, Steve London wrote:
> It will be on for several hours at a time, then disappear. Nothing else
> like it between 40 and 60 MHz. I would never have noticed it, except it
> sometimes parks itself on 50313, the 6 meter FT8 frequency.
I strongly recommend NK7I's technique, using a wide waterfall from an
SDR over 24 hours to study the comings and goings of what are often
multiple sources, and identifying one or more as what you're hearing.
This gives clues about WHEN to DF it, and on what frequency(ies).
Also, my applications note about using that spectrum/waterfall to
determine whether the source is electronically generated or arcing,
usually in the power distribution system.
k9yc.com/publish.htm
73, Jim K9YC
------------------------------
Message: 2
Date: Sat, 23 Dec 2023 16:28:12 -0500
From: <k1ttt.dave@gmail.com>
To: "'Steve London'" <n2icarrl@gmail.com>, "'Rfi List'"
<rfi@contesting.com>
Subject: Re: [RFI] Peculiar Noise
Message-ID: <01c401da35e6$ef5d72c0$ce185840$@gmail.com>
Content-Type: text/plain; charset="us-ascii"
I tracked down a noise like that many years ago to a tv preamp on an
external antenna, would wander up and down the band but occasionally liked
to park on a local repeater input.... first step is to find it, then figure
out what it is!
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: telnet://k1ttt.net:7373
-----Original Message-----
From: RFI <rfi-bounces+k1ttt=arrl.net@contesting.com> On Behalf Of Steve
London
Sent: Saturday, December 23, 2023 14:34
To: Rfi List <rfi@contesting.com>
Subject: [RFI] Peculiar Noise
Anyone care to make a guess at this ?
https://www.kkn.net/~n2ic/n2ic_noise.mp4
I have flipped the main breaker and turned off all UPS's in the house.
Peaks SW, which is towards a neighborhood over a mile away, and a large
copper mine, 2 miles away. There is also a line of 14.4 kV power lines in
that direction.
It will be on for several hours at a time, then disappear. Nothing else like
it between 40 and 60 MHz. I would never have noticed it, except it sometimes
parks itself on 50313, the 6 meter FT8 frequency.
73,
Steve, N2IC
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------------------------------
Message: 3
Date: Sat, 23 Dec 2023 14:05:57 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
To: rfi@contesting.com
Subject: Re: [RFI] Peculiar Noise
Message-ID:
<d88469f7-a109-413d-8dd3-1179b8b9d7e1@audiosystemsgroup.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 12/23/2023 1:28 PM, k1ttt.dave@gmail.com wrote:
> I tracked down a noise like that many years ago to a tv preamp on an
> external antenna, would wander up and down the band but occasionally liked
> to park on a local repeater input..
This can be either instability in the preamp or from an SMPS PSU. Years
ago, we traced that sort of issue to instability in the preamp for
wireless microphone receivers. It helped that the contractor on the
project was a ham.
73, Jim K9YC
------------------------------
Message: 4
Date: Sat, 23 Dec 2023 22:11:26 +0000
From: David Eckhardt <davearea51a@gmail.com>
To: jim@audiosystemsgroup.com
Cc: rfi@contesting.com
Subject: Re: [RFI] Peculiar Noise
Message-ID:
<CAODdWWGYfU+jMfbtkf2HUYfMYNj8uGgWYEgYi1MKOZp9UiDFEQ@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Try FM demodulation. I have something much like that on 160-meters. It's
from one of the more-or-less local FM BC stations mixing with an AM
station.
Dave - W?LEV
On Sat, Dec 23, 2023 at 10:06?PM Jim Brown <jim@audiosystemsgroup.com>
wrote:
> On 12/23/2023 1:28 PM, k1ttt.dave@gmail.com wrote:
> > I tracked down a noise like that many years ago to a tv preamp on an
> > external antenna, would wander up and down the band but occasionally
> liked
> > to park on a local repeater input..
>
> This can be either instability in the preamp or from an SMPS PSU. Years
> ago, we traced that sort of issue to instability in the preamp for
> wireless microphone receivers. It helped that the contractor on the
> project was a ham.
>
> 73, Jim K9YC
>
>
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
--
*Dave - W?LEV*
------------------------------
Message: 5
Date: Sat, 23 Dec 2023 22:51:01 +0000 (UTC)
From: AA5CT <jwin95@yahoo.com>
To: 'Rfi List' <rfi@contesting.com>, "nlsa@nlsa.com" <nlsa@nlsa.com>
Subject: Re: [RFI] Sources of wideband hiss
Message-ID: <926333542.2772505.1703371861726@mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8
Q: What mode are you using to note 'hiss'?
Can I ask whey you hear in AM mode, IOW, 'envelope detection' mode (vs say,
SSB)?
de AA5CT Jim
On Saturday, December 23, 2023, 1:14:01 PM GMT-6, <nlsa@nlsa.com> wrote:
Dear friends,
What are some sources of wideband hiss?? I'm talking about an unstructured,
apparently unmodulated many-dB increase in the noise floor across the 2m
band*? No associated birdies or other noticeable signals, just a nasty hiss.
I see it in the direction of high-voltage power lines 2km away and also
toward a couple of houses I just a few hundred meters distant.? The
mechanisms of those sources are not necessarily the same of course.? Ideas
welcome.
Best regards,
Michael
*I don't know whether it affects other HF or VHF bands.
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------------------------------
Message: 6
Date: Sat, 23 Dec 2023 23:48:24 +0000
From: David Eckhardt <davearea51a@gmail.com>
To: Frank W3LPL <donovanf@starpower.net>
Cc: Rfi List <rfi@contesting.com>
Subject: Re: [RFI] Sources of wideband hiss
Message-ID:
<CAODdWWFA7-UPaeOS-EwOajktPPO5zwvpUQpa3PdmYZfUShkFuA@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
The "hiss" should be demodulated best in AM mode with a wide bandwidth.
Does it contain any component of grid power? If so, that would be a strong
indication of bad power distribution. If not, dig deeper, but use AM demod
with a wide BW.
Also, in sleuthing interfering RFI, why try to identify WHAT is it? That
really doesn't help much in determining WHERE the source might be. Once
you know the source, you can formulate a fix. Just determining what it
might be really doesn't lead to a fix other than knowing what service to
point a finger at. Do the DFing first.
Dave - W?LEV
On Sat, Dec 23, 2023 at 7:20?PM Frank W3LPL <donovanf@starpower.net> wrote:
> Like all other RFI, the first steps are
>
> 1. turn off all AC power in your own home and turn off
> all UPSes. If the noise disappears, you can use your
> circuit breakers as a next step in isolating the RFI source
>
> 2. If that fails, use a small directional antenna and hand portable
> radio to determine the location of the source
>
> Guessing the source is rarely useful
>
> 73
> Frank
> W3LPL
>
>
>
>
>
> ----- Original Message -----
> From: nlsa@nlsa.com
> To: "Rfi List" <rfi@contesting.com>
> Sent: Saturday, December 23, 2023 7:09:53 PM
> Subject: [RFI] Sources of wideband hiss
>
> Dear friends,
>
> What are some sources of wideband hiss? I'm talking about an unstructured,
> apparently unmodulated many-dB increase in the noise floor across the 2m
> band* No associated birdies or other noticeable signals, just a nasty
> hiss.
> I see it in the direction of high-voltage power lines 2km away and also
> toward a couple of houses I just a few hundred meters distant. The
> mechanisms of those sources are not necessarily the same of course. Ideas
> welcome.
>
> Best regards,
>
> Michael
>
>
>
> *I don't know whether it affects other HF or VHF bands.
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
> _______________________________________________
> RFI mailing list
> RFI@contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi
>
--
*Dave - W?LEV*
------------------------------
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End of RFI Digest, Vol 251, Issue 3
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