Message-ID: <EA6D0562B6EB456398548B9D8C8F0607@White>
From: "Markus Vester" <markusvester@aol.com>
To: <rsgb_lf_group@blacksheep.org>
References: <8FA94C1DE6F6465C9C511D7A455AB4BB@ns94d01ae4d850> <F26467A8FDE74DEE8C44E22DA4A450C5@2a2d7ed321c6425> <4CE85C77.5010109@kpnmail.nl> <4CF0B70E.1050009@online.fr> <D304E73B-04EC-417F-8666-E2467C14D4D3@numeo.fr> <4CF18164.1020505@online.fr> <op.vmvnu8aeyzqh0k@pc-roelof> <4CF29F87.5020305@online.fr> <6945F555095B4289B040095A46142012@White>
Date: Sun, 28 Nov 2010 20:45:15 +0100
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Subject: Re2: LF: T/A  [137kHz]  Grabber noisy !
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...counting the 1ms pixels, the FM rate seems to be about 71 Hz, plus=
 or=20
minus soundcard samplerate deviation. Googling for "72 Hz plasma" brou=
ght up=20
that this is a standard framerate for Pioneer plasma TVs. My assumptio=
n is=20
that the framerate may be modulating the current consumption, and thus=
 the=20
power supply chopper frequency.

Do you have a portable receiver to locate the noise? You may also be=
 able to=20
see the chopper fundamental (eg. ~ 45 kHz ?), by connecting the antenn=
a=20
directly to a soundcard with 96 kHz samplerate.

73, Markus


From: Markus Vester
Sent: Sunday, November 28, 2010 8:03 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: T/A [137kHz] Grabber noisy !


Hi Jean Pierre,

on Spectrogram it looks like an FM-modulated source, sweeping between=
 130
and 141 kHz, typical for a switched mode power supply harmonic. But th=
e
strange thing is that the modulation rate is 70 Hz, instead of the usu=
al 100
Hz. Perhaps this could be traced to the frame rate of some monitor or=
 plasma
TV?

Best 73,
Markus


From: "Jean-Pierre M=E9r=E9 (F1AFJ)"
Sent: Sunday, November 28, 2010 7:29 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: T/A [137kHz] Grabber noisy !

Hi Roelof ,
I think that my QRM is local (perhaps CPL) I made capture and an audio
recording, you can download it here:
http://jpmere.online.fr/LF/QRM_137kHz/
73  Jean-Pierre F1AFJ

Le 28/11/2010 12:07, Roelof Bakker a =E9crit :
> Hello Jean-Pierre and all,
>
> Have you also noted increased wideband noise last night.
> The band noise faded up and down every few seconds with 6 - 10 dB.
> I could here it on LF and also on 160m, though less pronounced.
>
> It got less as the evening progressed.
>
> Any ideas?
>
> 73,
> Roelof Bakker, pa0rdt
>=20