Message-ID: <000e01c2e3dd$4d108100$3704210a@Hugh>
From: "Hugh M0WYE" <m0wye@thersgb.net>
To: rsgb_lf_group@blacksheep.org
References: <LOBBIDNOENMNHIBGDCKBOEBLDIAA.g3wkl@btinternet.com>
Date: Thu, 6 Mar 2003 12:38:28 -0000
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Subject: LF: Re: LF broadband QRN?
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Hi John,
If you can pick it up on a LW radio, or other portable RX, maybe you could
go walk-about with that and track it down.

What you describe sounds very much like the sort of buzzy noise I get from
Low Energy Light Bulbs. Some of these seem to suddenly start generating a
lot of noise when they near the end of their life, and some of them change
frequency as they warm up. If someone goes in the bathroom for a pee there's
no problem ... but if it's poo I have to wait 'til they've finished. ...
sorry to lower the tone of the conversation !

I once had a lot of mains harmonics appear on argo due to a mains hum on the
input to the sound card.

I'm probably not being a lot of help, but you have my sympathy ...

73
Hugh M0WYE


----- Original Message -----
From: "John W Gould" <g3wkl@btinternet.com>
To: "Rsgb_Lf_Group@Blacksheep.Org" <rsgb_lf_group@blacksheep.org>
Sent: Thursday, March 06, 2003 12:02 PM
Subject: LF: LF broadband QRN?


> Since the 73kHz tests on Tuesday I have been monitoring at several times a
> day and find a consistent and steady  noise-level that is about 20dB below
> the signal at 138.8kHz, and about 6dB below the one at 75kHz. Its a mains
> type of buzz, beating at times with itself.  Like most I have had this in
> the past and put it down to RFI from switched-mode PSUs, however, it was
> only sporadic in the past so I am wondering if it's something new.  It
seems
> to be all the way up the LF band to just below the LW broadcast band (but
> that cut-off could be a function of my aerial's resonance set at 73kHz).
>
> The only thoughts that I have is ADSL or signalling on the HV underground
> cable somewhere beneath my garden. Certainly, ADSL will have become much
> more used locally since I last did an serious listening on LF, but I would
> have thought the radiation would be fairly low from the balanced overhead
> telephone lines that are at least 200m from my aerial. I would have
thought
> that the shielding around underground HV mains cables would be sufficient
to
> stop low-level signaling causing problems.
>
> I can't see a real reason why TV related interfernce should increase near
to
> my home.  How far away do TV's etc need to be before they cause problems,
or
> is it more caused by the interference conducting itself along the mains
> cabling, etc.
>
> Any thoughts?
>
> 73 John, G3WKL
>
>
>