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" <[email protected]>
To: "[email protected]" <[email protected]>
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
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