[RFI] Noise Search

Eric Gustafson Eric Gustafson <n7cl@mmsi.com>
Mon, 9 Oct 2000 08:50:44 -0700

Hi Bob,

The noise you describe is very characteristic of touch controlled
lamps.  They have the spectral characteristics you describe.  And
they make as much or more noise when the load is turned off as
they do when the lamp is lit.  Two other sources with this
characteristic (and the noize zones spaced from 50 to 200 KHz
apart) are automatic security lights (indoor or outdoor) and
battery charging uninterruptable power supplies.  If you have any
of these three types of devices in your house, unplug them all
from the AC power and plug them in one at a time to see if they
are the culprit.  Turning them off at their front panel or the
touch plate will not silence them.

I also had a Radio Shack "feature rich" telephone that acted
somewhat similarly for a few months prior to completely failing.
It went to the long death throes following a nearby ligthning
strike.  If it hadn't finally quit working on its own, I'd have
never found it.

Unfortunately, all of these sources are robust enough that they
may actually be a house or two away from you and still be quite
irritating.  Good Luck.

73, Eric  N7CL

>From: "kmarch" <kmarch@ix.netcom.com>
>Date: Sun, 8 Oct 2000 15:05:29 -0700
>One of the noises that I am going to search and destroy has a
>particular characteristic.  I wonder if anyone has an idea of
>what it could be.  The noise is a series of modulated (garbage)
>about 3 or 4 kHz wide and spaced about 30 kHz across the
>spectrum.  The noise is always on, late at night, 24 hrs. Once
>in a while the noise changes.  It becomes stronger and is then
>spaced every 47 kHz across the spectrum. It stays that way for
>an hour or two, then reverts back to the normal 30 kHz
>spacing. It is stringest low frequency (80M), can't be heard on
>160M, but can be heard up to 15 M.  Has anyone run into that
>kind of noise? ( This is noise number 3 of the 5 I am tracking,
>most of which are broad band.)  Thanks, Bob

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