[RFI] Finding house noise sources

Michael C Martin mike at rfiservices.com
Tue Jan 19 08:47:35 EST 2016

When hunting an inside noise, with the noise
active, if it's safe turn off the circuits not
associated with the noise source. This will reduce
the amount of noise distributed on to the circuits
that aren't the source circuit. It will still
radiate on the neutral and ground but at a lower

Michael C. Martin
RFI Services
PO Box 411
Traceys Landing, MD 20779
mike at rfiservices.com

-----Original Message-----
From: RFI [mailto:rfi-bounces at contesting.com] On
Behalf Of David Robbins
Sent: Tuesday, January 19, 2016 8:38 AM
To: rfi at contesting.com
Subject: Re: [RFI] Finding house noise sources

> So how might I best localize a source of
internal house RFI when 
> nothing is plugged in? Is there something like a
stud finder that will 
> allow me to follow the path of wiring behind

yes there is...
usually you turn the breaker off, plug in one of
the units to an outlet on the circuit and that
puts a signal on the wire that you can trace.  
effective ranges vary, some work on hot circuits
some are better on dead ones.  I have only limited
experience but prefer the dead circuit method as
the signal 'should' stop at the breaker in the box
and not carry over to other circuits.

the obvious questions are, what kind of bulb is in
that overhead light?  and, is it on a dimmer?
other bad possibilities could be a dying switch or
socket that is arcing.  I have even seen
incandescent lights generate noise, a small gap in
the filament can arc for quite a while before the
bulb completely dies.  taking out the switch from
the box to check for wires heading somewhere other
than to the light might point to hidden loads...
doing the same for the outlets might be useful
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