[RFI] Finding house noise sources

Gary Smith Gary at ka1j.com
Tue Jan 19 09:24:16 EST 2016


That is a good idea. I don't want to disconnect the K3, it'll be a 
bugger to connect everything back up again. I do have a Corsair I can 

attach to a battery and bring it around the house so I can hear it & 
I have plenty of 75 ohm cable from connecting my RF antennas (even 
though its the flooded & overly stiff variety). I bet that will help 
me find the noisy spots pretty well. I'll give it a try.



> 1. Walk around the house with a portable AM radio, or
> 2. Connect a long piece of coax with a short probe on it to your 
> station RX, and walk around the house with the coax/probe.
> Dave Hachadorian, K6LL
> Yuma, AZ
> -----Original Message----- 
> From: Gary Smith
> Sent: Monday, January 18, 2016 2:52 PM
> To: rfi at contesting.com
> Subject: [RFI] Finding house noise sources
> Hi,
> I need some ideas on how to track down some noise sources inside 
> the
> house. I thought it would be just switching off breakers and then
> unplugging the electronics on that circuit till I find the one 
> that
> has failed and deal with that. No, there's more to it that I just
> discovered.
> For some time I have been having noise on my HI-Z Triangular. It 
> is
> NW of the house. A salt marsh sans anything electric from the S 
> to
> almost N to the West of me. The least noise was N, toward AMTRAK 
> 100'
> away and when I would turn the aiming direction clockwise, I 
> would
> get more RFI until the maximum between the south and the NW. 
> Also, My
> be3am located at the center of the roof identified much the same. 
> I
> quit using the beam because the noise was too much. For the most
> part, the noise seemed to come from the direction of neighbors 
> who
> are only to the SE & S of me.
> I asked my YL to watch my monitor, connected to the P3, as I 
> flipped
> off breakers. On the 2nd flip she said the noise was gone. The 
> only
> outlets I could find at fault are the overhead light in the 
> hallway
> and one bank of wall plugs in the kitchen. Nothing in the kitchen
> when unplugged stops the interference. Somehow, something unknown
> that is attached to the circuit is causing this problem and I 
> have to
> track that down.
> The attic was filled with that paper mache kind of blown 
> insulation
> and all of the wires are covered. That will make finding and 
> tracking
> the wire to the overhead light difficult, I have no markers to 
> where
> to safely step. I can do it bit by bit of course but I just can't
> look and follow the wires. In the basement, there is a false 
> ceiling
> that holds the wires and some of them are in an area very 
> difficult
> to access.
> But the problem remains that when that one circuit is eliminated,
> most if not all the noise goes away and I find nothing attached 
> in
> line except that one overhead light and it was not on when we did 
> the
> test.
> It was brought to my attention that a defective doorbell 
> transformer
> can cause major issues but the doorbell is not on the same 
> circuit
> and though I looked for that transformer, it's not in the closet 
> or
> anywhere else I can find. The electrician was a gem. Still, I'd 
> like
> to check it out, it's had power on it since 1969.
> 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 walls?
> Thanks & 73,
> Gary
> KA1J
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