[CVARC] Re: RFI Nightmare

  • From: Ed Hutchinson <ehutch@xxxxxxxxx>
  • To: cvarc@xxxxxxxxxxxxx
  • Date: Mon, 18 Dec 2017 08:53:07 -0500

It would be interesting to know if it is inside or outside the home.  W1CL had an ongoing "discussion" with his utility because he could measure loud broadband noise emanating from a transformer with a faulty insulator.  I think it was finally resolved but Howie hasn't been on the 160m net for many months and I don't know for sure if it got fixed.

For a while I had a persistent S8 noise floor that was making 160M almost impossible.  It started in the summer so I just assumed it was QRN.  It turned out to be a brand new LED bulb in a lamp that is left on many hours per day.  I changed the bulb with a different LED and the problem went away.

Most of Randy's noise is very likely from a single source and finding it is essential. Unfortunately there are probably hundreds of possible sources in a typical home.  If it is coming from outside it is much more difficult to resolve. There are "computers" in almost every appliance and they can be efficient noise sources.  I would start by unplugging or at least turning off things one at a time, and it wouldn't hurt to put an oscilloscope on any switched power supplies in use.   An "igniter" for a boiler that is not turning off properly will make a lot of RF (and it will run up the utility bill) more experience.... There is no magic fix.

Ed, n1fmp


On 12/18/2017 08:27 AM, Catherine James wrote:

You will probably need to track down the sources of the noise, and see if you 
can suppress them with ferrite or other filters.  You can't fix the problem at 
the antenna unless it is coming from a specific direction and can be put in the 
null of the loop.

Did you try rotating the loop to see if the noise drops off in certain 
orientations.

--------------------------------------------
On Sun, 12/17/17, Randy Davenport <pastor.spaceboy@xxxxxxxxx> wrote:

  I live in a second floor apartment that is a remodeled 1874 home.  It is part 
of a church.  I recently
  tried a mag loop in my apartment and the noise floor is about s8+  I need 
help! Any suggestions? Would an AC line
  filter be helpful? What ferrite mix? Anybody have any extra ferrites or other 
devices?
  Randy ka4nma





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