[RFI] Does a power pole generating RFI always generate ultrasonics?

Alan Robinson robinsah at engr.orst.edu
Mon Jun 7 21:52:47 PDT 2010

Hi Stu,

The only sources I have found that had NO audio signal were lightning arresters. As other folks have pointed out, you need a "line of sight" to the source to "hear" it. Sometimes you have to "look" at the pole from multiple locations to hear the source.

If the source is inside the hardware you won't hear it. All of the sources I have found that were not inside could be heard from the ground, although a line sniffer is a big help too. I use both 440 MHz and 675 MHz beam antennas to DF the sources before using the ultrasonic locator. 

Good luck with your hunting.



  ----- Original Message ----- 
  From: Stu Phillips 
  To: rfi at contesting.com 
  Sent: Monday, June 07, 2010 3:46 PM
  Subject: [RFI] Does a power pole generating RFI always generate ultrasonics?

  I'm tracking a power pole near my QTH that is generating RFI from 15m on
  up.  With a combination of HF and VHF antenna, I'm pretty sure I've
  tracked to the correct pole.  This pole is generating more of a
  "cracking/poping" form of RFI rather than a constant arc like RFI.


  I recently built an Ultrasonic detector as an additional tool in my bag
  - it seems to work as I can hear tire noise, rubbing fingers, rat
  repeller etc...  BUT...


  When I check out this pole, I can't hear anything ultrasonic wise.


  So my question...


  Does a power pole generating RFI ALWAYS generate ultrasonics that are
  strong enough to be heard from the ground?



  Stu K6TU

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  RFI at contesting.com

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