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Re: [RFI] FW: Topband: Exciting noise sources (Tim Duffy K3LR)

To: <rfi@contesting.com>, <kb4t@arrl.net>
Subject: Re: [RFI] FW: Topband: Exciting noise sources (Tim Duffy K3LR)
From: "Alan Robinson" <robinsah@engr.orst.edu>
Date: Tue, 29 Mar 2011 13:13:51 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Hi Frank,

Thank you for writing such a great email. You have been so helpful that I 
hesitate to add anything, but here are a few comments for this reflector (I am 
sure you know this info).

 I use the Radar Engineers equipment. I have an RE Model 240 RFI Locator, a 
Model 250 Ultrasonic, and a Model 247-B Hotstick Line Sniffer. I think they are 
well worth the cost and are invaluable for RFI locating.

I use the method developed by Marv Loftness (KB7KK) as described in his book 
"AC Power Interference Handbook, Third Edition", available from ARRL and HRO 
(and other places). This method is the one Mike Martin (K3RFI) teaches in his 
excellent work shops.

Basically the method involves searching with an AM receiver and compact beam 
antenna tuned in the 2 meter band to locate the noise within a few poles. Then 
I use a 6 element 440 MHz beam (Cushcraft Model A4496S) to identify "the pole". 
Then I use the ultrasonic the try to locate the offending hardware. 

(Side bar): I do use the RE 240's scope to get a "fingerprint" of the 
interference. Then look for that "fingerprint" in the field. For a description 
of this see Marv's book.

I do NOT climb poles. I have used the 247 hotstick sniffer to train linemen in 
its use. (I have a small portable noise generator for training). Then they use 
it with a bucket truck to find the problem hardware and fix it.

Note: The lightening arrestors that I have found had NO audio signature. 
However, one was so "hot" I got a very strong signal with my 675 MHz 8 element 
beam. I do usually find an audio signature with the Ultrasonic. This helps the 
linemen to identify the problem hardware.

I have also tried locating with the MFJ Model 852, dipole only, power line 
noise detector. This has not worked well for me. I would like to try their 
Model 856 with the built in 3 element beam. Perhaps this would work well to get 
within a few poles of the source. But I believe you really need to use 440 to 
450 MHz to get "the pole".

Well that's about it for now. Thank you again, Frank, I read all of your 
postings very carefully.



  ----- Original Message ----- 
  From: Frank Haas KB4T 
  To: rfi@contesting.com 
  Sent: Monday, March 28, 2011 11:27 PM
  Subject: Re: [RFI] FW: Topband: Exciting noise sources (Tim Duffy K3LR)

  Thank you, Jim. 

  All that I share here is the direct result of experience in the field. I'm
  pleased to be able to share what I know. Knowing that what I share is of
  value is the highest praise possible. 


  Frank N. Haas KB4T
  Utility Interference Investigator

  >>>> Original Message <<<<

  Date: Mon, 28 Mar 2011 22:49:05 -0700
  From: Jim Brown <jim@audiosystemsgroup.com>
  Subject: Re: [RFI] FW: Topband: Exciting noise sources (Tim Duffy
  To: rfi@contesting.com

  Frank Haas KB4T wrote:

  > Frank N. Haas KB4T 

  Many thanks for your excellent mini-tutorial. VERY useful stuff, and in
  complete agreement with everything I understand or have read on the topic
  that I consider to be solid.


  Jim Brown K9YC 

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