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Re: [RFI] More on 160 M RFI - significance of hum bands

To: Pete Smith N4ZR <n4zr@comcast.net>
Subject: Re: [RFI] More on 160 M RFI - significance of hum bands
From: dalej <dj2001x@comcast.net>
Date: Wed, 29 Mar 2017 17:56:44 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Do you hear the noise on 10 meters,(6 meters even better if you have a gain 
antenna) if so it may be power line.  If you don’t it may be somebody's 
switching supply, charger or who knows what, but not power line.  

If I suspect a power line noise then I try to get a heading with my beam on 10 
m. or 6, then walk the line with my airband walkie-talkie.  Makes for a nice 
walk anyway.  Once you find the pole or poles then call the power company and 
help them when they come out.  That has how I’ve handled power line noise in 
the past.  

If it’s a neighbors TV, computer, charger etc then that is a whole new ball 
game.  Hope that is not.  Check your own house first.  

73 and GL

Dale, K9VUJ


On 29, Mar 2017, at 17:29, Pete Smith N4ZR <n4zr@comcast.net> wrote:

I'm having more trouble than I expected localizing my power-line interference. 
In particular, one component of the interference varies from almost negligible 
to whopping big, as visualized on HDSDR, and often appears in wide bands 22 KHz 
apart..  See the Dropbox link 
<https://www.dropbox.com/s/qaxt7qnyl51hnp3/hum%20bars.png?dl=0> for a visual.  
You can see the hum every 120 Hz on the audio display - when I move the AM 
passband away from the hum bands, the 120-Hx multiplesessentially disappear.  
The bands themself vary, without apparent pattern, from very strong - as seen 
in the illustration- to invisblle/inaudible. Just now, they stuttered a few 
times and then disappeared from the waterfall (and the audio) entirely, in the 
course of a few seconds.  With the AM passband in one of the hum bands, the 
base noise level is about S9; without them, it is S7, which still isn't great, 
but worst things first.

Really puzzling - any advice on what I'm seeing and how to track it down will 
be much appreciated.


-- 

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
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