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

To: RFI List <rfi@contesting.com>
Subject: Re: [RFI] More on 160 M RFI - significance of hum bands
From: donovanf@starpower.net
Date: Wed, 29 Mar 2017 19:26:03 -0400 (EDT)
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Hi Pete, 


Nothing in your report suggests power line noise. 


The best way to isolate RFI is always by using directive antennas 
to find the source. A small loop antenna should do the job for you. 


73 
Frank 
W3LPL 

----- Original Message -----

From: "Pete Smith N4ZR" <n4zr@comcast.net> 
To: "RFI List" <rfi@contesting.com> 
Sent: Wednesday, March 29, 2017 10:29:29 PM 
Subject: [RFI] More on 160 M RFI - significance of hum bands 

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 
spotting RTTY activity worldwide. 
For spots, please use your favorite 
"retail" DX cluster. 

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