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[TenTec] strange QRM/QRN/RFI source?

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Subject: [TenTec] strange QRM/QRN/RFI source?
From: larrylg@sbcglobal.net (Larry Greenberg)
Date: Wed May 14 22:48:59 2003
Hello... first the obvious a power transformer.. Data stream? A cable 
transponder-leak sometimes cable co.s provide internet access. Otherwise-  Are 
you rural or urban?  Is the noise constant or pulsating? Larry N5BEA

wb5jnc@juno.com wrote:
Greetings all,

(First, my apologies for the length of this post, but I wanted to give as much 
info as possible in the hope of tracking down whatever we are hearing. TNX.)

I'd like to enlist the aid of the "brainpower" of this group in identifying the 
source of some strange QRM/QRN/RFI that has shown up in the past few days at my 
QTH. It all started Monday night when my XYL asked me what she was hearing on 
the AM BC band. She's a KC Royals baseball fan (the result of having grown up 
on a Kansas dairy farm) and one of the Royals stations she usually listens to 
is on 690 KHz. I started investigating and we discovered that the signal was 
also showing up around 830-840, 970 (+/-), etc. as well. I went through the 
routine of checking everything in the house -- no computers, etc. on -- and 
even flipped the main breaker for a few seconds (the interference was still 
there). I also did some "sniffing" with an AM portable radio and the signal 
seemed to be strongest around both the electrical outlets and telephone jacks, 
making me think that is how the interference is coming in (both power and phone 
are aerial and obviously in close proximity).

I also checked and found the signal on 160M at around 1800, 1935, 2070, and 
2215. (I say "around" because it was 6 KHz or so wide and seemed to vary in 
bandwidth.) It sounds like some sort of data stream; perhaps the best way I can 
think of to describe it is that it sounds similar to a slow scan signal. I'm 
calculating that the fundamental is in the 138-139 KHZ range based on the 
spacing of the signals.

At this point I'm wondering if possibly this is a DSL system at a neighbor's 
house gone haywire (as there are DSL channels in the 138-139 KHz range), but if 
any of you have any better answers, I'd like to hear them.

TNX/73, Al

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