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[RFI] Another Treadmill causing RFI (with recording)

To: RFI <rfi@contesting.com>
Subject: [RFI] Another Treadmill causing RFI (with recording)
From: Don Kirk <wd8dsb@gmail.com>
Date: Sat, 25 Apr 2015 22:28:45 -0400
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
Yesterday I decided to track down interference on 160 meters which I had
suspected for some time to be from one of my neighbors treadmill or similar
exercise equipment based on recent experiences from my wife's treadmill and
the amount of time the interference is present (typically 30 to 45
continuous minutes at a frequency of one time per day or less).

Using a portable receiver connected to an adjustable preamp and 14"
diameter shielded loop I tracked the signal down to my next door neighbors
electrical power entrance.  Later in the day I asked my neighbor who was
exercising at 6:30am, and she said she was, and she said she was using a

I also asked my neighbor if she sometimes uses her treadmill at 3:30pm
(which is another time I hear this interference), and she said she
certainly does.

I recorded the signal and have uploaded my recording on youtube, and the
recording includes a spectrum plot captured using my RTL-SDR receiver.
Here is a link to my youtube recording for those interested.

I talked with my neighbors husband this afternoon, and told him I would
like to test a line filter on his treadmill similar to the system I use on
my wife's treadmill to see how effective it is in reducing or eliminating
the interference (my neighbor and I have an excellent working
relationship).  When we both have some free time we will give it a try.

I rank my sources of interference as follows

   - VFD drives (from treadmills or HVAC systems)
   - Switch mode power supplies
   - Plasma TVs
   - Arcing power lines

Just FYI,
Don (wd8dsb)
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