Interference From MXQ Smart TV Box / Streaming Media Player Power Supply

On August 3, 2016 I detected a repeating interference pattern on 160 meters and my 3 point fed pennant receive antennas indicated the interference was at a heading of 145 degrees from my home. I then tracked down the interference to my neighbors house utility service entrance (electricity, cable, phone) that's approximately 150 feet from my RX pennants at an approximate heading of 145 degrees using my portable direction finding equipment, but had difficulty finding the guilty device using my DF gear in the house,

Repeating interference pattern shown below.

(Using Kenwood TS180s wideband IF output into an SDR receiver)

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Recording of the interference (youtube video link): http://www.youtube.com/watch?v=B0oHz2vfnNQ&feature=youtu.be

This evening (Aug 9, 2016) I finally resorted to shutting off one breaker at a time to help identify what part of the house was the likely source, and it turned out to be the Master Bedroom (turning off the Master Bedroom circuit breaker was the only breaker that had an impact, and it totally killed the interference). We (my neighbor and I) then went to the bedroom with my DF gear and detected strong interference from the area of the TV, cable box, and Amazon "MXQ Smart TV Box / Streaming Media Player" that were located in the Master Bedroom.

Unplugging the MXQ Smart TV Box power supply killed the interference. I tried a Delta 20DRGG5 input line filter between the MXQ Smart TV Box power supply and the wall outlet, but this had very little impact on reducing the interference. I then wound 11 turns of the 2 conductor extension cord that fed power to the MXQ wall wart power supply (SMPS) through a 2.4" OD Fair-Rite #31 mix toroid core, and this immediately killed the interference. I wanted to wind 14 turns on the toroid core but that was not possible with the existing plug on the extension cord. My neighbor was amazed at how simple the solution was for eliminating the RFI, and I have to admit I was surprised how quickly we solved the problem.

Picture below of the power supply feeding the MXQ Smart TV Box: Model BM-118A with a rated output of 5 Vdc, 2amps.

RF choke consisting of 11 turns wound through a 2.4" OD Fair-Rite #31 mix toroid core.

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