RFI at W9RE

On October 10th, 2016 Mike (W9RE) reported the following "I have been experiencing a noise on 160 and 80 for the past couple of months that peaks N/NE from my qth. It has peaks every 32.5/65 KHz across 80meters."

Mike subsequently asked for my assistance in tracking down the RFI (radio frequency interference). On October 15th Mike and I used my HF radio direction finding equipment to track down the interference, and we're 99.9% certain we have tracked the noise down to a residential home that's located 0.25 miles from Mikes home at a heading of 8 degrees. The 8 degree heading closely agrees with Mikes original reported direction of N/NE. Mike will now follow up with the homeowner to identify what device is causing the interference.

Below is a picture of Mike's panadapter capturing the interference on 80 meters which shows the interference occurring at intervals of approximately 32.5 kHz with the strongest interference occurring every 65 kHz.

(CLICK ON PICTURE FOR HI-RESOLUTION VERSION)

Youtube video recording the interference and direction finding activities: http://www.youtube.com/watch?v=UCu0WMyBCJY&feature=youtu.be

October 22, 2016 update

Mike (W9RE) got together with the homeowner at the suspect house today and they tracked the source of the interference down to an incorrect wall wart power supply powering a Linksys 20 port switch. See Mike's full report below.

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Don,

The homeowner thought it might be a terrestrial antenna bi directional preamp (and he even knew the bidirectional amp only amplifies one way but passes data the other way), I noticed on my little AM radio that 1260 was completely obliterated in his garage where the DMark (on the outside) and the modem, router and switcher were located. He unplugged the preamp with no change in level. Then I had to draw out his system to visualize it and try and sectionalize it. He had Comcast for internet and TV

Here is his system

!-----------Wireless Router

DMark----------Cable Modem---------Router------------ 20 port switcher-----!

!------------Switch in basement

The service came in through the wall from the DMark went up to a loft where the Modem and Router were located then back down to the other side of the DMark to a box that housed the 20 port switcher.

That made it a little confusing.

He unplugged some things and the level went down but not completely gone. The 20 port switcher (Linksys) was the oldest piece of equipment. He then unplugged the 20 port switcher and the noise went away completely and I had my wife confirm at home that it was gone also. He looked at the wall wart for it and said it was 3 VDC at 1 amp. We both agreed that was a really odd wall wart. He looked up the model on the net and it said it should be a 12 VDC 1 amp supply. He quickly looked for one and didn’t find one so I said I would go home and look for one and at least bring back a 12 Vdc UPS that I had and we could try it and see if problem solved. While I was home looking he called said he found a wall wart that was 12 VDC 1 amp and to check and see if I had any noise which I didn’t. He said the 3 V switcher was very warm.

Thanks for all your help,

Mike W9RE

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(website created and maintained by Don Kirk (wd8dsb), October 18, 2016)