Where is that blasted noise coming from?

Evil RF noise in Ethernet over power adapters

My internet comes in at a corner of the house.  In that room I have my cable modem and a WIFI router.  Unfortunately the WIFI is seemingly non-existent at the other end of my house and especially in the upper floor opposite the WIFI router.  I tried re-orienting it and different antennas to no avail.

As a solution, I purchased an Ethernet over powerline adapter.  This routed the Ethernet through the house wiring to receivers plugged into outlets at points where the WIFI was weak, thus providing Internet access to those rooms.  The model I purchased also had ethernet ports which I needed for some of my older devices.

Ethernet over powerline seemed like an ideal solution.

Typical Ethernet over powerline adapter
All was well until a few months ago... I noticed a broadband noise on 40m and 80m in my shack.  I turned off the power to the house and switched to battery on my KX3 and the noise was gone.  So the interference was coming from my house.

The Search

I restored the power and fired up my Yaesu HT which has general coverage receive and tuned it to 7030kHz.  I walked around the house and conducted a bit of a fox-hunt for the offending noise.  The noise occurred at every outlet in the house !!!

I tracked it down to one of the Ethernet powerline receivers.  I unplugged it from the wall and discovered blissful silence.  I figured it had just gone bad.  It was out of warranty so back to the store I went and purchased another set.  This time it was a different brand, as the first one was no longer carried.

I installed the new adapters and everything was fine... for a time.

Fool me once shame on you, fool me twice shame on me

This week the noise returned with a vengeance.  Being wiser I went straight to the new adapter and unplugged it.  Yep it had gone bad again.  It was in warranty but I'd learned my lesson.  Whatever sort of RF filtering these devices have doesn't last.  Something zaps them.  I can't plug the receiver into a AC line filter because it stops it from receiving the Ethernet over powerline.

So out they came and back to the electronics store I went.  This time I purchased a WIFI extender with Ethernet ports built-in.  I'm back to blissful RF quiet (to a degree) at my QTH.

The moral of the story

If you have RF noise at your shack and you use these devices, check them out.  They could be the S9 noise culprit.  If you haven't bought them, take my advice and don't chance it.

I didn't think a WIFI extender would work for me because my laptop can't even detect the WIFI in some of my rooms but the WIFI extender (at least the Netgear model) seems to work well.  I now have blessed Internet in every room and no more broadband RF noise.

That's all for now

So lower you power and raise your expectations (and rid yourself of pesky RF noise)

Richard, AA4OO
Richard Carpenter, AA4OO, is a regular contributor to AmateurRadio.com and writes from North Carolina, USA. Contact him at [email protected].

8 Responses to “Where is that blasted noise coming from?”

  • Dave WD8CIV:

    I went through the same process a couple of years ago, only the culprit here was a wall-wart power supply connected to a digital audio converter between my TV and a separate sound bar. I didn’t do an autopsy but I suspect it was a cheap switching power supply and whatever they put in it to prevent switching noise from being conducted back out onto the house wiring had failed.

    DFing the noise with a handheld receiver was pretty much impossible because the noise was EVERYWHERE in my house. So I switched off one breaker at a time until the noise went away, then went snooping along that circuit to see what was plugged in. Fortunately it was the living room, and not something inaccessible like my water heater.

  • Skip Flem, nt1g:

    I thought the 12V1Amp switching WallWort was causing me QRN, from AM to wiping out the
    baseballgame on FM, until I unplugged the ethernet cable to my ADS-B Raspberry Pi…and
    installed a USB WIFI dongle and ALL the noise went away.

  • David WB4ONA:

    You should report these products to the manufacturer as well as the FCC. Not that reporting them to the FCC will do anything: Remember, the FCC is the big government agency that gave them emissions compliance in the first place (once they paid the FCC large sums of money)!

  • Mike VE3WDM:

    I had real issue a few years ago with my plasma TV it was nuts and wiped out 80% of all bands. We have since moved and changed out the TV. We have an LCD tv with no issues.
    73, Mike

  • NK7Z:

    Most Ethernet over power line adapters now are filtered for the ham bands… As you said, something broke to make them cause a problem… I use an older set of filtered adapters, (Netgear), and they are quiet inside the Ham bands, but if you SWL they are a beast…

    I do RFI location for our local club, and one of the ways to locate an Ethernet over Power Line adapter as an SWL issue is to look for a sharp drop in signal level as you approach any ham band…

    for a series of articles on locating and correcting RFI.

  • William 13865:

    Can you aim it at the Isil

  • William 13856:

    Wrong number

  • Paul, W3FIS:

    I had considered power line adapters, but opted to a “repeater” that I got off of Amazon for around $16. Works fine.

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