interference

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  • Question
  • Updated 3 months ago
I've been having interference during the daytime hours, worst on 160 and 80, and visible but not terribly bad on 40. I've gone through the house and turned off everything, unplugged all the wall warts, and it isn't in here, although I didn't kill the power to the entire house and run off battery.  I've attached a screenshot. Anyone see anything like this?
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Michael N3LI

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Posted 3 months ago

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Steve Sterling

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Looks like my neighbor's heat pump/air conditioner.  They have a Lennox.
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Michael N3LI

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I'll have to pay them a visit. Both have natgas though.
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Robert Lonn

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Anyone Close have SOLAR on their roof????
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Roger Thompson AD5T

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Looks a lot like the Ethernet LAN interference shown at https://www.nk7z.net/wp-content/uploads/2018/01/Ethernet-wide.png

73,
Roger, AD5T

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Michael N3LI

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It sure does. Different band, but similar spacing.
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Michael Walker, Employee

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Hi Michael

I saw that on 6M.  In my case, I replaced 1 patch cable with one I made personally and trusted.  And, that fixed it.

If you haven't look closely on your patch cables.

va3mw
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Michael N3LI

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Hi Michael, I'll take a look at all of them. Might try running direct from the Maestro with the max number of other cables unplugged.
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Mark NS9N

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Run the radio on battery and shut your mains off. I had the same issue from a wall wart power supply that I forgot was connected. With the mains off if it is still there then it is time to figure out which neighbor is causing the issue. In this case some fox hunting skills come in handy with a SDR receiver connected to a laptop and a directional antenna. If it is not in your house then the fun begins, how well do you really know your neighbors?
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Michael N3LI

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The neighbors here are pretty nice folks. I wouldn't expect any real issues. The interesting thing is the house beside me is rented by people who are seldom there, and the other side they are seldom home. Some might say the ideal neighbors! 
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Dave - W6OVP

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>Run the radio on battery and shut your mains off.

That's always step 1. Make sure it's not in your house.

Then ran the FLEX 6300 on a UPS and monitored it with an iPad.

Then used a portable AM radio to chase down the culprit. It was a new Keurig automatic coffee maker that radiated S8 when was plugged in but switched OFF! Adding an inline AC switch solved that problem (when not actually making coffee).
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N8AUM

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Lucky that you found it! I have soo much RFI that I don't know where to begin. A major problem I found are the new LED lights, made in China of course. 
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Michael N3LI

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"Coffee occasionally overrules RFI!"

K. Janeway, Captain USS Voyager
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EA4GLI - 8P9EH - Salvador

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Try unplugging usb devices in the computer.
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Michael N3LI

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I tried that, with no luck 8^(
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Doug K0DV

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Try using a different computer and listen to those bands while the main computer is off. It looks like switching supply interference and some of us never think to check the computer we are running SmardSDR on.
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Michael N3LI

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I tried it with DogPark on my Mac. Same noise.  Added to the mystery, it is 8:20 p.m. EDT, and the noise is gone. I had a meeting at 5:30, so I wasn't here when it went away. It will likely be back tomorrow.
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Scott Russell - N1SER

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I get this on 40m, happens several times during the day at about the same time every day. Screenshot taken from this video.

https://youtu.be/_neGlivzDjw


(Edited)
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Michael N3LI

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Whoa! That is some freaky looking stuff
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Scott Russell - N1SER

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Yeah no kidding right? It’s driving me nuts.
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Norm - W7CK

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Looks a lot like a MPPT solar charge controller.  They act like a switching voltage regulator converting sometimes >100v down to 12, 24 or 48v used by the battery system.  The controller must be really hard to filter because they all send the switching frequency as a darn signal out over the wire all the way back to the panels.  The panels and wiring act as a huge transmitting antenna.  Not very likely anyone in your neighborhood is charging a battery bank with solar though.

Does anyone have a RV parked close by?  If it is plugged in, the chargers on them are terrible. Lots of noise.  Just cruise through a RV park with your HF gear running in your vehicle.  S9+15 noise.....
Some folks also have solar on their RV to keep batteries topped off.   If they are using an MPPT controller, you'll know it.

Another culprit I recently ran into was a Cisco POE Ethernet Switch.  I bought two of these to power my POE security cameras.  Terrible noise generators.  I couldn't quiet them down much at all and gave up.  I have since sold them on Ebay and replaced them with NetGear POE Switches.  Although they aren't perfect, I have been able to clean them up enough to no longer be an issue.

Noise and HOAs are taking some of the enjoyment out of this hobby......

Norm - W7CK
(Edited)
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Scott Russell - N1SER

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There is a house down the street that had solar installed. The systems they install here do not charge batteries, they just use the solar power during the day. I’ve been wondering about this house. Other than that no RV’s allowed in the neighborhood.
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Eric Gruff

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You might contact KQ6RS (see QRZ.com) - this looks like a solar system and he's been tracking down many in his neighborhood as one particular brand is especially prone to QRMing many frequencies. Randy also published an article in a recent issue of QST on the same subject.
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Scott Russell - N1SER

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Thank you, I will for sure.
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Scott Russell - N1SER

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Eric, so to follow up, I emailed Randy and he replied very quickly and said my RFI doesn’t look like solar since it’s not continuous. He thinks it’s something else.

So I re-read his QST article and ordered the W6LVP Loop Experimenters Kit so I can make the small loop Randy used for direction finding the source. So we’ll see how that works once I get it all setup. It will be a fun project.

Thanks for the recommendation and reminder of the QST article, I remember reading it but forgot about it. :)

73, Scott N1SER
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Eric Gruff

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Scott - great. Randy's a great guy with a career in RF engineering behind him. Good luck in solving the QRM issue!
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David Warnberg

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Lots of Solar Pool pumps coming online these days, panels ramp up the controller and the DC pool pump will also ramp up as the sun gets higher in the sky... if a neighbor has a pool look for 3 or 4 solar panels on the roof is all.. not a full array... 

Yeah I had one, we've moved... DC pumps are the worst.
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Paul Menown

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I had similar interference to Michael but on 17meters, I only noticed that they were not on my ipad, narrowed it down to my computer monitors, both made by AOC, so going to have to source interference free 23" monitors, any suggestions?
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Mark NS9N

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Dell monitors have been flawless. Four of them running at my station and zero interference.
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wa4wab

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17,20 & 40 are the ones I have issues with. Will look into some of the suggestions posted above. Thanks
(Edited)
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wa4wab

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I was able to pin point my source of interference, it is the monitor in this case. It sits three inches away from the 6400M, will try and put more distance between them and see what happens.  Anyone have ideas on how to filter this kind of thing out?

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EA4GLI - 8P9EH - Salvador

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I fixed mine by grounding the monitor chasis.
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wa4wab

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Thanks for the tip, but that didn't solve the problem in this case. Added ferrite snap-on beads and that got rid of  all but a very small amount.
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Eric Gruff

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For those of you with monitor QRM, a first step is putting good-quality snap-on ferrites on all leads going to the monitor(s) and radio, including coax. If the interference is strong enough to radiate directly into the radio, physical separation or replacing the monitor(s) are your best choices.

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wa4wab

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Ferrite beads removed 95% Eric, thanks for the reminder! :)  Now to chase down that last bit......

I guess we can get complacent sometimes and forget the obvious. All of this gear was working just fine with the Flex 5000a & Yaesu analog radios before the 6400M came on board.


(Edited)