Chasing computer or digital RFI

[N4LTA]

I have some periodic interference on my sdr that sounds like like digital noise. I have unplugged everything that I have in the house that I can think off and it is not reduced. Any ideas?

Thanks
Pat
N4LTA

[W1ITT]

Just unplugging things might not be definitive.  It's best to run your receiver on a battery and pull the main breaker to the house.  This will shut off all the sneaky stuff that seems to be off...but may not be.  These include furnaces, wired in smoke detectors, intrusion detectors, etc.
The other thing that needs to be done is to shut off anything that might be backed up by an Uninterruptible Power Supply.  I got snookered on this a couple years back when I pulled the main breaker and went around dumb and happy thinking the noise was external.  Finally it dawned on me that I was running a cable modem and router off the UPS, and guess what!  It was a noise maker.  Later I dumped the cable and disconnected their coax at the entrance block.   Now I have new noises, but that's a different story.
73 de Norm W1ITT

[N4LTA]

Thanks Norm,

I was convinced that the signal was external to the house. Today, I did as you said, and with the main off, the signal disappeared.

The problem was isolated to my back yard roll off roof observatory. Turning things off in the observatory, led to two Meanwell switching power supplies or the loads they are serving. I have never had problems with the Meanwell supplies, before, so it may be the equipment on the telescope and mount powered by the supplies. This includes a NUC computer and monitor,  powered  router, a computer within the Bisque MX+ mount, several CCD cameras and focusing equipment. I'll track the culprit down when I get the observatory back up. It has been down since the fire in April.

Pat
N4LTA

[WA3JVJ]

I have had similar problems; one major generator of noise is some new under counter LED lights in our kitchen.

[K8DI]

I have had similar problems; one major generator of noise is some new under counter LED lights in our kitchen.

Many of the low cost devices use unlabelled USB power adapters. These things are terrible for RF and safety. I’ve got several that were terrible S9 wide band noise sources where replacing the adapter with one that actually met UL and FCC rules eliminated the noise.

Ed

[WD5JKO]

Good thread Pat,

   I might suggest that any "Man Caves" we have also have a main disconnect switch. For long term hibernation, just kill that circuit.

With the recent preventable power outage in Texas, I was without power for at least 4 nights. The XYL bailed on me, and took the CAT! Too cold she said!!

Anyway, the bar was open, I had a heavy blanket, DC lights, and I had my Sony SW receiver. Tuning to some 49m stations, there was some horrific, and periodic line noise...the same as I have been

fighting for years. What was gone was the usual sizzling line noise that a blanker takes out nicely. In my case the power outage shut down my side of the street, and adjacent street. It was

good to know the noise issue was outside my home, and NOT on the 7200v lines pole to pole in the back of my yard.


  Pat, you were lucky to find such a simple solution.

Jim
Wd5JKO