Best way to filter noise for AM band?

[bgadow]

Earlier this year I started noticing the lower half of the AM band was dead/full of hash at my house, or even in the driveway. I'd been putting off doing anything about it but, as I have a radio on the workbench that I'm fixing for someone else, I'd really like to get the band "back". So, this weekend I turned up the volume loud on one of my favorite consoles (a late 30's Delco) and walked around the house unplugging things to seek the offender. The winner? The new Frigidaire refrigerator we bought early this year! I'm guessing it can be blamed on the "inverter compressor technology". I've googled the problem but wasn't satisfied with the solutions. Does anyone here have firsthand experience in fixing it?

[DavGoodlin]

The FCC seems to have abandoned any concern about "consumer" equipment making line hash. Energy star mania has had some unpleasant side effects, by an R-lamp LED type by a major manufacturer. As handy as it is for servicing, I turn it off when testing!
A 4 ft LED shop-light from Costco is noise-free in comparison. I recommend them for benches more than 4-ft LED replacement T8/T12 tubes, that use line voltage to the bi-pins/tombstones and do create some noise as I just found out.

After you identify noise source, a portable AM radio is a good tool to determine if the inverter is conducting noise out via the line connection OR generating noise radiated mostly in proximity. This can be confirmed by moving the radio close by the refrig. and controls, then along its cord, then next to other AC circuits, wires, etc.

If noise drops as you move away then, like some electronic-ballast fluorescent lamps, is direct radiated but still may affect an AC-powered radio elsewhere in the house. I assume its compressor is well-grounded and shielded as any appliance would be.

An M-derived filter, using neutral/line to ground Y2-rated .05mf caps on both sides of a common-mode inductor, in line with the refrigerator compressor may reduce line-carried noise. Closer to the source the better, without voiding the short warranty.

I have had some success putting the cord receptacle-mounted filters from PC power supplies into 30s-40s consoles, especially if noise comes on the AC line from uncontrollable sources. Nobody seems to mind a grounded cord anyway. I have been able to tune AM easily on some sets, even in the basement. Other sets seem to have noise only on parts of the band with "peak" concentrations at certain frequencies. I have worse 60 hz buzz-type noise during the day, I have shut down every branch breaker in the house and outbuildings yet it persists. One radio with an oversized filter cap momentarily plays clearly when you pull the plug out, nailing it as line-borne noise.

Using a Euro-model Sanyo 9v AM portable and surveying on bad days, wondering if its from coming from the only other neighbor on the pole transformer, 300 feet away. The noise seems to vary considerably but is coming from the line. Switching phase at the breakers sometimes helps but as a light or something else is switched on, the noise returns. House wiring, though grounded, seems to make a nice repeater system.

I'm just happy having 3 AM stations that play music. But from 20 and 60 miles away, so just during daylight hours.

[bgadow]

I'd started by walking around with a cheap old AM transistor radio which generated a large amount of hash around some wiring and, in particular, around my stereo which was turned off; unplugging it didn't cure anything. Unplugging a power strip that was turned off made the noise worse. Fun stuff.

[zeno]

Shut the whole house down & see if it goes away. If it doesnt get
rid of anything with batteries including cars & cell phones.
If you think you got everything its probably coming from another house
or a utility.
If it goes away bring up each breaker alone one at a time. If you find it
just run that line & unplug things one at a time. You will probably find more than one source, just go for the worst first. Let us know how it goes.

73 Zeno
LFOD !

[maxhifi]

Another way to approach this, if you get lucky, is to use a portable radio to find a spot in the house which is free from interference, and then situate your radio there. I found a spot in my house which is somehow a null for all interference, and now I can once again listen to AM radio without unplugging half the house. It even picks up DX, just like it used to.

[DavGoodlin]

Originally Posted by bgadow

I'd started by walking around with a cheap old AM transistor radio which generated a large amount of hash around some wiring and, in particular, around my stereo which was turned off; unplugging it didn't cure anything. Unplugging a power strip that was turned off made the noise worse. Fun stuff.

Its a "Faraday cage" of competing noise, sometimes it cancels. Even a blind squirrel can get a nut once in a while.

[DavGoodlin]

Originally Posted by maxhifi

Another way to approach this, if you get lucky, is to use a portable radio to find a spot in the house which is free from interference, and then situate your radio there. I found a spot in my house which is somehow a null for all interference, and now I can once again listen to AM radio without unplugging half the house. It even picks up DX, just like it used to.

My experience exactly, seems my basement is a good spot apparently I wonder if the early radio folks just scouted a spot like that.

[JohnCT]

Originally Posted by zeno

Shut the whole house down & see if it goes away.
73 Zeno
LFOD !

Yep.

I rarely use the only antique radio I keep in the upstairs, but I noticed my Radiola 62 was struggling to even get local stations through the blizzard of noise that covered almost the entire band, but was worse about 1000khz and down. I was sure it got NY sports radio from central CT when I first put it in the FLR, but now it was just pure noise.

When my Emerson 911 transistor couldn't get anything, I knew something was up. I threw the main breaker and immediately the transistor came to life, picking up dozens of stations across the whole band. I started snapping on breakers one by one and found many problems.

I had IR light fixtures in the driveway making a ton of noise and probably the worst offender was my cable modem and router. My alarm system also generates noise.

John

[DavGoodlin]

Apparently Part 15 of the FCC does not apply to a growing list of line-powered noise makers. The motion-sensing lights are a good example.

Fortunately the utility's smart meter / main C.B. is on a structure away from the house. Service runs underground 80 feet but If I get within 6 feet of the meter, the AM portable is silenced by intense data bursts. These do not seem to travel into the house but they do seem to go back up the pole riser conduit.

[Tony F]

I've pretty well given up on trying to use my antique A.M. radios. My house used to be very usable. Then my neighbors right next door started "automating" their whole house. Everything has to be controlled from their smart phones. They have had contractors there "seems like forever" installing new crap and every once awhile coming back to fix repeated problems from crap made in china. The "hash" is all over the band and there isn't anything i can do about it, short of moving elsewhere. It really sucks to know that one of your favorite hobbies is kibosh-ed due to inconsiderate people living next door who don't give a damn.
Tony

[Titan1a]

I understand. It also comes from malfunctioning street lights.