Strange Noise..Back

Status
Not open for further replies.

rcvmo

Member
Joined
Aug 11, 2004
Messages
433
Location
Romulus, Mi.
Our group was discussing wrapping the component in aluminum foil and grounding the foil.
I've got a cable modem and have birdies about every 100 KHz. Wrapped the modem in foil which took out 70% of the noise.
Just a start, now have to go after the CFL ballasts, LCD screen power supplies, etc.
Good Luck
 

kruser

Active Member
Premium Subscriber
Joined
Nov 25, 2007
Messages
4,987
Location
West St Louis County, MO
Just wondering if anyone else cares to chime on this mysterious noise?
I did listen to your last sample and it is unlike anything I've heard. I have traced and found and cured a LOT of noise coming from my own equipment as well as outside sources over the years but yours is a new one.

I myself use a process of elimination if I cannot find it quickly.
I did not see that you have done these drastic steps yet so..
I start by killing AC power to the entire place one breaker at a time. If or when the noise dies then great, it is a fairly easy process to determine what outlets or lights the breaker that stopped the noise feeds. With luck, your panel is labeled for each breaker to give you a starting point in your search. Power that circuit back up and see if your noise returns. I've had some noise that does not return immediately like from computers or routers that take time to boot up. Plus some noisy circuits need to heat back up before the offending signal drifts back on frequency again. Then you have the noise that always drifts around! Either way, patience can play a big part with this method and especially with intermittent noise. One thing is almost certain with this method however providing you have turned all UPS units off first. That being, the noise will almost always quit immediately when you kill the power if it is coming from your own home and not a battery powered device. This is the best method I've found for finding RFI or noise coming from my own equipment. If you have family in the house then you may wish to send them out for pizza or something while you conduct your tests or it may cause undesired side effects like bad arguments or divorce!
Anyway, try that first but if killing the AC power for your entire house does not stop it then look at battery powered devices second. I recently had an RCA 2 line corded phone that was radiating noise every 2 kc while it was powered only from a 9 volt backup battery. Needless to say, killing the AC power did not stop that noise until I also found and removed that backup battery. So pay attention to devices that are AC and battery powered as either source of power can keep them running and you would need to remove both sources to eliminate it. I've also had simple electro-mechanical clock movements (the kind that run from an AA battery) cause nuisance interference. Your biggest offenders will usually be modems (cable or dsl), routers, computers and switching type power adapters. Heck, almost any modern day consumer electronics device can cause this noise as nothing truly turns off any longer. I wonder how on/off switch companies survive… Most of this equipment should die if you kill your AC power at the circuit breaker panel unless you have UPS units. Oh yes, I've had several UPS units (mostly APC) that emit crud on SW or HF bands. Mostly very low level though but still enough to wipe out that weak signal you desire! The older plain and simple APC units were always fine but my noise problems started with them when I bought some of the "Smart-UPS" models. They were great at providing power and protection but sucked for noise. Those are some of the first things I turn off when noise sniffing these days as my offending devices are usually plugged into one for protection. I've never had to physically open any of my UPS up and remove a battery lead as simply turning them off was enough for my tests. I did have to unplug the APC units from the wall however to kill the still active charging circuit as it was still supplying power to the noise generator within. I'm sure some new models may still have enough of some circuit running that could spew noise but I doubt it would sound anything like your noise. The older wall wart type power adapters that have true transformers within are also rarely a problem. You can tell one from a switching type as the old type are heavy while the newer and more common switching types are very lightweight. Some switching type supplies are very bad noise generators but they generally emit raspy harsh noise more like a bad lamp dimmer does. Or they can emit dead carriers with a strong clean signal but never heard one with data sounds.
If after you kill all your AC power and remove any battery from devices and UPS units, you still have noise then it is a safe bet it is coming from a neighbor. Does this noise happen at any time of day or night? This can sometimes be a clue as to the source. Pay attention to if the noise starts soon after a neighbor arrives home from work/school etc. I had a neighbor with a really bad lamp dimmer and that is exactly how I determined who had the bad dimmer. He was understanding as the dimmer was also wiping out his DSL signal as well as mine and several others in the building. I felt like a fool approaching him about it though! Someone I think in this thread mentioned CFL's. Yes, they can and do cause interference but I've never heard one sound anything close to your sample. We have tons of them in the common public hallways and stairways. I sniff them with an AOR AR8200 portable and have yet to find one that emitted anything more than a foot or two. Oddly, I use them as well in our restroom and I did have one fail in a way that it caused bad noise but again, nothing like yours. I still walk the halls when I get new noise however and sniff them all.
Being as you can make the noise appear by just touching the antenna jack makes me think it is very localized to your area and may be fairly easy to find through the process of elimination.

So that is how I approach noise after I try the simple things. I hope you find it. And if you do, then comes the fun of fixing it! I actually have much fun doing this as it can be a good challenge. That phone I mentioned, I tracked the noise to a small daughter board mounted to the main board. I unsoldered the little board and built a complete solid sheet copper cage around it on all sides and even placed tiny ferrite beads on all wire leads. It only helped slightly so now that phone sits in pieces in a junk box for other projects! The phone would work without the board but the board was needed for the phone to power up. I installed a switch that I would turn off power to the board after the phone powered up before I broke down and bought an at&t labeled phone made by who knows. It does not cause any interference.

One other thing I do after I do the drastic stuff above and have zero luck is to use the radio as a sniffer. Put as small a length of wire in the antenna jack that allows you to get a tiny meter reading. Then start walking around and see if you can find a spot that shows a significant increase in the level. Start in your own home and yard and then start walking further such as to a neighbors house. If you find a hot spot with good signal then hope you are friends with the neighbor and figure out a way to approach them so they do not think you have lost your mind. I've actually done this many times as I live in an apartment. Some neighbors have been very understanding and I even made some good friends but some have simply slammed the door in my face.
I don't advise this if you live in a bad neighborhood or have some suspect neighbors that have a lot of late night or suspect traffic in and out!

Good luck and do report back if you find the source. I've been wanting to put together a list of interferers from all my notes I've kept over the years and your noise is one I'd love too include as it almost has a rhythm to it!
 

hawkeye32

Member
Premium Subscriber
Joined
Apr 30, 2008
Messages
602
Location
Windsor
Thanks Kruser for the valuable info :) I Have already done the above in regards to cutting the power off and going breaker by breaker. Noise still their, I went to do some troubleshooting yesterday to find the source, but now the source is gone ( go figure). Turned on the radio today as i am typing this and the noise is gone. Our houses here are close together, so only thing i have to keep an eye on when the neighbours come home and see if the noise comes back. I have noticed this noise is off and on, but when it comes on, its pure havoc, it is now even appearing on the Ham bands as well (14000 USB). I have come to the conclusion at least i think i have it is something relatively close. As noted above, i think it may be wifi network coming froma neighbours house, it is the only thing that makes logical sense. Wish i had a laptop then i could pull up and see what wifi networks are avail and how close. In my house their are no wifi networks, i do have a router, but its not wireless and yes its a d-link. That was the first thing i tried unplugging from the wall, but didn't help. I will post back as soon as the noise comes back and i do the troubleshooting steps, you have mentioned above. Once again i appreciate all the folks that have helped so far. I am fairly new to this hobby on the HF side.

Actually a question does come to mind. I do have 2 scanners that are plugged into a external antenna outside (discone). With the scanners off can they still produce noise? I have a pro-2096 and a bc898t. Even thou i have unplugged those as well, but where i am a noob at is when it comes to UPS sources.

Another note here to, i have taken the R71A outside, and the noise is still their. Like i say when the noise comes back again, the hunt will be on.

Also to Kruser, yes you can use the noise sample if you wish for your list, if thats what you were asking. I have no problems what so ever :). hopefully here in the next couple of days i will have a solution and fix to the problem.
 

hawkeye32

Member
Premium Subscriber
Joined
Apr 30, 2008
Messages
602
Location
Windsor
The sound file i uploaded, i think i accidently deleted lol. I am still working on this so just going to post it up here, in case anyone cares to hear or help. Also too i have another one that i will re-post up. Different noise altogether. Is their a website that i can learn and hear samples of Interference noise? I am a noob as they say when it comes to this type of stuff. Thanks for all the help
 

Attachments

  • noise 2.zip
    122.9 KB · Views: 57

hawkeye32

Member
Premium Subscriber
Joined
Apr 30, 2008
Messages
602
Location
Windsor
here is sound clip 2, to me sounds like a helicopter lol
 

Attachments

  • helicopter.zip
    94 KB · Views: 77

hawkeye32

Member
Premium Subscriber
Joined
Apr 30, 2008
Messages
602
Location
Windsor
I do have some pics of the results from a software program. that a guy on here did for me, but i can't make heads or tails of it. If someone could help that would be cool.
 

Attachments

  • untitled.zip
    49.2 KB · Views: 77
  • 2nd pic.zip
    49 KB · Views: 70

hawkeye32

Member
Premium Subscriber
Joined
Apr 30, 2008
Messages
602
Location
Windsor
I have finally found the culprit!!!! It was a cellphone charger that was plugged in on my 2nd floor!!!!. Radio is downstairs, i am amazed at how sensitive it is. But if anyone has a cellphone that is Sony Ericsson, and you use a usb cord. Beware!!! lol. I hope this will help others!!!
 

hawkeye32

Member
Premium Subscriber
Joined
Apr 30, 2008
Messages
602
Location
Windsor
I have copied what is on the bottom of the charger, so if anyone else has this same charger and is experiencing the same thing, then they will know

Universal Charger

Model No: 230UNIV3N1-B
Input: 100v-0.2a 60Hz
12-24v 700mA
Output: 5.0v- 1000mA
Made in China
 
Status
Not open for further replies.
Top