QRM and filtering
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Over the last 2 weeks some QRM has shown up and I have tried some of the NR and NB filtering options to get rid of it and it's not really working to well. I am not sure if I am using the proper filtering or the settings I am using are off. I have an audio example of the QRM or even RFI on my blog site. The link is below I feel if you listen to it that may help. Mike http://ve3wdm.blogspot.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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I had a nasty noise of s9 plus for a week or so. Finally tracked it down to
the wall wart on my XYL's sling box. It had been there for years but I'd noticed it had always been warmer than most of them although it seemed to work okay. Apparently, it must've gone bad and started generating a terrible hash. When I pulled it the problem was immediately solved. 73, Lou WA3MIX ----- Original Message ----- From: "Ron D'Eau Claire" <[hidden email]> To: "'Mike Weir'" <[hidden email]>; <[hidden email]> Sent: Friday, October 22, 2010 5:10 PM Subject: Re: [Elecraft] QRM and filtering > That sounds like arcing somewhere Mike (BTW, it's QRN - N - noise instead > of > QRM -M for interference from other stations). > > It could be a power line insulator. Sometimes a fluorescent bulb dying > sounds like that as the starter keeps re-engaging. I've heard that sort of > thing from some street lights that are flickering. Sodium lamps generally > create hash, but ordinary incandescent bulbs, in a street light or > somewhere > in the house, can do exactly the same (their filaments sometimes fail but > are still touching and there is intermittent arcing across the opening). > > Unfortunately the possibilities are as endless as the number of places > there > might be something arcing over. > > How's the weather been? The advent of the rainy season sometimes causes > dirty power line insulators to arc. When it rains enough it may wash the > dirt off the insulator it may stop all by itself. > > I'd tackle it like others have chased RFI here: start switching off > circuits > throughout the house while listening. If it stops, you are in luck - it's > something under your control in the circuit you shut down. > > If not, you'll need to start hunting with a portable radio. Follow the > strongest signal along the power lines. At that point you can start to > enlist the help of your power company. Cooperation varies a lot, but some > are extremely helpful. > > One time I was bedeviled with noise like that and couldn't track it down. > It > was emanating from the general area of several blocks in the neighborhood. > Then, one night after dark, I noticed something while taking a walk. A > intermittent weak flashing on one of the power poles. And there it was - a > dirty insulator arcing over. The utility came out within a couple of days > and hosed down all the insulators in the neighborhood! > > Ron AC7AC > > -----Original Message----- > > Over the last 2 weeks some QRM has shown up and I have tried some of the > NR > and NB filtering options to get rid of it and it's not really working to > well. I am not sure if I am using the proper filtering or the settings I > am > using are off. I have an audio example of the QRM or even RFI on my blog > site. The link is below I feel if you listen to it that may help. > Mike > http://ve3wdm.blogspot.com > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Several years ago a guy that lived about a block and a half away stopped by
the house one afternoon for the purpose of informing me that I was "interfering" with his radio and TV. I asked him if he was getting it right now, and he said yes. Told him, that I was also having a lot of problem with some type of noise; and since I am outside working, that would eliminate me as the source. Invited him into the house and turned on my receiver; bingo, the noise level was about an S7, and it peaked when I turned my beam towards his house. I told him that I believed the interference source was near him, and asked if I could go over to his house with him and see what I could find. Of course, his tone had changed and he was more than happy for me to look into the problem. Took a small portable radio over and I found the noise level was very high in his house. Asked him if it would be alright if I turned the power off to his house. He didn't have any problem with that, and as soon as I opened the main breakers, the noise disappeared. After a little "detective work", I traced the source of the interference to the doorbell transformer. Disconnected it, and told him to go buy a new one. Of course we were both "happy campers". Dick K8ZTT -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Lou Kolb Sent: Friday, October 22, 2010 4:24 PM To: elecraft Subject: Re: [Elecraft] QRM and filtering I had a nasty noise of s9 plus for a week or so. Finally tracked it down to the wall wart on my XYL's sling box. It had been there for years but I'd noticed it had always been warmer than most of them although it seemed to work okay. Apparently, it must've gone bad and started generating a terrible hash. When I pulled it the problem was immediately solved. 73, Lou WA3MIX ----- Original Message ----- From: "Ron D'Eau Claire" <[hidden email]> To: "'Mike Weir'" <[hidden email]>; <[hidden email]> Sent: Friday, October 22, 2010 5:10 PM Subject: Re: [Elecraft] QRM and filtering > That sounds like arcing somewhere Mike (BTW, it's QRN - N - noise instead > of > QRM -M for interference from other stations). > > It could be a power line insulator. Sometimes a fluorescent bulb dying > sounds like that as the starter keeps re-engaging. I've heard that sort of > thing from some street lights that are flickering. Sodium lamps generally > create hash, but ordinary incandescent bulbs, in a street light or > somewhere > in the house, can do exactly the same (their filaments sometimes fail but > are still touching and there is intermittent arcing across the opening). > > Unfortunately the possibilities are as endless as the number of places > there > might be something arcing over. > > How's the weather been? The advent of the rainy season sometimes causes > dirty power line insulators to arc. When it rains enough it may wash the > dirt off the insulator it may stop all by itself. > > I'd tackle it like others have chased RFI here: start switching off > circuits > throughout the house while listening. If it stops, you are in luck - it's > something under your control in the circuit you shut down. > > If not, you'll need to start hunting with a portable radio. Follow the > strongest signal along the power lines. At that point you can start to > enlist the help of your power company. Cooperation varies a lot, but some > are extremely helpful. > > One time I was bedeviled with noise like that and couldn't track it down. > It > was emanating from the general area of several blocks in the neighborhood. > Then, one night after dark, I noticed something while taking a walk. A > intermittent weak flashing on one of the power poles. And there it was - a > dirty insulator arcing over. The utility came out within a couple of days > and hosed down all the insulators in the neighborhood! > > Ron AC7AC > > -----Original Message----- > > Over the last 2 weeks some QRM has shown up and I have tried some of the > NR > and NB filtering options to get rid of it and it's not really working to > well. I am not sure if I am using the proper filtering or the settings I > am > using are off. I have an audio example of the QRM or even RFI on my blog > site. The link is below I feel if you listen to it that may help. > Mike > http://ve3wdm.blogspot.com > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __________ Information from ESET NOD32 Antivirus, version of virus signature database 5556 (20101022) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 5556 (20101022) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Quite a coincidence.
In 1978 I had horrible RFI that blanketed HF and 2 meters and also affected TVs and even people's stereo systems. Naturally, my neighbor asked if it could be my ham radio. At one point I looked out and saw another guy walking up and down the street with a portable radio, the same thing I'd been doing. But it was impossible to localize the noise - it seemed to come from every power pole and every circuit. Finally the power company was called in and they found that the source was my neighbor's doorbell transformer. A couple years later I'd bought a house was seriously chasing DX with the great sunspot peak when the same kind of noise came back. Again, neighbors up the street wondered if it was my ham radio. And again, attempts to trace the noise were futile. I finally walked up to the neighbors' house, which did seem pretty hot, and pressed the doorbell button. The noise stopped momentarily. So I told them their doorbell transformer was likely at fault and they replaced it. Problem solved. 73- Nick, WA5BDU On 10/22/2010 6:08 PM, Dick Williams wrote: > > After a little "detective work", I traced the source of the interference to > the doorbell transformer. Disconnected it, and told him to go buy a new > one. Of course we were both "happy campers". > > Dick K8ZTT > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Dick Williams-2
On 10/22/2010 4:08 PM, Dick Williams wrote:
> After a little "detective work", I traced the source of the > interference to the doorbell transformer. Disconnected it, and > told him to go buy a new one. When I was doing residential RFI-hunting in the 1970s-1990s, doorbell transformers were the number one source of intermittent buzzing radio noise. -- 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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What is there about a transformer that causes so much grief? Curious...
73 jim ab3cv ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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They are cheaply built with little insulation. A good power surge or lightning strike will puncture the insulation and the primary will arc to the frame/core on peaks of the wave. Door bell transformer failure will have a marked 120 Hz rough note. The homeowner should consider themselves lucky if you find it for them as old transformers are often simply screwed to floor joists under the floor in the area of the front door. The arcing represents a fire hazard. Fortunately, more modern door bells, etc. eliminate the old transformers. 73, ... Joe, W4TV On 10/22/2010 10:49 PM, Jim Miller wrote: > What is there about a transformer that causes so much grief? Curious... > > 73 > > jim ab3cv > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Jim AB3CV
On 10/22/2010 7:49 PM, Jim Miller wrote:
> What is there about a transformer that causes so much grief? Curious... If you mean the doorbell transformer, the insulation dries out and turns start shorting, leading to excessive heating and internal arcing. They usually have an internal thermostat to cut it off when hot, and after it cools down it starts all over again. If you mean the big black can on the pole, it's rarely the transformer's problem, usually it's loose hardware or arcing over the insulators. -- 73 de K2ASP - Phil Kane Elecraft K2/100 s/n 5402 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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--- On Sat, 10/23/10, Phil Kane <[hidden email]> wrote:
> If you mean the doorbell transformer, the insulation dries out > and turns start shorting, leading to excessive heating and > internal arcing. They usually have an internal thermostat to > cut it off when hot, and after it cools down it starts all > over again. If that was true then why don't ALL transformers have thermal cutouts? Or stated another way, why are only doorbell transformers allowed to be built so cheaply that their insulation dries out and arcs? The thermal switch is there to protect against cheap doorbell pushbutton switches that occasionally get stuck in the closed/ON position, which is only supposed to be momentary. If that happens the transformer will heat up rapidly and the thermal switch opens to protect the circuit. Unfortunately, it looks like the energizing current in the transformer primary creates enough heat to open the switch just enough to arc and keep the doorbell operational. That's what's happening at my home...I really must replace my transformer again. 73, Ken Alexander VE3HLS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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