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#1
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Bill Baka wrote:
With my scope synced to 60 Hz I can see two big spikes and lots of little ones that take a while to settle down. Thanks for the reply, Bill Baka What sort of antenna are you using? You might be able to configure something, although I'm not exactly sure what, that can provide more directivity and maybe escape from some of the junk noise. Don't just write it off because of the all the Chinese crap thats out there. A problem crept up here once, right about Christmastime, where I got a steady rhythmic buzz a couple of times per second. Figured it was a neighbors Christmas lights or something. Switched off all my breakers and it persisted. Could hear it several hundred feet away from my house on a portable radio. It was everywhere, impossible to null or peak. But it persisted for months AFTER Christmas. Then a main breaker to my house (in the panel out front with the meter) crapped out and had to be replaced. Guess what? No more noise! So there I was putting up with the noise and blaming neighbors and Red China and the problem was something so simple - just difficult to localize. Just food for thought. Good luck, Bill M |
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#2
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On 05/22/2010 01:40 PM, Bill M wrote:
Bill Baka wrote: With my scope synced to 60 Hz I can see two big spikes and lots of little ones that take a while to settle down. Thanks for the reply, Bill Baka What sort of antenna are you using? You might be able to configure something, although I'm not exactly sure what, that can provide more directivity and maybe escape from some of the junk noise. I have a sort of long wire, 25 feet, and the other side is grounded to a chain link fence. There is not enough room to put up much else unless I run a wire to the house behind me. Yup, two rental houses on one lot. My stepdaughter lives in the back and I don't even know if she could figure out the concept of radio DX noise. She is a cable TV addict and not at all inclined to radio. I do have a radio direction finder that I can run with a solar cell I picked up, so I can walk it around in the sun and try to find the major noise source that way. When I scoped it, it looked like a lot of SCR's triggering at various points so I kind of figure it may be SCR light dimmers. Don't just write it off because of the all the Chinese crap thats out there. A problem crept up here once, right about Christmastime, where I got a steady rhythmic buzz a couple of times per second. Figured it was a neighbors Christmas lights or something. Switched off all my breakers and it persisted. Could hear it several hundred feet away from my house on a portable radio. It was everywhere, impossible to null or peak. But it persisted for months AFTER Christmas. Then a main breaker to my house (in the panel out front with the meter) crapped out and had to be replaced. Guess what? No more noise! Nah, my breakers are good. I have a touch lamp with an SCR in it (Chinese, of course) and it makes noise even when turned off. Louder when it is on. It does seem to be from other houses. So there I was putting up with the noise and blaming neighbors and Red China and the problem was something so simple - just difficult to localize. Just food for thought. Good luck, Bill M I think I will get my RDF and go hunting tomorrow. Thanks, Bill Baka |
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#3
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Bill Baka wrote:
On 05/22/2010 01:40 PM, Bill M wrote: Bill Baka wrote: With my scope synced to 60 Hz I can see two big spikes and lots of little ones that take a while to settle down. Thanks for the reply, Bill Baka What sort of antenna are you using? You might be able to configure something, although I'm not exactly sure what, that can provide more directivity and maybe escape from some of the junk noise. I have a sort of long wire, 25 feet, and the other side is grounded to a chain link fence. There is not enough room to put up much else unless I run a wire to the house behind me. Yup, two rental houses on one lot. My stepdaughter lives in the back and I don't even know if she could figure out the concept of radio DX noise. She is a cable TV addict and not at all inclined to radio. I do have a radio direction finder that I can run with a solar cell I picked up, so I can walk it around in the sun and try to find the major noise source that way. When I scoped it, it looked like a lot of SCR's triggering at various points so I kind of figure it may be SCR light dimmers. yes, with puny antennas and rental houses and chain link fences and stepdaughters who are "cable tv addicts" to blame you really must attack some cogent RFI initiatives from your part. That's what I was alluding to before. |
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#4
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On 05/22/2010 05:19 PM, Bill M wrote:
Bill Baka wrote: On 05/22/2010 01:40 PM, Bill M wrote: Bill Baka wrote: With my scope synced to 60 Hz I can see two big spikes and lots of little ones that take a while to settle down. Thanks for the reply, Bill Baka What sort of antenna are you using? You might be able to configure something, although I'm not exactly sure what, that can provide more directivity and maybe escape from some of the junk noise. I have a sort of long wire, 25 feet, and the other side is grounded to a chain link fence. There is not enough room to put up much else unless I run a wire to the house behind me. Yup, two rental houses on one lot. My stepdaughter lives in the back and I don't even know if she could figure out the concept of radio DX noise. She is a cable TV addict and not at all inclined to radio. I do have a radio direction finder that I can run with a solar cell I picked up, so I can walk it around in the sun and try to find the major noise source that way. When I scoped it, it looked like a lot of SCR's triggering at various points so I kind of figure it may be SCR light dimmers. yes, with puny antennas and rental houses and chain link fences and stepdaughters who are "cable tv addicts" to blame you really must attack some cogent RFI initiatives from your part. That's what I was alluding to before. Yeah, but I have the 'longish' wire at the farthest point from any electricity lines as is possible. If I run it back to her place then it will be parallel to her power lines, so it might be worse. I just hope I can find a bad connection on a power line so I can get the local electric company to fix it. I might get blown off on that though. Bill Baka |
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#5
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"Bill Baka" wrote in message
... On 05/22/2010 01:40 PM, Bill M wrote: What sort of antenna are you using? You might be able to configure something, although I'm not exactly sure what, that can provide more directivity and maybe escape from some of the junk noise. I have a sort of long wire, 25 feet, and the other side is grounded to a chain link fence. There is not enough room to put up much else unless I run a wire to the house behind me. Yup, two rental houses on one lot. My stepdaughter lives in the back and I don't even know if she could figure out the concept of radio DX noise. She is a cable TV addict and not at all inclined to radio. I do have a radio direction finder that I can run with a solar cell I picked up, so I can walk it around in the sun and try to find the major noise source that way. When I scoped it, it looked like a lot of SCR's triggering at various points so I kind of figure it may be SCR light dimmers. I think I will get my RDF and go hunting tomorrow. Thanks, Bill Baka To add to what Scott Dorsey said, the chain link fence may be a problem in itself. The zinc galvanizing protects the steel below from rusting, but it provides a nonlinear junction with any other metals touching it, especially copper. Your radio needs a good ground with the shortest ground lead possible. Get a good copper-clad ground rod at the home improvement store. Locate it below the window closest the radio and run a short, heavy gauge wire from it to the radio. Your radio should also be grounded to the power line ground for safety. The preamp must be very linear and have an exceptionally high dynamic range to not cause problems. If it does not, RF interference at one frequency will mix with all other signals to produce a cacophony of noise. Your receiver should be more than sensitive enough on the lower bands to not need a preamp. If you must use it on the higher bands, consider using a high-pass filter ahead of the preamp. It will attenuate the lower frequencies (where the noise is the strongest) yet allow the higher frequencies to pass with little to no attenuation. The Timewave (formerly JPS) ANC-4 and the MFJ 1026 noise cancellers work quite well if you have a single noise source or if one noise source dominates. With multiple sources, they do not work nearly as well. For a homebrew version, see the article by W7XC in the July, 1994 QST. Note that there are several subsequent corrections and additions to this article (9/1994, 1/1995, 9/1996). Be persistent with the power company but do not get your hopes up. I once called the power company and they sent a crew out. They listened with their truck two-way radio and said they could not hear any noise. Of course, the truck radio was FM! :-( 73, Barry WA4VZQ |
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#6
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On 05/23/2010 07:05 PM, WA4VZQ wrote:
"Bill wrote in message ... On 05/22/2010 01:40 PM, Bill M wrote: What sort of antenna are you using? You might be able to configure something, although I'm not exactly sure what, that can provide more directivity and maybe escape from some of the junk noise. I have a sort of long wire, 25 feet, and the other side is grounded to a chain link fence. There is not enough room to put up much else unless I run a wire to the house behind me. Yup, two rental houses on one lot. My stepdaughter lives in the back and I don't even know if she could figure out the concept of radio DX noise. She is a cable TV addict and not at all inclined to radio. I do have a radio direction finder that I can run with a solar cell I picked up, so I can walk it around in the sun and try to find the major noise source that way. When I scoped it, it looked like a lot of SCR's triggering at various points so I kind of figure it may be SCR light dimmers. I think I will get my RDF and go hunting tomorrow. Thanks, Bill Baka To add to what Scott Dorsey said, the chain link fence may be a problem in itself. The zinc galvanizing protects the steel below from rusting, but it provides a nonlinear junction with any other metals touching it, especially copper. Your radio needs a good ground with the shortest ground lead possible. Get a good copper-clad ground rod at the home improvement store. Locate it below the window closest the radio and run a short, heavy gauge wire from it to the radio. Your radio should also be grounded to the power line ground for safety. Good advice but this house is old and does not have a third wire ground line. There is one at the junction box, but only two lead wire feeding the house. It may be time to sink a ground rod under my window. The preamp must be very linear and have an exceptionally high dynamic range to not cause problems. If it does not, RF interference at one frequency will mix with all other signals to produce a cacophony of noise. Your receiver should be more than sensitive enough on the lower bands to not need a preamp. If you must use it on the higher bands, consider using a high-pass filter ahead of the preamp. It will attenuate the lower frequencies (where the noise is the strongest) yet allow the higher frequencies to pass with little to no attenuation. I try to DX on anything from 540KHz to 31 MHZ, so it is a mixed bag. The noise waveform on the scope is the same with and without the preamp in the loop. If it is power line I could always hook a scope probe to the high (hot) side of the 110 VAC and take a look. I can easily build a simple filter to take out the 60 Hz power line and just look for spikes. The Timewave (formerly JPS) ANC-4 and the MFJ 1026 noise cancellers work quite well if you have a single noise source or if one noise source dominates. With multiple sources, they do not work nearly as well. For a homebrew version, see the article by W7XC in the July, 1994 QST. Note that there are several subsequent corrections and additions to this article (9/1994, 1/1995, 9/1996). I'm thinking that one of these or something I design would be synced to the power line and just take out a piece at a time. A one shot for the delay to the biggest noise pulse (variable by me) and another one shot with variable width to cover the width of the noise pulse. A double section one shot and a digital switch like a DG411 could take out the worst pulse. Depending on my ambition I could make another few for the next biggest pulses, but at some point all the chopping of the signal might make the actual signal un-listenable. Be persistent with the power company but do not get your hopes up. I once called the power company and they sent a crew out. They listened with their truck two-way radio and said they could not hear any noise. Of course, the truck radio was FM! :-( 73, Barry WA4VZQ The only thing I have ever gotten out of the power company was an extra transformer due to overload from one transformer feeding about ten houses, all with A/C going. They finally gave in and put in another so that only 5 houses per transformer was the end game. I tried the noise thing a while back and they just asked if I had power, and I said yes, then they said 'NO'. With so few of us non-internet addicts around these days they could care less about radio reception. About ten years ago I located a noisy pole and told them but they did nothing until it arced over and burned off the top of the pole. Only then did they respond, and it was way more expensive than fixing it in the first place would have been. Thanks, Bill Baka |
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