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#1
November 28th 07, 01:14 PM
posted to rec.radio.shortwave
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RFI:0 Introduction
RFI Post 0: An Introduction
I am 56 years old enjoy SWL, guitar, folk and some rock music and science fiction. I road a motorcycle for 25 years until I became enlightened with the idea that even IF I was a perfect rider, I had no control over the other idiots on the highway. I make no claim to special expertise in the RFI arena, I have been a SWL since June 1962. I have been a ham since 1974 and currently hold an extra class ham license. Some of my friends call me an accidental ham. I had never intended get a ham license but after the "Night of the Tornadoes" in 1974,I decided to get smart and gain the skill set for back up communication. These days about the only time I use my ham license is during nasty weather. I am an engineer by training and have been a working engineer for the last 35 years. I have avoided each and every chance to move up the ladder into management, Over the years I have had the opportunity to learn at the knees of several very bright people. Many wise assed kid.. A retired communication specialist from the army who lived across the street interrupted my experiments with a spark gap transmitter and taught me CW. A friend of my Dad was a Radio TV repair man and he gave me a lot of help and practical advice. Another friend's father was a ham and helped me tweak our 100mW CB HTs to operate with the receive and transmit crystals interchanged. In Jr High School my science teacher pulled some strings and I was allowed to take an AP physics course in the 8th grade. During High school I made the odd choice of going to vocational school while taking college prep courses. After working for a few years, I went to college and after graduation I have been lucky enough to work in electronics, mainly in the telecommunication field and I have done a lot of moonlighting in other electronic areas. Early in my radio listening experience I learned that noise was the single biggest limitation to what I could receive. I spent years coming to an understanding what noise is and how it effects our ability to understand any communication. For several months in the summer of 2007 I had the opportunity to work at a FCC certified EMI laboratory. The lab only dealt with conducted emissions as opposed to radiated emissions. It was quite an experience. I learned that FCC Class B acceptance is Damn near worthless. A device can be legal and still radiate like mad. I also learned that "medical devices", like my wife's APAP(sleep apnea breathing assist) are not regulated by the FCC but instead the FDA sets the rules. And the FDA doesn't know squat about RFI. The owner discovered "nose candy" and had to sell the business, but I gained a lot of appreciation for how RFI, or more properly EMI, is measured. I burned two weeks of vacation to allow the lab to complete some contractual obligations and to oversee the disassembly of the lab for shipment to South Korea. I ended up with some odds and ends that the buyers didn't want. I took photos and had the owner sign off on everything that he gave me. Among the useful "stuff" that found it's way home was several Mini Circuits ZFSC-2-6 hybrid power dividers, rated for ~60KHz through 60MHz. Several ZFSC-2-1 hybrids rated for 5 through 500MHz. A bunch of attenuators, dummy loads and a couple of LISNs. and a AC mains RFI/EMI sniffer probe that is connected directly to the AC mains for measurement of devices too large to bring to a lab.. What is a LISN? Line Impedance Simulator Network. The FCC specifies a magic simulator that everyone has to use for conducted RFI emission testing. It doesn't have much connection to the reality of home, office or commercial AC mains, but it is a standard. I also ended up with enough 1/4 rat wire to shield a large room. And enough 1/8" woven copper panels to build an 8'X8'X8' cage. And I ended up three RF tight doors with frames, finger stock RF gaskets .because the buyers intended to use much larger doors. Along the way I was lucky enough to read W1HIS's wonderful work on "Common Mode Chokes", and even luckier to engage Chuck via Email and his comments and thoughts have been a great help the last year or so in my attempt to understand, find and eliminate or at least reduce RFI. My wife says that I am no longer a SWL, but instead I have become an avenging angel devoted to ridding the world of RFI. I think she is wildly optimistic! In the posts that follow, and in the web page that I hope to construct some day "real soon now", I will try to spread the information that others have shared with me and my few contributions in the RFI reduction arena. In rereading this I find it appears that my life was a lot more ordered then reality would suggest. There were many false steps, trips down the wrong road and general silliness. And before I die I expect that some of my current beliefs will be shown to be wrong, or at least incomplete. My posts are not intended to address every aspect of RFI and noise. Think of this as the Idiots Guide to RFI. Or the Cllff notes version. And please even when you disagree with what I say, please understand that everything I suggest is based on actual real world experience and not from what I learned in school are read in technical manuals. And that I am not selling anything and don't expect to gain anything other then satisfaction from this effort. And if the flame wars start I will simply stop posting. If we are going to disagree, then let us try to be civil. Terry |
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#2
November 28th 07, 01:26 PM
posted to rec.radio.shortwave
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RFI:0 Introduction
wrote in message ... RFI Post 0: An Introduction I am 56 years old enjoy SWL, guitar, folk and some rock music and science fiction. I road a motorcycle for 25 years until I became enlightened with the idea that even IF I was a perfect rider, I had no control over the other idiots on the highway. I make no claim to special expertise in the RFI arena, I have been a SWL since June 1962. I have been a ham since 1974 and currently hold an extra class ham license. Some of my friends call me an accidental ham. I had never intended get a ham license but after the "Night of the Tornadoes" in 1974,I decided to get smart and gain the skill set for back up communication. These days about the only time I use my ham license is during nasty weather. I am an engineer by training and have been a working engineer for the last 35 years. I have avoided each and every chance to move up the ladder into management, Over the years I have had the opportunity to learn at the knees of several very bright people. Many wise assed kid.. A retired communication specialist from the army who lived across the street interrupted my experiments with a spark gap transmitter and taught me CW. A friend of my Dad was a Radio TV repair man and he gave me a lot of help and practical advice. Another friend's father was a ham and helped me tweak our 100mW CB HTs to operate with the receive and transmit crystals interchanged. In Jr High School my science teacher pulled some strings and I was allowed to take an AP physics course in the 8th grade. During High school I made the odd choice of going to vocational school while taking college prep courses. After working for a few years, I went to college and after graduation I have been lucky enough to work in electronics, mainly in the telecommunication field and I have done a lot of moonlighting in other electronic areas. Early in my radio listening experience I learned that noise was the single biggest limitation to what I could receive. I spent years coming to an understanding what noise is and how it effects our ability to understand any communication. For several months in the summer of 2007 I had the opportunity to work at a FCC certified EMI laboratory. The lab only dealt with conducted emissions as opposed to radiated emissions. It was quite an experience. I learned that FCC Class B acceptance is Damn near worthless. A device can be legal and still radiate like mad. I also learned that "medical devices", like my wife's APAP(sleep apnea breathing assist) are not regulated by the FCC but instead the FDA sets the rules. And the FDA doesn't know squat about RFI. The owner discovered "nose candy" and had to sell the business, but I gained a lot of appreciation for how RFI, or more properly EMI, is measured. I burned two weeks of vacation to allow the lab to complete some contractual obligations and to oversee the disassembly of the lab for shipment to South Korea. I ended up with some odds and ends that the buyers didn't want. I took photos and had the owner sign off on everything that he gave me. Among the useful "stuff" that found it's way home was several Mini Circuits ZFSC-2-6 hybrid power dividers, rated for ~60KHz through 60MHz. Several ZFSC-2-1 hybrids rated for 5 through 500MHz. A bunch of attenuators, dummy loads and a couple of LISNs. and a AC mains RFI/EMI sniffer probe that is connected directly to the AC mains for measurement of devices too large to bring to a lab.. What is a LISN? Line Impedance Simulator Network. The FCC specifies a magic simulator that everyone has to use for conducted RFI emission testing. It doesn't have much connection to the reality of home, office or commercial AC mains, but it is a standard. I also ended up with enough 1/4 rat wire to shield a large room. And enough 1/8" woven copper panels to build an 8'X8'X8' cage. And I ended up three RF tight doors with frames, finger stock RF gaskets .because the buyers intended to use much larger doors. Along the way I was lucky enough to read W1HIS's wonderful work on "Common Mode Chokes", and even luckier to engage Chuck via Email and his comments and thoughts have been a great help the last year or so in my attempt to understand, find and eliminate or at least reduce RFI. My wife says that I am no longer a SWL, but instead I have become an avenging angel devoted to ridding the world of RFI. I think she is wildly optimistic! In the posts that follow, and in the web page that I hope to construct some day "real soon now", I will try to spread the information that others have shared with me and my few contributions in the RFI reduction arena. In rereading this I find it appears that my life was a lot more ordered then reality would suggest. There were many false steps, trips down the wrong road and general silliness. And before I die I expect that some of my current beliefs will be shown to be wrong, or at least incomplete. My posts are not intended to address every aspect of RFI and noise. Think of this as the Idiots Guide to RFI. Or the Cllff notes version. And please even when you disagree with what I say, please understand that everything I suggest is based on actual real world experience and not from what I learned in school are read in technical manuals. And that I am not selling anything and don't expect to gain anything other then satisfaction from this effort. And if the flame wars start I will simply stop posting. If we are going to disagree, then let us try to be civil. Terry WOW. Burr |
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#3
November 28th 07, 01:39 PM
posted to rec.radio.shortwave
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RFI:0 Introduction
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