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#231
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Mike Coslo wrote
What is the basis for 50 watts? NCRP Report No. 86, "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields", Copyright 1986, National Council on Radiation Protection and Measurements, and ANSI/IEEE C95.1-1992, "Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz", Copyright 1992, IEEE, Inc. 73, de Hans, K0HB |
#232
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"Mike Coslo" wrote
That says quite a lot. You asked a reasonable direct question. "Yes" is a reasonable direct answer, hard for anyone to misinterpret for "No" or "Maybe" or "Depends on what 'is' means". 73, de Hans, K0HB |
#233
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Hans K0HB wrote:
Mike Coslo wrote What is the basis for 50 watts? NCRP Report No. 86, "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields", Copyright 1986, National Council on Radiation Protection and Measurements, and ANSI/IEEE C95.1-1992, "Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz", Copyright 1992, IEEE, Inc. And that 50 watts affects calss A different than Class B? I seriously doubt that a person that cannot handle 100 watts shild have any license. Maybe class A shouldn't be alloed to have antennas over 10 feet off the ground either. Nasy falls. - Mike KB3EIA - |
#234
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KØHB wrote:
"Mike Coslo" wrote That says quite a lot. You asked a reasonable direct question. "Yes" is a reasonable direct answer, hard for anyone to misinterpret for "No" or "Maybe" or "Depends on what 'is' means". It tells me what you think is a serious answer. I though you were perhaps being facetious or obtuse. You were not, and that tells me a lot. - Mike KB3EIA - |
#235
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"Mike Coslo" wrote
And that 50 watts affects calss A different than Class B? Of course not. (This is another of those 'novel' questions.) But my intention is that the Class B (learners permit with training wheels) test be ultra simple, to allow as many applicants as possible. For that reason, requiring qualification in esoterica like "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields" is inappropriate. Thus the 50W power level recommended by the NCRP and ANSI/IEEE ensures a modicum of safety for these beginners. In the process of preparing for Class A (without training wheels) license, the candidate would need to explore the RF-exposure safety issues which would be on the qualification test. Then we could expect that they'd have some appreciation of the hazards and how to ensure that their station is engineered in compliance with the MPE criteria mandated by 97.13(c). 73, de Hans, K0HB |
#236
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In article , Mike Coslo
writes: Hans K0HB wrote: Mike Coslo wrote What is the basis for 50 watts? NCRP Report No. 86, "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields", Copyright 1986, National Council on Radiation Protection and Measurements, and ANSI/IEEE C95.1-1992, "Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz", Copyright 1992, IEEE, Inc. Hans dropped in a nice bibliographic note but did NOT say HOW he arrived at his magical 50 W limit. :-) Way too many variables in the amateur radio "station" arrangement to say with some kind of certainty that 50 W is THE limit for any class. FCC already showed that with a survey of some typical California ham stations along with measurements of fields courtesy of a couple of other government agencies and the hams who let them all prowl around their property. And that 50 watts affects calss A different than Class B? I seriously doubt that a person that cannot handle 100 watts shild have any license. Maybe class A shouldn't be alloed to have antennas over 10 feet off the ground either. Nasy falls. 100 Watts in a 50 Ohm system has an RMS RF Voltage of 70.7. That's on the verge of burning human skin tissue. 50 Watts in a 50 Ohm system has 50 V RMS RF...still on the verge of burning human skin tissue, although not as badly. 100 W of RF is little, piddly stuff to what I'm used to...like 15 KW up- close-and-personal on HF, including walking around in antenna fields of many and varied HF emitters...and 40 KW PEP HF stuff in antenna fields in 1955. Most of us being personal with such powers weren't suffering ill effects and almost all of us weren't licensed in any "classes." We got the messages through. --------- For some really in-depth looks at radio frequency radiation, go to the Brooks AFB website and the documents at the USAF School of Aerospace Medicine. The following is the cover page for one of the shorter documents released in 1996: http://www.brooks.af.mil/afrl/HED/he...uman-exposure/ cover.gif.html That document title number is AL/OE-TR-1996-0035. It was prepared in 1994. Be prepared to do a little math to find the permissible RF field strengths...not much, just a little. There's also FCC Office of Engineering and Technology Bulletins 56 and 65 available on the FCC RF Safety webpage. Only a few ANSI standards are free for download (if available), the same with the IEEE site. Maybe Hans will reveal what kind of aluminum suit he wears when he fires up his "2.5 KW with increased drive" HF amplifier. :-) LHA |
#237
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"Bert Craig" wrote in
: "Alun" wrote in message ... "Bert Craig" wrote in et: "Alun" wrote in message ... What is annoying is that a skill test is foisted on those who don't have the desire to use the skill. Alan, I'm gonna let you in on a secret...although I know that you're already aware of it. Preparing for and passing the 5-wpm Elemnt 1 test does NOT leave one ready to use the skill OTA. It only gives one a taste so that one may make an educated choice as to whether or not they wish to persue CW any further. 5 wpm is certainly too slow to prove much, but it only still exists at that level as a residual requirement to meet the old s25.5, which has since been changed so that no code test is required atall. If the FCC truly thought that a CW test was necessary, the speed would be higher. Agreed, I was pointing out a very beneficial secondary benefit. It "requires" one to place themselves in a position from which to make an educated decision. As I mentioned in another post, the mode is really not the issue...the having to really learn it is. Do away with the published Q&A pools and watch the whining escalate. Well, I think that the real issue is that it's a different kind of test. Exactly. Also, if I hear CW on my frequency I may be able to read it with some difficulty, but if I hear RTTY or PSK31 there is no chance. You may have just touched on a selling point for CW. 73 de Bert WA2SI Whilst that is true, the point I was making is actually that since I can't read RTTY or PSK by ear, and they are legal modes, it doesn't help all that much that I can read CW (albeit not terribly well, since I never use it). 73 de Alun, N3KIP I understand the point you were making. If I could just ask you why you bothered to take the code test(s)? 73 de Bert WA2SI To get all the _phone_ frequencies |
#238
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"Bert Craig" wrote in
: "Alun" wrote in message ... "Kim W5TIT" wrote in : "Bert Craig" wrote in message news ![]() gy.com... "Alun" wrote in message ... It just so happens that I don't like CW, in the sense of I have no desire to use it. That should be OK too, but for some reason it bothers you. Why? No it does not bother me that someone who has learned it chooses not to use it. They have made that decision from a position of knowledge and experience. This is radically different from a person judging it and saying they will never use it when they do not have that knowledge and experience to draw on. Dee D. Flint, N8UZE Right on the money, Dee. Larry pointed this out earlier, but not as eloquently as you. 73 de Bert WA2SI It fascinates me that you won't accept someone's plain and simple truth that they don't like CW--even if they don't have experience with it--because you reason that they need to have "knowledge and experience" with it. Well, I know people who are quite well-versed in CW who don't like it, people who haven't ever even tried it and don't like it, and people who have taken and passed a 5wpm test and don't like it. I also know people from those same three categories that do like CW operation. It's pretty much as simple as folks who do or don't like most other things in life. Either ya like it or ya don't. Kim W5TIT I think that you have hit upon a very important point there, Kim. A good analogy might be not liking an item of food that you haven't tried, because it looks disgusting on your plate. If you eat some you might like it, or not, but there are probably all kinds of other things that contain the same nutrition. These guys are like a parent telling a child that they have to eat their brocolli. But they aren't my parents and I don't like brocolli, or CW. I take vitamins, and work phone. Slight difference, Alun. Nobody's forcing anybody to learn code. There exists a no-code Technician license for those who do not wish to have to pass the 5-wpm code exam. 73 de Bert WA2SI Not really true. No HF privileges with that licence, as we all know. |
#239
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KØHB wrote:
"Mike Coslo" wrote And that 50 watts affects calss A different than Class B? Of course not. (This is another of those 'novel' questions.) But my intention is that the Class B (learners permit with training wheels) test be ultra simple, to allow as many applicants as possible. For that reason, requiring qualification in esoterica like "Biological Effects and Exposure Criteria for Radiofrequency Electromagnetic Fields" is inappropriate. Thus the 50W power level recommended by the NCRP and ANSI/IEEE ensures a modicum of safety for these beginners. I would counter that it is a good idea for the initiate to know right off the blocks that RF has some potential problems associated with it. And while everyone talks about RF exposure, there are other problems associated with RF that a person should know before they are allowed to legally operate a rig. I had a problem trying to tune a longwire once, and my trusty MFJ tuner nailed me good - bad knob design - it shouldn't have the metal rim on the knob, which allows for some capacitive coupling, so it seems. RF burns hurt! Power was probably around 50 watts. I think the responsible thing to do, if safety is a concern, would be to get those safety guidelines out of the way BEFORE going to advanced licenses. I also hope that your regulations would prohibit the Class B hams from making or using a magloop antenna. I just did some calcs on a small magloop for 40 meters, and at 50 Watts there is almost 5 kV across the tuning cap. Ouch! In the process of preparing for Class A (without training wheels) license, the candidate would need to explore the RF-exposure safety issues which would be on the qualification test. Then we could expect that they'd have some appreciation of the hazards and how to ensure that their station is engineered in compliance with the MPE criteria mandated by 97.13(c). I think the candidate needs to know the safety issues long before this. If the potential ham is smart enough to learn them for class A, they should be smart enough to learn them for class B. If safety is first, they shouldn't learn it second. |
#240
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"N2EY" wrote:
(snip) The idea isn't that they'll have a high level of expertise right off, but that they'll reach that level through the 'incentive' of having to either upgrade or leave the air. (snip) To me, the entire idea is a solution seeking a problem. Since I don't think the current license holders are lacking, I don't see any real benefit (and I don't think the FCC will either). Regardless, his proposal would require a complete re-write of all the rules relating to license class, when a single sentence added to the existing rules would accomplish virtually the same thing - "All license holders, except Extra, must obtain the next higher license class within five years of obtaining their current license." Another sentence might describe what will happen if that doesn't occur. Dwight Stewart (W5NET) http://www.qsl.net/w5net/ |
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