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#101
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On 08 Apr 2005 21:18:37 GMT, Steveo wrote:
Lancer wrote: On 08 Apr 2005 20:45:44 GMT, Steveo wrote: "Landshark" wrote: "Steveo" wrote in message That's a long camper haul up and down those hills they call mountains in Virginia and W Virginia.. 14 hour drive to and from for one of the guys that lives local to me. I had my Bronco trucked down, then flew, much easier. Man the fuel prices suck! $2.18 here Steve... Glad my car gets almost 30 mpg... I spent about $300 in fuel round-trip to Bristol. ugh It's a good thing I don't have to spend money on fuel. Only on my wife's car, but not mine. Vinnie S. |
#102
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On Fri, 08 Apr 2005 13:59:47 -0400, Dave Hall
wrote in : snip Maybe you had difficulty, but there are a very large number of hams -and- CBers who don't share your ineptitude. A dipole is a dipole. It has 0 db of gain, Wrong. A 1/2-wave Hertzian dipole has a gain of roughly +3 dBi in free space. It has 0 dB when referenced to itself. and that assumes a resonant dipole . That's an assumtion -you- made, and it's also wrong: A resonant dipole can be any multiple of 1/2-wave, and has a gain that differs depending upon the length and directionality. If the dipole is non-resonant and requires a tuner to force an impedance match, it will have further losses. Wrong again. A tuner only adds insertion loss, which is usually quite small if it's built with quality components. The insertion loss is easily overcome by slightly increasing the length of the elements, which is no big deal since the antenna is already non-resonant. It won't stand a chance against a commercially produced (or home made if you are so-inclined) 5/8th wave vertical (with proper radials, not an Imax). Well guess what, Dave -- a 5/8-wave antenna is a non-resonant antenna and requires some method of impedance matching. Thank you. I've done this type of antenna myself and never had any problems with local contacts -- in fact, it worked a lot better than the 9' whip on the truck. I find that very hard to believe, assuming identical height and conditions, as my own experiences prove otherwise. Oh, the humanity..... I ran a home brewed wire dipole on CB years ago, and used it in addition to my main 5/8th wave antenna. While the dipole worked well when the skip was running, locally, the signal from the dipole was a few "S" units less than the ground plane. With 4 watts of power, you don't get much range on a horizontal wire dipole strung in a tree. Well there's your problem, Dave -- I didn't say anything about horizontal. On the contrary, it's better if it isn't. Yea, if you're talking local. For DX, horizontal is usually better for a number of reasons, most notably a lower noise floor and better take off angle. A horizontal dipole can have a wide variation in take-off angle depending on height above ground, ground resistance, proximity to other structures or objects, etc. And the noise floor may be slightly lower but that's a product of it's directivity, as compared to a vertical which is omnidirectional. A pair of phased verticals, as well as any other directional antenna or antenna array, will also have the effect of lowering the noise floor. Like I said before, just throw some wire up into the trees (or whatever tall object happens to be available). Didn't you read the link I posted? Of course. But a dipole is a basic antenna. It has no gain. Wrong again. As I said before, a 1/2-wave Hertzian dipole in free space has about 3 dB gain over an isotropic antenna; but a dipole is merely an antenna with two elements and is not limited to a 1/2-wave Hertzian configuration. Not only that, but a tuner isn't limited to dipole antennas -- they can load up a long-wire just as easily. A properly made purpose built CB antenna will out perform it. Get a clue, Dave. You're an Extra, right? What's the name of that tech school you claim to have attended? Let's look at this from a practical standpoint. If a non-resonant, tuner fed dipole worked so well, then why aren't all CB'ers using one? Why would people want huge 5/8th wave antennas then? Better tell Jay to forget about selling his Interceptor, since a simple non-resonant dipole will work just as well and for far less money. This resounds back to your argument that roger-beeps were illegal because most radios didn't include them. The problem is that a tuner requires a little skill and practice to use, which is beyond the scope of the intended purpose of the service (a plug-n-play radio service). A tuner requires readjustment when changing channels within the CB, and most CBers don't want to deal with the hassle. Regardless, there are still many CBers that do indeed use a tuner, not just with prefab antennas but also with homebrew and beverage-can hooks. And just about every CBer who runs a tube linear uses a tuner because it's built into the amp, which by itself blows big holes in your "practical" argument. Then there is the issue of the non-resonant 5/8-wave antenna..... oh, Dave, when will you learn? A non-resonant dipole has ONE big advantage. It's a compromise antenna that will work on all the HF bands. That's great if you don't have the room to put up single band antennas for each band. But like any compromise, it will not work as well as a dedicated antenna for each band. Such a compromise is usually acceptable for a ham who has 1500 watts on tap. But for a 4 watt CB'er, who needs to squeeze every watt of ERP he can for best local range, he needs a high gain efficient antenna. If that were the case then every CBer would have a 5-el yagi on a 30' mast and a 9' whip on their vehicles. For ham band use, I agree with you, just not for CB. What's the name of that tech school, Dave? What's your call sign Frank? I'm not a ham. I answered your question, now you answer mine: what's the name of your tech school, Dave? Frank, your experience with both ham and CB radio is sorely lacking. You read a few books and web sites and think you have all the answers. OTOH, I've walked the walk for the last 30+ years and have played with more antennas and equipment than I can remember. I have also been in contact with people in the know when it comes to antennas. What I know, I know through experience, and that's worth 10X what you read in any book. Which explains why your theory is severely lacking. If you took the time to actually learn why these things work and -then- applied them to your experiences, you could be the guru you think you already are. But you don't and you're not. Instead you do things backwards: you theorize about radio based on your own experience, then read only enough to validate your own conclusions whether they are right or not. Check this out, Dave: Education doesn't come from a textbook that some geek sat down and wrote just for ****s and giggles. It's a compendium of knowledge that has been collected from over a century of research, experimentation and practical experience by experts in all aspects of the field. Those experts didn't become experts simply by playing with CB radios as a hobby for 30 years. And an education doesn't include a couple textbooks, a few lectures and a test -- it also includes years of experience with the practical application of that knowledge. When you mock those that have a formal education and extensive experience in electronic communication then you mock the same people who made the television set you watch way too much, the telephone and cell-phone infrastructure that keeps this world talking, the NASA and JPL engineers who communicate with space probes billions of miles away, etc, etc, etc. While I may not have participated in any world-changing technology, I certainly have an education and the experience in the field that puts you to shame. Yet -you- try to teach -me- theory based on your education from a third-rate vocational tech school, a few years in a CB shop, and your experience in =amateur= radio. And here's the kicker: Do you have any idea where I came up with the idea to just throw a couple wires in the air and load them up with a tuner? A ham. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#103
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On Fri, 08 Apr 2005 13:28:53 -0400, Dave Hall
wrote in : On Thu, 07 Apr 2005 16:44:59 -0700, Frank Gilliland wrote: On 07 Apr 2005 23:32:45 GMT, Steveo wrote in : snip I suppose they drive like that everyplace..it's a matter of being in the wrong place at the wrong time, or your truck is a magnet. I have one of those too. I think -I'm- the magnet. The Dart I drove in college was hit 5 times, the LTD got hit twice before it was totalled, the S-15 was rear-ended by an ambulance, the LeBaron was hit three times in two weeks, etc. I've had the S-10 for two years and it's been hit twice -- both times while it was parked! All in Spokane. Fortunately, I've only been hit once when I had a passenger, and that was the ambulance wreck so at least there was help available if someone got hurt. There's something cosmic about that. I've had 2 major accidents in my whole life, and both were in the same car. Neither were my fault. Nothing is ever your fault, Dave. We discussed this problem in your last therapy session. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#104
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Lancer wrote:
On Thu, 07 Apr 2005 20:03:26 -0400, jim wrote: Frank Gilliland wrote: On 07 Apr 2005 23:32:45 GMT, Steveo wrote in : snip I suppose they drive like that everyplace..it's a matter of being in the wrong place at the wrong time, or your truck is a magnet. I have one of those too. I think -I'm- the magnet. The Dart I drove in college was hit 5 times, the LTD got hit twice before it was totalled, the S-15 was rear-ended by an ambulance, the LeBaron was hit three times in two weeks, etc. I've had the S-10 for two years and it's been hit twice -- both times while it was parked! All in Spokane. Fortunately, I've only been hit once when I had a passenger, and that was the ambulance wreck so at least there was help available if someone got hurt. Ok, I'm stepping off the soap box now..... ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- got hit by a beer distributor saleswoman (go figure) and enjoyed the bennies of not reporting it hehehe Ok, got to ask... beer or? was on the way to a womans softball game (as i was the manager) with a female in the truck so it was beer ![]() |
#105
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Hey Vinnie............I can help you. The formula for a 1/4 wavelength
radiator is (234 / F) whereby F is the frequency in MHz. This will give you the length in feet. For the radials, (237 / F) will give you that length. Always remember...multiply the radiator length by 1.05 and that is another way of calculating the 1/4 wavelength radials. The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you have the radials at a 90 degree angle with respect to the radiator. If you have the radials drooped at a 45 degree angle, the impedance rises to approximately 50 ohms. If you have a single radial drooped at a 180 degree angle with respect to the radiator, the impedance rises to 75 ohms. There was an article in RF Design magazine a few years back, explaining why certain impedances are used in the RF industry. 72 ohms was the impedance that produced minimum cable losses...........50 ohms is a happy medium. On a final note...........at 37 ohms, you will have a VSWR of 1.3 to 1.................at 75 ohms, you will have a VSWR of 1.5 to 1. What is the difference here? For a transmitter with a tube output and an internal matching network, you wouldn't really see much effect. For a typical solid state transmitter, there would be some difference between the two antenna impedances, because the broadband solid state transmitter would be called upon to deliver more current to the antenna. It probably wouldn't have any effect, unless the ALC circuit was aggressive in its operation. In this case, power foldback would occur into the 37 ohm load. Would it happen? Probably not. I hope this helps. Pete "Frank Gilliland" wrote in message ... On Wed, 06 Apr 2005 20:14:16 -0400, Vinnie S. wrote in : On Wed, 06 Apr 2005 17:15:08 GMT, Lancer wrote: Why should I be nice? I -was- nice. We have had civil converstations, and I even gave him enough info to install the antenna in his attic, which apparently worked quite well. Then he stuck his finger into the political lion cage and turned into a sniveling crybaby after getting scratched. As for being a general-class amateur, there are literally hundreds of hammie websites that cover nothing but antennas, not to mention the ARRL manual. If he's so serious about radio, why beg a CB group for info on how to install a prefab antenna? J.H.F.C, how did he pass the exam without knowing a few antenna fundamentals? And if part of the hobby is to learn about radio comm, why ask a CB group for tech info when there are countless resources available for hams? Isn't anyone elmering the kid? I thought your were elmering him Frank? He really doesn't need one anyway, he buys his antennas. Even something as simple as a dipole, or sloper... Do you have a problem with that? Show me the rules on antenna requirements, please. Looks like Vinnie is going to be a General-class appliance operator. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#106
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On Sun, 10 Apr 2005 19:58:28 GMT, "Pete KE9OA"
wrote in : Hey Vinnie............I can help you. The formula for a 1/4 wavelength radiator is (234 / F) whereby F is the frequency in MHz. This will give you the length in feet. For the radials, (237 / F) will give you that length. Always remember...multiply the radiator length by 1.05 and that is another way of calculating the 1/4 wavelength radials. It should be noted that these formulas are only appoximations. Actual sizes are dependent upon the conductivity and diameter of the elements, and the quantity and angle of the radials. When building a resonant antenna it's a good idea to make the elements a little long and trim to resonance. The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you have the radials at a 90 degree angle with respect to the radiator. If you have the radials drooped at a 45 degree angle, the impedance rises to approximately 50 ohms. If you have a single radial drooped at a 180 degree angle with respect to the radiator, the impedance rises to 75 ohms. These are impedances for antennas in free space, and are practical only if you can mount your antenna well above the ground and away from any tall objects. There was an article in RF Design magazine a few years back, explaining why certain impedances are used in the RF industry. 72 ohms was the impedance that produced minimum cable losses...........50 ohms is a happy medium. Close. For lowest loss, the optimum characteristic impedance of coax is 76.9 ohms. 70-73 ohm coax is used as a compromise between low loss coax and coax optimized for minimization of flashover, the latter having an impedance of about 60 ohms. And while many people have many different ideas as to why 50 ohm coax is made, it is just a compromise between low-loss/low-flashover coax of 72 ohms and coax optimized for handling power (about 30 ohms, which is too lossy for practical transmission lines). On a final note...........at 37 ohms, you will have a VSWR of 1.3 to 1.................at 75 ohms, you will have a VSWR of 1.5 to 1. What is the difference here? For a transmitter with a tube output and an internal matching network, you wouldn't really see much effect. For a typical solid state transmitter, there would be some difference between the two antenna impedances, because the broadband solid state transmitter would be called upon to deliver more current to the antenna. It probably wouldn't have any effect, unless the ALC circuit was aggressive in its operation. In this case, power foldback would occur into the 37 ohm load. Would it happen? Probably not. ......uh, what? Both tubes and transistors use matching networks, so I don't know what distinction you are trying to make there. Power will be reflected from an antenna/coax mismatch -regardless- of whether you have a tube or transistor final. And what does an ALC circuit have to do with transmission line propogation? I hope this helps. Pete ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#107
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On Sun, 10 Apr 2005 19:58:28 GMT, "Pete KE9OA"
wrote: Hey Vinnie............I can help you. The formula for a 1/4 wavelength radiator is (234 / F) whereby F is the frequency in MHz. This will give you the length in feet. For the radials, (237 / F) will give you that length. Always remember...multiply the radiator length by 1.05 and that is another way of calculating the 1/4 wavelength radials. The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you have the radials at a 90 degree angle with respect to the radiator. If you have the radials drooped at a 45 degree angle, the impedance rises to approximately 50 ohms. So far, that is what I have read. What I am going to do is this. I am going to add the 45 angled GP, simply because it is fairly cheap, and because it will be much easier to put it up now, than later. The formula you gave indicates that radials should be about 8.8 feet at 27 MHz. If these radials fair poorly, I will take Lancer's advice and build my own. For some reason, the radials are 6 feet. I don't know if they ran 9 feet of wire in there, or what. If you have a single radial drooped at a 180 degree angle with respect to the radiator, the impedance rises to 75 ohms. I won't do this. There was an article in RF Design magazine a few years back, explaining why certain impedances are used in the RF industry. 72 ohms was the impedance that produced minimum cable losses...........50 ohms is a happy medium. On a final note...........at 37 ohms, you will have a VSWR of 1.3 to 1.................at 75 ohms, you will have a VSWR of 1.5 to 1. What is the difference here? For a transmitter with a tube output and an internal matching network, you wouldn't really see much effect. For a typical solid state transmitter, there would be some difference between the two antenna impedances, because the broadband solid state transmitter would be called upon to deliver more current to the antenna. It probably wouldn't have any effect, unless the ALC circuit was aggressive in its operation. In this case, power foldback would occur into the 37 ohm load. Would it happen? Probably not. I hope this helps. Pete It's does help, Thanks ! I am borrowing an Autek RF analyzer to check the antenna while I am up in the tree. Most people that have purchase this antenna, say that it is tuned very well to 27.205. I should be flat up and down in CB and 10 meters for about 1 MHZ. I will follow up. Vinnie S. |
#108
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On Fri, 08 Apr 2005 17:02:43 -0400, Vinnie S.
wrote in : On Fri, 08 Apr 2005 13:30:51 -0400, Dave Hall wrote: Believe me. I have nothing to worry about. Vinnie S. You don't believe his callsign is WA3MOJ do you? I don't know what to believe from him. But if some lardass steps foot on my property, I will look thru his wallet for ID will I hold his face in the dirt. And if he doesn't have a wallet, then I will get the info from the car. .....oh brother, he's a crybaby -and- a tough-guy. This is just too good to be true! And it don't look like I am the only one !!! I did a little search on you in the archives. This is precious. http://groups-beta.google.com/group/... 2f3b40d85682 Don't you think it's time you quit with the killfile charade? You aren't fooling anyone when you reply to half my posts via piggybacks and swim through Google juice to read even more of them. Maybe he is a true tough guy. Stranger things have happened. It's a amazing what a little info you can get on a poster's history on Google, Dave. My favorite about this info on Frank, it the imaginary McDonald's, and the fishing trip he had at the lake in a storm !!!! It's amazing how quickly some people resort to digging up the past when they can't deal with the present. Heck, even Dave agrees with me on this one -- every time I bring up Bush's DUI or business failures, Dave says they are irrelevant. So Vinnie, are you calling Dave a liar? ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#109
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![]() "Frank Gilliland" wrote in message ... On Sun, 10 Apr 2005 19:58:28 GMT, "Pete KE9OA" wrote in : Hey Vinnie............I can help you. The formula for a 1/4 wavelength radiator is (234 / F) whereby F is the frequency in MHz. This will give you the length in feet. For the radials, (237 / F) will give you that length. Always remember...multiply the radiator length by 1.05 and that is another way of calculating the 1/4 wavelength radials. It should be noted that these formulas are only appoximations. Actual sizes are dependent upon the conductivity and diameter of the elements, and the quantity and angle of the radials. When building a resonant antenna it's a good idea to make the elements a little long and trim to resonance. Very true..........I use a spectrum analyzer with a directional coupler and trim for maximum return loww. The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you have the radials at a 90 degree angle with respect to the radiator. If you have the radials drooped at a 45 degree angle, the impedance rises to approximately 50 ohms. If you have a single radial drooped at a 180 degree angle with respect to the radiator, the impedance rises to 75 ohms. These are impedances for antennas in free space, and are practical only if you can mount your antenna well above the ground and away from any tall objects. Also true, but a good starting point. There was an article in RF Design magazine a few years back, explaining why certain impedances are used in the RF industry. 72 ohms was the impedance that produced minimum cable losses...........50 ohms is a happy medium. Close. For lowest loss, the optimum characteristic impedance of coax is 76.9 ohms. 70-73 ohm coax is used as a compromise between low loss coax and coax optimized for minimization of flashover, the latter having an impedance of about 60 ohms. Good memory. And while many people have many different ideas as to why 50 ohm coax is made, it is just a compromise between low-loss/low-flashover coax of 72 ohms and coax optimized for handling power (about 30 ohms, which is too lossy for practical transmission lines). On a final note...........at 37 ohms, you will have a VSWR of 1.3 to 1.................at 75 ohms, you will have a VSWR of 1.5 to 1. What is the difference here? For a transmitter with a tube output and an internal matching network, you wouldn't really see much effect. For a typical solid state transmitter, there would be some difference between the two antenna impedances, because the broadband solid state transmitter would be called upon to deliver more current to the antenna. It probably wouldn't have any effect, unless the ALC circuit was aggressive in its operation. In this case, power foldback would occur into the 37 ohm load. Would it happen? Probably not. .....uh, what? Both tubes and transistors use matching networks, so I don't know what distinction you are trying to make there. Power will be reflected from an antenna/coax mismatch -regardless- of whether you have a tube or transistor final. And what does an ALC circuit have to do with transmission line propogation? This pertains to solid state amateur transceivers that don't have an adjustable output matching network.........most of today's units have fixed-tuned bandpass filters after the output stage. I am not referring to transmission line propagation; I am referring to the fact that, with a fixed-tuned output network that expects to see a 50 ohm characteristic impedance, the ALC can fold back the power. Usually, that doesn't occur until a VSWR of 2 to 1 is reached. My explanation is for illustrative purposes only. I hope this helps. Pete ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#110
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Sounds good, Vinnie....................feel free to e-mail me directly if
you have any questions. Pete "Vinnie S." wrote in message ... On Sun, 10 Apr 2005 19:58:28 GMT, "Pete KE9OA" wrote: Hey Vinnie............I can help you. The formula for a 1/4 wavelength radiator is (234 / F) whereby F is the frequency in MHz. This will give you the length in feet. For the radials, (237 / F) will give you that length. Always remember...multiply the radiator length by 1.05 and that is another way of calculating the 1/4 wavelength radials. The feedpoint impedance of a 1/4 wave ground plane is 37 ohms when you have the radials at a 90 degree angle with respect to the radiator. If you have the radials drooped at a 45 degree angle, the impedance rises to approximately 50 ohms. So far, that is what I have read. What I am going to do is this. I am going to add the 45 angled GP, simply because it is fairly cheap, and because it will be much easier to put it up now, than later. The formula you gave indicates that radials should be about 8.8 feet at 27 MHz. If these radials fair poorly, I will take Lancer's advice and build my own. For some reason, the radials are 6 feet. I don't know if they ran 9 feet of wire in there, or what. If you have a single radial drooped at a 180 degree angle with respect to the radiator, the impedance rises to 75 ohms. I won't do this. There was an article in RF Design magazine a few years back, explaining why certain impedances are used in the RF industry. 72 ohms was the impedance that produced minimum cable losses...........50 ohms is a happy medium. On a final note...........at 37 ohms, you will have a VSWR of 1.3 to 1.................at 75 ohms, you will have a VSWR of 1.5 to 1. What is the difference here? For a transmitter with a tube output and an internal matching network, you wouldn't really see much effect. For a typical solid state transmitter, there would be some difference between the two antenna impedances, because the broadband solid state transmitter would be called upon to deliver more current to the antenna. It probably wouldn't have any effect, unless the ALC circuit was aggressive in its operation. In this case, power foldback would occur into the 37 ohm load. Would it happen? Probably not. I hope this helps. Pete It's does help, Thanks ! I am borrowing an Autek RF analyzer to check the antenna while I am up in the tree. Most people that have purchase this antenna, say that it is tuned very well to 27.205. I should be flat up and down in CB and 10 meters for about 1 MHZ. I will follow up. Vinnie S. |
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