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#22
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(I Am Not George) wrote in
m: "hypocrite Landshark" wrote: "BP" wrote in message ... (I Am Not George) wrote in m: "Twistedhed" wrote in message ws.com... KC8LDO, offended the nation and disgraced himself by undermining the death and tragedy in NYC while comparing it to his personal crusade of cleaning up the cb channels with: That's easy to explain. As another poster a short time back said about Part 95 rules "I don't care", well you see what happens when that mind set gets applied in a different context. It is very apparent they didn't care about human life either, including their own. Leland C. Scott KC8LDO ARRL Member Leland Scott is one of the most honest and honorable men ever to post in rrcb and your twisted propoganda can't ever change that. LMAO! Ditto!!! Landshark what proof do you have that Leland is other than what I say he is Look Mom, I found a google troll.. ..."Get rid of it, dear.. they're disgusting, filthy vermin" |
#23
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#24
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In p7jpc05ugaf983cn5th32r7rd99cgvbh71@2355323778, Lancer
wrote: snip Wrong, the coil has very little radiation. The open air coil has less loss because the losses are less in an open air coil. (resistive losses, capacitive coupling losses, form loss) Do a search on coil Q Care to argue that point? I would. What happens when you bring a solid sheet of conductive material close to the end of a coil? Eddy currents -- it has tremendous losses, the Q drops like a rock, and it's inductance is unpredictable. It's a royal bitch to design a shielded IF/RF coil or transformer to be used for high frequencies, and shielding is almost -never- used for power RF coils and transformers unless there is some serious space between the inductor and shield, hence the popularity of toroid cores for those applications. And since a bigger coil makes a bigger field, you need much more 'free space' to maintain a high-Q. Vertically mounting a big coil above the sheet metal of a vehicle results in a very lossy coil. 4) A stainless steel antenna is less efficient than a copper antenna of the same length. not if its electrically shorter than the stainless one Electrically shorter? You meant physically shorter. I can take a 18 foot antenna and make it electrically shorter than 9 feet while still keeping it 18 feet long. dumbass The difference between copper and stainless steel is not very significant at 27 MHz. What -is- significant is that bare copper will quickly form a layer of corrosion (visible or not) which will render an excellent conductor useless for RF. So unless you are willing to polish and degrease the antenna every day, I'll take the stainless. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#25
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On Mon, 14 Jun 2004 05:20:37 -0700, Frank Gilliland
wrote: In p7jpc05ugaf983cn5th32r7rd99cgvbh71@2355323778, Lancer wrote: snip Wrong, the coil has very little radiation. The open air coil has less loss because the losses are less in an open air coil. (resistive losses, capacitive coupling losses, form loss) Do a search on coil Q Care to argue that point? I would. What happens when you bring a solid sheet of conductive material close to the end of a coil? Eddy currents -- it has tremendous losses, the Q drops like a rock, and it's inductance is unpredictable. It's a royal bitch to design a shielded IF/RF coil or transformer to be used for high frequencies, and shielding is almost -never- used for power RF coils and transformers unless there is some serious space between the inductor and shield, hence the popularity of toroid cores for those applications. And since a bigger coil makes a bigger field, you need much more 'free space' to maintain a high-Q. Vertically mounting a big coil above the sheet metal of a vehicle results in a very lossy coil. I would think that 4 feet would be more than enough distance. So you would say that a large air wound coil has more loss than a small diameter coild wound on a solid form? |
#26
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In , Lancer
wrote: On Mon, 14 Jun 2004 05:20:37 -0700, Frank Gilliland wrote: In p7jpc05ugaf983cn5th32r7rd99cgvbh71@2355323778, Lancer wrote: snip Wrong, the coil has very little radiation. The open air coil has less loss because the losses are less in an open air coil. (resistive losses, capacitive coupling losses, form loss) Do a search on coil Q Care to argue that point? I would. What happens when you bring a solid sheet of conductive material close to the end of a coil? Eddy currents -- it has tremendous losses, the Q drops like a rock, and it's inductance is unpredictable. It's a royal bitch to design a shielded IF/RF coil or transformer to be used for high frequencies, and shielding is almost -never- used for power RF coils and transformers unless there is some serious space between the inductor and shield, hence the popularity of toroid cores for those applications. And since a bigger coil makes a bigger field, you need much more 'free space' to maintain a high-Q. Vertically mounting a big coil above the sheet metal of a vehicle results in a very lossy coil. I would think that 4 feet would be more than enough distance. It would depend on the diameter of the coil. I remember there is an equation somewhere to determine the loss, but it involves some heavy calculus and it's too early in the morning for integrals. So you would say that a large air wound coil has more loss than a small diameter coild wound on a solid form? No, not necessarily. If the wire diameter is the same, the smaller coil might easily be more efficient due to lower DC resistance. Distributed capacitance isn't much of an issue at 27 MHz unless you have lots of close-wound turns, and even then it's not necessarily a loss but a factor that affects the coil's reactance. Regardless, there are very effective winding techniques to reduce that problem. There are many low-loss coil form materials available, such as Teflon, some of the better quality ceramics, and even grooved hardwood makes a decent core at RF frequencies (however, PVC sucks above a couple hundred kHz). There is also the issue of weather conditions that can significantly affect an open coil regardless of whether or not the wire is insulated -- rain/humidity, snow, air pollutants (ozone can make a -=BIG=- difference!), etc. Even the speed of the vehicle can have an effect on the properties of an open coil. For the sake of consistency and longevity, a smaller coil that is sealed from the elements (as a whole) is a far better choice for anyone serious about the issue. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#27
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![]() "BP" wrote in message ... (I Am Not George) wrote in m: "hypocrite Landshark" wrote: "BP" wrote in message ... (I Am Not George) wrote in m: "Twistedhed" wrote in message ws.com... KC8LDO, offended the nation and disgraced himself by undermining the death and tragedy in NYC while comparing it to his personal crusade of cleaning up the cb channels with: That's easy to explain. As another poster a short time back said about Part 95 rules "I don't care", well you see what happens when that mind set gets applied in a different context. It is very apparent they didn't care about human life either, including their own. Leland C. Scott KC8LDO ARRL Member Leland Scott is one of the most honest and honorable men ever to post in rrcb and your twisted propoganda can't ever change that. LMAO! Ditto!!! Landshark what proof do you have that Leland is other than what I say he is Look Mom, I found a google troll.. .."Get rid of it, dear.. they're disgusting, filthy vermin" LOL!!! I love it. All I do is type Ditto to "LMAO" and notice Geo calls ME a hypocrite. He should talk, right BP. He defends Doug a known Felon, repeater jammer, porn poster, spammer, nut case. Leland defends Doug too, so George has no legs to stand on when calling other people hypocrites. Landshark -- Treat people as if they were what they ought to be and you will help them become what they are capable of becoming. |
#28
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On Mon, 14 Jun 2004 08:14:58 -0500, itoldyouiamnotiamnotgeorge
wrote: Lancer wrote in news:d26rc0h5q71rrak6oho7lll899pk768s4l@ 4ax.com: I would think that 4 feet would be more than enough distance. So you would say that a large air wound coil has more loss than a small diameter coild wound on a solid form? There are no large coil cb antennas where the coil is 4' from the vehicle roof, they are all mounted 18" or less. Bug Catchers aren't.. so all isn't correct. |
#29
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Replacing the lower section with pvc for flexibility. Sorry this thread is
hard to follow....too much off topic content. Chris "Lancer" wrote in message news:2mnoc0p0cgsoo8ro0am9fiqsisoms2utlt@2355323778 ... On Sat, 12 Jun 2004 23:52:38 GMT, "Chris" wrote: Thanks. I just wanted to prove to myself that I could make my own antenna and see how well it worked. There are 2 reasons for the large coil. In comparing a few antennas of roughly equal length, the ones with large open coils tend to be more broad-banded. Larger materials also have less resistive loss and more radiating are. The lower part doesn't really have to be 1/2' copper pipe but it was the first thing I thought of. I'm going with copper wire wrapped on pvc shortly. Chris Chris; Nice looking antenna, large open air coils are more efficient. Some people see a large open air coil and think its all about power handling capability. Are you planning on replacing the coil with pvc wrapped with wire, or the lower section? If you want to beef up the lower secton you might take a trip to a hamfest and pick up a lower section of a Newtronics Hustler. |
#30
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On Mon, 14 Jun 2004 14:02:15 GMT, "Chris"
wrote: Replacing the lower section with pvc for flexibility. Sorry this thread is hard to follow....too much off topic content. Chris; yes there is, and for that I apologize. PVC gets very brittle when exposed to sun or cold. You might need to think about hooking some kind of line to it keep from losing the top of the antenna in case it breaks. |
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