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#1
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On May 21, 5:48*am, Kevin Alfred Strom
wrote: bpnjensen wrote: On May 20, 10:32 am, bpnjensen wrote: ...and I'm gonna use existing trees to put it up about 30 feet above ground, 15 feet above my rooftop on a 5x100 foot suburban lot. *Power lines both in front and back of my house, the ones behind are much higher voltage, but not real high-tension wires. All other things being equal, am I better off: 1 - Putting this thing up parallel to, or more perpendicular to, the powerlines? 2 - Having the coax meet the wire at the base of the tree and grounding it there, or running the coax up the tree and then depending on the outer braid on the coax for ground purposes? *The coax is grounded at the first termination point at my MFJ antenna phasing unit using a short, heavy copper wire to a ground rod. Thanks, Bruce Gentlemen, Peter and Kevin, thank you for the excellent ideas - some I knew, some ARE new - I don't have a lot of room to experiment, but my trees are situated so as to allow a generally perpendicular orientation to the power lines, my main nemesis. *Unfortunately, 30 feet is about as high as I can practically put them, but it's higher than what I have now, so anything is an improvement, eh? *Again, thanks :-) You're welcome. Scaling the inverted L I described to half size -- 30 feet vertical and 45 feet horizontal -- will still give excellent performance. 73, Kevin, WB4AIO. --http://kevinalfredstrom.com/- Hide quoted text - - Show quoted text - Thanks! Mine is likely to be 30 feet vert and about 65 feet horz. Bruce |
#2
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bpnjensen wrote:
On May 21, 5:48 am, Kevin Alfred Strom wrote: bpnjensen wrote: On May 20, 10:32 am, bpnjensen wrote: ...and I'm gonna use existing trees to put it up about 30 feet above ground, 15 feet above my rooftop on a 5x100 foot suburban lot. Power lines both in front and back of my house, the ones behind are much higher voltage, but not real high-tension wires. All other things being equal, am I better off: 1 - Putting this thing up parallel to, or more perpendicular to, the powerlines? 2 - Having the coax meet the wire at the base of the tree and grounding it there, or running the coax up the tree and then depending on the outer braid on the coax for ground purposes? The coax is grounded at the first termination point at my MFJ antenna phasing unit using a short, heavy copper wire to a ground rod. Thanks, Bruce Gentlemen, Peter and Kevin, thank you for the excellent ideas - some I knew, some ARE new - I don't have a lot of room to experiment, but my trees are situated so as to allow a generally perpendicular orientation to the power lines, my main nemesis. Unfortunately, 30 feet is about as high as I can practically put them, but it's higher than what I have now, so anything is an improvement, eh? Again, thanks :-) You're welcome. Scaling the inverted L I described to half size -- 30 feet vertical and 45 feet horizontal -- will still give excellent performance. 73, Kevin, WB4AIO. --http://kevinalfredstrom.com/- Hide quoted text - - Show quoted text - Thanks! Mine is likely to be 30 feet vert and about 65 feet horz. Bruce That'll work well, too. Putting a few radials on the ground (or, even better, elevated a few feet above the ground) connected to the coaxial feedline's shield will help the low angle (most distant) reception. Recent studies indicate that radials don't need to be a quarter wave long for best results as previously believed, either. About 195 divided by the frequency in MHz (with the answer in feet) is near ideal, but they will still help at any length. I've used flat rotor cable with the conductors pulled apart, or separated strands of telephone PBX cable, stapled to the grassy yard with staples made from cut up coat hangers bent into a U shape and hammered over the wire every five or ten feet. If it's done carefully, you can mow over them the same day without problems. After a few weeks, the grass buries them and you can hardly tell the wires are there. If I was going to build a new inverted L today, I'd elevate the feedpoint and radials about seven feet for higher efficiency -- but it would look a bit more obtrusive. Good luck with the antenna, Kevin, WB4AIO. -- http://kevinalfredstrom.com/ |
#3
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On May 21, 11:07*am, Kevin Alfred Strom kevin.st...@revilo-
oliver.com wrote: bpnjensen wrote: On May 21, 5:48 am, Kevin Alfred Strom wrote: bpnjensen wrote: On May 20, 10:32 am, bpnjensen wrote: ...and I'm gonna use existing trees to put it up about 30 feet above ground, 15 feet above my rooftop on a 5x100 foot suburban lot. *Power lines both in front and back of my house, the ones behind are much higher voltage, but not real high-tension wires. All other things being equal, am I better off: 1 - Putting this thing up parallel to, or more perpendicular to, the powerlines? 2 - Having the coax meet the wire at the base of the tree and grounding it there, or running the coax up the tree and then depending on the outer braid on the coax for ground purposes? *The coax is grounded at the first termination point at my MFJ antenna phasing unit using a short, heavy copper wire to a ground rod. Thanks, Bruce Gentlemen, Peter and Kevin, thank you for the excellent ideas - some I knew, some ARE new - I don't have a lot of room to experiment, but my trees are situated so as to allow a generally perpendicular orientation to the power lines, my main nemesis. *Unfortunately, 30 feet is about as high as I can practically put them, but it's higher than what I have now, so anything is an improvement, eh? *Again, thanks :-) You're welcome. Scaling the inverted L I described to half size -- 30 feet vertical and 45 feet horizontal -- will still give excellent performance. 73, Kevin, WB4AIO. --http://kevinalfredstrom.com/-Hide quoted text - - Show quoted text - Thanks! *Mine is likely to be 30 feet vert and about 65 feet horz. Bruce That'll work well, too. Putting a few radials on the ground (or, even better, elevated a few feet above the ground) connected to the coaxial feedline's shield will help the low angle (most distant) reception. Recent studies indicate that radials don't need to be a quarter wave long for best results as previously believed, either. About 195 divided by the frequency in MHz (with the answer in feet) is near ideal, but they will still help at any length. I've used flat rotor cable with the conductors pulled apart, or separated strands of telephone PBX cable, stapled to the grassy yard with staples made from cut up coat hangers bent into a U shape and hammered over the wire every five or ten feet. If it's done carefully, you can mow over them the same day without problems. After a few weeks, the grass buries them and you can hardly tell the wires are there. If I was going to build a new inverted L today, I'd elevate the feedpoint and radials about seven feet for higher efficiency -- but it would look a bit more obtrusive. Good luck with the antenna, Kevin, WB4AIO. --http://kevinalfredstrom.com/- Hide quoted text - - Show quoted text - Thanks again - my space for radials is super limited - no more than about 15 feet in any direction, and usually less - but maybe if there are enough of them it would help make up for it. I have a pretty good ground here - near the edge of SF Bay and only about 10 feet above sea level, our ground water is pretty brackish and seeps upward too. I don't know that this would help with the low- angle reception, though. Maybe a ground rod plus attached radials? Bruce |
#4
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bpnjensen wrote:
On May 21, 11:07 am, Kevin Alfred Strom kevin.st...@revilo- oliver.com wrote: bpnjensen wrote: On May 21, 5:48 am, Kevin Alfred Strom wrote: bpnjensen wrote: On May 20, 10:32 am, bpnjensen wrote: ...and I'm gonna use existing trees to put it up about 30 feet above ground, 15 feet above my rooftop on a 5x100 foot suburban lot. Power lines both in front and back of my house, the ones behind are much higher voltage, but not real high-tension wires. All other things being equal, am I better off: 1 - Putting this thing up parallel to, or more perpendicular to, the powerlines? 2 - Having the coax meet the wire at the base of the tree and grounding it there, or running the coax up the tree and then depending on the outer braid on the coax for ground purposes? The coax is grounded at the first termination point at my MFJ antenna phasing unit using a short, heavy copper wire to a ground rod. Thanks, Bruce Gentlemen, Peter and Kevin, thank you for the excellent ideas - some I knew, some ARE new - I don't have a lot of room to experiment, but my trees are situated so as to allow a generally perpendicular orientation to the power lines, my main nemesis. Unfortunately, 30 feet is about as high as I can practically put them, but it's higher than what I have now, so anything is an improvement, eh? Again, thanks :-) You're welcome. Scaling the inverted L I described to half size -- 30 feet vertical and 45 feet horizontal -- will still give excellent performance. 73, Kevin, WB4AIO. --http://kevinalfredstrom.com/-Hide quoted text - - Show quoted text - Thanks! Mine is likely to be 30 feet vert and about 65 feet horz. Bruce That'll work well, too. Putting a few radials on the ground (or, even better, elevated a few feet above the ground) connected to the coaxial feedline's shield will help the low angle (most distant) reception. Recent studies indicate that radials don't need to be a quarter wave long for best results as previously believed, either. About 195 divided by the frequency in MHz (with the answer in feet) is near ideal, but they will still help at any length. I've used flat rotor cable with the conductors pulled apart, or separated strands of telephone PBX cable, stapled to the grassy yard with staples made from cut up coat hangers bent into a U shape and hammered over the wire every five or ten feet. If it's done carefully, you can mow over them the same day without problems. After a few weeks, the grass buries them and you can hardly tell the wires are there. If I was going to build a new inverted L today, I'd elevate the feedpoint and radials about seven feet for higher efficiency -- but it would look a bit more obtrusive. Good luck with the antenna, Kevin, WB4AIO. --http://kevinalfredstrom.com/- Hide quoted text - - Show quoted text - Thanks again - my space for radials is super limited - no more than about 15 feet in any direction, and usually less - but maybe if there are enough of them it would help make up for it. I have a pretty good ground here - near the edge of SF Bay and only about 10 feet above sea level, our ground water is pretty brackish and seeps upward too. I don't know that this would help with the low- angle reception, though. Maybe a ground rod plus attached radials? Bruce That sounds good. The brackish water in the far field will definitely help. The inverted L will work without the radials, just not as well for the more distant stations. All the best, Kevin, WB4AIO. -- http://kevinalfredstrom.com/ |
#5
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On May 21, 11:25*am, Kevin Alfred Strom kevin.st...@revilo-
oliver.com wrote: bpnjensen wrote: On May 21, 11:07 am, Kevin Alfred Strom kevin.st...@revilo- oliver.com wrote: bpnjensen wrote: On May 21, 5:48 am, Kevin Alfred Strom wrote: bpnjensen wrote: On May 20, 10:32 am, bpnjensen wrote: ...and I'm gonna use existing trees to put it up about 30 feet above ground, 15 feet above my rooftop on a 5x100 foot suburban lot. *Power lines both in front and back of my house, the ones behind are much higher voltage, but not real high-tension wires. All other things being equal, am I better off: 1 - Putting this thing up parallel to, or more perpendicular to, the powerlines? 2 - Having the coax meet the wire at the base of the tree and grounding it there, or running the coax up the tree and then depending on the outer braid on the coax for ground purposes? *The coax is grounded at the first termination point at my MFJ antenna phasing unit using a short, heavy copper wire to a ground rod. Thanks, Bruce Gentlemen, Peter and Kevin, thank you for the excellent ideas - some I knew, some ARE new - I don't have a lot of room to experiment, but my trees are situated so as to allow a generally perpendicular orientation to the power lines, my main nemesis. *Unfortunately, 30 feet is about as high as I can practically put them, but it's higher than what I have now, so anything is an improvement, eh? *Again, thanks :-) You're welcome. Scaling the inverted L I described to half size -- 30 feet vertical and 45 feet horizontal -- will still give excellent performance. 73, Kevin, WB4AIO. --http://kevinalfredstrom.com/-Hidequoted text - - Show quoted text - Thanks! *Mine is likely to be 30 feet vert and about 65 feet horz. Bruce That'll work well, too. Putting a few radials on the ground (or, even better, elevated a few feet above the ground) connected to the coaxial feedline's shield will help the low angle (most distant) reception. Recent studies indicate that radials don't need to be a quarter wave long for best results as previously believed, either. About 195 divided by the frequency in MHz (with the answer in feet) is near ideal, but they will still help at any length. I've used flat rotor cable with the conductors pulled apart, or separated strands of telephone PBX cable, stapled to the grassy yard with staples made from cut up coat hangers bent into a U shape and hammered over the wire every five or ten feet. If it's done carefully, you can mow over them the same day without problems. After a few weeks, the grass buries them and you can hardly tell the wires are there. If I was going to build a new inverted L today, I'd elevate the feedpoint and radials about seven feet for higher efficiency -- but it would look a bit more obtrusive. Good luck with the antenna, Kevin, WB4AIO. --http://kevinalfredstrom.com/-Hide quoted text - - Show quoted text - Thanks again - my space for radials is super limited - no more than about 15 feet in any direction, and usually less - but maybe if there are enough of them it would help make up for it. I have a pretty good ground here - near the edge of SF Bay and only about 10 feet above sea level, our ground water is pretty brackish and seeps upward too. *I don't know that this would help with the low- angle reception, though. *Maybe a ground rod plus attached radials? Bruce That sounds good. The brackish water in the far field will definitely help. The inverted L will work without the radials, just not as well for the more distant stations. All the best, Kevin, WB4AIO. --http://kevinalfredstrom.com/- Hide quoted text - - Show quoted text - Sounds like radials are the ticket - thanks! |
#6
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WB4AIO offers some excellent information and I would like to add the
following: Generally speaking, (Note I stated GENERALLY SPEAKING here) end fed antennas tend to be most directional in line with their longitudinal axis. In other words, an inverted-L, end fed, would pick up the greatest capture in the direction that it is "pointing." Center fed antennas GENERALLY tend to be most directional perpendicular to their longitudinal axis. Again, I stress these are VERY BROAD and GENERAL rules of thumb. Of course there are always exceptions such as the center fed Zepp which tends to be most directive off its ends. As one respondent stated...experiment. There is a reason they call technical suppositions "theories." It is because they are just that, theories only. Real world performance is whatever you get and can be morphed by ground conductivity, nearby structures, interactions and terrain as well as theories that are conventional but one day will be refuted. |
#7
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On May 21, 3:58*pm, "Clive" wrote:
WB4AIO offers some excellent information and I would like to add the following: Generally speaking, (Note I stated GENERALLY SPEAKING here) end fed antennas tend to be most directional in line with their longitudinal axis. In other words, an inverted-L, end fed, would pick up the greatest capture in the direction that it is "pointing." Center fed antennas GENERALLY tend to be most directional perpendicular to their longitudinal axis. Again, I stress these are VERY BROAD and GENERAL rules of thumb. Of course there are always exceptions such as the center fed Zepp which tends to be most directive off its ends. As one respondent stated...experiment. There is a reason they call technical suppositions "theories." It is because they are just that, theories only. Real world performance is whatever you get and can be morphed by ground conductivity, nearby structures, interactions and terrain as well as theories that are conventional but one day will be refuted. Thanks, Clive - my room to experiment is extremely limited, but I will do what I can. |
#8
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On May 21, 6:58*pm, "Clive" wrote:
WB4AIO offers some excellent information and I would like to add the following: Generally speaking, (Note I stated GENERALLY SPEAKING here) end fed antennas tend to be most directional in line with their longitudinal axis. In other words, an inverted-L, end fed, would pick up the greatest capture in the direction that it is "pointing." Center fed antennas GENERALLY tend to be most directional perpendicular to their longitudinal axis. Again, I stress these are VERY BROAD and GENERAL rules of thumb. Of course there are always exceptions such as the center fed Zepp which tends to be most directive off its ends. As one respondent stated...experiment. There is a reason they call technical suppositions "theories." It is because they are just that, theories only. Real world performance is whatever you get and can be morphed by ground conductivity, nearby structures, interactions and terrain as well as theories that are conventional but one day will be refuted. I like that last sentence and believe it. |
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