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#1
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Hi,
Just getting back on the air after many years of silence and I find myself struggling over the choice of antennas. I need something that I can easily raise and lower (get out of site due to CCR rules) so we're talking about a compromise. I do have room for a couple of radials (max 30 ft) as long as they can buried in the ground 180 degrees apart (not ideal). The antenna will have to be installed within about 4 feet from the side of my house. I was hoping to find a self supporting vertical betwwen 30 and 40 ft hight that could pivit at the base (might need to purchase that separately) so it can be laid down flat on the ground next to the house when not in use. I plan on purchasing an auto tuner if necessary. The vertical can have no physical radials on the antenna itself. And by the way, I live in the hills above Henderson, NV so the quality of the ground isn't good; lots of rock and hard clay with poor drainage. Purchase price up to $400.00 OK. Any ideas of what might work in my situation? Many thanks in advance! |
#2
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On Tue, 19 Jul 2011 15:21:09 -0700 (PDT), Jay Scherberth
wrote: Purchase price up to $400.00 OK. Any ideas of what might work in my situation? Hi Jay, Google for "Sleeve Dipole" (a vertical) which consists of staged tubing, the upper element insulated from the lower. Do not connect the lower element to ground. Thread the driveline coax up inside the lower element and connect the shield to the top inside of the lower element. Connect the coax inner lead to the bottom of the upper element. As I said, google for images as this description may frustrate you. Invest the rest of your money (after buying sufficient quantity of tubing) in your tuner. You may still have a lot left over. 73's Richard Clark, KB7QHC |
#3
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Richard, isn't this pretty well what the GAP antenna does ??
Jim K4PYT ------------------- Hi Jay, Google for "Sleeve Dipole" (a vertical) which consists of staged tubing, the upper element insulated from the lower. Do not connect the lower element to ground. Thread the driveline coax up inside the lower element and connect the shield to the top inside of the lower element. Connect the coax inner lead to the bottom of the upper element. As I said, google for images as this description may frustrate you. Invest the rest of your money (after buying sufficient quantity of tubing) in your tuner. You may still have a lot left over. 73's Richard Clark, KB7QHC |
#4
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On Tue, 19 Jul 2011 22:12:17 -0400, "James"
wrote: Richard, isn't this pretty well what the GAP antenna does ?? Hi James, Yes, in large degree given my experience with the Gap Eagle. I figure it would draw more than the usual attention, and become a target for the covenants, deeds, and restrictions. 73's Richard Clark, KB7QHC |
#5
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![]() "Richard Clark" wrote in message Google for "Sleeve Dipole" (a vertical) which consists of staged tubing, the upper element insulated from the lower. Do not connect the lower element to ground. Thread the driveline coax up inside the lower element and connect the shield to the top inside of the lower element. Connect the coax inner lead to the bottom of the upper element. As I said, google for images as this description may frustrate you. Invest the rest of your money (after buying sufficient quantity of tubing) in your tuner. You may still have a lot left over. 73's Richard Clark, KB7QHC One of these for 10m was the first HF antenna I ever built. I wish I had known then about decoupling the feed line, as I never could get repeatable VSWR data, possibly due to common mode current. Maybe I'll rebuild it and try again with a suitable choke. I read about the sleeve dipole before I built it and I will pass on a caution: The end where the cable comes out is a high voltage point (expected for the ends of dipoles); higher powers may punch through the coax outer jacket to the coax shield. I use a piece of PVC plumbing pipe as additional separation inside the lower element and never had an issue. "Sal" Happy building. |
#6
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On Jul 19, 3:55*pm, Richard Clark wrote:
On Tue, 19 Jul 2011 15:21:09 -0700 (PDT), Jay Scherberth wrote: Purchase price up to $400.00 OK. Any ideas of what might work in my situation? Hi Jay, Google for "Sleeve Dipole" (a vertical) which consists of staged tubing, the upper element insulated from the lower. *Do not connect the lower element to ground. *Thread the driveline coax up inside the lower element and connect the shield to the top inside of the lower element. *Connect the coax inner lead to the bottom of the upper element. As I said, google for images as this description may frustrate you. Invest the rest of your money (after buying sufficient quantity of tubing) in your tuner. *You may still have a lot left over. 73's Richard Clark, KB7QHC Richard - Is there such a thing as a multi-band HF sleeve dipole or is this more of a VHF/UHF solution? |
#7
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On Tue, 19 Jul 2011 20:28:54 -0700 (PDT), Jay Scherberth
wrote: Richard - Is there such a thing as a multi-band HF sleeve dipole or is this more of a VHF/UHF solution? Hi Jay, It is multiband if your tuner can pull the SWR into reasonable limits. However, you do NOT want the overall length of the antenna to exceed roughly a 1.25 wavelengths of the highest frequency you intend to multiband. This is for two reasons at that frequency: 1. Difficult to tune at 1 wavelength; 2. Radiation is directed up at a high angle if longer than 1.25 wl. Please read Sal's perceptive comments about hi voltage exposure; and observe his statement about choking the line. Futher, and this complicates the simple rules above, your sleeve dipole does not need to be made of equal length elements. This raises the prospects of another topic: Vertical, Off Center Fed Dipoles. As for building ground radials - skip that wasted effort. You have too little footprint available, and your ground isn't conductive enough to present that much loss. This is why I suggested the sleeve dipole. 73's Richard Clark, KB7QHC |
#8
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![]() "Richard Clark" wrote in message ... snip ... your sleeve dipole does not need to be made of equal length elements. This raises the prospects of another topic: Vertical, Off Center Fed Dipoles. Yes. Mine was mounted with the end of the bottom element within reach from the ground. I lengthened just the bottom element experimentally with a simple clip lead -- and that worked. Sometime "cheesy" works. :-) "Sal" |
#9
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Jay Scherberth wrote:
Hi, Just getting back on the air after many years of silence and I find myself struggling over the choice of antennas. I need something that I can easily raise and lower (get out of site due to CCR rules) so we're talking about a compromise. I do have room for a couple of radials (max 30 ft) as long as they can buried in the ground 180 degrees apart (not ideal). The antenna will have to be installed within about 4 feet from the side of my house. I was hoping to find a self supporting vertical betwwen 30 and 40 ft hight that could pivit at the base (might need to purchase that separately) so it can be laid down flat on the ground next to the house when not in use. I plan on purchasing an auto tuner if necessary. The vertical can have no physical radials on the antenna itself. And by the way, I live in the hills above Henderson, NV so the quality of the ground isn't good; lots of rock and hard clay with poor drainage. Purchase price up to $400.00 OK. Any ideas of what might work in my situation? Many thanks in advance! Some thoughts on the subject... If you are going to have an auto tuner, the antenna itself need not be anything more than a piece of tubing. I have a 34 ft piece of tubing with a SGC-237 and that tuned 160 (kind of marginally) through 10 with no problem. I added a relay controlled loading coil to switch in for 160/80 and now it tunes 80 faster and 160 no problem. If your main interest is the lower bands, just make the tubing as long as you can get away with and let the auto tuner deal with it. If it is next to the house, drive in as much ground rod as you can and use a garden drip system along with some flowers or whatnot around the base of it. Whatever radials you can install are better than nothing. -- Jim Pennino Remove .spam.sux to reply. |
#10
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On Jul 19, 3:53*pm, wrote:
Jay Scherberth wrote: Hi, Just getting back on the air after many years of silence and I find myself struggling over the choice of antennas. I need something that I can easily raise and lower (get out of site due to CCR rules) so we're talking about a compromise. I do have room for a couple of radials (max 30 ft) as long as they can buried in the ground 180 degrees apart (not ideal). The antenna will have to be installed within about 4 feet from the side of my house. I was hoping to find a self supporting vertical betwwen 30 and 40 ft hight that could pivit at the base (might need to purchase that separately) so it can be laid down flat on the ground next to the house when not in use. I plan on purchasing an auto tuner if necessary. The vertical can have no physical radials on the antenna itself. And by the way, I live in the hills above Henderson, NV so the quality of the ground isn't good; lots of rock and hard clay with poor drainage. Purchase price up to $400.00 OK. Any ideas of what might work in my situation? Many thanks in advance! Some thoughts on the subject... If you are going to have an auto tuner, the antenna itself need not be anything more than a piece of tubing. I have a 34 ft piece of tubing with a SGC-237 and that tuned 160 (kind of marginally) through 10 with no problem. I added a relay controlled loading coil to switch in for 160/80 and now it tunes 80 faster and 160 no problem. If your main interest is the lower bands, just make the tubing as long as you can get away with and let the auto tuner deal with it. If it is next to the house, drive in as much ground rod as you can and use a garden drip system along with some flowers or whatnot around the base of it. Whatever radials you can install are better than nothing. -- Jim Pennino Remove .spam.sux to reply. Jim - You've given me new hope! How significant is the length and depth of the radials? I probably have about 30 feet each way along the side of the house. Are you suggesting a drip system around the ground rod to improve the quality of the ground or for decorative reasons or both? |
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