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#1
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On Sat, 22 Apr 2006 20:43:12 GMT, Telamon
wrote: In article , Monroe wrote: As a lone time listener but relative newbie to the tech, I've been educating myself on system basics including ground questions. Currently using a marginal 1.0 m steel post as a ground for a shortwave Rx application. Intention is to upgrade to a 8 - 10 ft ground rod (the only ground off of a 9:1 balun - post ground and balun bracket - that a coax feedline connects with the Rx; this associated with an inverted "L" antenna). I've read plenty of references to copper rod or copper clad ground rods but I've yet to have any local suppliers recognize this (let alone be able to supply). Standard availability in my area are galvanized steel ground rods. Are these of equivalent quality? Grounds are very important for single wire antennas. They are unimportant for balanced antennas like dipoles. If you have a single wire like your inverted L then the ground is important because it is only half the antenna. The ground is the other half. How well the ground rods work depends on the ground conductivity so the bigger rod may make an improvement or it may not. A better thing to do other rather than pound in another ground rod would be to add a ground radial. To test this without much pain attach a wire to the ground stake with a clamp and run it on top of the ground underneath your current antenna. Check out the difference it makes on your reception on several stations on different bands to see if it makes an improvement. If the wire laying on the ground makes a significant improvement then you take the effort to dig a shallow trench and bury it. The ground wire, even on a single wire antenna, may make little difference listening wise. I have an inverted L on 20 meters; the ground makes a huge difference on transmit, bringing down the SWR; but on receive, I hear no difference whether the ground is attached or not. bob k5qwg |
#2
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In article ,
Bob Miller wrote: On Sat, 22 Apr 2006 20:43:12 GMT, Telamon wrote: In article , Monroe wrote: As a lone time listener but relative newbie to the tech, I've been educating myself on system basics including ground questions. Currently using a marginal 1.0 m steel post as a ground for a shortwave Rx application. Intention is to upgrade to a 8 - 10 ft ground rod (the only ground off of a 9:1 balun - post ground and balun bracket - that a coax feedline connects with the Rx; this associated with an inverted "L" antenna). I've read plenty of references to copper rod or copper clad ground rods but I've yet to have any local suppliers recognize this (let alone be able to supply). Standard availability in my area are galvanized steel ground rods. Are these of equivalent quality? Grounds are very important for single wire antennas. They are unimportant for balanced antennas like dipoles. If you have a single wire like your inverted L then the ground is important because it is only half the antenna. The ground is the other half. How well the ground rods work depends on the ground conductivity so the bigger rod may make an improvement or it may not. A better thing to do other rather than pound in another ground rod would be to add a ground radial. To test this without much pain attach a wire to the ground stake with a clamp and run it on top of the ground underneath your current antenna. Check out the difference it makes on your reception on several stations on different bands to see if it makes an improvement. If the wire laying on the ground makes a significant improvement then you take the effort to dig a shallow trench and bury it. The ground wire, even on a single wire antenna, may make little difference listening wise. I have an inverted L on 20 meters; the ground makes a huge difference on transmit, bringing down the SWR; but on receive, I hear no difference whether the ground is attached or not. I don't know what your situation is so I can't comment on it. I have done the experimentation and found it makes a huge difference. It could be that your equipment grounded through the AC mains was enough for reception. This will be a poor solution in my area due to the fact that I live in town and the noise level on the AC mains is high. Basic circuit theory requires that current travels in a loop. No power flows in an open circuit. People recognize this obvious fact when considering DC circuits but for some reason it is forgotten when it comes to RF. The single wire of an Marconi type antenna is half the RF circuit where ground is the other half. The receiver input is across the antenna wire and ground. A Hertzian antenna such as a dipole has two elements that develop the voltage across the receiver input so an RF ground becomes superfluous. In any event I proposed a painless way for the OP to test whether a ground radial will help or not. I don't know what the soil conductivity is where the OP lives so I can't advise whether another ground rod will help or not but if an RF ground improvement can be made at the antenna location over the installed rod then the radial attached to the installed ground rod will make a significant difference. -- Telamon Ventura, California |
#3
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I need to email Mary DuRose over yonder in the Sydney,OZ area.She is
originally from Kansas.I lived in Salina,Kansas in 1957.She is from the Wichita area,or somewhere around there.My old brother in law has an Air Force buddy in Topeka,Kansas.His buddy used to work his Farm near Wetmore,Kansas.I am just as much Kansan as any other Kansans out there. cuhulin |
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