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#1
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Andy,
check out this site, it may you/someone else, regards http://www.ad5th.com/5-BTV.html http://www.ad5th.com/5-BTV.html I choose Polesoft Lockspam to fight spam, and you? http://www.polesoft.com/refer.html |
#2
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"Roger Adam" wrote in message
... Andy, Check out this site, it may you/someone else, Regards http://www.ad5th.com/5-BTV.html AD5TH Roger, Since you selected the Hustler 75 meter Super Resonator to make your Hustler 4-BTV into a 5-BTV model, I would add guys (as recommended in the Hustler installation manual) due to the weight at top and overall length of antenna. 3 or 4 guy wires should work well. Greg w9gb |
#3
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Why do hams persist on using "tuned" radials on the ground? They cut them to
"resonance" which means nothing. A wire cut for resonance on 40 meters and buried under 2 inches of soil is no where near resonant 7mhz. It would be much more effective if they just made all the radials as long as possible and forget this resonance stuff but no one listens. -- Steve N4LQ "Roger Adam" wrote in message ... Andy, check out this site, it may you/someone else, regards http://www.ad5th.com/5-BTV.html http://www.ad5th.com/5-BTV.html I choose Polesoft Lockspam to fight spam, and you? http://www.polesoft.com/refer.html |
#4
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What about the Hustler antenna instructions which provide the "correct
lengths" for cutting radials? Moreover they need not be "buried 2 inches" in the ground but can safely remain on the ground once grass growth effectively buries them. Also DX Engineering www.dxengineering.com has ground radials for sale which are "pre-cut to length". I assume they know what they are doing. Force 12 also recommends using "tuned radials" with their line of vertical antennas. I assume they too know more about antennas then I do. I researched this topic before installing my 5-BTV and tuned radials were always recommended. If length means nothing I could have gone with 6 inch radials if I followed your logic...eh? My 5-BTV installation with 72 "tuned" radials at this page 1. http://www.ad5th.com/5-BTV.html I am getting great reports so far but have only been on the air at this qth for a couple weeks. A new AL-80B arrives in 3 days which should improve my signal greatly. 73 / DX -- Charlie Ham Radio - AD5TH www.ad5th.com Live Blues Music www.492acousticblues.com "N4LQ" wrote in message ... Why do hams persist on using "tuned" radials on the ground? They cut them to "resonance" which means nothing. A wire cut for resonance on 40 meters and buried under 2 inches of soil is no where near resonant 7mhz. It would be much more effective if they just made all the radials as long as possible and forget this resonance stuff but no one listens. -- Steve N4LQ "Roger Adam" wrote in message ... Andy, check out this site, it may you/someone else, regards http://www.ad5th.com/5-BTV.html http://www.ad5th.com/5-BTV.html I choose Polesoft Lockspam to fight spam, and you? http://www.polesoft.com/refer.html |
#5
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What about the Hustler antenna instructions which provide the "correct
lengths" for cutting radials? Moreover they need not be "buried 2 inches" in the ground but can safely remain on the ground once grass growth effectively buries them. Also DX Engineering www.dxengineering.com has ground radials for sale which are "pre-cut to length". I assume they know what they are doing. Force 12 also recommends using "tuned radials" with their line of vertical antennas. I assume they too know more about antennas then I do. Tuned radials are necessary and appropriate when the radials are installed well above earth-ground level. When the antenna is mounted up at a significant height, there's very little coupling between the radials and ground, and the radials must be tuned in order to present a low impedance on the frequencies of interest. Once tuned, each radial presents a low-loss current path, and only a small number of such radials are required. When the radials are laid on the ground, buried, or placed a short distance above the ground, matters are very different. There is a great deal of capacitive coupling between the radials and the soil, and the soil also presents a (resistive and rather lossy) path for the current flow. As a result, two things are different: - The coupling to the soil de-tunes the radials and greatly lowers their Q. They no longer serve as a resonant system, and cutting them to a tuned length is no longer essential. - A much larger number of radials is necessary, in order to limit the losses which occur when the return current flows through the soil. So... in an elevated-antenna situation, as few as three or four radials can give you low losses, but the radials must be tuned. For a ground-mounted vertical, you need many more radials (dozens, and some people prefer over 100), but they don't need to be tuned, and there's not much performance difference to gain once the radials are at least about an eighth of a wavelength. I researched this topic before installing my 5-BTV and tuned radials were always recommended. For elevated antennas, that's true. For ground-mounted antennas, tuning is simply unnecessary. Take a look at http://www.cebik.com/gr.html which shows some antenna modelling and graphs for vertical antennas with ground-mounted radials. The chart of "Ground Radial Test 2" is an interesting one. It shows that there's only a very modest difference in performance (less than half of a dB!) between a 64-radial system using tuned quarter-wavelength radials, and a 64-radial system using radials which are only .15 wavelength long. If length means nothing I could have gone with 6 inch radials if I followed your logic...eh? It is not true that "length means nothing". 6-inch radials are too short to provide adequate coupling to the soil. It *is* true that "length is not critical". My 5-BTV installation with 72 "tuned" radials at this page 1. http://www.ad5th.com/5-BTV.html I am getting great reports so far but have only been on the air at this qth for a couple weeks. That's good news. The bad news is that you could have used non-tuned radials, and saved yourself some bother and perhaps some money (used somewhat shorter lengths of wire), and gotten equally-good reports. You didn't hurt yourself by tuning the radials. You just invested some effort (and perhaps some money) unnecessarily. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#6
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You're entitled to your opinion on this seemingly controversial topic.
73 / DX ..hope to catch you on the bands one day Dave -- Charlie Ham Radio - AD5TH www.ad5th.com Live Blues Music www.492acousticblues.com "Dave Platt" wrote in message ... What about the Hustler antenna instructions which provide the "correct lengths" for cutting radials? Moreover they need not be "buried 2 inches" in the ground but can safely remain on the ground once grass growth effectively buries them. Also DX Engineering www.dxengineering.com has ground radials for sale which are "pre-cut to length". I assume they know what they are doing. Force 12 also recommends using "tuned radials" with their line of vertical antennas. I assume they too know more about antennas then I do. Tuned radials are necessary and appropriate when the radials are installed well above earth-ground level. When the antenna is mounted up at a significant height, there's very little coupling between the radials and ground, and the radials must be tuned in order to present a low impedance on the frequencies of interest. Once tuned, each radial presents a low-loss current path, and only a small number of such radials are required. When the radials are laid on the ground, buried, or placed a short distance above the ground, matters are very different. There is a great deal of capacitive coupling between the radials and the soil, and the soil also presents a (resistive and rather lossy) path for the current flow. As a result, two things are different: - The coupling to the soil de-tunes the radials and greatly lowers their Q. They no longer serve as a resonant system, and cutting them to a tuned length is no longer essential. - A much larger number of radials is necessary, in order to limit the losses which occur when the return current flows through the soil. So... in an elevated-antenna situation, as few as three or four radials can give you low losses, but the radials must be tuned. For a ground-mounted vertical, you need many more radials (dozens, and some people prefer over 100), but they don't need to be tuned, and there's not much performance difference to gain once the radials are at least about an eighth of a wavelength. I researched this topic before installing my 5-BTV and tuned radials were always recommended. For elevated antennas, that's true. For ground-mounted antennas, tuning is simply unnecessary. Take a look at http://www.cebik.com/gr.html which shows some antenna modelling and graphs for vertical antennas with ground-mounted radials. The chart of "Ground Radial Test 2" is an interesting one. It shows that there's only a very modest difference in performance (less than half of a dB!) between a 64-radial system using tuned quarter-wavelength radials, and a 64-radial system using radials which are only .15 wavelength long. If length means nothing I could have gone with 6 inch radials if I followed your logic...eh? It is not true that "length means nothing". 6-inch radials are too short to provide adequate coupling to the soil. It *is* true that "length is not critical". My 5-BTV installation with 72 "tuned" radials at this page 1. http://www.ad5th.com/5-BTV.html I am getting great reports so far but have only been on the air at this qth for a couple weeks. That's good news. The bad news is that you could have used non-tuned radials, and saved yourself some bother and perhaps some money (used somewhat shorter lengths of wire), and gotten equally-good reports. You didn't hurt yourself by tuning the radials. You just invested some effort (and perhaps some money) unnecessarily. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#7
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On Fri, 7 Jan 2005 14:04:43 -0600, "Charlie"
wrote: You're entitled to your opinion on this seemingly controversial topic. 73 / DX ..hope to catch you on the bands one day Dave Possible the controversy is in your mind Charlie. The velocity factor using wires buried under ground is a fraction of the velocity factor in air or free space. Hence if you are hell bent on having resonance in your buried radial system (which in this application does nothing to improve system efficiency) they need be a whole lot shorter than the length = 234/F that is used for elevated radial systems. Danny, K6MHE |
#8
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On Fri, 7 Jan 2005 13:23:24 -0600, "Charlie"
wrote: |What about the Hustler antenna instructions which provide the "correct |lengths" for cutting radials? Moreover they need not be "buried 2 inches" in |the ground but can safely remain on the ground once grass growth effectively |buries them. Also DX Engineering www.dxengineering.com has ground radials |for sale which are "pre-cut to length". I assume they know what they are |doing. Of course they do.... they are separating fools from their money. |Force 12 also recommends using "tuned radials" with their line of |vertical antennas. I assume they too know more about antennas then I do. I'm sure. And they say, among other things (including some advertising hype) at: http://force12inc.com/brvinfo.htm "The most efficient radial system is one that is elevated above ground." Only then, does it pay (or matter) to tune the radials. |
#9
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I just want to thank all of you for your kindness and speediness in pointing
out my error as a new vertical antenna user. I am glad several of you had a laugh on me for burying tuned radials. Thank you for your kindness and courtesy. Hope to catch each and every one of you on the bands. I am grateful for the tact and diplomacy that many of you showed me. True Ham Spirit at it's best. Based on what I have been told by the gentlemen in this great group I could have used much shorter radials than any "tuned length". If that is right then I have achieved a much more effective radial system then what I would have had I not erred. Is this right? In other words I have more wire in the ground then I need..right? Now if that is so..does that hurt or help TY Roy 73 / DX -- Charlie Ham Radio - AD5TH www.ad5th.com Live Blues Music www.492acousticblues.com "Wes Stewart" wrote in message ... On Fri, 7 Jan 2005 13:23:24 -0600, "Charlie" wrote: |What about the Hustler antenna instructions which provide the "correct |lengths" for cutting radials? Moreover they need not be "buried 2 inches" in |the ground but can safely remain on the ground once grass growth effectively |buries them. Also DX Engineering www.dxengineering.com has ground radials |for sale which are "pre-cut to length". I assume they know what they are |doing. Of course they do.... they are separating fools from their money. |Force 12 also recommends using "tuned radials" with their line of |vertical antennas. I assume they too know more about antennas then I do. I'm sure. And they say, among other things (including some advertising hype) at: http://force12inc.com/brvinfo.htm "The most efficient radial system is one that is elevated above ground." Only then, does it pay (or matter) to tune the radials. |
#10
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On Fri, 7 Jan 2005 21:18:45 -0600, "Charlie"
wrote: I just want to thank all of you for your kindness and speediness in pointing out my error as a new vertical antenna user. I am glad several of you had a laugh on me for burying tuned radials Don't feel bad Charlie, we read the book. G I would really suggest you consider purchasing the current edition of the ARRL Antenna book. There is a whole chapter (3) devoted to the effects of ground. You'll find in more reliable information in that book than you ever see in antenna manufacturers' statements and claims. Oh, yes when it comes to radials you can't have too much wire in the ground, but you can hit the wall of diminishing returns. Bust of luck and 73 Danny, K6MHE |
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