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Cushcraft R7
hi just got this ant,what is the best hight to mount this at,
there site says mount 8 feet, will it work better mounted 30 feet of ground thanks dave browne --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.688 / Virus Database: 449 - Release Date: 18/05/2004 |
On Wed, 19 May 2004 19:19:21 +0100, "David Browne" dddd@ddd wrote:
hi just got this ant,what is the best hight to mount this at, there site says mount 8 feet, will it work better mounted 30 feet of ground Hi David, It may take a little more adjustment to tune, but that should be the only down-side. You should at least tune it at 8 feet (or similar, convenient height) first to confirm its construction. 73's Richard Clark, KB7QHC |
On Wed, 19 May 2004 19:19:21 +0100, "David Browne" dddd@ddd wrote:
hi just got this ant,what is the best hight to mount this at, there site says mount 8 feet, will it work better mounted 30 feet of ground thanks dave browne Don't know the "best" height, but usta live next door to a guy with an R7, and he mounted it at about 30 feet. It performed fine, as far as he was concerned. Main downside to the antenna is a fairly narrow tuning range on 40 meters. Bob k5qwg --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.688 / Virus Database: 449 - Release Date: 18/05/2004 |
On Wed, 19 May 2004 16:40:05 -0700, "Just Another Opinion"
wrote: Well Thierry your advice is good for a 1/4 wave vertical -- but not a half wave end vertical. There is absolutely nothing wrong with Thierry's advise. As the subject of radials/counterpoise/ground is often either over engineered or under engineered (often to no apparent difference to the distant contact). It may complicate the tune, but it may also bring reward. Lookup the theory and you will see why. http://www.njqrp.org/n2cxantennas/halfer/ Hi OM, If someone wants to invest in the treatment that Thierry suggests, there is no down-side - this "theory" notwithstanding (which, by the way makes no effort to prohibit it, to its credit). Multiple radials also serve to decouple the feed line which then provides a more robust reference against which the antenna operates. 73's Richard Clark, KB7QHC |
Richard, Thierry and the original poster I repeat:
The R7 is NOT a quarter wave vertical -- it is a half wave end fed antenna. A quarter wave radiator needs a ground plane or radials to work against for sure -- but Cushcraft sez a half wave antenna doesn't need radials as it is like a horizontal dipole turned vertical and end fed (high impedance) rather than center fed. I suggest you read and study the following: The Cushcraft manual it explicitly states "The R7 should not be attached to a ground radial system". URL: http://www.cushcraft.com/support/pdf/r7.pdf Do you know what is in the black box matching unit ?? If not see URL: http://www.iol.ie/~bravo/r7_vertical.htm A local Ham added radials -- couldn't tune the antenna -- so he added a tuner. When he ran a kilowatt into this mishmash -- the black box blew up. So he repaired it as in URL: http://www.iol.ie/~bravo/r7_vertical.htm He no longer has the added radials and tuner and runs a KW all the time with no ill effects -- let the experimenter beware. I know this is a controversial subject -- rehashed many times here, mostly because folks treat the R7 like a quarter wave vertical -- which it isn't and the R7 has that complex matching black box design which I wouldn't mess with by adding radials. Unless I had the proper test equipment and expertise to determine what effect added radials have on the impedances and matching. Cushcraft undoubtedly did this. More at URL: http://lists.contesting.com/archives.../msg00059.html AND http://dayton.akorn.net/pipermail/to...ch/037180.html Regarding decoupling the feed line -- Cushcraft recommends an RF choke 8 inches in diameter and ten turns on the coax. Me -- I trusted Cushcraft and followed their instructions. Been working great for 6 years now. I won't run out the brag tape on countries worked with it -- means nothing. -- From one currently in the Cloaked Mode Any clod can have the facts, but having opinions is an Art. Charles McCabe (1856 - ), San Francisco Chronicle "Richard Clark" wrote in message ... On Wed, 19 May 2004 16:40:05 -0700, "Just Another Opinion" wrote: Well Thierry your advice is good for a 1/4 wave vertical -- but not a half wave end vertical. There is absolutely nothing wrong with Thierry's advise. As the subject of radials/counterpoise/ground is often either over engineered or under engineered (often to no apparent difference to the distant contact). It may complicate the tune, but it may also bring reward. Lookup the theory and you will see why. http://www.njqrp.org/n2cxantennas/halfer/ Hi OM, If someone wants to invest in the treatment that Thierry suggests, there is no down-side - this "theory" notwithstanding (which, by the way makes no effort to prohibit it, to its credit). Multiple radials also serve to decouple the feed line which then provides a more robust reference against which the antenna operates. 73's Richard Clark, KB7QHC |
Richard, Thierry and the original poster
I also suggest you read the post by Roy Lewallen, W7EL titled Voltage fed vertical question -- From one currently in the Cloaked Mode |
On Thu, 20 May 2004 08:14:18 -0700, "Just Another Opinion"
wrote: Richard, Thierry and the original poster I repeat: Repetition is both tedious and changes nothing. The R7 is NOT a quarter wave vertical -- it is a half wave end fed antenna. Mantras soothe the soul certainly. A quarter wave radiator needs a ground plane or radials to work against for sure -- but Cushcraft sez a half wave antenna doesn't need radials as it is like a horizontal dipole turned vertical and end fed (high impedance) rather than center fed. Not needing and prohibiting are not the same thing. I suggest you read and study the following: The Cushcraft manual it explicitly states "The R7 should not be attached to a ground radial system". URL: http://www.cushcraft.com/support/pdf/r7.pdf Yeah, and page one: "System Grounding" One radial good. More radial bad. Yeah, sure. In fact a word search against the quote above returns 0 hits. So much for explicit statements and what "should" be read. I note the links below have the same breathless nature, which is to say a lot of air. Do you know what is in the black box matching unit ?? Yes I do. If not see URL: http://www.iol.ie/~bravo/r7_vertical.htm Another "should" be read? I think not. It's been posted here many times over the years and doesn't even broach the topic (the word "radial" appears nowhere). A local Ham added radials -- couldn't tune the antenna -- so he added a tuner. When he ran a kilowatt into this mishmash -- the black box blew up. So he repaired it as in URL: http://www.iol.ie/~bravo/r7_vertical.htm And this proves what (besides a penchant for repetition)? Another anonymous lid? Thanks, but no thanks, we have our quota here; too often appearing in the guise of learned lecturer complete with Cliff notes. This doubly quoted link does not describe the event you allude to, and in fact offers trap construction is more problematic than the invention of radials-as-evil. He no longer has the added radials and tuner and runs a KW all the time with no ill effects -- let the experimenter beware. Yeah, now there's a line - no experimentation in Amateur radio. We have enough Credit Card operators. I know this is a controversial subject -- rehashed many times here Ah, the voice of experience. I've been here 10 years and haven't seen this soap opera yet. mostly because folks treat the R7 like a quarter wave vertical -- which it isn't Repetition again, quite boring now. and the R7 has that complex matching black box design which I wouldn't mess with by adding radials. Unless I had the proper test equipment and expertise to determine what effect added radials have on the impedances and matching. Cushcraft undoubtedly did this. More at URL: http://lists.contesting.com/archives.../msg00059.html "There is no grounded part in an R7 type antenna" Which, of course, negates page one of the quoted manual above.... AND http://dayton.akorn.net/pipermail/to...ch/037180.html "The R7, like others in the R3-R8 series from Cushcraft, use some number of 39" 'radials'... They are not radials" Quality stuff there. Again, nothing here evidences the "should" of the "should" be read. The two quotes above offer repetition and no actual technical discussion. But then, this group is the place for that, and rightly so in the face of such tepid offerings. You should vet your offerings before submitting them as evidence. Regarding decoupling the feed line -- Cushcraft recommends an RF choke 8 inches in diameter and ten turns on the coax. Excellent advice for the 1960s. However, in the 21st century most correspondents here would appreciate how mediocre-to-poor that would be with a conventional choke looking into a half wave load. You seem to be at odds with experimentation with this last piece of advice. The link to the match box above suggests a far different means of choking. As this choking method does not appear in the Cushcraft liturgy, are we to assume the antenna will burst into demonic flames if this un-ordained device is used? Me -- I trusted Cushcraft and followed their instructions. Been working great for 6 years now. I won't run out the brag tape on countries worked with it -- means nothing. That has been demonstratively true here for years. Now, demonstrate the difficulties that will be imposed (if one follows Thierry's advice) by constructing a model readable by EZNEC that may be offered here for peer review. Testimonials do not pass as evidence in this forum as so many of them for the eh/cfa/fractal clog the system currently. 73's Richard Clark, KB7QHC |
Richard Clark wrote: On Thu, 20 May 2004 08:14:18 -0700, "Just Another Opinion" wrote: Richard, Thierry and the original poster I repeat: Repetition is both tedious and changes nothing. The R7 is NOT a quarter wave vertical -- it is a half wave end fed antenna. Mantras soothe the soul certainly. A quarter wave radiator needs a ground plane or radials to work against for sure -- but Cushcraft sez a half wave antenna doesn't need radials as it is like a horizontal dipole turned vertical and end fed (high impedance) rather than center fed. Not needing and prohibiting are not the same thing. I suggest you read and study the following: The Cushcraft manual it explicitly states "The R7 should not be attached to a ground radial system". URL: http://www.cushcraft.com/support/pdf/r7.pdf Yeah, and page one: "System Grounding" One radial good. More radial bad. Yeah, sure. In fact a word search against the quote above returns 0 hits. So much for explicit statements and what "should" be read. I note the links below have the same breathless nature, which is to say a lot of air. Do you know what is in the black box matching unit ?? Yes I do. If not see URL: http://www.iol.ie/~bravo/r7_vertical.htm Another "should" be read? I think not. It's been posted here many times over the years and doesn't even broach the topic (the word "radial" appears nowhere). A local Ham added radials -- couldn't tune the antenna -- so he added a tuner. When he ran a kilowatt into this mishmash -- the black box blew up. So he repaired it as in URL: http://www.iol.ie/~bravo/r7_vertical.htm And this proves what (besides a penchant for repetition)? Another anonymous lid? Thanks, but no thanks, we have our quota here; too often appearing in the guise of learned lecturer complete with Cliff notes. This doubly quoted link does not describe the event you allude to, and in fact offers trap construction is more problematic than the invention of radials-as-evil. He no longer has the added radials and tuner and runs a KW all the time with no ill effects -- let the experimenter beware. Yeah, now there's a line - no experimentation in Amateur radio. We have enough Credit Card operators. I know this is a controversial subject -- rehashed many times here Ah, the voice of experience. I've been here 10 years and haven't seen this soap opera yet. mostly because folks treat the R7 like a quarter wave vertical -- which it isn't Repetition again, quite boring now. and the R7 has that complex matching black box design which I wouldn't mess with by adding radials. Unless I had the proper test equipment and expertise to determine what effect added radials have on the impedances and matching. Cushcraft undoubtedly did this. More at URL: http://lists.contesting.com/archives.../msg00059.html "There is no grounded part in an R7 type antenna" Which, of course, negates page one of the quoted manual above.... AND http://dayton.akorn.net/pipermail/to...ch/037180.html "The R7, like others in the R3-R8 series from Cushcraft, use some number of 39" 'radials'... They are not radials" Quality stuff there. Again, nothing here evidences the "should" of the "should" be read. The two quotes above offer repetition and no actual technical discussion. But then, this group is the place for that, and rightly so in the face of such tepid offerings. You should vet your offerings before submitting them as evidence. Regarding decoupling the feed line -- Cushcraft recommends an RF choke 8 inches in diameter and ten turns on the coax. Excellent advice for the 1960s. However, in the 21st century most correspondents here would appreciate how mediocre-to-poor that would be with a conventional choke looking into a half wave load. You seem to be at odds with experimentation with this last piece of advice. The link to the match box above suggests a far different means of choking. As this choking method does not appear in the Cushcraft liturgy, are we to assume the antenna will burst into demonic flames if this un-ordained device is used? Me -- I trusted Cushcraft and followed their instructions. Been working great for 6 years now. I won't run out the brag tape on countries worked with it -- means nothing. That has been demonstratively true here for years. Now, demonstrate the difficulties that will be imposed (if one follows Thierry's advice) by constructing a model readable by EZNEC that may be offered here for peer review. Testimonials do not pass as evidence in this forum as so many of them for the eh/cfa/fractal clog the system currently. 73's Richard Clark, KB7QHC Did you get up on the wrong side of the bed this morning or something, Richard? 73, jk |
On Thu, 20 May 2004 10:29:41 -0700, Jim Kelley
wrote: Did you get up on the wrong side of the bed this morning or something, Richard? Hi Jim, Believe in three impossible things before breakfast. 73's Richard Clark, KB7QHC |
Richard Clark wrote in message . ..
On Thu, 20 May 2004 08:14:18 -0700, "Just Another Opinion" wrote: Richard, Thierry and the original poster I repeat: Repetition is both tedious and changes nothing. The R7 is NOT a quarter wave vertical -- it is a half wave end fed antenna. Mantras soothe the soul certainly. A quarter wave radiator needs a ground plane or radials to work against for sure -- but Cushcraft sez a half wave antenna doesn't need radials as it is like a horizontal dipole turned vertical and end fed (high impedance) rather than center fed. Not needing and prohibiting are not the same thing. I suggest you read and study the following: The Cushcraft manual it explicitly states "The R7 should not be attached to a ground radial system". URL: http://www.cushcraft.com/support/pdf/r7.pdf Yeah, and page one: "System Grounding" One radial good. More radial bad. Yeah, sure. In fact a word search against the quote above returns 0 hits. So much for explicit statements and what "should" be read. I note the links below have the same breathless nature, which is to say a lot of air. Richard, I don't know the answer to the main issue of this thread. I just don't know enough about antennas to speak as an expert. However, as a point of fact, the R7 manual does state on page 1 under the section titled "Location": 'Although the R7 will operate in almost any location, it will perform best if it is mounted vertically and located in the clear away from surrounding objects such as buildings, trees, powerlines, towers, guy wires, antennas and metallic objects. The R7 should not be attached to a ground radial system. Failure to heed these points will possibly degrade performance, detune the antenna and increase VSWR". When I clicked on the above link, a PDF file was opened. It appears that the manual was scanned and stored in PDF. In this case, no text search would be successful. FWIW, when I added radials to my R7 I was unable to tune it properly on all the bands. Once the radials were removed I was able to tune it up without problems. Thanks, Rick, K6RJ |
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David Browne wrote:
hi just got this ant,what is the best hight to mount this at, there site says mount 8 feet, will it work better mounted 30 feet of ground thanks dave browne --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.688 / Virus Database: 449 - Release Date: 18/05/2004 Ok, I spoke to the designer this evening, and I'll pass on what I learned. He was speaking fast, as he normally does, so I'm sure I missed a lot. Roy can confirm that, and Roy can confirm that he handed over another copy of his software to him just last week. Per the designer The R7 was built because he needed a multiband antenna in the fall of 90. The R5 was used as the base idea for the design. He worked on it over late fall and winter 90/91. The antenna project was up and down 2 to 3 times a day at times. The owner of Cushcraft heard of the backyard project in spring 1991, and "asked" that it be brought to work. Tomorrow at the latest. The antenna is not a half wave antenna, it is about a 3/8 wave antenna. The impedance is approximately 250 ohms, and a roughly 4.5 to 1 transform is done. There is a series cap of 41 pF for 40m. There are 7 radials of 49 inches, because Cushcraft had tons of 49 inch 5/8 whips for 2m. The R5 had 4, this needed more. There is a false resonance on 75m or 80m, and if you put power into it at that freq, you will burn up the matching system. And, to end this argument, do not ever add radials to the system, and do not remove any of the ones it comes with. It's a touchy match. tom K0TAR |
Golly Gee -- what happened to the great R7 radial debate ??? (:-(
Not one single reply to the excellent post below -- guess it did end the argument (:-) Thanks for the post Tom ------------------------------------------------------- "Tom Ring" wrote in message Ok, I spoke to the designer this evening, and I'll pass on what I learned. He was speaking fast, as he normally does, so I'm sure I missed a lot. Roy can confirm that, and Roy can confirm that he handed over another copy of his software to him just last week. Per the designer The R7 was built because he needed a multiband antenna in the fall of 90. The R5 was used as the base idea for the design. He worked on it over late fall and winter 90/91. The antenna project was up and down 2 to 3 times a day at times. The owner of Cushcraft heard of the backyard project in spring 1991, and "asked" that it be brought to work. Tomorrow at the latest. The antenna is not a half wave antenna, it is about a 3/8 wave antenna. The impedance is approximately 250 ohms, and a roughly 4.5 to 1 transform is done. There is a series cap of 41 pF for 40m. There are 7 radials of 49 inches, because Cushcraft had tons of 49 inch 5/8 whips for 2m. The R5 had 4, this needed more. There is a false resonance on 75m or 80m, and if you put power into it at that freq, you will burn up the matching system. And, to end this argument, do not ever add radials to the system, and do not remove any of the ones it comes with. It's a touchy match. tom K0TAR |
On Sun, 23 May 2004 08:14:41 -0700, "Keyboard In The Noise"
wrote: Golly Gee -- what happened to the great R7 radial debate ??? (:-( Not one single reply to the excellent post below -- guess it did end the argument (:-) Well, I found it interesting that the R7 is a 3/8 wave antenna, not a 1/2-waver. Which means radials might work as well as those 2-meter whips/decouplers sticking out at the base. Funny, I've never seen Cushcraft refer in their ads to their designs being "1/2 wave." Maybe that's just a myth somebody started... Bob k5qwg Thanks for the post Tom ------------------------------------------------------- "Tom Ring" wrote in message Ok, I spoke to the designer this evening, and I'll pass on what I learned. He was speaking fast, as he normally does, so I'm sure I missed a lot. Roy can confirm that, and Roy can confirm that he handed over another copy of his software to him just last week. Per the designer The R7 was built because he needed a multiband antenna in the fall of 90. The R5 was used as the base idea for the design. He worked on it over late fall and winter 90/91. The antenna project was up and down 2 to 3 times a day at times. The owner of Cushcraft heard of the backyard project in spring 1991, and "asked" that it be brought to work. Tomorrow at the latest. The antenna is not a half wave antenna, it is about a 3/8 wave antenna. The impedance is approximately 250 ohms, and a roughly 4.5 to 1 transform is done. There is a series cap of 41 pF for 40m. There are 7 radials of 49 inches, because Cushcraft had tons of 49 inch 5/8 whips for 2m. The R5 had 4, this needed more. There is a false resonance on 75m or 80m, and if you put power into it at that freq, you will burn up the matching system. And, to end this argument, do not ever add radials to the system, and do not remove any of the ones it comes with. It's a touchy match. tom K0TAR |
Hi Bob -- see URL:
http://www.cushcraft.com/support/pdf/r5.pdf Sez -- "Your R5 is a half wavelength vertical which does not require traditional ground radials" -- Keyboard In The Noise Opinions are the cheapest commodities in the world. Author unknown but "right on" -------------------------------------------------- "Bob Miller" wrote in message ... Funny, I've never seen Cushcraft refer in their ads to their designs being "1/2 wave." Maybe that's just a myth somebody started... Bob k5qwg |
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