Re: [Elecraft] KAT2 with EFHW antenna
Yup ... I was wrong again, but the trouble is I can't figure out why. I mean, it's easy to verify the cloverleaf pattern with EZNEC and I have done so, but I know that I have modeled something similar with an off-center feed in the past and gotten an end-fire pattern. As soon as I figure out what that was I'll come back here and try to clear up the confusion I have caused, but in the meantime let's all just agree that I don't know what I'm talking about. sigh ... 73, Dave AB7E On 8/25/2011 11:13 AM, Guy Olinger K2AV wrote: Sorry to interject, but a fullwave fed at the 25% point has a clover leaf pattern. It only has the two halfwaves in phase colinear behavior when fed very near the center. Even fed at 45% it has a significant cloverleaf lobe and a NULL in the center Easy to verify with any modeling program. 73, Guy. On Wed, Aug 24, 2011 at 8:37 PM, David Gilbert xda...@cis-broadband.com mailto:xda...@cis-broadband.com wrote: Yes, Don ... you are totally correct. For some reason I was thinking about a full wave antenna fed at the 25% point (I have built such antennas before), which looks like two colinear half waves fed out of phase. The current phasing along the antenna would indeed be much different and give a cloverleaf pattern if it were end fed. I wholeheartedly apologize for any confusion I may have created. 73 and thanks for catching my mistake. Dave AB7E On 8/24/2011 3:23 PM, Don Wilhelm wrote: Actually Dave, a full wavelength wire will have a 4 leaf clover pattern - that is neither broadside to the antenna, nor off the ends. Check out the pattern for a 1 wavelength long wire in the ARRL Antenna Book. The maximum radiation is about 28 degrees from the wire - the radiation from the end is almost zero. The elevation angle of maximum radiation is similar to a half wave dipole - about 15 degrees with a lesser lobe at 45 degrees (that is for a wire 70 feet high, at lower heights, the angle will be greater). 73, Don W3FPR On 8/24/2011 5:34 PM, David Gilbert wrote: I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
I've gotten to the point, that before I say anything about a model, I actually run it and play with it, to make sure I haven't forgotten something, or remembered something wrong. As to that particular antenna a center fed half wave antenna is troublesome. The better version of that if one wants that pattern is the extended double zepp, two 5/8 waves fed in phase, where you are feeding a lower impedance at the center, and it's a far less cranky antenna. The double zepp maintains its essential shape fed at 45% whereas the halfwave converts to cloverleaf. That's ancient knowledge, garnered by experience in the 40's and 50's without the benefit of software. These days if you can't look it up for free on the internet, it's forgotten. 73, Guy. On Fri, Aug 26, 2011 at 12:17 PM, David Gilbert xda...@cis-broadband.comwrote: Yup ... I was wrong again, but the trouble is I can't figure out why. I mean, it's easy to verify the cloverleaf pattern with EZNEC and I have done so, but I know that I have modeled something similar with an off-center feed in the past and gotten an end-fire pattern. As soon as I figure out what that was I'll come back here and try to clear up the confusion I have caused, but in the meantime let's all just agree that I don't know what I'm talking about. sigh ... 73, Dave AB7E On 8/25/2011 11:13 AM, Guy Olinger K2AV wrote: Sorry to interject, but a fullwave fed at the 25% point has a clover leaf pattern. It only has the two halfwaves in phase colinear behavior when fed very near the center. Even fed at 45% it has a significant cloverleaf lobe and a NULL in the center Easy to verify with any modeling program. 73, Guy. On Wed, Aug 24, 2011 at 8:37 PM, David Gilbert xda...@cis-broadband.comwrote: Yes, Don ... you are totally correct. For some reason I was thinking about a full wave antenna fed at the 25% point (I have built such antennas before), which looks like two colinear half waves fed out of phase. The current phasing along the antenna would indeed be much different and give a cloverleaf pattern if it were end fed. I wholeheartedly apologize for any confusion I may have created. 73 and thanks for catching my mistake. Dave AB7E On 8/24/2011 3:23 PM, Don Wilhelm wrote: Actually Dave, a full wavelength wire will have a 4 leaf clover pattern - that is neither broadside to the antenna, nor off the ends. Check out the pattern for a 1 wavelength long wire in the ARRL Antenna Book. The maximum radiation is about 28 degrees from the wire - the radiation from the end is almost zero. The elevation angle of maximum radiation is similar to a half wave dipole - about 15 degrees with a lesser lobe at 45 degrees (that is for a wire 70 feet high, at lower heights, the angle will be greater). 73, Don W3FPR On 8/24/2011 5:34 PM, David Gilbert wrote: I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Sorry to interject, but a fullwave fed at the 25% point has a clover leaf pattern. It only has the two halfwaves in phase colinear behavior when fed very near the center. Even fed at 45% it has a significant cloverleaf lobe and a NULL in the center Easy to verify with any modeling program. 73, Guy. On Wed, Aug 24, 2011 at 8:37 PM, David Gilbert xda...@cis-broadband.comwrote: Yes, Don ... you are totally correct. For some reason I was thinking about a full wave antenna fed at the 25% point (I have built such antennas before), which looks like two colinear half waves fed out of phase. The current phasing along the antenna would indeed be much different and give a cloverleaf pattern if it were end fed. I wholeheartedly apologize for any confusion I may have created. 73 and thanks for catching my mistake. Dave AB7E On 8/24/2011 3:23 PM, Don Wilhelm wrote: Actually Dave, a full wavelength wire will have a 4 leaf clover pattern - that is neither broadside to the antenna, nor off the ends. Check out the pattern for a 1 wavelength long wire in the ARRL Antenna Book. The maximum radiation is about 28 degrees from the wire - the radiation from the end is almost zero. The elevation angle of maximum radiation is similar to a half wave dipole - about 15 degrees with a lesser lobe at 45 degrees (that is for a wire 70 feet high, at lower heights, the angle will be greater). 73, Don W3FPR On 8/24/2011 5:34 PM, David Gilbert wrote: I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Another simple end fed antenna was described by W2FRH in QST, March 2011, A Near End-Fed Antenna... . I just returned from a week at the Outer Banks and used this antenna with my K2 working DX from Europe and South America, plus several states. No trees near the beach house so it was a sloper from the top deck to a fence post. Measured SWR around 2:1 and the K2 matched to 1:1. 73 Bob K2GLS I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Steve Yates, AA5TB, has a very informative web page on EFHW antennas and how to build a parallel tuned circuit with a link coupled feed at the radio end to reduce the 1800 to 5000 ohm impedance to a 50 ohm non-reactive load. He has examples of both QRP and QRO versions of the circuit. I built the QRP version which uses a polyvaricon capacitor (available through Hendrix Kits among other sources) to create a very small tuning device that will match resonant End Fed half wavelength antennas on 40m, 30m, 20m, and 17m. I use it mostly with a 33 foot wire on 20m raised on a 31 foot Jackite fiberglass pole and have had fun working DX with 5 watts. It is easy to change bands by exchanging the wire with one cut for the band of interest. I do not use a counterpoise and do not have any trouble at the rig. Steve explains why this works. For higher power a one meter counterpoise helps. I use this antenna with a K1 and K2, both with internal antenna tuners. The tuners are not needed, but I leave them activated to easily compensate for any small mismatch across the band. Steve's page is found at http://aa5tb.com/efha.html William Ravenel, AI4VE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
And for those with more money than brains (that would be me) you can purchase an end fed halfwave antenna from the Emergency Radio Club of Hawaii for $42. I bought one and it works great with the entire Elecraft family. Great to have a simple yet efficient portable antenna that fits into a sandwich baggie. This site also has the plans to build this one on your own if you would prefer. The main website is at: http://www.earchi.org/proj_homebrew.html The page for building it yourself is at: http://www.earchi.org/pdf/endfed.pdf And the page for the 'easy way out' is at: http://www.earchi.org/pdf/endfed20.pdf 73, Stan WB2LQF KX1 #2411K1#2994K2# 6980K3#5244 K9 #1 (Cocoa the Chihuahua) Everything is QRP, even the dog. On Wed, Aug 24, 2011 at 9:54 AM, William Ravenel wrote: Steve Yates, AA5TB, has a very informative web page on EFHW antennas and how to build a parallel tuned circuit with a link coupled feed at the radio end to reduce the 1800 to 5000 ohm impedance to a 50 ohm non-reactive load. He has examples of both QRP and QRO versions of the circuit. I built the QRP version which uses a polyvaricon capacitor (available through Hendrix Kits among other sources) to create a very small tuning device that will match resonant End Fed half wavelength antennas on 40m, 30m, 20m, and 17m. I use it mostly with a 33 foot wire on 20m raised on a 31 foot Jackite fiberglass pole and have had fun working DX with 5 watts. It is easy to change bands by exchanging the wire with one cut for the band of interest. I do not use a counterpoise and do not have any trouble at the rig. Steve explains why this works. For higher power a one meter counterpoise helps. I use this antenna with a K1 and K2, both with internal antenna tuners. The tuners are not needed, but I leave them activated to easily compensate for any small mismatch across the band. Steve's page is found at http://aa5tb.com/efha.html William Ravenel, AI4VE __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Stan, that's not a true half wave radiator on most bands. They suggest a wire length of 20 or 30 feet, which will be efficient on 12 through 6 meters where it's at least 1/2 wavelength long, but on the lower frequency bands it's just a short random length wire with an auto-transformer to assist with impedance matching. There's a huge difference between a full-size radiator and a short one that is made resonant using supplemental inductance. It will work as you, I, or anyone who has used a short, random length wire can attest, but it's efficiency is much lower than a radiator that is physically a half wavelength long. There's just nothing that can replace physical size for an efficient antenna. Not too much is lost on even multiples of a half wavelength. The impedance at a full wavelength, two wavelengths, etc., drops with each multiple, but still remains far above that impedance of even a 1/4 wave length radiator. And when dealing with any end-fed antenna worked against ground, higher impedance at the end of the antenna means higher efficiency for a given ground. 73, Ron AC7AC -Original Message- And for those with more money than brains (that would be me) you can purchase an end fed halfwave antenna from the Emergency Radio Club of Hawaii for $42. I bought one and it works great with the entire Elecraft family. Great to have a simple yet efficient portable antenna that fits into a sandwich baggie. This site also has the plans to build this one on your own if you would prefer. The main website is at: http://www.earchi.org/proj_homebrew.html The page for building it yourself is at: http://www.earchi.org/pdf/endfed.pdf And the page for the 'easy way out' is at: http://www.earchi.org/pdf/endfed20.pdf 73, Stan WB2LQF KX1 #2411K1#2994K2# 6980K3#5244 K9 #1 (Cocoa the Chihuahua) Everything is QRP, even the dog. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Ron, the one I purchased for $42 is for 20 meters and came with a 33 foot radiator. A mathematical half wave at 14 MHz would work out to 32.8 feet. It did not come with a counterpoise nor was one recommended. It loaded up nicely for me as received. I later tried a short counterpoise and did not note any difference in performance. I use a short coax of about 12 feet for portable work. It seems to work very well and only having to worry about hanging one end is convenient. And the wire is a nice quality that resists tangling. The documentation that came with mine warned that for 40 meter use, I'd need to replace the radiator with a 66 foot length and a wing nut arrangement is provided for that. I've never tried it on 40 meters. Ron, I'm no antenna expert (hence more money than brains) but I'd like to add that the precursor to this EFWHA came right out of the KX1 documentation. It's just a double BNC connector with a 28' radiator and a 33' counterpoise. I moved to the EFHWA because I got tired of untangling the two wires. In a side by side test, both antennas sounded the same to my ear. I retired the double BNC affair in favor of the EFWHA because I figured the EFWHA was a more efficient radiator, as you pointed out. Something my ears wouldn't necessarily disclose to me. I apologize for not having re-read the material on those links I provided. Apparently something has changed since I purchased mine. 73, Stan WB2LQF On Wed, Aug 24, 2011 at 11:06 AM, Ron D'Eau Claire wrote: Stan, that's not a true half wave radiator on most bands. They suggest a wire length of 20 or 30 feet, which will be efficient on 12 through 6 meters where it's at least 1/2 wavelength long, but on the lower frequency bands it's just a short random length wire with an auto-transformer to assist with impedance matching. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
33 feet is a 1/2 wave on 20 meters all right. I was using the figures given in the homebrew article that suggested a much shorter wire. Yes, Wayne came up with the 28' radiator with 33'counerpoise as a combination that the little ATU in the KX1 could handle on all the bands it covers. The KX1 ATU has a more limited matching range than most of the tuners, including the other tuners in Elecraft rigs, because there simply wasn't room for more inductor/capacitor combinations in very limited space available. 73, Ron AC7AC -Original Message- Ron, the one I purchased for $42 is for 20 meters and came with a 33 foot radiator. A mathematical half wave at 14 MHz would work out to 32.8 feet. It did not come with a counterpoise nor was one recommended. It loaded up nicely for me as received. I later tried a short counterpoise and did not note any difference in performance. I use a short coax of about 12 feet for portable work. It seems to work very well and only having to worry about hanging one end is convenient. And the wire is a nice quality that resists tangling. The documentation that came with mine warned that for 40 meter use, I'd need to replace the radiator with a 66 foot length and a wing nut arrangement is provided for that. I've never tried it on 40 meters. Ron, I'm no antenna expert (hence more money than brains) but I'd like to add that the precursor to this EFWHA came right out of the KX1 documentation. It's just a double BNC connector with a 28' radiator and a 33' counterpoise. I moved to the EFHWA because I got tired of untangling the two wires. In a side by side test, both antennas sounded the same to my ear. I retired the double BNC affair in favor of the EFWHA because I figured the EFWHA was a more efficient radiator, as you pointed out. Something my ears wouldn't necessarily disclose to me. I apologize for not having re-read the material on those links I provided. Apparently something has changed since I purchased mine. 73, Stan WB2LQF __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Just speculating -- I bet a half-wavelength wire in inverted-L configuration fed at the base with a parallel-tuned circuit would work well. The high-current part of the vertical piece would be at the top, there would be plenty of current in the horizontal part too, and very little local ground current. On 8/24/2011 6:54 AM, William Ravenel wrote: Steve Yates, AA5TB, has a very informative web page on EFHW antennas and how to build a parallel tuned circuit with a link coupled feed at the radio end to reduce the 1800 to 5000 ohm impedance to a 50 ohm non-reactive load. He has examples of both QRP and QRO versions of the circuit. I built the QRP version which uses a polyvaricon capacitor (available through Hendrix Kits among other sources) to create a very small tuning device that will match resonant End Fed half wavelength antennas on 40m, 30m, 20m, and 17m. I use it mostly with a 33 foot wire on 20m raised on a 31 foot Jackite fiberglass pole and have had fun working DX with 5 watts. It is easy to change bands by exchanging the wire with one cut for the band of interest. I do not use a counterpoise and do not have any trouble at the rig. Steve explains why this works. For higher power a one meter counterpoise helps. I use this antenna with a K1 and K2, both with internal antenna tuners. The tuners are not needed, but I leave them activated to easily compensate for any small mismatch across the band. Steve's page is found at http://aa5tb.com/efha.html William Ravenel, AI4VE __ -- Vic, K2VCO Fresno CA http://www.qsl.net/k2vco/ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Phil, You might try a 67' length of wire (EFFW antenna). I've used that (and a 32' EFHW) on 20 a lot with my K1 with the KAT1 installed...tunes to close to 1:1 just fine. Have fun at Crater Lake. There are some neat places along the rim for hamming. It's a 2000 mile drive (one way) for me but I've gotten there twice within the past several years. See http://www.prismnet.com/~nielw/qrp/CraterLake_july04.jpg and http://w0vlz.blogspot.com/2009/08/after-three-weeks-5300-miles-and-12.html 73, Niel - W0VLZ Message: 2 Date: Tue, 23 Aug 2011 16:00:17 -0700 From: Phillip Shepardph...@riousa.com Subject: [Elecraft] KAT2 with EFHW antenna To:elecraft@mailman.qth.net Message-ID:lnejjggbopigkcikmckdeegoiaaa.ph...@riousa.com Content-Type: text/plain; charset=us-ascii I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E On 8/24/2011 2:14 PM, Niel Wiegand wrote: Phil, You might try a 67' length of wire (EFFW antenna). I've used that (and a 32' EFHW) on 20 a lot with my K1 with the KAT1 installed...tunes to close to 1:1 just fine. Have fun at Crater Lake. There are some neat places along the rim for hamming. It's a 2000 mile drive (one way) for me but I've gotten there twice within the past several years. See http://www.prismnet.com/~nielw/qrp/CraterLake_july04.jpg and http://w0vlz.blogspot.com/2009/08/after-three-weeks-5300-miles-and-12.html 73, Niel - W0VLZ Message: 2 Date: Tue, 23 Aug 2011 16:00:17 -0700 From: Phillip Shepardph...@riousa.com Subject: [Elecraft] KAT2 with EFHW antenna To:elecraft@mailman.qth.net Message-ID:lnejjggbopigkcikmckdeegoiaaa.ph...@riousa.com Content-Type: text/plain;charset=us-ascii I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Actually Dave, a full wavelength wire will have a 4 leaf clover pattern - that is neither broadside to the antenna, nor off the ends. Check out the pattern for a 1 wavelength long wire in the ARRL Antenna Book. The maximum radiation is about 28 degrees from the wire - the radiation from the end is almost zero. The elevation angle of maximum radiation is similar to a half wave dipole - about 15 degrees with a lesser lobe at 45 degrees (that is for a wire 70 feet high, at lower heights, the angle will be greater). 73, Don W3FPR On 8/24/2011 5:34 PM, David Gilbert wrote: I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
I believe you must get into several wavelengths before you get significant end directivity from a long wire. My reference says that the angle of the main lobe to the antenna is about 55 degrees when the wire is a wavelength long, compared to 90 degrees at 1/2 wavelength. It takes a wire more than 7 wavelengths long for the angle of the main lobe to 20 degrees off of the end. For a horizontal wire, the angle of maximum radiation with respect to the horizon continues to be a function of height in wavelengths above ground. So, for a given wire a specific height above ground, as the frequency goes up, the lobes will slowly move toward the end and should be at an even *lower* elevations in the higher frequencies since the wire is higher above ground in terms of wavelengths. Of course one has to feed the wire. That's why most of us who use an end fed wire have it arranged as an inverted L. Mine is about 40 feet vertical from the rig, then 90 feet horizontally. So the radiation is a strong mix of vertical and horizontal polarization. On my favorite band, 20 meters, the vertical section is about optimum for low-angle vertical radiation and the height is perfect for low angle horizontal radiation. It works very well across the HF spectrum. I use an external homebrew tuner to provide physical separation between the very RF hot (on some bands) end of the wire and the rig (and me at the rig). As for impedance, it will be highest and 1/2 wavelength and diminish at longer lengths. Cranking a sample antenna into EZNEC shows that the impedance of a typical real-world wire at 1/4 wavelength long is about 35 ohms as expected. At 1/2 wave it's about 1500 ohms. At 1 wavelength it's about 800 ohms. At 2 wavelength it's about 300 ohms, and so on. Of course many things affect the actual impedance including the diameter of the radiator itself. Ron AC7AC -Original Message- I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E On 8/24/2011 2:14 PM, Niel Wiegand wrote: Phil, You might try a 67' length of wire (EFFW antenna). I've used that (and a 32' EFHW) on 20 a lot with my K1 with the KAT1 installed...tunes to close to 1:1 just fine. Have fun at Crater Lake. There are some neat places along the rim for hamming. It's a 2000 mile drive (one way) for me but I've gotten there twice within the past several years. See http://www.prismnet.com/~nielw/qrp/CraterLake_july04.jpg and http://w0vlz.blogspot.com/2009/08/after-three-weeks-5300-miles-and-12.html 73, Niel - W0VLZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Yes, Don ... you are totally correct. For some reason I was thinking about a full wave antenna fed at the 25% point (I have built such antennas before), which looks like two colinear half waves fed out of phase. The current phasing along the antenna would indeed be much different and give a cloverleaf pattern if it were end fed. I wholeheartedly apologize for any confusion I may have created. 73 and thanks for catching my mistake. Dave AB7E On 8/24/2011 3:23 PM, Don Wilhelm wrote: Actually Dave, a full wavelength wire will have a 4 leaf clover pattern - that is neither broadside to the antenna, nor off the ends. Check out the pattern for a 1 wavelength long wire in the ARRL Antenna Book. The maximum radiation is about 28 degrees from the wire - the radiation from the end is almost zero. The elevation angle of maximum radiation is similar to a half wave dipole - about 15 degrees with a lesser lobe at 45 degrees (that is for a wire 70 feet high, at lower heights, the angle will be greater). 73, Don W3FPR On 8/24/2011 5:34 PM, David Gilbert wrote: I'm not sure I see the advantage. A full wave end fed antenna would theoretically have the same very high feedpoint impedance, and would additionally blow most of it's radiated energy at a fairly high angle off the ends of the antenna instead of broadside at a lower angle. If you find it that easy to tune, I suspect that electrically it really isn't that close to a full wavelength ... possibly because of coupling to earth (if it is low) or nearby structures. Either that or there is a lot of loss in the system somewhere. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Phillip Shepard wrote: I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. Probably normal. End-fed half-wave antennas are 4-5000 ohms impedance, so you're asking the tuner to match an 80-100:1 SWR which is beyond the range of most tuners. 73, Bill -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-S-meter-oddities-tp6676870p6718255.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
The simple answer to your question is no. An end fed halfwave would theoretically present a few thousand ohms to your feedline, giving you an SWR of several tens to one. Consider this it is likely that the tuner with the greater loss will more easily give you a match to a difficult load. 73, Dave AB7E On 8/23/2011 4:00 PM, Phillip Shepard wrote: I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
But, on the positive side, that very high impedance means an unusually efficient antenna since there is almost no ground current flowing at all. I use a setup like that at my home station - 1/2 wavelength long wire on 80 meters - with a homebrew manual L-network. Does a great job. One reason why small auto-tuners cannot handle that huge impedance is because of the voltages involved. Thousands of volts commonly exist even with fairly low power. The capacitors and inductors in most automatic tuners simply aren't rated for that. Ron AC7AC -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of David Gilbert Sent: Tuesday, August 23, 2011 4:20 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] KAT2 with EFHW antenna The simple answer to your question is no. An end fed halfwave would theoretically present a few thousand ohms to your feedline, giving you an SWR of several tens to one. Consider this it is likely that the tuner with the greater loss will more easily give you a match to a difficult load. 73, Dave AB7E __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Phil, As others have responded, attempting to tune the end of a half-wave wire is beyond the range of most tuners, including the KAT2. Your added wire provided a compromise length, because the feedpoint impedance was reduced. Because the impedance of the EFHW is high, my favorite tuning section for a half wave antenna is a parallel tuned tank circuit - the radiator connects to one side of the parallel circuit and your counterpoise (or ground) connects to the cold end. Tune the paralled tank circuit for resonance near the operating frequency (and make it a permanent part of the antenna). Then wrap a few turns around the ground end of the inductor and use that link to connect to the KAT2. The fixed tuned circuit will handle the high impedance, and the impedance of the link will be much lower (depends on the square of the turns ratio). The KAT2 will do the job of matching into that link as you move about the band. In other words, you make a fixed tuner that becomes part of your EFHW dipole (no variable capacitor to tune the antenna - use a fixed capacitor that resonates with the inductor approximately mid-band. The KAT2 will tune quite nicely into the link winding and produce a low SWR. The alternative is to use a non-resonant wire length that provides a sufficiently low impedance as to be within the matching range of the tuner. The W3EDP antenna is one of those examples. Use that approach if you want to use the same antenna wire for multiple bands. As I recall, the W3EDP radiator is 85 feet long and the counterpoise is 17 feet for use on 80 meters and up. Half those lengths would work on 40 and up. I look at the W3EDP as sort-of an off-center-fed dipole - the counterpoise does not have to be on the ground to work well. 73, Don W3FPR On 8/23/2011 7:00 PM, Phillip Shepard wrote: I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
Thanks for all of the great advice. This reflector is a fountain of knowledge! I checked the 33' antenna/16' counterpoise combination with an MFJ259B, and it indicated over 25:1 SWR. Extending the antenna to 39' and adding a second radial of 6' gave an SWR reading of about 11:1 with the antenna analyzer. The KAT2 seems to handle that much better. This will get me through one or two SOTA peaks at Crater Lake later this week; and I can look for better solutions after that. Thanks again. 73, Phil, NS7P -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net]On Behalf Of Phillip Shepard Sent: Tuesday, August 23, 2011 4:00 PM To: elecraft@mailman.qth.net Subject: [Elecraft] KAT2 with EFHW antenna I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KAT2 with EFHW antenna
An EFHW is a very efficient antenna, but the usual tuner needs help. One way to use the EFHW is to put a toroidal winding at the base of the antenna, between the tuner and the antenna. Bifilar or trifilar or quadrifilar windings configured as a tapped winding will reduce the tough impedance to something that the tuner will handle easily. The 80 meter version of this, an end-fed half-wave L fed against ground is probably the best single wire antenna for 80 meters that there is. 73, Guy. On Tue, Aug 23, 2011 at 11:50 PM, Phillip Shepard ph...@riousa.com wrote: Thanks for all of the great advice. This reflector is a fountain of knowledge! I checked the 33' antenna/16' counterpoise combination with an MFJ259B, and it indicated over 25:1 SWR. Extending the antenna to 39' and adding a second radial of 6' gave an SWR reading of about 11:1 with the antenna analyzer. The KAT2 seems to handle that much better. This will get me through one or two SOTA peaks at Crater Lake later this week; and I can look for better solutions after that. Thanks again. 73, Phil, NS7P -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net]On Behalf Of Phillip Shepard Sent: Tuesday, August 23, 2011 4:00 PM To: elecraft@mailman.qth.net Subject: [Elecraft] KAT2 with EFHW antenna I have been using my K2 with an MFJ tuner to feed an end fed halfwave wire for portable use (like SOTA). The 20m antenna is 33' long and I use one or two 16' counterpoise wires. It seems to work well for what it is and 10W. I just built and installed the KAT2 ATU into the K2 to lighten my pack by the loss of the MFJ. The KAT2 tuner checked out fine on the bench, but it had a very hard time getting a good match to the antenna. In AUTO mode, it only got the SWR down to about 5:1. I put it in ALT mode, and it spent a long time searching before it got down to between 3:1 and 4:1, depending on the 20m frequency. I added about 2 of wire to the antenna, and the tuer got down to about 2:1 to 2.5:1. I added another foot of wire (now 36'), and it got down to about 1.5:1. Five or six feet added yielded a perfect match (1:1). So I now have a 39' wire for 20m use. Is this normal? Should the KAT2 be able to more easily match the 33' halfwave antenna? Thank you. 73, Phl, NS7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
