ATU vs. External Tuner
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I have a k3 with internal antenna tuner connected to a 40 meter dipole
in the attic. Will the internal ATU work for me visiting other bands or would I be better off installing a tuner between the rig and the antenna? Is an auto tuner more preferred than automatic? Thanks to all for your time. -- Frank KD8FIP _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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That depends on what antennas you will be using on other bands and what the SWR will be. Although the KAT3 will match a wider range of loads than the internal ATUs in most non-Elecraft radios, the SWR still exists between the output of the tuner and the antenna, and and can result in considerable signal loss if coaxial cable is used (see http://www.g4ilo.com/antenna.html). I used a KAT2 to tune a non-resonant loop in my attic for several years, but my shack is in the room directly below the attic and the length of the coax was only about 8 feet. If you are a much longer distance from your antenna feed point then you would be better off either using open wire feed and an external balanced tuner, or else using a battery powered remote automatic ATU in the attic at the feed point so you use a coax feeder without undue loss. If you will be trying to use your 40m dipole on other bands then the mismatch will be quite considerable on most of them and you should consider one or other of the options stated above. If on the other hand you add resonant lengths for other bands to the same feed point, creating a fan dipole, then you should be able to get a good match on those bands and you will be able to use the KAT3 without worrying about feeder loss.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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All of the suggestions so far are good; however, it sure would be great if Elecraft would offer a true remote tuner that can be mounted at the antenna feedpoint. This might even alleviate the need for some of us to consider a KPA800, etc. As an alternate, maybe a kit to make the existing KAT3 remoteable would be good. 73, Henry - K4TMC K3/100 #98 -----Original Message----- From: Julian, G4ILO <[hidden email]> To: [hidden email] Sent: Sun, 26 Oct 2008 12:31 pm Subject: Re: [Elecraft] ATU vs. External Tuner Frank MacDonell wrote: > > I have a k3 with internal antenna tuner connected to a 40 meter dipole > in the attic. Will the internal ATU work for me visiting other bands > or would I be better off installing a tuner between the rig and the > antenna? Is an auto tuner more preferred than automatic? Thanks to all > for your time. > That depends on what antennas you will be using on other bands and what the SWR will be. Although the KAT3 will match a wider range of loads than the internal ATUs in most non-Elecraft radios, the SWR still exists between the output of the tuner and the antenna, and and can result in considerable signal loss if coaxial cable is used (see http://www.g4ilo.com/antenna.html). I used a KAT2 to tune a non-resonant loop in my attic for several years, but my shack is in the room directly below the attic and the length of the coax was only about 8 feet. If you are a much longer distance from your antenna feed point then you would be better off either using open wire feed and an external balanced tuner, or else using a battery powered remote automatic ATU in the attic at the feed point so you use a coax feeder without undue loss. If you will be trying to use your 40m dipole on other bands then the mismatch will be quite considerable on most of them and you should consider one or other of the options stated above. If on the other hand you add resonant lengths for other bands to the same feed point, creating a fan dipole, then you should be able to get a good match on those bands and you will be able to use the KAT3 without worrying about feeder loss. ----- Julian, G4ILO. K2 #392 K3 #222. http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham Directory http://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 -- View this message in context: http://n2.nabble.com/ATU-vs.-External-Tuner-tp1379087p1379371.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: Fwd: ATU vs. External Tuner - Please
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At 12:47 PM 10/26/2008, [hidden email] wrote:
>All of the suggestions so far are good; however, it sure would be >great if Elecraft would offer a true remote tuner that can be >mounted at the antenna feedpoint. This might even alleviate the >need for some of us to consider a KPA800, etc. or does it illuminate a need for two remote tuners 100 watt and later a 2 killerwatt for the kpa1500.. both viable worldwide markets....for all brands of stuff ... and small enough not to be factory built....KITS !!!! YEA !!! .... bill _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Frank MacDonell
Frank,
Since the dipole is in the attic, you are probably not getting perfect swr without a tuner. The antenna is a compromise unless you have a very large attic with little metal near by. If you have trimmed it for resonance at 40 meters I assume it is quite a bit shorter than a standard dipole due the proximity of the roof and wood work. If the dipole is actually resonant at 40 meters then it will work poorly on 20 meters even if you can match it at the radio with some combination of feedline and tuner. Please note that a perfect dipole up high in the clear will not be 1 to 1 swr at resonance but will be 70 to 90 ohms. Do not fall into the trap of trying to obtain a perfect match on every band. I would try a non resonant length (g5rv style) fed with coax. It will be more effective on multiple bands and the SWR will not be too high to tune as it is on the second harmonic with a resonant dipole. The antenna center impedance of the g5rv lengths (102' or 88' if in the clear) avoids extreme high impedances on several of the HF bands. The coax losses should be be acceptable on most bands. I would certainly try that with the K3 tuner If you have carefully trimmed the 40 meter for resonance in place in the attic, try adding about 25% length and if necessary folding the ends to fit. There is nothing wrong with trying fan dipoles if you have the space and can trim appropriately. I am sure others will correct my ball park numbers. I also would not get carried away about the perfect feedline length for feeding a g5rv. The best feed line is the shortest one that goes from the antenna to the tuner. That said, if the coax line is very long, then a remote tuner is nice. The K3 tuner is excellent. I would use it . If you fall into a good automatic remote tuner use that. But consider the fact that resonant antennas to not necessarily radiate better than properly tuned non resonant lengths. John KH7T Frank MacDonell wrote: > I have a k3 with internal antenna tuner connected to a 40 meter dipole > in the attic. Will the internal ATU work for me visiting other bands > or would I be better off installing a tuner between the rig and the > antenna? Is an auto tuner more preferred than automatic? Thanks to all > for your time. > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I have a situation that is similar! I have a 40 meter dipole in the attic
of a single story ranch type home. Diope elevation about 12 feet, with ends bent at 90 degrees to make it fit in attic. It is fed with 75 ohm twin lead. I am using it as a dipole on 40/30/20 meters OK with a K1 and a T1 external tuner. Results pretty good considering on those bands. I have also used it on 80 and 160 meters by shorting the feeder and connecting to the "hot" (center conductor on BNC jack) and a counterpoise to the ground connection on the T1. Results were usable on 80 meters and 160 even though it is a "stretch" on 160! Could fairly constantly work a station 200-250 miles distant with weak signals on that band. I haven't a lot of "radio time" available these days as my XYL had a stroke last year and duties around the house keep me busy and away from getting on the air. I do have an "HF Packer" amplifier I built a few years ago, and it gives me around 25-35 watts on all bands with around 2 watts drive from the K1. Eventually I plan on getting an "Inverted L" antenna up on that side of the house in the trees and working it against a counterpoise and ground rod. 73, Sandy W5TVW ----- Original Message ----- From: "John Buck" <[hidden email]> To: "Frank MacDonell" <[hidden email]> Cc: "Elecraft" <[hidden email]> Sent: Sunday, October 26, 2008 4:19 PM Subject: Re: [Elecraft] ATU vs. External Tuner > Frank, > > Since the dipole is in the attic, you are probably not getting perfect > swr without a tuner. The antenna is a compromise unless you have a very > large attic with little metal near by. If you have trimmed it for > resonance at 40 meters I assume it is quite a bit shorter than a > standard dipole due the proximity of the roof and wood work. > > If the dipole is actually resonant at 40 meters then it will work poorly > on 20 meters even if you can match it at the radio with some combination > of feedline and tuner. Please note that a perfect dipole up high in the > clear will not be 1 to 1 swr at resonance but will be 70 to 90 ohms. Do > not fall into the trap of trying to obtain a perfect match on every band. > > I would try a non resonant length (g5rv style) fed with coax. It will > be more effective on multiple bands and the SWR will not be too high to > tune as it is on the second harmonic with a resonant dipole. The > antenna center impedance of the g5rv lengths (102' or 88' if in the > clear) avoids extreme high impedances on several of the HF bands. The > coax losses should be be acceptable on most bands. I would certainly > try that with the K3 tuner If you have carefully trimmed the 40 meter > for resonance in place in the attic, try adding about 25% length and if > necessary folding the ends to fit. There is nothing wrong with trying > fan dipoles if you have the space and can trim appropriately. > > I am sure others will correct my ball park numbers. I also would not > get carried away about the perfect feedline length for feeding a g5rv. > The best feed line is the shortest one that goes from the antenna to the > tuner. > > That said, if the coax line is very long, then a remote tuner is nice. > The K3 tuner is excellent. I would use it . If you fall into a good > automatic remote tuner use that. > But consider the fact that resonant antennas to not necessarily radiate > better than properly tuned non resonant lengths. > > John KH7T > > Frank MacDonell wrote: >> I have a k3 with internal antenna tuner connected to a 40 meter dipole >> in the attic. Will the internal ATU work for me visiting other bands >> or would I be better off installing a tuner between the rig and the >> antenna? Is an auto tuner more preferred than automatic? Thanks to all >> for your time. >> >> > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.175 / Virus Database: 270.8.3/1747 - Release Date: 10/26/2008 9:27 AM _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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The balanced antenna, center fed, with balanced line, is the lower loss system of many. The fun part... is that while looking for inexpensive feedline, I've found that the "poor, fast replaced" speaker lead wire... you know the stuff, clear, copper, and only two conductors, work out very nicely for an antenna. In fact... a broad banded, dipole can be fashioned out of that wire, with the two elements having the ends twisted together, and still using just one run of the wire for feed, works right nice. The balanced line feeds through walls and up past the insulation nicely too. And the T-1 tunes it real nice.
--... ...-- Dale - WC7S in Wy Stay organized with simple drag and drop from Windows Live Hotmail. Try it _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Please remember that before vacuum tubes, etc, hams were communicating with all kinds of gear. Return to ur roots, string up something and try it! Modern rigs are SWR protected so don't worry so much... experiment, and stop looking to experts for their GREAT advice. Have fun! Charles Harpole [hidden email] ________________________________ From: [hidden email] To: [hidden email]; [hidden email]; [hidden email] Subject: RE: [Elecraft] ATU vs. External Tuner Date: Sun, 26 Oct 2008 16:49:31 -0600 CC: [hidden email] The balanced antenna, center fed, with balanced line, is the lower loss system of many. The fun part... is that while looking for inexpensive feedline, I've found that the "poor, fast replaced" speaker lead wire... you know the stuff, clear, copper, and only two conductors, work out very nicely for an antenna. In fact... a broad banded, dipole can be fashioned out of that wire, with the two elements having the ends twisted together, and still using just one run of the wire for feed, works right nice. The balanced line feeds through walls and up past the insulation nicely too. And the T-1 tunes it real nice. --... ...-- Dale - WC7S in Wy ________________________________ Stay organized with simple drag and drop from Windows Live Hotmail. Try it _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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