K2 ATU and 43-ft Vertical
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Does anyone have any experience with trying to match one of these 43-ft
verticals, that are being offered by several manufacturers, using the K2s internal ATU? Is it able to find a match on 80-meter CW? Are there any particular brands of 43-ft verticals that you like or don't like? Most of these verticals that I have seen are in the mid to upper $300 range, except for the fiberglass one from S9 Antennas. Any opinions on that particular antenna? Thanks in advance for any information offered. 73, Paul - N8XMS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Paul, the K2 internal tuner is a wide-range device and should be able to
match the 43 ft vertical from 10 thru 80 unless you happen to pick an unfortunate length of feedline. The impedance seen by the tuner will depend on the feedline length. All of the available 43 ft verticals should work equally well electrically. Their mechanical construction and subsequent ruggedness will vary as will their ease of assembly and erection. I just use a 43 ft piece of AWG 12 wire suspended from a lightweight fiberglas Spiderbeam pole, and it works fine. Total cost should be less than $150, mostly for the pole. It cannot be emphasized highly enough that the performance of any of these antennas will depend almost entirely on the radial system used. Try for at least 32 radials, each as long as your space permits up to 65 ft or so. Other than the radials, the next best thing you can do to improve performance is to use a remote tuner at the base. This will eliminate most of the feedline losses you will incur when using the K2 internal tuner. I use a CG-3000, and it is "okay". I would dearly love for Elecraft to offer a remote tuner, however!! Are you listening, Aptos ;>) ? 73 Craig AC0DS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Paul Huff-3
Paul,
That is not an easy question to answer, and for your particular case, we do not have enough facts. It would be necessary to know the configuration of the radial field for that vertical, then plug that information into an antenna modeling program to find the impedance at the feedpoint to the antenna for any frequency of interest. After that, you must specify the feedline (both the type, the velocity factor and the length), as well as the details of any matching network at the base of the antenna. It is not a simple question, and the right answer is "maybe" Once all that information is available, the feedpoint impedance at the shack end of the transmission line can be calculated. With the feedpoint impedance at the shack end known, then the L network values to match it to 50 ohms resistive can be calculated. A look at the specifications for the KAT2 indicate the maximum inductance available and the maximum capacitance. If the required inductance and capacitance for the calculated L network is less than the maximum values available for the KAT2, then the answer is a definite yes. A 43 ft vertical is a bit short on 80 (but not impractical). There was a recent article in QST with a tuner at the base of a 43 ft vertical to provide a good match on 80 and 160. A 43 ft vertical is a 43 ft vertical, and the major difference between them is the effective electrical diameter of the radiator, the mechanical construction, and the price - take your pick. There is no magic in the 43 ft. length except it is practical to erect without a large crew tugging on guy lines, many can simply be "walked up". 73, Don W3FPR Paul Huff wrote: > Does anyone have any experience with trying to match one of these 43-ft > verticals, that are being offered by several manufacturers, using the K2s > internal ATU? Is it able to find a match on 80-meter CW? Are there any > particular brands of 43-ft verticals that you like or don't like? Most of these > verticals that I have seen are in the mid to upper $300 range, except for the > fiberglass one from S9 Antennas. Any opinions on that particular antenna? > > Thanks in advance for any information offered. > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K2 ATU and 43-ft Vertical
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In reply to this post by Paul Huff-3
As Don mentioned, the 2-part article in QST was written by AD5X and can also
be seen here: http://www.ad5x.com/images/Articles/Match160.pdf I built one of these "matching networks" (it's not a tuner) for my 43' vertical and it works very well on 160, 80 and up. The AD5X matching network is a very clever design and makes tuning of this short radiator quite easy as it offsets the huge capacitive reactance of these antennas and even allows control of the relays right over your feedline. Very slick. I have a Zero Five vertical and it is made very well, has been up about 3 years and still looks brand new. The only difference is that with the AD5X matcher I can tune it on 160 and 80 now! The feedline makes a huge difference primarily due to the loss that will impact your performance with poor SWR. If you have a lossy feedline (like RG8X like I used at first) the antenna will appear to match pretty easily. If you switch (like I did to 1/2" hardline, with its much lower loss) you'll see the impact of all of that capacitive reactance in making tuning of the 43' antenna very difficult especially on 160 and 80. In fact, I could not match it at all on 160. 73, Bob W5OV -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Paul Huff Sent: Saturday, June 05, 2010 5:20 PM To: [hidden email] Subject: [Elecraft] K2 ATU and 43-ft Vertical Does anyone have any experience with trying to match one of these 43-ft verticals, that are being offered by several manufacturers, using the K2s internal ATU? Is it able to find a match on 80-meter CW? Are there any particular brands of 43-ft verticals that you like or don't like? Most of these verticals that I have seen are in the mid to upper $300 range, except for the fiberglass one from S9 Antennas. Any opinions on that particular antenna? Thanks in advance for any information offered. 73, Paul - N8XMS ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: K2 ATU and 43-ft Vertical
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In reply to this post by Paul Huff-3
Paul:
Wire works exactly the same as aluminum so don't get carried away with the shiny look! The S9 approach makes sense. A few wires lashed to the pole or inside the pole will do. 80m is where the need for lots of radials come in since 43' is considered short for that band. Spend the $$ saved on aluminum on a remote tuner. Coax will do ok except for 80m where the Z is very low and SWR high. The K2's tuner will do fine but on 80m there's a risk of excessive current through the tuner's torroids. I've burnt them up on low Z antennas before. Above 14 mHz, a 43' vertical develops a high angle lobe, straight up, and isn't considered good for DX but will work. An inverted L, 100ft long, would be a better antenna and cheaper! Reads: http://www.eham.net/articles/21272 Got money? http://www.dxengineering.com/Parts.asp?ID=3408&PLID=286&SecID=142&DeptID=45&PartNo=DXE-MBVE-1-3ATP Rigging it up to work better: http://www.ad5x.com/images/Articles/Match160.pdf Ultimate....No tuner needed. Low loss. Green. http://www.steppir.com/files/Vertical%20FACT%20Sheet.pdf Steve N4LQ ----- Original Message ----- From: "Paul Huff" <[hidden email]> To: <[hidden email]> Sent: Saturday, June 05, 2010 6:20 PM Subject: [Elecraft] K2 ATU and 43-ft Vertical > Does anyone have any experience with trying to match one of these 43-ft > verticals, that are being offered by several manufacturers, using the K2s > internal ATU? Is it able to find a match on 80-meter CW? Are there any > particular brands of 43-ft verticals that you like or don't like? Most of > these > verticals that I have seen are in the mid to upper $300 range, except for > the > fiberglass one from S9 Antennas. Any opinions on that particular antenna? > > Thanks in advance for any information offered. > > 73, > Paul - N8XMS > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Paul Huff-3
> Does anyone have any experience with trying to match one
> of these 43-ft > verticals, that are being offered by several > manufacturers, using the K2s > internal ATU? Is it able to find a match on 80-meter CW? > Are there any > particular brands of 43-ft verticals that you like or > don't like? Most of these > verticals that I have seen are in the mid to upper $300 > range, except for the > fiberglass one from S9 Antennas. Any opinions on that > particular antenna? Paul, I know power limits are not the problem with the K2 barefoot, but consider on 80 meters the base impedance of a fat 43 foot vertical with a modest radial system is about 12 - J 290 ohms. It would be worse with a thin wire. You would have to supply almost 1200 volts peak at almost 3 amperes to the antenna base to apply 100 watts on 80 meters. Since the 50 ohm SWR is over 100:1 on 80, it would be very difficult to get a significant percentage of your transmitter power into it on 80 (and impossible on 160) unless you put a real matching system right at the antenna. (and no, an unun is not a matching system and won't fix 80.) On 60 and 40 meters things are OK. SWR is under 6:1 so feedline efficiency would be OK without the unun. On 30 and 20 things are tough again, but far more workable than 80 and the unun at the base would help. Without the unun SWR is about 30:1. With the 4:1 unun maybe 8:1 SWR. Personally the only way I would have an antenna like that is if I remoted a good tuner right at the base. Otherwise I'd buy a trap vertical like a 6BTV or that Butternut vertical that actually has things that act like traps but that are not called traps by name. Overall, unless you put a tuner very close to the antenna, a trap vertical would work a whole lot better. For 80 you could base load the thing, and a 43 foot vertical with a good ground would be decent. Just make sure the antenna has a good base insulator, because at 100 watts you'd have over 1000 volts at the antenna base. DX Engineering has the best mechanical construction and a very good base insulator. 73 Tom ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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