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#1
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Autotuner and dipole
I recently acquired an ldg lz 100 and hooked it up as soon as I got
it. The dipole I have now will tune with a manual tuner to below 1.5:1 on 40m-10m. The autotuner won't tune to below 1.5:1 in any band. Am I doing something wrong or did I just not get a decent tuner. I oftentimes won't even get an SWR green light to show it has tuned and when I do, the SWR is high. Should I put a balun on or what? The dipole is 66 feet long in my attic... but as I stated, it tunes awesome with the manual tuner. If you want to email me, please email to The email here is incorrect. |
#2
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Greg wrote: I recently acquired an ldg lz 100 and hooked it up as soon as I got it. The dipole I have now will tune with a manual tuner to below 1.5:1 on 40m-10m. The autotuner won't tune to below 1.5:1 in any band. Am I doing something wrong or did I just not get a decent tuner. I oftentimes won't even get an SWR green light to show it has tuned and when I do, the SWR is high. Should I put a balun on or what? The dipole is 66 feet long in my attic... but as I stated, it tunes awesome with the manual tuner. If you want to email me, please email to The email here is incorrect. You should be able to tune the antenna on 40 meters, as it is resonant around 7.1 mHz to start with. 20 meters - maybe. 15 meters should tune okay. Your manual tuner tunes okay because it will tune a much higher range of mismatches, assuming it is a "T" type tuner. The autotuner I have seen that has the widest range for tuning mismatches is of all things, an MFJ. This doesn't mean your tuner is bad, From what I have seen of the LDG's - they are nice well constructed units. I'd keep it and modify the antenna. - Mike KB3EIA - |
#3
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Greg, Most 'auto-tuners' have limited tuning 'range' when compared to 'manual' tuners, that's because of expense, size limitations, and so on. Since I know nothing about your 'LDG' tuner, that's what I'd have to guess is happening. Doesn't mean that there's necessarily anything wrong with it, just that it can't 'do' what you're asking of it... 'Doc |
#4
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Thks for replies. I am going to keep it. I think it will come in handy for FD
when I run a random wire up a tree. I will certainly look into some of the specs for this tuner and adjust the antenna accordingly. Shows my ignorance that you can just throw up an antenna and tune it with an autotuner. Thanks again. Always a big help!! 73 Greg |
#5
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Gregg,
Measure the SWR without a tuner on the various bands. you should be able to tell whether the autotuner will tune that. Tam/WB2TT "Greg" wrote in message om... I recently acquired an ldg lz 100 and hooked it up as soon as I got it. The dipole I have now will tune with a manual tuner to below 1.5:1 on 40m-10m. The autotuner won't tune to below 1.5:1 in any band. Am I doing something wrong or did I just not get a decent tuner. I oftentimes won't even get an SWR green light to show it has tuned and when I do, the SWR is high. Should I put a balun on or what? The dipole is 66 feet long in my attic... but as I stated, it tunes awesome with the manual tuner. If you want to email me, please email to The email here is incorrect. |
#6
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The LDG tuners will tune a fairly large range and should work in your
application. Look at the QST reviews of a collection of auto tuners for details. Are you using a balanced feedline? If so, you should use a 1-1 or 4-1 current balun to make the connection to the tuner. If you are using coax feed use a 1-1 current balun at the feed point. Knowing just the SWR does not give you the feed line input impedance which you need to know to understand if the tuner will match. You can use Eznec to tell you the feed point impedance and a program like TLW to model the input impedance and calculate the L and C values for a L network tuner (LDG is a L network tuner). Of course, if you can borrow an analyzer you can just measure it. Depending on the feed line length you may just be unlucky and a change in the feed line length will transform the impedance into something that will match. TLW will help you figure that out. I use a LDG RT-11 to feed my 136' dipole and it will match on 160 through 10. I use a length of 450 ohm ladder line to a 4-1 current balun to the tuner and of course coax to the radio. I selected the length of the ladder line to insure the match. Larry Greg wrote: I recently acquired an ldg lz 100 and hooked it up as soon as I got it. The dipole I have now will tune with a manual tuner to below 1.5:1 on 40m-10m. The autotuner won't tune to below 1.5:1 in any band. Am I doing something wrong or did I just not get a decent tuner. I oftentimes won't even get an SWR green light to show it has tuned and when I do, the SWR is high. Should I put a balun on or what? The dipole is 66 feet long in my attic... but as I stated, it tunes awesome with the manual tuner. If you want to email me, please email to The email here is incorrect. |
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