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HELP WITH DIPOLES AND INVERTED V'S

Discussion in 'Amateur Radio Antennas' started by TonyV225, Jun 8, 2009.

  1. TonyV225 Supporting Member

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    I run an inverted V (G5RV) and I know that there mixed feeling on this antenna and its uses I use mine for 17-80 meters it seems to work pretty well but I know I dont have it high enough to start with but as I said its been working for me.

    I am wondering what you other operators suggest as far as how highh the Apex should be and also how high the ends should be at for the best operation performance. I am looking to put something else up and also was looking to get more ideas on something better and more efficient.



    I was looking at getting into 160 meters and have a few achers to work with but I know these antennas for 160 are pretty long and thought of looking into this before deciding what to put up if theres somethiung I can use to cover 17-160 or that will work on all HF maybe Ill do that.

    I have the newest ARRL anttena classics book I have been looking at that and want some firsthand experiences and ideas from operators on this forum. Ide really like to try 160 but the most important is to get 17-80 the best I can for now. Thanks.......Tony
     
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  2. W5LZ Crotchety Old Bastard

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    There really isn't any hard-n-fast rule about a G5RV's height, other than saying higher is better. If it's high enough so that the ladder line portion isn't close to touching dirt, it's usually high 'enough' to work. Not well, but 'work'. A G5RV is a compromise antenna at best, and was only intended for use on 20 meters. It's marginally useful on harmonic frequencies, but so are other antenna. I guess you can tell I'm not exactly thrilled with G5RV's.
    If you don't have room for a real live 160 meter dipole, then use whatever room you have to get up a 'shortened' version of some kind of 160 meter antenna. They take some effort, but an inverted 'L' with a very good ground radial system works very well. Again, it's a matter of as much vertical height as you can get and then the rest horizontal. A loaded antenna of some kind will 'work'. Any loaded antenna isn't going to be as 'broadbanded' as an unloaded one, but, if it fit's the room you have, it's better than nothing. For most of us, that 'better than nothing' antenna is about all that we have room for, especially on 160 meters.
    A multiband antenna to cover all bands is certainly possible. Sometimes isn't to practical as to price, or abilities, but certainly possible. Just depends on how much you are willing to put up with or do without.
    I'm not a fan of vertical antennas in general. There have been one or two that I thought really did well (on both ends of it), but they are not cheap or simple, and do require a very good ground system. One is a 'HT18' ('18HT'?) 'HighTower', the other one is basically the same thing except you build it. The hardest part as far as I'm concerned is that ground system, I hate messing with them.
    One of these days... as soon as I win the lottery... yeah, right.
    - 'Doc
     
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  3. Moleculo Administrator Staff Member

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    Tony, how much height do you have to work with on your tower, or whatever it is you're using?
     
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  4. TonyV225 Supporting Member

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    well ide like to stay within the 50-60 foot mark or section but can attatch higher up on the tower if need be. I actually have about 50 more feet I was going to put up but Im also on a 60 foot hill so I was going to put these other sections up as another whole tower instead.
     
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  5. Beetle Well-Known Member

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    Length for a dipole is important, but height above ground is NO LESS important. One-half wavelength is a bare minimum height for a dipole, and on 80 meters, that's about 130 feet. Since 160 meters is twice 80 meters, 1/2 wavelength there would be about 260 feet.

    Anything less than those heights, for a simple dipole, will result in mainly NVIS results (which may be just fine for what you want).

    As far as "G5RV" antennas: if it isn't 102 feet long, with 35 feet of parallel feeder it isn't a real G5RV. There's no such thing as a "half size G5RV", or a "double size G5RV". Build it yourself, experiment with feeder type and length and see for yourself what works and what doesn't.

    If you have a very good tuner and a very VERY good counterpoise/"RF ground" you can generally feed a good 80 meter dipole against ground with good results.
     
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  6. Captain Kilowatt Professional Amateur Staff Member

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    I can't add much more than has already been said. As with any antenna the higher the better and that goes for the apex or the ends as well. I was going to suggest an inverted L antenna for 80 or 160m but Doc beat me to it.I have a non-resonant inverted L hanging down the side of my tower in a rather poor configuration I will admit. There are no radials under it and the ground is connected to the tower about four feet above the ground where the feedpoint is. The tower is well grounded with three bonded ground rods 7-8 feet deep. If memory serves me correctly there are four short radials at the base of the tower about 20-25 feet long but that's all. The wire is about 30 feet verticle and 70 feet horizontal and is only spaced a few feet from the tower at the top.The feedpoint impedance is very low on 160m,in the order of 17 ohms but on 80m it is around 225 ohms. I used a home made 4:1 transformer at the feedpoint to raise the impedance on 160m and it requires very little in the way of L or C to match it.I have had decent luck with it on 160m throughout the North East and on 80m it works well into Europe. I even worked ZS6CCY in Vallwater, South Africa with it using 100 watts and it was already nearly two hours past his sunrise.I know it would work better further from the tower and with radials but such is the case with "temporary" antennas that become not so temporary.
     
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  7. TonyV225 Supporting Member

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    my G5RV is over 100 feet and has the twin lead for feeding it. It is made by radiowaves ibelieve there called. I was also told to stay away from those smaller cut G5RV antennas. I was also suggested to add wire to my G5RV for use on 160. I know theres alot one can do so before I start I wanted to ask questions here on the forum.
     
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  8. rfoverlord guardian of freedom

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    Tony,
    how high up are the ends and are you running this as a flat top or inverted "v" also how is it oriented N-S or E-W? Iv'e tried a couple of different dipole configurations 102' and 133' and a fan dipole (it actually worked good 10-20) but that was getting to big to keep up in the wind. My best ant so far has been a homebrewed cobra ant. 73' per leg physically made with rad shack 3 conductor rotor control wire fed with a quarter wave length of 450 ohm twinlead from a DX engineering 1:1 balun plays real nice 10-160 of course 160 has always within 1800 miles but it works. 10-40 i don't even need a tuner.
     
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  9. Beetle Well-Known Member

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    A "quarter wave length" doesn't tell us much since this is a multiband antenna apparently. Quarter wave on which band?
     
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  10. TonyV225 Supporting Member

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    Ok its sold as a multiband antenna I find myself mostly on 75-80 meters but I do skip around a bit from time to time. I am looking for ideas or advice on whats my best bet to run as an antenna double bazooka, flat topped dipole etc.

    As far as my G5RV the apex is at maybe 35-40 foot the ends are about 6 foot or so off the ground I know they need to all go higher but before getting help here to get this done because I obviously am not in the health to be doing this myself I want to look at other possible options as far as a multiband basically what as far as a multiband is better than a G5RV and as far as my G5RV what height should I run this apex and ends if I were to leave this up?

    Right now the apex would be poited west.
     
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  11. Beetle Well-Known Member

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    Center fed doublet as long and as high as practical. Balanced feedline directly to the tuner. Build the antenna yourself and use a good commercial feedline and quality insulators. For multiband operation it doesn't get much simpler or more effective. Might need to experiment with feedline length for some bands; might not.

    All antennas are compromises in some way, and this one is no exception.
     
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  12. HiDef Active Member

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    You got some good answers and, well...

    A lot depends on what you want to work.

    If it's DX on 160 and 80 the antenna needs to be quite high to keep up with the Jonses. If you want to be regional and work your buddies a few states over 60 feet in the center is optimum for 80 meters. 120' and your low angle will skip right over their heads. Plenty of folks on 80 use dipoles at 30' year after year. Same folks are not DX hounds.


    Remember that maximum radiation takes place at the current maximum points of the antenna. Put up 130 feet center fed and the center will be doing most of the work on 80. Same antenna on 40 radiates most from halfway out on both wires.

    The trick with a multiband antenna is to use good balanced line. Twinlead and windowline both suck when wet. Use real open wire line with plastic or ceramic spreaders. Feed with a good quality tuner designed for a wide range balanced load.

    Double Bazooka is a cool name for a unnecessarily heavy antenna which loses power deliberately to exhibit low SWR over a small increase in bandwidth over it's dipole cousin.
     
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  13. W5LZ Crotchety Old Bastard

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    :)
    Now that's the best description of a double bazooka antenna that I've seen in a long time!
    I'm also a fan of parallel feed lines. Not having found any of the 'bare' wire type ladder line in quite a few years, I use what I can find. Did the 'DIY' ladder line -once-, don't plan on doing that again, I hope! Oooo, that's fun. Also found that while it's wet, just as said, it does change tuning over a fairly wide range. Using wax, etc, does not help things, since most waxes are conductive to some extent. Just like your millage, that 'conductivity' changes.
    Best advice for a tuner when using ladder line is the 'biggest' one you can find. Not big as in power, but component 'size', usable range of tuning. Oh well, lot's of little thingys can make a big difference...
    - 'Doc
     
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  14. rfoverlord guardian of freedom

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  15. Lazybones1222 W9WDX Amateur Radio Club Member

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    That's what I run. Love it. Simple. Works great. Cheap to build.
     
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