G5RV or Hustler 6BTV

Discussion in 'Becoming an Amateur Radio Operator/Upgrading Privi' started by AK4BM, Jul 9, 2009.

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  1. K9ZMD

    K9ZMD Subscriber QRZ Page

    Stop. Those buried radials are wasted if you mount the vertical 10 feet off the ground. Radials on the ground, or just beneath the surface, are only of value to a ground mounted vertical. They must extend from the feed point of the antenna in (ideally) a spoke pattern from the base of the antenna. The good news is, they do not have to be tuned, just make them long enough to fill the available space. The bad news is, you need at least 16 of them, and up to 40 of them to make your antenna effective. Although a ground mounted vertical without radials may make some contacts, it takes the added planning & work of installing radials to make it a truly effective antenna.

    If you elevate the antenna, you must still have the radials extend from the feed point; in this case, they must be arranged in an elevated spoke pattern from the antenna. The angle can be anything from 90 degrees (horizontal) to drooping about 45 degrees from the feed point. The good news is, good effectiveness can be obtained with 4 tuned (quarter wave length) radials per band. The bad news is, that means about 20 wires up in the air for a 5 band vertical. As you can see, an elevated vertical also takes some planning & work.

    I would kill for a a back fence of even 130 feet, because I could then fit an 80-10 meter doublet without any bending. I will avoid disparaging G5RV performance, but will point out that a G5RV requires a length of balanced line that should drop straight down from the antenna (how high can you string that wire?). Then, you have a long run of coax between the balanced line and the radio shack. Whether you call that wire antenna a G5RV or a doublet, the entire transmission line between the antenna and the antenna tuner will have varying, often very high, SWR as you switch from band to band. Far better it should be low loss balanced line all the way, rather than a significant length of lossy coax.

    As already suggested in a previous post, a doublet would be a good choice. Hard to beat, in fact, unless you have the space to string a full wave 80 meter horizontal loop. Either type would be an effective multi-band antenna when fed with balanced line. So, let's talk over the concerns you have about bringing balanced transmission line from the antenna to the radio shack, OK? 73

    Gary, K9ZMD/6
     
  2. NN4RH

    NN4RH Premium Subscriber QRZ Page

    The BTV series of antennas can be very effective if installed properly with adaquate radials. The vertical will give you lower take-off-angle of your transmitted signal than a horizontal antenna low to the ground, meaning that you'll be able to work more distant stations. Not nearly as good as a dipole a half wavelength up in the air, but good enough to work DX.

    What ZMD said is very important. Mounting the vertical elevated but using buried radials is pointless. The radials have to . . . well, radiate . . . from the base of the antenna.

    So either ground-mount the BTV and use buried radials, or elevate the BTV and use tuned elevated radials.

    My advice is that 16 buried radials is enough. 8 is not enough. 32 is somewhat better but you see dimininshing returns with more than that. Try to make them at least as long as the antenna is tall and that will be good enough. They don't have to be straight. They don't have to be buried but will work if just pinned to the ground.

    Elevated antenna with elevated radials is better. But the radials have to be tuned, two radials each band about 1/4 wavelength. A consideration is that all that wire up in the air plus the vertical itself might attract undesirable attention from nosey neighbors and an Homeowners Association if you have one.
     
  3. AK4BM

    AK4BM Ham Member QRZ Page

    I think ground mouting is going to be the answer....with new radials. I aquired a 500 foot spool of 12 gauge wire yesterday....for free.

    Only problem is as I push it away from the house, I get closer to a chain link fence....both will affect performance.
     
  4. NN4RH

    NN4RH Premium Subscriber QRZ Page


    It might. It might not.

    I used to have a 6BTV ground mounted in a different location. At that time my wife insisted that it be located in a certain place, which happened to be next to the concrete patio, between two big old rhododendran bushes, and about 12 feet from the house, which at that time had aluminum siding. So I had 16 radials on only one side i.e. 180 degrees instead of full 360 around. I never had much luck working anything south of me with that setup, but it was good to the other directions.

    I currently have my 80/40/30/15m vertical (an HF2V) located about half way between a concrete patio and a chain link fence, about 20 or 25 feet from each. But there's 40+ feet in the other two directions. I have 32 buried radials, they're of course shorter in the short directions and up to maybe 50 feet long in the other directions. The radials that come up to the chain link fence are connected to the fence at ground level. Antenna works fine.
     
  5. W6ONV

    W6ONV Ham Member QRZ Page

    I also buried a majority of my 58 radials a few inches under the ground for my 6BTV (now SteppIR BigIR MkIII), maybe that was more to please the XYL than anything else. I have had fairly good luck over the years with the 6BTV, working DX.
     
  6. K0RGR

    K0RGR XML Subscriber QRZ Page

    If you ground mount the radials, they do not have to be 'tuned' and they can be shorter than 1/4 wave if you have normal ground conductivity. 25 foot radials are fine for 4 meters. Lots of shorter radials are better than just a few long ones.

    Now, having said that, I can tell you that I operated for years with a HyGain Hytower that probably never had more than 6 working radials on it, and it was a great antenna. I wonder how good it would have been with 16 or more!
    You can do amazing things when you're ignorant.

    There is a technique to installing the radials that is supposed to work well. I'm planning to try it here next week when I put up my 43' vertical. You cut the grass fairly short - though not 'scalped' and stretch your radial wires out straight on the ground. Then, you work them down into the grass and pin them with lawn staples every 3-4 feet. Allegedly, after a few weeks, you won't know they're there - the grass will pull them down into the lawn. I hope it works as I hate to repair lawn movers.
     
  7. NN4RH

    NN4RH Premium Subscriber QRZ Page

    Yes, it works. That's what I did, rather then cutting slits and burying, when I added a second vertical this past winter. Just like you said except I did not "work them down into the grass" - just laid them out and pinned them about every 5 or 6 feet. I laid them down during the winter. The first time I mowed this spring I walked the area and checked and added a few pins where the wire wasn't totally down. They disappeared into the thatch about a month into the growing season. Can't even tell they're there anymore.

    I used an awful lot of pins, though. If I do another one, I'll probably just go back to cutting slits with my edger and tucking the wires in, like I did the first one. It was not that much trouble to bury, really.
     
  8. AI3V

    AI3V Ham Member QRZ Page

    When you install that 6btv, and you find you still need to run a tuner to cover from 75-80M, Rethink my post.:D

    Rege
     
  9. AI3V

    AI3V Ham Member QRZ Page

    6btv Has a 100 khz bandwidth at the 2:1 VSWR points on 75/80.

    I guess if you only want to cover 1/5 of the band.....

    Rege
     
  10. KL7AJ

    KL7AJ Ham Member QRZ Page


    One of each
     
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