G5RV Inverted V

Discussion in 'General Technical Questions and Answers' started by K1PAR, Jul 15, 2006.

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  1. K1PAR

    K1PAR Ham Member QRZ Page

    Open question to anyone who would care to reply.

    What do you think of using a G5RV as an inverted V?

    I am thinking about doing that as opposed to going flat top. No trees or much else handy to hang from and inverted V would get me back on the air quicker.(I have a 2 meter antenna on a 25' mast I could use as center point)

    Tnx 73
  2. N4AUD

    N4AUD Ham Member QRZ Page

    I had one in that configuration and made lots of contacts with it. If you are without an antenna at all, I'd go for it!
  3. K1PAR

    K1PAR Ham Member QRZ Page

    I should also note that I am going from a 42' trap sloper to the G5RV in hopes of better transmission properties with my 80 watts.
  4. W5MLR

    W5MLR Ham Member QRZ Page

    Any antenna is better than no antenna at all.  The G5RV as an inverted V is not an ideal antenna, but it has served me well in many situations.  On Guam, I could count on getting thru to Japan, Australia, Korea, and Mainland China as well as others.  From Mt Laguna in the mountains east of San Diego, I could get thru to Washington State and southern British Columbia, and Texas through to Georgia.  And that was only over a few hours of operation.  So by all means, if the G5RV in an inverted V is the only antenna you have at hand, Use It!
  5. KR2D

    KR2D Ham Member QRZ Page

    The center of my G5RV is up about 35 feet, the ends are lower, maybe 20 feet on one end and 25 on the other. With 100 watts, I've made contacts all over North America, South America, Europe, the Caribbean, and Russia.

    The only way to know if it works better than your 42' trap sloper is to try it.
  6. K8AG

    K8AG Subscriber QRZ Page

    I have seen studies that indicate the cancellation is really significant. I have been supporting a derivative of a G5RV from the ends for a few years now with good results.

    I would slope it if needed to keep from bending the dipole section.

    That's my 2 cents.

    73, JP, K8AG
  7. K2WH

    K2WH Premium Subscriber QRZ Page

    Why a G5RV? Just put up a dipole, flat top or inverted "V" and feed it with ladder line and a tuner. Can't get better than that and the antenna will cost you next to nothing.

    G5RV is not a very good antenna. There is no magic to it. It is designed so one may use it without a tuner provided it is installed "By the Book". Any deviation from typical installation, and you will not obtain a good match on certain bands and you will only have to go out and get a tuner anyway.

    Put up a dipole.

  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Any piece of wire connected to your transmitter will work; it's just a matter of degree.

    Problems with an inverted vee G5RV at 25' are numerous, but include:

    -Center's not up high enough. A G5RV is fed through a 31.5' length of ladder line that must all be suspended above ground to work properly; if you have the center of the antenna at 25', that's impossible.

    -Possible/probable coupling between that ladder line and the supporting pole/mast, if it is conductive. If it's wooden or something, no problem.

    -The G5RV, like any doublet, is "too long" on the bands above 20m. On 10m, it's six halfwaves not-in-phase and the resulting radiation pattern looks like lobes favoring the wire tips (ends) and not the broadsides. As such, when you install one as an inverted vee, especially a *low* inverted vee, you're aiming most of your radiated energy directly into the earth. (That doesn't mean it won't work, as the earth's a pretty good reflector that will simply bounce most of the applied energy back upwards towards the sky; the real issue is that most of that will be radiated at undesirable angles and not where you'd really want it to be.) This will also happen to a somewhat lesser degree on 12m and 15m.

    -Of course, 25' high at the apex is too low for it to work much on 80m at all, or work well on 40m. It'll probably be okay on 20m.

    My first thought would be: "How can I get this up higher?" and considering perhaps a mast extension to make it 35' or 40' or whatever you can do...

  9. K1OU

    K1OU Banned QRZ Page

    Something we actually agree on! How frustrating is it to try to pull somebody out of the soup on 75 who is running a G5RV with 100 watts? It's about 1 db below mental telepathy....
  10. NT7N

    NT7N Ham Member QRZ Page

    The G5RV inverted, with greater than 90 degrees between legs should work fine. I prefer a 102 ft center fed dipole with TV twin lead (not the cheap stuff) to a 4:1 balun then a foot or two of mini 8 coax to a tuner.

    Mine is an old Van Gorden version with the old feed cut off and TV twin lead soldered on about a foot from the center insulator to an old MFJ tuner.

    You could easily make one with two 51 ft pieces of wire to a center insulator with the twin lead tied directly at the insulator. Less expensive than a commercial G5. I run 100 ft or so or of twin lead.

    Mine is about 25 ft at the center and droops on both ends and is not straight. Works fine on 80 through 20 meters. Allows pretty good 75 meter use, only about a db or so down from a full 135 ft dipole on 75 according to some analyses. I would not consider it a dx antenna. Good Luck, Don NT7N Redmond, Oregon
  11. M5ABN

    M5ABN Ham Member QRZ Page

    I've used a G5RV as a inverted V whilst working /P from my caravan and had very good reports. Just be careful not to bring the ladder feed down too close to the mast.
    Give it a try and good luck.
    Peter M5 ABN
  12. VA3ARS

    VA3ARS Ham Member QRZ Page

    It should work fine if you use a non-conductive mast, good Balun at the end of the Ladder line and the shortest possible coax.
    73, va3ars
  13. G8ADD

    G8ADD Ham Member QRZ Page

    I lowered my G5RV to 20 feet for NVIS on 5 megs. To my surprise it still brings in lots of DX and I have worked five continents with 5 watts from my FT817 since then. I have seen the inverted V recommended and I have also seen it criticised, so it looks as if you will just have to try it and see how it works for you.

    Two thoughts about the G5RV. Firstly it was designed as a 20 metre antenna, and secondly, its designer preferred to use it as a doublet with twin feeder. The coax and multi-band operation came later.


    Brian G8ADD
  14. WZ4I

    WZ4I Ham Member QRZ Page

    The G5RV is better than nothing at all. Take the previous advice and install a dipole, feed it with ladder line, and use a tuner with a balanced output.
  15. K1PAR

    K1PAR Ham Member QRZ Page

    Thanks for the input. One of my biggest problems is limited budget, paying for a house and car come first. I am going to install the G5RV tree to tree, it's about 120' between them. My guess is both limbs are above the 20' mark and will probably do something to raise the center of the antenna. It is not going to be installed where I orignally wanted but I guess this is a close second. Either way it is not going to be above 30' high and the coax run is 70+ feet and no way to make it shorter. My rig is a Kenwood TS-830S with an MFJ Deluxe Versa Tuner II and the G5RV is from Antennas and More (I'n not much of a builder). The original owner tuned the rig down to 80 watts output and I am not sure it is doing that now but it's what I have got to work with.
    Again thanks for the imput. Good DX and 73!

  16. KD5ZER

    KD5ZER Guest

    I have a g5rv set up as an inverted v. The center is about 18ft off the ground. I work dx daily on 20 meters with it and no one has a prob hearing me on 40, 60, or 75 meters.

  17. N4AUD

    N4AUD Ham Member QRZ Page

    If you can afford a roll of 14 awg or better 12 awg wire you can build a dipole or loop antenna, including the ladder line.

    I bought some "mini popsicle sticks" and drilled holes in them just big enough so they would slide on the insulated wire. I had already measured both wires and marked the placements for the popsicle spreaders with a Sharpie. I stretched the two wires, slid the spreaders into place, and put a dab of hot glue to hold them in place.

    I was concerned about the wooden spreaders lasting, but another poster said his lasted for years.

    I look for bargains and I think I paid $5 for the wire I used for about 90 feet of ladder line. If you have a soldering iron or a propane torch, solder and a way to measure there are a lot of antennas you can build, and you can build them as well as or better than the commercial models.
  18. WZ4I

    WZ4I Ham Member QRZ Page

    You're going to have a lot of transmitted signal loss on all bands, except 20 meters (the G5RV is a 20 meter 1 ½ wave wire antenna, with a 34ft ladder line matching section) by using coax on a non-resonant dipole antenna. You’d be much better off using ladder line from A to Z on a non-resonant dipole. Anyhow, good luck!
  19. W5DXP

    W5DXP Ham Member QRZ Page

    If you use an antenna analyzer on a G5RV, you will find that the coax SWR is not bad on 80m, 40m, 20m, and 12m and that the G5RV *system* exhibits resonances on or near those bands. It is an old wives' tale that the G5RV is an all-HF band antenna. But that doesn't mean the G5RV is a one-HF-band antenna. It works reasonably well on 80m, 40m, 20m, and 12m with an antenna tuner. There is not a prohibitive amount of SWR losses in the coax on those four HF bands. To see how/why the matching section works well on 80m and 40m, please see: http://www.qsl.net/w5dxp/G5RV.HTM

    And 34 ft is too long for the matching section. It is supposed to be 1/2WL on 20m including the velocity factor. With a VF of 0.9, the matching section length is about 31 feet. With the 300 ohm ladder-line that I use, the VF is close to 0.8 which results in a matching section of about 27.5 ft.
  20. WZ4I

    WZ4I Ham Member QRZ Page

    A foot here, a foot there. All I know is the folks whom I know that have switched from a G5RV to a dipole fed with ladder line from A to Z, don’t go back to the G5RV. Your mileage may vary…
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