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Thread: G5RV (JR) High SWR when wet

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  1. #1

    Default G5RV (JR) High SWR when wet

    In common with many G5RV users i've noticed that the SWR on my half size (inverted V) goes high when wet by rain etc.

    My external ATU can still handle it however the fwd RF power is much lower.

    As far i understood this is happening due to the feeder ladder arrangement typical of the G5RV.

    What would be the best solution or modification to minimize this issue? (if any)

    many thanks in advance

    73 de Rod / 2E0RPS
    73 de Rod 2E0RPS
    [url]http://www.qrz.com/db/2E0RPS[/url]

  2. #2
    Join Date
    Jul 2001
    Posts
    21,474

    Default

    Move to the desert, or put up a coax fed antenna !

    Not being smart, just stating an answer !

    Ladder line is going to have losses when wet, and really cannot be avoided. I have spoken out against G5RV style antennas for a good while, since they are a compromise, at best, and a terrible compromise at worst!

    You would be far better off with antennas tuned for each band of interest, or at least a "Fan dipole" arrangement being fed with coax, if you are in a very wet and humid situation.

    Just my 2c worth ! 73, and good luck. Jim

  3. #3
    Join Date
    Feb 2006
    Location
    The Desert
    Posts
    530

    Default NOT TRUE

    It rained here about three years ago.

  4. #4
    Join Date
    Jul 2001
    Posts
    21,474

    Default

    We had about 18 inches of snow on the ground a couple of days ago. Got above freezing, the rain came ( thank Goodness, not ICE ! ) and almost all the snow is gone !

    I'm sure my Johnson Matchbox could handle the difference in impedance, but I haven't had the radio on for the past three days. Too much family activity with Christmas, and all.

    "White Christmas" is a thing of the past, and so is most of the snow, for that matter!

    73, Jim

  5. #5

    Default

    QSL and many thanks for support .. all understood
    73 de Rod 2E0RPS
    [url]http://www.qrz.com/db/2E0RPS[/url]

  6. #6
    Join Date
    Apr 2001
    Location
    Shropshire. England.
    Posts
    17,218

    Default

    Some wire antenna's go out of tune in wet and damp weather, others don't. A half size G5RV can be "tuned" on other bands with a good ATU, but its so short, and its not always the feeder which causes the problems.
    Some vertical antenna's are like this, I have two, one is badly affected by wet conditions, the other one isn't.

    G0GQK

  7. #7

    Question

    QSL,

    i wonder if Hams using doublets are experiencing similar SWR issues on wet condition?
    73 de Rod 2E0RPS
    [url]http://www.qrz.com/db/2E0RPS[/url]

  8. #8
    Join Date
    Jan 2008
    Location
    Overland Park, KS
    Posts
    5,859

    Default

    Quote Originally Posted by 2E0RPS View Post
    QSL,

    i wonder if Hams using doublets are experiencing similar SWR issues on wet condition?
    That sounds normal here for both of my doublets. However, just a minor adjustment of one of the capacitive tuning elements usually corrects the readings and the output power returns to where it normally measures.

    Of course right now when we have a larger amount of snow than normal (highest in at least 20 years), one of the window lines is behaving poorly because it is under a "snow bank" where it enters the house!

    73,

    fp
    [FONT=T93Y][COLOR=#0000ff][B]ACFP

    [/B][/COLOR]
    [/FONT]

  9. #9
    Join Date
    Feb 2005
    Location
    51 Smirrells Road, Birmingham B28 0LA, UK.
    Posts
    5,911

    Default

    Yes, its normal, and due to water sitting on the ladder line. One way to reduce the effect is to replace the ladder line with old-fashioned open wire feeder, you can make this up using spacers purchased from Waters and Stanton.

    73

    Brian G8ADD
    "Only in silence the word, only in dark the light, only in dying life: bright the hawk's flight on the empty sky."

  10. #10
    Join Date
    Jan 2002
    Location
    Sheboygan, Wisconsin
    Posts
    432

    Default

    I propose you put up two antennas. Tune one for dry weather and the other for rain. Problem solved.
    73 Jon KC9AXZ
    [url]www.adapterguy.com[/url]

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