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Using a 9:1 unun for RV antenna

Discussion in 'On the Road' started by N2JDK, Nov 16, 2017.

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  1. N2JDK

    N2JDK Ham Member QRZ Page

    Just wondering if anyone actually has tried using an unun for their mobile vertical antenna? I would like to use either my 75m hustler or my Eagle one push up. Coax fed . (Both mounted to the ladder on the rv ) As I understand verticals on vehicles have a very low impedance which makes them difficult to tune. I don't operate on the road and when in rv parks the real estate is somewhat limited, so ground radials are not very practical when only staying for a few days.
    Any thoughts appreciated.

    Hoyt n2jdk
    Bokeelia Fl.
  2. KF5UMC

    KF5UMC Ham Member QRZ Page

  3. KF4ZGZ

    KF4ZGZ Ham Member QRZ Page

    The first thing I would try is a simple shunt coil.
    That being said ..... I have built the EARCHI endfed and used it with good results.
    I have even Insulated a mast from the ground, and attached the balun feed point to the mast and used the mast as a radiator.
    Worked 15m, 18m, and 20mfor an entire dx contest like this.
    Sooooo, try your idea, it might work.

  4. N2JDK

    N2JDK Ham Member QRZ Page

    Well, I finally picked up a 9:1 balun core (with windings ) and will be trying it out as soon as I can. Thanks for the replies, we'll see if it works.
    Hoyt n2jdk
  5. NT5A

    NT5A Ham Member QRZ Page

    This was a year ago ... How did it work??
  6. N8ZL

    N8ZL Ham Member QRZ Page

    End fed 1/2 wave antennas work great on RVs. I have fed them from the top of the metal ladder and use it as a counterpoise. However, you are fighting common mode currents on this type of antenna, the satellite receivers, dvd players, etc. in the coach do not respond well to these nasty currents. (I lost 2 receivers before I figured out that it was me causing the problem) "My" cure was to not use any part of the RV as a counterpoise, instead I stretch about an 1/8 wave wire down from the feed point and away from the unit. When in Florida for the winter I just bury it in the sand. If you want to use the ladder go with a 1/4 wave. I use an 8" whip for 10 meters and the ladder is about 7' long so this set up makes a good vertical dipole. I have also used center loaded verticals off the ladder and they work OK but a properly match HWEF out performs them. At least for me. BTW I use a 9:1 unun. . As for safety keep people in the Park away from the antenna ends, it will burn the crap out of someone. This includes the counterpoise.
    K3SZ likes this.
  7. K3SZ

    K3SZ Ham Member QRZ Page

    I operate portable from my RV as well but I use a couple of umbrella stands, fiberglass poles, and string up a 50' inverted-L and counterpoise, coax fed via a 9:1 UnUn.
  8. N8AFT

    N8AFT Subscriber QRZ Page

    Have had FB results using a 4:1 Un-Un with a portable 33' vert here.

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