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Thread: 5/8 Wave Base Antenna, no luck

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  1. #11
    Join Date
    Jan 2004
    Location
    Beautiful Downtown Colorado. (Montrose, SW corner)
    Posts
    27,985

    Default

    I've made a few 5/8 for 2M, needed a cap in series with the tap. Have to juggle the ant length, coil, tap, and cap. Eventually worked well.

    TOM K8ERV Montrose Colo

  2. #12

    Arrow

    here u go
    making the antenna like this you can use it on 2 meters and 6 meters to.
    click on the attachment/pic below.
    73

    ps QRZ messed the picture up and can't re edit the pic... but you can still see the comcept of the idea

    the whip is around 54 to 56 inchs long
    the coil is wound over 1 inch Diameter 3 turns with 1/4 inch spacing, and the top of the coil connects to the whip
    the bottom of the coil connects to the center conductor of your coax/feed line ONLY
    HINT: use a mirror mount or stud mount to accomplish this
    the shield MUST go to your ground plane this is a 5/8 wave on two meters and 1/4 wave on 6 meters.

    contact me if you need the picture in its true format
    www.qrz.com/k4eez for my email address
    again 7 3
    .
    Attached Images Attached Images
    Last edited by K4EEZ; 11-28-2008 at 02:58 PM. Reason: Edit................edit.............edit...
    We do not stop playing because we grow old;
    we grow old Because We Stop Playing.
    Never Be The First To Get Old

    Any System Is Only As Good As Its Weakest Component.
    .................................................................
    Web Link:
    [URL]http://groups.yahoo.com/group/K4EEZ/[/URL]

  3. #13

    Default good start . . . .

    Reading the books on antenna theory, the 5/8 wave has the maximum radiation at the hoirizon, but the feedpoint is nowhere near 50/75 ohms resistive, and there's a reactive component.

    Most mobile 5/8 wave antennas use a small series coil to electrically make it looke like a 3/4 wavelength antenna -- and as you should remember, odd multiples of a 1/4 wavelength have pretty much the same nominal impedance.

    Go one step further, and you'll discover that a 6 meter whip quarter wavelength will work rather well on 2 meters, and a 2 meter 1/4 wave whip will work pretty well on 440 MHz, because of the 3/4 wavelength thing.

    Little known fact -- most commercial high band 5/8 wave antennas will work on 6 meters, with an SWR of less than 2:1 in almost every case.

    Okay, you can figure out the rest.

    Gary WA7KKP

  4. #14

    Default

    Quote Originally Posted by WA7KKP View Post
    Go one step further, and you'll discover that a 6 meter whip quarter wavelength will work rather well on 2 meters, ...
    Gary, "work rather well" is a false statement. "Load rather well" might be true, but 3/4WL vertical monopole antennas send the majority of the radiation up at a high angle of radiation to be lost in space forever. If such configurations "worked rather well", initiated amateur radio operators would be using them but rarely is that the case. Most initiated hams use collinear phasing for their dual-banders.
    73, Cecil, www.w5dxp.com
    Can CO2 emissions save us from the coming ice age?

  5. #15

    Default

    DITTO...
    K4eeZ.



    Quote Originally Posted by WA7KKP View Post
    Reading the books on antenna theory, the 5/8 wave has the maximum radiation at the hoirizon, but the feedpoint is nowhere near 50/75 ohms resistive, and there's a reactive component.

    Most mobile 5/8 wave antennas use a small series coil to electrically make it looke like a 3/4 wavelength antenna -- and as you should remember, odd multiples of a 1/4 wavelength have pretty much the same nominal impedance.

    Go one step further, and you'll discover that a 6 meter whip quarter wavelength will work rather well on 2 meters, and a 2 meter 1/4 wave whip will work pretty well on 440 MHz, because of the 3/4 wavelength thing.

    Little known fact -- most commercial high band 5/8 wave antennas will work on 6 meters, with an SWR of less than 2:1 in almost every case.

    Okay, you can figure out the rest.

    Gary WA7KKP
    We do not stop playing because we grow old;
    we grow old Because We Stop Playing.
    Never Be The First To Get Old

    Any System Is Only As Good As Its Weakest Component.
    .................................................................
    Web Link:
    [URL]http://groups.yahoo.com/group/K4EEZ/[/URL]

  6. #16
    Join Date
    Jun 2006
    Posts
    49

    Default

    Well, I went the route of some of the suggestions and ended up with a 3/4 wave antenna. Not what I wanted, so I started over and finally got the 5/8 wave antenna to work:

    I found the tap point to be about 3-2/3 turns from the top of the coil. The "whip" part is 47.5 inches long. (I also discovered that I had some bad coax causing most of my problems before)






  7. #17
    Join Date
    Jun 2006
    Posts
    49

    Default

    BTW, the S)239 is screwed into the bottom of the brass coupling, so I need to figure out a way to mount it!

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