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Wolf River Coil on CHA Spike Question

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KL2WX, May 18, 2021.

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  1. KL2WX

    KL2WX Premium Subscriber QRZ Page

    I'd like to try a Wolf River Coil with a collapsible whip on a Chameleon CHA Spike for portably use. I need an adapter to connect the coil to the spike with a 259 connector on it for coax output, but I'm not finding one as I don't know what it would be called. Any help would be appreciated!
     
  2. KD1JT

    KD1JT Ham Member QRZ Page

  3. KD1JT

    KD1JT Ham Member QRZ Page

    3/8 x 24 coupler.
     
  4. KL2WX

    KL2WX Premium Subscriber QRZ Page

  5. K7JOE

    K7JOE Subscriber QRZ Page

    If the bottom of the wolf river dummy-load is a 3.8 x 24 thread, which I am pretty sure it is, your best bet is to go to your nearest truck stop and pick up a "truck mirror mount" that has an SO239 connector on a 3/8 x 24 stud and "barrel". Unscrew the barrel and toss it aside. Just screw the coil to the mirror mount so239 stud. Dont forget to make sure the washer is still in there. Then get a 2 foot length of solid rod or part of a ground rod, and sharpen one end. Clamp the mirror mount to the solid rod and use your foot to put it in the ground.

    A way more effective method is to use a proper low loss and high Q tappable coil like the ones MFJ sells or the texas bug catcher or Webster band spanner. The issue is the wolf river dummy load is made of stainless steel - the wolf river dummy load thus gets hot and can even melt the PVC casing -- because stainless is a very poor conductor - just go compare it to aluminum or copper or tin or silver plated copper (other brand x coil).

    A better approach, beside using brand X instead of Wolf river, is that you should elevate the coil as much as possible above ground. Antenna base loading (at the feed-point close to earth) is the least efficient method to load an antenna. Elevating the coil 4 to 5 feet above earth will dramatically increase radiation and reduce ground losses.

    This is a good web site ... you can even make your own. KØBG.COM (k0bg.com)

    see below -- a wolf river dummy load go through thermal meltdown ....


    [​IMG]
     
    AK5B likes this.
  6. KD1JT

    KD1JT Ham Member QRZ Page

    Yeah, i fixed that above.
     
  7. K7JOE

    K7JOE Subscriber QRZ Page

    Like these...
     

    Attached Files:

  8. KL2WX

    KL2WX Premium Subscriber QRZ Page

    I think electrically this would work, but I'd rather the coil be directly on top of the spike.

    https://www.dxengineering.com/parts/mfj-347?rrec=true

    Mechanically I need 3/8" on the top to connect to the coil and 3/8" on the bottom to connect to the spike.

    Electrically the coax center conductor should connect to the coil and the shield should connect to the spike. Side coax connection would be most convenient. I may have to build something, but I'm surprised this isn't available commercially.
     
  9. AK5B

    AK5B Ham Member QRZ Page

    If you can fly by using elk or moose antlers for wings up there in America's last frontier you ought to be able to build something from scratch (at least in my way of thinking). :D

    As noted previously, there are better ways to load a vertical---and it behooves us as hams to aim for optimum results whenever possible---but I will leave that subject for another day.

    73,

    Jeff
     
  10. KL2WX

    KL2WX Premium Subscriber QRZ Page

    I'm sure I can fab something up. This isn't the holy grail antenna. Just something to backpack with that I can deploy in a couple of minutes without a lot of parts or fuss. I appreciate it!
     
    AK5B likes this.

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