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Base An idea for strengthening iMax 2000 top section

Discussion in 'CB Antennas' started by Mars, May 29, 2018.

  1. Mars

    Mars New Member

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    I've read numerous owner comments stating the top section of the iMax 2000 top section makes them nervous seeing it bend in high winds. I slipped a 4' section of 1/2" thinwall PVC pipe over the top section and held everything in place using hot-melt Gorilla Glue brand poured in & around both ends of the PVC tubing. It's very similar in strength to what is used on the iMax elsewhere. It still flexes but not as wildly as without it and there appears to be no undue stress placed on the other two antenna sections. I did a somewhat unscientific test on a gusty day by temporarily standing/anchoring the antenna against my house and taking measurements at the tip of the top section with & w/o the PVC tubing in place. There's about a 50% reduction in top section flex when control points were marked & measured repeatedly. The 4' section of PVC is painted white to match the antenna.


     

  2. M0GVZ

    M0GVZ Sr. Member

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    Don't. It is good that it is bendy as that takes stress off the lower sections, especially the bottom section. It'll take longer than a gusty day or two to see the effects of what you've done. Keep an eye out for splitting and the bottom section of tube coming loose in the metal section.
     
    milkman21218, JAF0, Unit 194 and 2 others like this.
  3. Mars

    Mars New Member

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    Thank you for your concern. I thought about that before going through with the idea. Since the center section still flexes normally, that shouldn't stress the bottom section. Keep in mind the PVC is thin wall, not the stiff pipe often used in residential plumbing. It's flexible much like PEX tubing is and the "sleeve" (if that's what we can call it) is short so the entire top section still flexes in a nice smooth curve.
     
  4. fourstringburn

    fourstringburn W9WDX Amateur Radio Club Member K5KNM

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    I wouldn't do it either. MOGVZ called it right. It's the lower section that gets the most stress.

    I had an Imax that cracked right at the lowest section where the fiberglass meets metal. I live in the southwest where summer humidity's are very low and wind gusts can get up to 60 mph or more. This combination overtime dried out the antenna and one windy day, it finally split then toppled over.

    If anything, reinforce the lowest section if you feel the need.
     
    JAF0, Unit 194 and Captain Kilowatt like this.
  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    I agree with both above. The top section can almost tie itself in a knot and still be fine. It is basically a mobile antenna and you know how much wind they can stand. You just increased the windload on the top section which puts even greater stress on the bottom section due to leverage.
     
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  6. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Welcome to WWDX!
     
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  7. Unit 194

    Unit 194 Well-Known Member

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    I never had a problem with the top section of my IMAX 2000 so "if it ain't broke, don't fix it".
     
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  8. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    FWIW I have seen the top section bend back at nearly 90 degrees in a storm and after things were over there was no harm done. It's fiberglass. It will take it.
     
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  9. JAF0

    JAF0 New Member

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    ...you've also increased wind loading. o_O
     
    Unit 194 likes this.
  10. Onelasttime

    Onelasttime Well-Known Member

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    Normally when an element breaks on an omni it is the bottom or middle section. When the top takes a hit it is usually do to too much rf or a lightning strike.
     
  11. L2

    L2 Member

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    I agree. When hurricane Sandy brought mine down it broke at the bottom section.
     
  12. Blackcat630

    Blackcat630 Sr. Member

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    Years ago my first IMAX broke at the very bottom of the middle section. It was 65 ft at the feed point. My old qth was surrounded by open fields and the straight line winds were too much...
     
  13. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    We must have hurt his feelings telling what he did was wrong. He hasn't posted here since his first two day whirlwind May 29 and May 30.
     
  14. Mars

    Mars New Member

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    Not upset - I'm still here :whistle: - just haven't checked in since summer has me busy with other things.... like relocating the radio bench to another room in the house and installing a new 30' mast, ground wires, & feedlines for the antennas.
     
    Unit 194 and Shadetree Mechanic like this.
  15. 357

    357 Walkin' the dog

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    I've had 3 Imax bottom sections cracked right out of the box.
    Some people dont know its cracked when its new its hard to see.

    If it rains and the swr goes up, its cracked.

    lesson learned

    the top has never broke on me.
    If it did I'd trim down a 9' SS whip
     

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