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Bend radius of LMR-200?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KE0CU, Aug 13, 2017 at 4:39 PM.

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  1. KE0CU

    KE0CU XML Subscriber QRZ Page

    I was using a piece of LMR-200 cable yesterday to make some jumpers with ferrite core chokes. The Times-Microwave spec sheet had this to say about the bend radius for this product:

    Bend radius: installation 0.5 in.
    Bend radius: repeated 2 in.

    Does that mean while "installing" you can bend it once with a bend radius of 0.5 in. and keep it bent, or bend it once during installation and you must then unbend it to > 2 in. radius after installation? Probably not well said but does anyone know what this spec means?

    Hank/ke0cu
     
  2. NH7RO

    NH7RO Ham Member QRZ Page

    I think that's about right; if you're installing the bend permanently (like in a balun box or enclosure of some sort) then .5 inch is fine but if it's going to be flexed from time to time then 2 inches is the smallest radius one can use without the risk of dielectric migration occurring sooner or later.

    Bottom line; fine for winding around/through a toroid.

    73,

    Jeff
     
  3. KE0CU

    KE0CU XML Subscriber QRZ Page

    Thanks, Jeff!
     
  4. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    In shielded high voltage cables there is a minimum bend radius and a minimum "pulling bend radius". You can't know how many arguments this has fostered. Cable manufacturers exceed the pulling bend radius when installing cable on cable reels all they time. When questioned about this they respond that the cable is not being pulled when installed on a reel.
     
  5. K7JEM

    K7JEM Ham Member QRZ Page

    I think you would be better off winding the balun with a coax that had a solid dielectric. The foam can more easily allow the center conductor to "migrate" to the edge, possibly even shorting out after time. The solid cables are much less problematic in this regard.
     

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