Is choke enclosure really needed

Discussion in 'Ham Radio Discussions' started by KN4FAZ, Feb 12, 2020 at 4:14 PM.

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  1. KN4FAZ

    KN4FAZ Ham Member QRZ Page

    I intend to build a 1:1 choke based on a T240-43 ferrite wrapped with RG58 coax to install at the feed point of a G5RV. I'm a believer in the phrase " you can't fool mother nature", that is, you are probably not going to keep moisture from penetrating anything left exposed to the weather. That, plus added heat dissipation by not enclosing the choke, leads me to ask, is it necessary?

    Thanks and 73.
     
  2. N2EY

    N2EY Premium Subscriber QRZ Page

    Yes, an enclosure is necessary, if you want the balun/choke to last.

    A proper enclosure will not let moisture in.
     
    K4AGO and AA7QQ like this.
  3. W4NNF

    W4NNF XML Subscriber QRZ Page

    You'd no doubt be OK for a while--assuming you adequately waterproof connections at least. But as EY says, if you want it to last you need to provide a waterproof enclosure--and check it once in a while. ;)
     
    K4AGO likes this.
  4. K4PIH

    K4PIH Ham Member QRZ Page

    Dip it in something. Wax, varnish, how about coating it with Flex Seal?
     
    KA4DPO likes this.
  5. K3XR

    K3XR Ham Member QRZ Page

    Electric boxes from your local home improvement store are very effective. Look for the box with a rubber seal.
    This on the Lowes site also Amazon.
    Cantex 5133709 Electrical Box
    [​IMG]
     
    KU3X, W4IOA, W4NNF and 3 others like this.
  6. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    And for an SO-239, and eyelets, you can get rubber washers at Tractor Supply. I would also spray, or paint some flex seal rubber around them.
     
    W4NNF, N2EY and K3XR like this.
  7. KN4FAZ

    KN4FAZ Ham Member QRZ Page

    What would be expected to fail if exposed to weather, coax, connectors or ferrite?
     
  8. AA7QQ

    AA7QQ Ham Member QRZ Page

    Mother Nature just laughs at Flex Seal.

    Ed
     
    WR2E likes this.
  9. KB7WG

    KB7WG Ham Member QRZ Page

    I would assume they have spray cans of varnish now days. Give it 6 or 7 coats.
     
  10. KK5JY

    KK5JY Premium Subscriber QRZ Page

    You do not want ferrite exposed to the weather. It is a mechanically fragile material. Very fragile. So the less stress it has to endure, the longer it is going to last.

    Hail could easily break ferrite. For that matter, ferrite under mechanical stress could even be broken by a nosy bird.

    The heat cycle stresses from repeated exposure to the sun, not to mention the uneven heating--due to some of the ferrite being exposed to the sun and some being shadowed behind coax--isn't going to help its longevity, either.

    You could probably get away with an unboxed choke if it was tied up under the eaves of a house or in the shade of a tree (at least in summer), but if you want ferrite to last, put it in an enclosure of some kind.

    Even the W2DU-style chokes, which are just ferrite beads stacked on a length of coaxial cable, typically have heatshrink applied to the stack, for durability.
     
    KA4DPO and VK4HAT like this.

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