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. VK4HAT

    VK4HAT Ham Member QRZ Page

    Non of the above will fail. The point of enclosing it is so the ferrite does not get wet. You do not want the properties of the ferrite to change by being wet. If you took the wound balun and dipped the whole thing in plastidip, or use conformal coating or potting compound, then it would not need to be in a case. However, you would need to ensure that they do not break down over time with UV etc.+ the mechanical considerations listed by @KK5JY

    Easiest thing is to stick it in a box, grommet in, grommet out and a weep hole for condensation.
     
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  2. WA7PRC

    WA7PRC Ham Member QRZ Page

    Feeding my Cushcraft A3S Yagi, I used a PVC cap to house a FT-240-43 choke. I installed it open-side-down on the underside of the Yagi boom:
    [​IMG]
    It was in place and worked MANY years here in "Everwet", WA.
     
  3. KW4GT

    KW4GT Ham Member QRZ Page

    Ferrite materials have been 'fired' in a kiln, that is they're a ceramic type material. I've never seen ferrite cores rust and I've had some out in the weather for years. All the ones I've ever used are glazed, which is going to make them pretty impermeable to water. If someone can come up with manufactures data that says otherwise I'm not going to worry about my ferrite chokes getting wet.

    Powdered iron cores, of course, are a completely different animal.
     
    WA7PRC likes this.
  4. KD8SLQ

    KD8SLQ Ham Member QRZ Page

    In addition to protecting the components from the weather, the box plays another significant role. The box takes the mechanical stress of the antenna installation. Without the box, the whole assembly is handing on the electrical connections of your assembly. The unit will physically last longer without the additional load on your parts.
     
    N2EY and K3XR like this.
  5. KN4FAZ

    KN4FAZ Ham Member QRZ Page

    (KD8SLQ) My plan was to secure the assembly to a section of ABS to relieve any mechanical strain.
    (KK5JY) The thermal expansion and contraction mentioned is something I had not considered and (VK4HAT) a valid point in reference to water possibly changing the characteristics of the choke.
    (WA7PRC) The idea of building it in a PVC cap, or any enclosure, left open at the bottom is valid in the sense that you can't keep mother nature out but having good air flow will dry and cool the choke.

    Thanks for the input, I've only been licensed for a few years, sometimes my reach exceeds my grasp and every day I seem to learn something new.
    73
     
  6. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    All good advice and solutions however, the choke should not get hot. Heat is an indicator of loss, and a well designed antenna and feed line system should be very low loss.

    There is absolutely nothing wrong with putting your choke in a small light weight enclosure, and sealing it with RTV or similar. Monkey Sh-t tape will also make an excellent weatherproof seal. I have an Icom AH4 that had been outside in the elements, rain, snow, ice, and blazing summer heat, for three years and absolutely nothing got into it. Moisture can absolutely cause problems, mostly when it is wicked into the coax, or the ladders line.
     
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    In 'bout 10 years, mine never got wet. The antenna was on the windward sifde of my house. Everett (aka "Everwet") WA looks west thru the Strait of Juan de Fuca that channels yuuge storms my way.
     
  8. W4IOA

    W4IOA Ham Member QRZ Page

    Boxed mine like this when I had my yagi, nice and tidy look and never had a problem. For my 17m dipole just put it in an old pill bottle with silicone, but that was only a temporary installation until I bought and got a GAP Titan installed. The pill bottle held up for the 18 months without issues.
     
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  9. K4AGO

    K4AGO Ham Member QRZ Page

    Flex Seal only works on flat bottom boats made with window screen. :D
     
    KU4X, W4NNF and KA4DPO like this.
  10. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    Years ago we used bees wax. Only problem is that it tends to harden over time, and is a bugger to get off if you need to do repairs.
     

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