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PL-259 connector on 434MHz antenna: bad idea?

Discussion in 'General Electronics Chat' started by earckens, Apr 13, 2018.

  1. earckens

    earckens Member

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    I obtained a 5 dBi 434MHz antenna with a male PL-259 connector. I read the usefulness of this type of connector is limited to 30 or so MHz.
    If I connect a female PL-259 to BNC connector and then to RG58 cable would that be acceptable for 434MHz use? Or should I junk this antenna?
     
  2. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Where?

    All good at 434MHz. Just curious, what power levels?

    Anyway, see this list...

    What's your plan?
     
  3. earckens

    earckens Member

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  4. dave miyares

    Dave New Member

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  5. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    The PL 259 and SO 239 connectors go back a long way. Here is what Amphenol says about their PL 259:
    "Originally intended for use as a video connector in radar applications, UHF coaxial connectors are general purpose units developed for use in low frequency systems from 0.6 - 300 MHz. Invented for use in the radio industry in the 1930’s, UHF is an acronym for Ultra High Frequency because at the time 300 MHz was considered high frequency.

    UHF connectors feature a threaded coupling. UHF connectors are popularly used because of its ease of assembly. The UHF solderable screw-on termination feature requires no specialized crimping tools".

    Amphenol UHF Connectors.

    My read on several specifications sheets is about the same in that 300 MHz is the upper frequency limit.

    The Wiki shows a pass band of 100 MHz as I read it. The design is from an era when anything over 30 MHz was considered UHF. The design runs back to the 1930s.

    Ron
     
  6. earckens

    earckens Member

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    So, not usefull on a 434MHz antenna?
    Would it matter at low powerlevels as for the HC-12?
     
  7. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    As to power no, the HC-12 a small 100 milli-watt transmitter. During my early days it was not unusual for guys to run 1 KW using the old PL 259 in ham radio. The PL 259 would not really be useful because of not only its upper frequency limit and the loss but it is also a rather large and bulky connector. With the HC 12 there are likely much better options and much smaller options. Similar to what you see used on wireless routers. Here are some examples of what I am getting at.

    Ron
     
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  8. dave miyares

    Dave New Member

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  9. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    What 434MHz antenna are you using? The one recommended by AAC (to mate to the on-board IPEX20279-001E-03 antenna socket), or something else?

    Anyway, upon further investigation, I'm thinking signal losses will be excessive (especially from the cabling) and awkward with your current plan.

    And ditto to ron.
     
  10. earckens

    earckens Member

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    Thanks for that info; conclusion: ditch that antenna.

    I have been looking for an alternative for the helix antenna supplied with the HC-12 because I need to mount it a meter or so further from where this module sits.
    From the info received here I will use u U.FL connector (to connect to the pcb connector) with coax to female or male SMA connector to attach the antenna.
     
  11. unclejed613

    unclejed613 Well-Known Member

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    from what i've seen of tests done with PL-259/SO-239 adaptors, the losses at 450Mhz or so are small, about 1 to 2 db. return losses are about -10db, which is an SWR of about 1.9:1. it's usable, but not ideal.
     
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  12. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Many amateur and commercial UHF transceivers (1W to 100W RF power output@ 420 to 512MHz) are sold with SO239s.
     
  13. nsaspook

    nsaspook Well-Known Member

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  14. earckens

    earckens Member

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  15. unclejed613

    unclejed613 Well-Known Member

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    yeah that's the one i was looking at. follow the curves for PL/SO, and they perform a bit better than most people think, but they are still not in the "very good-excellent" category, but in the "usable" category. interesting how the first one has peaks and dips in it on the return loss chart. they also have peaks and dips in the forward loss chart, but still below 0.5db. just don't use any UHF barrel adaptors, those are worse than just using the PL/SO connectors.
     
  16. earckens

    earckens Member

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    What is a barrel adaptor?
     
  17. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    Barrel adaptors and barrel connectors are just connectors which might for example go from one connector type to another or from one type connector to the same sex of that connector type. For example BNC Male to BNC Male. Here are several examples on Amazon.

    Ron
     

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