Duplexer or Antenna Switch?

Discussion in 'General Technical Questions and Answers' started by 2E0RPS, Sep 11, 2008.

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  1. 2E0RPS

    2E0RPS Ham Member QRZ Page

    I'm using two Transceivers.

    One for HF and the second for VHF/UHF. My multiband aerial will cover all these bands.

    If i connect the aerial to the two transceivers (one antenna to two transceivers) should i use a Duplexer or a 2 way antenna coax switch?

    Many thanks in advance

    73 de Rod /2E0RPS
  2. G3TXQ

    G3TXQ Ham Member QRZ Page


    You need the 2-way coax switch.

    By the way, I'm intrigued to know what antenna you have that's giving you HF, VHF and UHF coverage?

  3. 2E0RPS

    2E0RPS Ham Member QRZ Page

    Thanks Steve,

    I've got a 2way coax switch but it think it was designed for CB only not sure if i can use it on HF/VHF/UHF bands.

    In regard to the antenna I'm using a Sandpiper MV6+3 multiband vertical made in Britain.

    in reality the antenna is designed to cover 80 to 6m. However with the addition of counterpoise wire it works well on all HF bands including 2m and 70cm in the sense that i can engage all city repetaers with an overall VHF/UHF SWR below 1.7.

    73 de Rod / 2E0RPS
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I disagree. You can use a 2-way switch, sure, but then you'd be on "either" HF or VHF/UHF and you couldn't use them both at the same time.

    With a duplexer, you can use both rigs simultaneously, up to the power limitation and isolation rating of the duplexer.

    I have some from Comet rated 600W PEP on HF and 200W PEP on VHF-UHF and they are essentially lossless and have >60 dB isolation HF:VHF. As such, just as efficient as a "switch," but allows operation with both rigs and a common antenna at the same time.

    The duplexer is likely to cost more, but not that much more. A very good coax switch that's low loss and high isolation at UHF is in the $80 range ($USD). A duplexer to do this job is in the $100 range ($USD), so the premium is not large for the added versatility.

  5. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    ::Thought I'd give you a reference. I see Comet now has a "600W" model that does exactly what you're looking for, and it's cheap:

    Model CF-360A:

    HF/6M-440MHz Duplexer
    Band Pass
    Ins. Loss
    Max Power
    600w PEP
    600w PEP
    More than 45dB
    Low In:
    High In:


    Steve WB2WIK/6
  6. K3ACE

    K3ACE Ham Member QRZ Page

    Isn't the correct term a "diplexer"? I thought a duplexer was used when simultaneously transmitting and receiveing on the same antenna...ie a repeater.
    Last edited: Sep 11, 2008
  7. 2E0RPS

    2E0RPS Ham Member QRZ Page

    Thanks for your input WB2WIK

    I see your point. Obviously the possibility to use the rigs simultaneously without switching is a better option.

    73 de Rod /2E0RPS
  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    ::In this case, the term "duplexer" is appropriate, as you can indeed transmit and receive simultaneously using one: You can transmit on HF and receive on VHF (duplex); or the other way around (duplex); or you can receive on both bands (diplex); or you can transmit on both bands (diplex).

    I think "duplexer" is a perfect description of what these little units truly are.

  9. K3ACE

    K3ACE Ham Member QRZ Page

    Didn't think of it that way. Of course you can listen to a subband while txing on the primary. I am that much smarter now.
  10. 2E0RPS

    2E0RPS Ham Member QRZ Page

    Thanks again.

    The antenna will be connected to a Yaesu FT920 (HF to 6m) and an IC 706MKIIG (2 to 70cm) in few words the duplexer has to cover 1.3 to 50mhz / 144-440mhz. Will have to be a different model than the one you mentioned. in anycase i understood what i need now..many thanks 73 de Rod /2E0RPS

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