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Diplexer/Triplexer - freq plot & outdoor use

Discussion in 'General Ham Radio Discussion' started by archjeb, Dec 7, 2017.

  1. archjeb

    archjeb
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    Folks,

    Couple of questions and I was hoping someone had some experience in this area they could share.



    First off, I would like to use two (maybe a 3rd) antennas with a single feedline. I see a ton of diplexer's and triplexers out there at a reasonable cost.
    The only concern I have is that most have a finite frequency range.
    For example, the Diamond MX62m, http://www.diamondantenna.net/mx62m.html, has a frequency range for the two ports of 1.6-56/76-470. This is great for my TX/RX general use - One Antenna for HF and one for vhf/uhf.
    But I like to also monitor some of the local state/city agencies on 850+Mhz. How much attenuation can I expect after the 470Mhz? Does anyone have an SA/TG plot of one of these diplexers to see what I'd be looking at?
    I really didn't want to go with a triplexer and a 3rd antenna just to RX those 800-900Mhz for RX...

    My second question is for outdoor use. Most of the diplexer's and triplexer's are not outdoor rated. I think most are using them off the back of the radio that has a separate HF and VHF/UHF port to combine to a single feedline. I of course want to use it on the antenna side for this use case. What have you done to weather proof these for this use case? I guess a PVC outdoor box by the antenna mast would work; Just wish they had N connectors or so239 connectors instead of the pigtails they have...


    Any lessons learned using these would be much appreciated.

    Thanks,

    -J
     

  2. Tallman

    Tallman
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    W9WDX Amateur Radio Member, KW4YJ EXTRA class

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    Do you mean antenna switchers?
     
  3. archjeb

    archjeb
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    I prefer not to use a switch...just a passive filter / diplexer to do the job. But it appears that the only thing commercially available is a split with HF/ VHF-UHF where UHF max's out at 470Mhz. There are triplexers that go into the 1.2G range, but then they combine HF and VHF; UHF is on the secondary port.

    -J
     
  4. BBI

    BBI
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    I have Comet and Diamond diplexers that have N-connectors on the UHF side pigtails.

    I have not put diplexers outside, but I have considered thoroughly wrapping one with self-vulcanizing silicone tape, followed by a coat of liquid tape spray to be sure.
     
  5. archjeb

    archjeb
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    Hi BBI,

    Did you ever check on a Tracking Generator and SA to see what the frequency response curve is on it? I'm curious of how fast things roll off on the upper UHF range.

    -J
     
  6. BBI

    BBI
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    No, I did not do that. Sorry.

    I plugged one into the single output of a dual-band radio to split it off into 2 separate amplifiers, one for each band. I plugged another one into the amplifiers to feed one dual band antenna. It works fine, so that's all I did.
     
  7. N0NB

    N0NB
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    If you trust MFJ "quality", the MFJ 4946SN may be close to what you're looking for.

    I've considered the same thing of using a tower mounted triplexer for some 6m, 2m, and 70cm loops. I've not heard of many good things regarding the quality of the cable on those with the pigtails.

    WiMo out of Germany offers a mast mounted 2m/70cm diplexer rated at 100 Watts.
     

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