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Suggestions for a 2MLDPA TX RX duplexer/combiner?

John WA7UAR
John WA7UAR Member ✭✭
edited June 2020 in Third-Party Software
Looking for suggestions for a duplexer/combiner to join my normally split feed line configuration into a single common feed line from the back of my 2MLDPA. Thank you!
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Answers

  • WX7Y
    WX7Y Member ✭✭✭
    edited June 2020
    Easy enough to build one but I seen one on MFJ Web site  a MFJ-1708SDR TX/RX switch that should do what you want, looking at the Schematic and reading the description.

    Hope this is what you where asking about.
    73's
    Bret
    WX7Y

  • John WA7UAR
    John WA7UAR Member ✭✭
    edited February 2019
    Thanks for responding Bret but I don’t think the 1708SDR is what I’m looking for. The amplifier in the picture can push out 70 watts on 2 meters. I think I’m looking for a duplexer that can merge the two separate N-type antenna connections into a single feed line connection. Maybe one of these from Comet or another manufacturer? But maybe my terminology is wrong? Maybe a diplexer/splitter/combiner?

    http://www.cometantenna.com/amateur-r...
  • David-N5PSM
    David-N5PSM Member ✭✭
    edited March 2019
    Why not change the internals to combine the connections?  I think DEM will help you with documentation?   Mine was ordered with both connections combined.
  • Mack
    Mack Member ✭✭✭
    edited February 2019
    I agree with David. DEMI provides instructions to rewire the RF and IF connections as combined or separate. It usually takes me less than 20 minutes to make the changes if you have moderate soldering skills. Or if not, send the unit back to DEMI to make the changes. 

    73,

    Mack
    W4AX
  • David-N5PSM
    David-N5PSM Member ✭✭
    edited February 2020
    John,   Did you problem get resolved?

  • John WA7UAR
    John WA7UAR Member ✭✭
    edited February 2019
    Thanks David. Sandra at Down East Microwave Inc. responded to my query with the following: “Now if you are using a external amplifier then the proper T/R relay needed will depend on the amount of power you will be running. As a example you could use a CX520D. This particular relay will only be good to 300W at 144MHz. If you are running more power then you will want to look for a different model that will be good for the amount of power you will be running. And pay attention to select one that has >60dB of isolation.” I’d prefer an external device approach to combine feeds in the short run so I have a quick and flexible way to reverse things if ever needed. But if I can’t find something then I can fall back on rewiring the internal connections. Any other suggestions for an external solution that is in a nice case and ready to “plug in and go”?
  • John WA7UAR
    John WA7UAR Member ✭✭
    edited February 2019
    I finally decided to go with this unit from MFJ after reading more about it in the March QST magazine. https://www.mfjenterprises.com/Product.php?productid=MFJ-1708B Thanks everyone.

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