I'm looking at picking up the TYT TH-9800, which is a Quad-Band FM radio on 10m/6m/2m and 440 (I'm lucky enough to have some 6m and 10m repeaters in the area). I know there exists quad band antennas for this radio, however not only are they a bit of a compromise on all bands, but they all use UHF connectors for the mount connection - which I am very against. So I began my search for a triplexer so I could use 3 separate antennas, this should be more efficient than the one quad band, allow me to swap out the HF antennas as needed, have a much larger selection of antennas, and allow me to switch the HF side (via antenna switch) to another radio while also not sacrificing 6m/2m/440.

I started searching online, however no one that I've found makes such a triplexer - the best off the shelf solution I can do is 2 diplexers; one VHF/UHF and 6m/HF diplexer with a second 6m and HF diplexer. I'm not the biggest fan of that solution. So I started looking into the DIY/Homebrew approach, which also was unfruitful. I found plenty of resources for making diplexers, but very little for triplexers.

So here's the TL;DR: does anyone know the proper formulas to make triplexers and/or know of any good resources for building?

Below is what the end state would look like, also with an AnyTone 6666 for 10m AM/SSB/CW. I should also note this will be a mobile solution, thus only focusing on 10m for now.

                    TYT 9800                 AT6666
                    --------                 ------
                        |                      |
                        |                      |
                   -----------                 |
           ___     |triplexer|                 |
    2m/440 \|/     -----------                 |
            |       |   |   |                  |
            |-------|   |   |    ----------    |
     ___                |   |----| sw box |----|      ___
     \|/ 6m             |        ----------           \|/ HF/10m
      |                 |            |                 |
      |-----------------|            |-----------------|
  • 1
    $\begingroup$ Have you tried looking at Elsie (filter design software)? I do not have it in front of me but I believe it has that capability $\endgroup$ Commented Jul 25, 2020 at 22:17
  • 1
    $\begingroup$ Welcome to HamSE. I hope we can help. I wonder, though, why do you want to use an n-plexer instead of a simple antenna switch? $\endgroup$
    – Brian K1LI
    Commented Jul 25, 2020 at 23:08
  • $\begingroup$ I've found the Elsie software, but it's Windows only, I run Linux exclusively. But I may give it a shot under Wine. Also, the reason I don't want to use a switch (from the 9800 anyway) is I'd like to easily go between bands while underway (this is a mobile station after all). $\endgroup$ Commented Jul 25, 2020 at 23:56
  • 2
    $\begingroup$ Are you sure a triplexer is more efficient than a multiband antenna? $\endgroup$ Commented Jul 27, 2020 at 14:27

1 Answer 1


If you don't mind shifting your DIY attention to a home-brew 6m/10m vertical (perhaps a trap implementation), you might look at a triplexer like this that gives:

  • low pass at <90 MHz for 10/6m
  • mid pass at 130-200 MHz for 2m
  • hi pass at 380-500 MHz for 70cm

This obviously has the UHF connectors that you're looking to avoid, but that is easily addressable with adaptors right at the box.

I know this is proposing a solution that is different to your original question, but since it's been unanswered for so long, I thought I'd throw something at it in the event you or others might find some use in it.

  • $\begingroup$ The more common term for a "mid pass" filter would be a band pass filter. $\endgroup$
    – Jim
    Commented Jun 29, 2022 at 15:01

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .