# DIY Triplexer for HF (low), 6m (med), and 2m/440 (high)

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
|                 |            |                 |
|-----------------|            |-----------------|

• 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 – Chris K8NVH Jul 25 at 22:17
• 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? – Brian K1LI Jul 25 at 23:08
• 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). – Michael KC1MJP Jul 25 at 23:56
• Are you sure a triplexer is more efficient than a multiband antenna? – Phil Frost - W8II Jul 27 at 14:27