G4NSJ – Triplexer 6m 2m 70cms



I’ve just installed a Diamond MX-2000 triplexer for use with my triband antenna. The triplexer is bidirectional. As you can see from the diagram below, three radios can be connected to one triband aerial, or three aerials can be connected to one radio.

Triplexer - 6m 2m 70cms
If you have limited space for aerials, then a tribander is a worthwhile investment. I prefer separate radios for separate bands, rather than a so-called shack in a box, so the triplexer is the answer… one aerial for three radios.

A triplexer consists of three bandpass filters.

I’ve not yet carried out any tests with my Nano VNA, but I’ve received weak signals on 2 metres while transmitting on 6 metres, and vice versa, with no noticeable desensing.


Passband frequency Insertion loss Power
1.6 to 60 MHz less than 0.15 dB 800 Watts
110 to 170 MHz less than 0.2 dB 800 Watts
300 to 950 MHz less than 0.25 dB 500 Watts

Impedance – 50 ohms

VSWR – less than 1.2 (in amateur bands)

Isolation – more than 60dB (in amateur bands)

The triplexer.

Pictured below is my triplexer in situ. Diamond MX-2000 Triplexer




A Diplexer is a device that allows two different transceivers to share a single antenna. Both signals need to be at different frequencies by a significant amount so the filters can easily separate them. The frequency difference might be around 95MHz in the case of the 6 metre and 2 metre amateur bands.


A Duplexer is a device that allows a transmitter and receiver to use a single antenna simultaneously, while working on similar frequencies. A duplexer would be used on an amateur radio repeater where the difference between the transmitted and received frequencies might only be 600kHz.