Some time ago N4IS ordered a triplexer board to build a triplexer to use with his Waller Flag receiving antenna on low bands (1.8, 3.5 and 7 MHz). I’ve never thought of using triplexer that way, but it turned out to be a good idea to have all three low bands available from a dedicated receiving antenna to any radio in SO2R setup.
Using a software, I designed a new low band triplexer for him for 160-80-40 meter bands and later, I built the triplexer for low bands.
In a regular RX/TX operations, it can be used with multi-band vertical or wire antenna. If you do not need 160 meter band, you can use it as a duplexer simply terminating 160 band port with 50 ohm load (You have to build 160M band part of schematics anyway).
I’ve built some duplexers before to be used with 40 and 80 meter dual-band antennas, but this is the first time I built the triplexer for low bands.
Below is all information for low band triplexer I built for a regular TX/RX usage.
Please, see some parts values from schematics below. On a triplexer PCB 20M is 160M, 15M is 80M and 10M is 40M.
As expected all numbers for a low bands triplexer are a little bit better than those for a high band triplexer.
- Insertion Loss is below 0.08dB
- Return Loss > 26dB (VSWR < 1.1)
- Band Isolation is better than -32dB
- 100 Watt output power 100% cycle
- 200 Watt PEP
Please, use pictures above as a reference for the coil types and number of turns to the table below. Capacitor values can be +-1% of calculated values.
|Name||Value||Core/Caps Type||# of Turns or Caps|
|L160-5||895 nH||Air Coil||9t 15-20mm in diameter|
|C160-1||1557 pF||Mica or TDK HV||Any values (4 to 5 caps)|
|C160-2||1192 pF||Mica or TDK HV||Any values (3 to 5 caps)|
|L80-4||610 nH||Air Coil||7t 15-20mm in diameter|
|C80-1||709 pF||Mica or TDK HV||TDK Low-Dissipation|
|C80-2||1806 pF||Mica or TDK HV||Any values (4 to 5 caps)|
|C80-3||466 pF||Mica or TDK HV||Any values (4 to 5 caps)|
|C80-4||3200 pF||Mica or TDK HV||TDK Low-Dissipation|
|C40-1||484pF||Mica or TDK HV||TDK Low-Dissipation|
|C40-2||1551 pF||Mica or TDK HV||Any values (5 caps)|
|C40-3||590 pF||Mica or TDK HV||TDK Low-Dissipation|
|C40-4||4513 pF||Mica or TDK HV||Any values (4 to 5 caps)|
|C40-5||2184pF||Mica or TDK HV||TDK Low-Dissipation|
Please, see some graphs below. 160M band tuned mostly for 1.8-1.9MHz range.