Tribander and Triplexer with BPFs setup should bring no interference at all between bands, except 2nd harmonics from 20M TX to 10M RX, like 14025KHz TX will give 28050 KHz 2nd harmonics signal.
The harmonics level depends mostly on an Antenna type (No LC trap antennas are better in this term), and Triplexer design. With bad LC traps on a tribander antenna, the 2nd harmonics can cover the entire 10M band up to S3-S4 noise level.
Tribander without LC traps behave much better in this term.
Some numbers achieved for the VA6AM Triplexer:
- Insertion Loss (IL) < 0.15dB
- Band Isolation > -30dB. I got better than -40dB attenuation between 10 and 20 meter bands.
- Return Loss (RL) > 26dB. It means there is no SWR higher than 1.1 on all bands.
- 100 watt output power with 100% cycle
- 200 watt output power PEP
- For the triplexer design the most important thing is a close to 50 Ohm impedance on every band and antenna port.