Presented here are some high power low pass filters for 144 and for 432 MHz. These filters are coaxial step impedance filters and can take a lot of RF power. In fact the power is limited by the connector. Off course the 7/16 connector can tale a lot more power.
The inner and outer conductor are separated by a 0.3mm thin teflon sheet. Tuning this filter can be best done by terminating one end with a good 50 Ohm load and measuring the S11 on the other end. A good match will assure you a low loss. The stop band attenuation has never been a problem.
Below are the construction details of the filters:
Measurements by Jack Smeets, PE1KXH