All RF amplifiers will “react” in some way when a low pass filter is attached. This reaction is mainly caused by reflected harmonics. All RF amplifers generate harmonics. When a low pass filter is attached to the amplifer most of the harmonic energy is reflected back to the transistor causing reduced efficency and output power. The transistor will also run hotter.
The new LDMOS transistors have higher gain at high frequencies and create more harmonics; therefore, they are more sensitive to the reflections from the low pass filter. For this reason we have developed a state of the art low pass filter to match the state of the art transistors. This filter terminates all harmonics up to 550MHz with a 50 ohm 250W termination. This filter will improve the performance of all FM amplifiers.
This low pass filter is designed for use with the BLF574 and BLF369 modules operating up to 1200W.
– Silver Plated #8 AWG inductors.
– Teflon circuit board.
– 0.1dB Insertion loss typical.
– 30dB Return loss typical.
– 1/4 inch aluminum base.
– 3 inch x 6 inch size.