The L54123 from Mercury Systems is a Diplexer with Frequency f1 1.567 to 1.583 GHz, Frequency f2 1.219 to 1.235 GHz, Attenuation 65 to 70 dB, Insertion loss 1.9 dB, Frequency 1.567 to 1.583 GHz / 1.219 to 1.235 GHz. Tags: Module with Connectors, Cavity. More details for L54123 can be seen below.