The 74-37-02A from TX RX Systems is a RF Duplexer with Frequency 144 to 174 MHz, Band 1 144 to 174 MHz, Power 400 W, Insertion Loss 1.35 dB, Isolation 80 dB (Between Channel) / 57 dB (Per Channel). Tags: Rack Mount. More details for 74-37-02A can be seen below.