220-MHz Transmit Combiner Cuts Intermodulation Interference

The DB4370-DPM series of transmit combiners for the 217- to 221-MHz range uses high Q tuned cavities to greatly reduce intermodulation (IM) interference in radio installations. With the increasingly crowded spectrum and many tower sites, frequency planning alone can no longer alleviate intermodulation interference. The DB4370-DPM series is available in two- to eight-channel configurations that feature low insertion loss at frequency separations down to 50 kHz. The voltage standing-wave ratio (at 50 ohms) is less than 1.25:1 at the input and less than 2:1 at the output. Maximum power rating is 125 W. The units are shipped pre-tuned and installed in a 55-in. frame rack.