John, A couple questions.
What are you using for interconnect cables, antenna, feedline ? Tell us something about the RF environment Hostile or not ? What type of radio are you using ? That Motorola duplexer is a very poor duplexer. With all the holes in them after a few years they may generate more noise than the suppress. All interconnecting cables need to be superflex or some other solid shielded cable. Any RG type cable the braided shield becomes illuminated and will cause noise and if there is a non linear junction can produce intermod. Send me the details and I will try and make some suggestions. Robert / KD4PBC
