Awhile back someone had posted about tuning up ;a duplexer that looked good on the network analyzer but still had receiver desense and replacing the duplexer with another would cure the problem. This might be one of those cases where trying different length interconnect cables between the transmitter and the duplexer might cure the problem as the transmitter could be generating spurs that cause receiver noise. This could be one of those "the transmitter doesn't like reactive loads" things. With a particular duplexer connected to the transmitter with a certain length cable it may cause the transmitter to act up. Something to look at.
73 Gary K4FMX
