Last evening (Tuesday) there was a K6 calling on SO-50 almost the entire pass.  He obviously had a rx issue as he didn't respond to many calls.  He unintentionally QRM'd several QSO's.  Full duplex is not necessarily mandatory however if after a few calls without a return call, one may have a rx problem.  Caution with that PTT button especially on the FM birds. 73 Bob W7LRD Seattle (Go Seahawks)