In response to this thread and our experiences, we have put a web page together that includes the information from a previous email in this thread, some of the responses, and some plots and pictures explaining the problem having to do with potential desense issue on D-Star (and other) repeaters.
The link to this new page is here: http://utahvhfs.org/dstar_repeater_installation.html In particular, this page includes plots showing the responses typical of duplexers used in amateur service - and why the duplexer alone may be inadequate by itself - especially if it is used at a site shared with other services, even if they aren't anywhere near the ham frequencies in use! 73, Clint KA7OEI
