Hello, Captains,In my twenty years (!!) of Flight Simulator (the first one was even before Windows and MS), I have never seen a working Transponder, except the basic when it gets a number from ATC.1 - Does anyone know if and where there is one?2 - What exactly are all the functions that are marked in the PMDG instrument, although they don't work?3 - Why no one develops one?ThanksBPilot

2) Sorry, but the functions on the PMDG transponder do work.You can TEST the transponder and you can get Traffic and resolution Advisories, suggest you read the manuals about the TCAS gauge and how to get it to 'see' other aircraft.If you fly on line with the likes of VATSIM then the transponder squwak code identifies your a/c to ATC and transmits your altitude.So far from not working it does a pretty good job IMO.Dave