Jerry Conner said (in part):
I have a hard time with all the purest, my way or the highway mentality
I am hearing.
It's not that it's a elitist mentality, it's simply a technical requirement for successful operation. Even on a FM satellite, operating without full duplex would be about like trying to use your local 2M repeater with a transmitter and no receiver turned on until AFTER you called someone. You have no way of knowing if someone else is talking. Since on most FM satellites, the idle time between conversations is measured in milliseconds, your chances of successfully hitting an idle spot without knowing if your are getting through is quite slim. On SSB or CW on a linear satellite, without full duplex, you will forever be chasing trying to figure out where your downlink is. Even with complete computer control of dopler shift, you will still be chasing the other guy.
On an FM satellite, the situation goes something like this. A contact ends, and for example three people key up to make a call at essentially the same time. Depending on signal levels, maybe one person has a strong enough signal to capture everyone else, but more likely there is a massive hetrodyne between several signals. With everyone operating full duplex, we all hear that either someone else is capturing the uplink or the hetrodyne and drop carrier. If you're not using full duplex, you blindly keep transmitting and creating interference for the rest of the users.
The exception to all this is that if you are operating in a location that has almost no one to talk to (Hawaii comes to mind) since you are almost the only one around, you might get away without full duplex most of the time. A decade or so ago, every night there was a SE to NW pass that was well off the southern California coastline - such that the footprint only covered 50 - 100 miles along the coast. There were a small enough number of us in the footprint that we could actually hold several minute conversations with one or two other people. Non full duplex would likely have worked in that case. However for the previous pass that covered most of the US, I would not have even considered it.
BTW, note that in my first sentence, I said "it's simply a technical requirement for successful operation." The key word there was successful. Without full duplex you will occasionally make a contact (especially as mentioned earlier if you are almost the only person in the footprint), but if you want to routinely be successful on busy passes, there is no alternative to being full duplex. Period.
Jim Walls - K6CCC