Thanks for the reply Erich. I will give that configuration a try.
Hi Tim, I have described the feature on my website www.dk1tb.de http://www.dk1tb.de , Engl. page 'Downloads', sect. 5g (Buffer Interfaces). You don't need a PC with a phyical COM port. The voltage at the DTR pin of my USB-to-Serial converter (which generates the Radio 2 COM port) changes between +6 (high) and -6 V (low), when the user switches between v/u and u/v satellites. The corresponding option in menu 'Options' must be checked, of course.
If the DTR pin is low, the buffer interface locks and the relay remains open. If the pin is 'high', the interface is routed and the relay closes. I do not have a transfer relay, but have successfully tested the function with a 12 volt coax relay.
73s, Erich, DK1TB