What does switching to digital mode on Yaesu Xcvr's (or any other HF radio) actually do?
The documentation states that "specific digital mode selections, which include custom BFO offsets to optimize the receive and transmit passbands for the mode selected".
So the context of this question is a friend whom recently purchased an FT-840 HF Xcvr which doesn't have a digital mode selection to speak of. How can he tune his radio to match the performance of a radio with a digital mode option? Besides BFO offsets, what else does digital mode do, and how would one mirror that same configuration on a radio without "digital mode"?
Page 36: Digital Mode selecion : PSK31-L or PSK31-U http://www.download.n7tgb.net/yaesu/ft897/ft-897_operating_manual.pdf