The Pi-Star has the capability of working across digital modes. This means you can use a C4FM (YSF) radio to talk on DMR and vice-versa....
The FT-70D is a great little radio that I always recommend for new hams as well as for experienced hams who want to try digital voice....
To work simplex with your DMR or C4FM radio please do not use the FM analog national call frequencies 2m (146.520 MHz) or 70cm (446.000...