Besides being illegal for use in GMRS, I think you'd find the simplex repeater (store and forward) really annoying in very, very short time. By "BF" I am guessing you mean Baofeng? Your abbreviations are not necessarily anyone else's. Better to use the full word. Yes, you can use a Baofeng for the receive part of a repeater, but you won't be happy. It will be desensed by the transmit side, and isn't a particularly sensitive radio for this purpose. If you're serious about building a repeater, get a pair of decent mobile radios. Interconnect them properly and use a decent duplexer and antenna. If it was me, I'd use Motorola CDM's, but I already have the software, cables, and experience with them.