I presume you are either going to use it on GMRS or on amatuer radio. I have built two repeaters out of Motorola micor radios and they both worked okay. The older trunk mount radio's use crystal heaters in the channel elements and as a rule, can easily meet the freq stability requirements. It is still a lot of work to do, when you can buy desktop repeaters like the Vertex VXR7000 for about $1200. I have seen some desktop units go on ebay for less than $600. Unless you are just a glutton for punishment or an experimenter, it "aint worth the effort"!