for a mobile radio a stable radio and un-locked clarifier is a must,, no mobile that has a locked clarifier is going to always be on frequency, especially around here with winter temp changes from cold vehicle (-10*f to 80*F) to heated up interior. I have the optima mk3 in the mobile now and no problem talking to anyone no matter what the interior temp is, just tune the clarifier and talk,, if the interior and radio warms up some just touch up the clarifier, no need for a freq counter
now my maxlog m-8800 never needed the clarifier touched no matter what the temp when I had it in the mobile last winter, but the optima receives so much better and easier to tune through the band that it is now my radio of choice for the mobile