The power supply that comes with the unit is 10v @ 500mah and the cradle reads 8.30v and the battery is rated @ 7.4v. The first thing to do it ditch the no name wall wart (10v) and just use a better quality dc 9v 500mah or even 1 amp power supply to be a closer match. I believe that the base has a built in dc to dc converter to step down the voltage of 10v down to 8.30v and the rest is just given off as heat (not good). I will try this with my radio and report back.
P.S. Make sure you run the 9v ps at tip + and sleeve -