You should not need an external tuner unless you run an amplifier after the radio. One thing I will tell you about the internal tuners, if it takes a lot of time to tune in on several bands and it seems to hunt for a long time there is an easy fix and you don't even have to take the covers off. Simply connect your radio straight to a resistive dummy load and for each band start the auto tune and then go to each band and let the auto tune "Zero out." I bought a Kenwood at a ham fest at a great price with a "Defective" auto tuner. I hooked it up in my truck on a good antenna and it did the tuning hunt. SWR did not get down into a level I would use. Took it to my bench and hooked it up on the dummy load it hunted for about 20 seconds on each band and tuned in. Went back through and checked it again and it adjusted for less than a second on each band. On the same antenna where it would not tune in, it locked in quickly and SWR was low. So it works fine now.