Low power carrier setting on these radios is 10 watts. Problem is the lower the carrier the more negative peak cutoff you're going to get because of the low output voltage from the series pass modulator.
It gets so bad around or below the optimum carrier range of 25 watts that you can't approach 100% positive peaks before RF cutoff. An improvement can be seen adding a 10 ohm resistor between the driver and final. This is outlined in another tread in this category.