Unless we want lightning fast antenna rotation, we're going to need some sort of gearbox with virtually any motor we're likely to find. We could gear the drive to a simpler pot as well.
Gus, I used a pulse width modulator to slow my DC motor down with out having to loose a lot of power. This eliminated the resistor and the motor ran cooler. Mine cost $80.00 usd out of Canada but I understand that they are nothing more then modified fluorescent light dimmers. My thought would be to count the pulses instead of a pot. I think we will be stuck with gear motors if the goal is to go small and have lots of torque. Even with the PWM mine was a gear motor but it beats a big restive load hands down.
I would like to move away from stops and find another way to establish 0~360az and 0~90/180ex indication so as to enable continuous rotation to do continuous sky scan or search and rescue with out having to wind up and damage my coax. I am not sure what battle ship radar uses for constant rotation but that would be the ticket.
Bob Campbell KB3PMR