What is the difference in the Ham series of rotors?
The Ham-M rotor was released in 1957, and there were 5 series with the last rotor being produced in 1973. The Ham-M rotor would have the series number, 1 – 5, followed by 3 digits which indicated the week and year of manufacture. For example, a rotor with the series number 5 322 would be a Ham-M, series 5, manufactured in the twenty-second week (the ’22’ in ‘322’) of the year 1973 (the ‘3’ in ‘322’). A Ham-M has a single-levered control box with a meter. In 1973 the mold for making the Ham-M control unit shell was destroyed in a fire. So rather than spend the money to replace the mold, the Ham-2 was born. The rotor was the same as the Ham-M, but the control unit was replaced with a three-button unit with a continuous meter reading. In 1977 the Ham-3 rotor was released. The Ham-3 supported a new motor with an internal brake, as well as a brass motor gear. The brake wedge was redesigned, as was the brake housing, which gave the new unit a capacity for more wind surface area. The control
