The Alliance Tenna-Rotor® consists of two units: the rotor unit, which mounts on the mast below the antenna, and the control box, which is placed on or about the TV receiver. These are interconnected by a four- or five-conductor cable. The theory of operation concerns two separate circuits. The first is the power circuit, which in all Tenna-Rotors® transmits the power that actuates the motor and rotates the antenna. The second is the indicator or signal circuit, which reports the rotor’s progress back to the control box. In the K-22, the signal circuit turns on the panel light when the rotor reaches the stop or end of rotation. In the T-10, T-12, T-20, and T-45, the signal circuit registers the antenna direction on the control box indicator. The signal circuit in the U-83, U-98, and U-100 actuates the escapement assemblies, causing the rotor to turn to the desired position automatically. The Model C-225 is an automatic, transistorized unit using a unique patented Phase-sensing unit. The use of this bridge circuit results in extreme accuracy, quiet operation of control, and constant synchronization. Rotation is attained from a reversible, capacitor-type 24 volt, AC motor and is limited by mechanical stops within the rotor housing. The U-83, U-98, and U-100 controls are protected by a thermostat within the rotor or control assembly. The Alliance Tenna-Rotor® Models K-22, T-12, and U-98 produced after June 1, 1958, have been changed from a speed of 2 RPM to a speed of 1 RPM. This change makes possible better orientation for “color” and “black and white” television reception, improves torque, braking, and general overall performance. Kits are available to convert the T-10, U-83, K-22, T-12, and U-98 rotors manufactured before June 1, 1958, to 1 RPM.