The 24v SteppIR power supply has been discontinued, the 33v is now the replacement for all power supplies.
For all control cable lengths the 33v is now standard. It is available as an upgrade for existing antennas and shipping with all new antennas. For cable runs over 300 feet we recommend the Remote Driver Board (see controller information page). The remote driver board allows you to run cat5e cable up to 2000 feet away from the tower base (power required at tower for this option)