In systems using multiple (indoor & outdoor) antennas, a certain distance is required to keep your antennas from receiving each other's signal and oscillating and shutting the amplifier down. At least 50 feet of separation is recommended for any repeater system; this means 50 linear feet, NOT 50 FEET OF CABLE. Metal roofing and other non-RF permeable materials can also help to provide a barrier against oscillation.

Requirements:
• 50db amplifiers require 50 feet total separation.
• 60db PCS (1900MHz) amplifiers require 68 feet of total separation.
• 60db Cellular (800 Mhz) amplifiers require 75 feet of total separation.