Spec Sheet Preview: The Alpha Communications® IA543 Power Pack Amplifier is a self-contained unit not requiring an external amplifier. The IA543 is designed for use with 5, 4 or 3 wire apartment speaker type stations and provides amplification, control and power circuits needed to operate a complete apartment intercom system. Voice volume control and tone volume control are easily adjustable through the screwdriver slot on the front panel. It is also a direct replacement for the previous model(s) PK543 and PK543A. Additional functions include multiple entrance …