We have a SIEDLE NG 602-01 (23.3VAC 0.3A, 12VDC 1.6A) mains rectifier in the cellar which supplies the Siedle NS711-01 secondary signal device at the door and the bell panel (Siedle Vario Audio) outside. Can I simply replace the panel outside with the Uni G4 or do I need to do more? If so, can someone explain what I need to do? I would be very grateful for any feedback.