The power input to the XA-1900-1 and RA-1900-1 box is designed to accept AC or DC voltages. In order for proper operation, the AC level should not drop below 14 volts rms or the DC level, below 15 volts DC. As long as this criteria is met, unregulated sources may be used. To prevent damage, voltages higher than 18 volts AC or 25 volts DC should not be applied. Suitable voltages can be obtained from various low voltage transformers or from a FiberLink XP-1000A, 115 to 14 VAC plug-in adapter.