The ES-242U is a 2 x 12 Time Code and Frequency Distribution Amplifier with an Automatic Switchover feature. It is designed to provide a simple/automatic method for switching between a Primary and Secondary Source. The unit receives time code (AM or TTL) or a frequency reference (100 Hz to 100 KHz) from two different sources (A & B). If a fault is detected from the primary source (A) the unit automatically switches to the backup source (B). Once a fault is detected, the unit remains in the "B" state until manually reset. A switchable audible alarm also sounds when a fault is detected. Front panel mounted LED's indicate status and a toggle switch allows manual switching between A and B inputs.