To drive the Vibration Exciter Type 4809 To drive the Mini-Shaker Type 4810 safely to full rating General Purpose Power amplifier 75 VA power output capability Switchable 5 A or 1.8 A max. current limiting 40 dB voltage gain Built-in attenuator and continuously variable gain control Low distortion over wide frequency range Built-in protection against sort-circuit and excess heat sink temperature Front panel indicator light showing clipped output signal