Check the listing for details. Krohn-Hite 3750 Variable Filter, .02-20 KHz, High, low, Band pass filter. Condition: Used. Listed at 275.00 USD. This unit powers up and the power supply rails are in-spec (shown in the attached video). The Krohn-Hite 3750 Variable Filter is a versatile band-pass filter designed to provide high-quality signal conditioning in the frequency range of .02-20 KHz. This filter, manufactured by the reputable brand Krohn-Hite, allows for customizable filtering options with its high and low pass filters, making it ideal for various applications in RF and microwave pass filters, signal sources and conditioning, and measurement and inspection. Its precision engineering and adjustable settings make it a valuable tool for improving signal quality and achieving accurate measurements in a range of industrial and business settings. Comes with a copy of the operations manual.