The Krohn-Hite Model 3988 Butterworth/Bessel dual channel filter is one of a family of filters carefully designed with the user in mind, providing ease of operation, reliability and price competitiveness.
The 3988 provides a tunable frequency range from 0.03Hz to 1MHz in the low-pass mode and 0.03Hz to 300kHz in the high-pass mode. Both modes are extended down to 0.003Hz with the 002 option. The frequency response characteristic is either maximally flat (Butterworth) for clean filtering in the frequency domain, or linear phase (Bessel) to provide superior pulse filtering.
Each channel of the 3988 is an 8-pole, wide range, low-pass/high-pass filter or an amplifier providing gains to 70dB in 0.1dB steps. The 3988 will accept input signals of æ10V peak at 0dB gain and has selectable ac or dc coupling. Overload detectors are standard and assist the user in detecting input signals or incorrect gain settings. Ninety-nine groups of non-volatile memory for storage of front panel set-ups are stored in battery-backed CMOS which can be recalled with a simple command.
With the Model 3988, the user can simply connect two channels in series to achieve band-pass operation or two in summed parallel for band-reject operation.