Selectable
Features Apply to Each Channel Two
Channel
Cutoff Frequency Range: 0.03Hz to 1MHz
Attenuation Slope: 48dB/Octave
Selectable Filter Modes: Low-Pass and High-Pass
Selectable Responses: Butterworth and Bessel
Selectable Pre-Filter and Post-Filter Gains
Selectable Input Type: Differential and Single-Ended
Amplifier (Filter By-Pass) Mode
Options 002:
extends low end cutoff
to 0.003Hz. Rack Mount Kit:
Part No. RK-37, permits installation of the
Model 3988 into a standard
19" rack spacing. Extended 1 Year Warranty:
Part No. EW3988.
Related
Models 3900 - LP - 1Hz
to 99kHz - 2-Ch Elliptical 3901 - LP/HP/BP/BR
- 1Hz to 99kHz - 2-Ch Elliptical 3940 - LP/HP/BP/BR
- 3Hz to 2MHz - 2-Ch
Butterworth/Bessel 3944 - LP/HP/BP/BR
- 3Hz to 2MHz - 4-Ch
Butterworth/Bessel 3945 - LP - 3Hz
to 25.6MHz - 3-Ch Butterworth or Bessel 3955 - LP - 170Hz
to 25.6MHz - 2-Ch Butterworth or Bessel
> 3988 - LP/HP/BP/BR - 0.03Hz to 1MHz - 3-Ch
Butterworth/Bessel
DESCRIPTION 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.
BAND-PASS/BAND-REJECT OPERATION 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.
APPLICATIONS
Applications for the 3988 are ultra-sound measurements, random noise testing,
sound recording, suppressing interference in audio communications and related
fields of medical, geological, geophysical, oceanographic, military and more.
All these features and more are backed with the quality Krohn-Hite has provided
in filters since 1949.
SPECIFICATIONS
FUNCTIONS
(Each Channel)
Low-pass
filter, high-pass filter, voltage gain amplifier.
FILTER MODE Type:
8-pole, Butterworth/Bessel. Attenuation: 48dB/octave. Tunable Frequency Range fc: Low-pass, 0.03Hz
to 1MHz; high-pass, 0.03Hz to 300kHz; (option 002, 0.003Hz). Frequency Resolution: 3 digits, 0.1Hz to max fc; 2 digits,
0.03Hz to 0.099Hz; (option 002, 1 digit, 0.003Hz to 0.009Hz; 2 digits, 0.01Hz
to 0.099Hz). Cutoff Frequency Accuracy: ±1%, 0.5Hz to 50kHz; ±2%, 50.1kHz to max fc;
±5%, 0.03Hz to 0.5Hz (option 002, ±5%, 0.003Hz to 0.5Hz). Relative Gain at fc: –3dB, Butterworth; –12.6dB,
Bessel. High-Pass Bandwidth (0dB Gain): >4MHz. Stopband Attenuation: >80dB. Maximum Input: ±10V peak at 0dB gain, reduced in proportion to gain setting;
±7V peak for LP, fc >500kHz, fsig >500kHz. Pre-Filter Gain: 0dB, 10dB, 20dB, 30dB, 40dB, 50dB, ±0.2dB. Post-Filter Gain: 0dB to 20dB in 0.1dB steps, ±0.2dB. Wideband Noise (2MHz bandwidth detector): 0dB gain, <300µVrms for fc
£5kHz,
<500µVrms for fc
£50kHz,
£1mVrms
for fc >50kHz. Max. gain, <25µVrms RTI. Harmonic Distortion: –80dB at 1kHz. DC Stability: Typically ±2mV/°C.
AMPLIFIER MODE Bandwidth:
>7MHz min. gain; >700kHz max. gain. Response: ±0.1dB typical, ±0.5dB max. Gain: 0dB to 70dB in 0.1dB steps, ±0.2dB. Input (Differential or single-ended +(in phase), –(inverted):
CMRR: >60dB to 10kHz; >50dB to 100kHz.
Sensitivity: 3mV peak with 70dB total gain for 10V peak output.
Maximum Input: ±10V peak at 0dB gain, reduced in proportion to gain
setting.
Impedance: 1 megohm in parallel with 100pf.
Coupling: ac (0.16Hz) or dc.
Maximum DC Component: ±100V in ac coupled mode.
Output: Maximum Voltage (open circuit): ±10V peak.
Maximum Current: ±80mA peak.
Impedance: 50 ohms.
DC Offset: Adjustable to zero volts.
Harmonic Distortion (1V output): –80dB (0.01%) to 10kHz; –60dB (0.1%)
to 100kHz.
Wideband Noise (RTI, 2MHz BW detector): 300µVrms min. gain; 25µVrms
max. gain.
DC Stability (RTI): Typically ±10mV/ 6C.
GENERAL Crosstalk Between
Channels: –85dB below full scale with input
source <50 ohms. Low-Pass Phase Match Between Channels: ±2° to 500kHz, ±5° to 1MHz. High-Pass Phase Match Between Channels: For fc
£100kHz,
±2° for fsig £500kHz,
2° times fsig/500kHz for fsig to 2MHz; for fc
>100kHz, ±5° for fsig
£500kHz,
5° times fsig/500kHz for fsig to 2MHz. Gain Match Between Channels: ±0.2dB max. to 100kHz. Switch: For selection of Input, +(in phase), Differential or –(inverted). Memory: 99 selectable groups; memory is non-volatile battery-backed CMOS. Self-Test Diagnostics: MPU checks unit upon power-up. Display indicates
failure mode. Displays: 7 segment, green, LED; 0.3" high. Remote Programming:
IEEE-488.1 interface. Subsets: SH1, AH1, T6, L4, SR1, RL1, PP1, DC1, DT0, C0,
E1. Operating Temperature: 0°C to 50°C. Isolation to Chassis: ±200Vdc. Input/Output Connectors: BNC. Power: 50 watts. Dimensions and Weights: 3.5" (9cm) high, 8.5" (21.8cm) wide, 18" (46.2cm)
deep; 12 lbs (5.4kg) net, 14 lbs (6.3kg) shipping. Accessories: 6 foot, 3-terminal line cord, operating manual.
OPTIONS 002: extends low
end cutoff to 0.003Hz. Rack Mount Kit: Part No. RK-37, permits installation of the Model 3988
into a standard 19" rack spacing. Extended 1 Year Warranty: Part No. EW3988.
OPTIONAL
ACCESSORIES
CAB-010:
GPIB Cable with
Connectors, 2-Meters
CAB-011:
GPIB
Cable with Connectors, 1-Meters
CAB-025:
Cable, BNC, 3ft, Low Noise
Specifications apply
at 25°C, ±5°C.
Specifications subject to change without notice.
