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DESCRIPTION
The
Krohn-Hite Model 3940 programmable, dual channel, Butterworth/Bessel filter
offers a programmable or benchtop filter covering a cutoff frequency range from
3Hz to 2MHz. It has a
frequency
response characteristic
of maximally flat (Butterworth) for clean filtering in
the frequency
domain, or
linear phase (Bessel) to provide
pulse signal filtering. The passband gain is unity, and
the attenuation
slope is 24dB/octave per channel. The
3940 will accept input signals of ±4.5V peak
and
provides input
and output gains of 0dB or 20dB which can
be selected via the front panel
keyboard or over the GPIB
bus.
CONFIGURATIONS
The filter
can be programmed to operate in low-pass, high-pass,
band-pass or band-reject modes,
or the two channels
can be interconnected to achieve 48dB/octave high-pass or
low-pass slopes.
STORING SET-UPS
The Model
3940 offers to the user 99 groups of non-volatile memory
for storage of front panel
set-ups,
which are stored in
battery-backed CMOS. Set-ups can then be recalled with a
simple
command.
The 3940
also provides a self-test diagnostics upon power-up
of its internal memory to insure the
unit
is
operating properly. If a failure occurs, the display will
indicate which ROM or RAM has
failed.
APPLICATIONS
Applications
for the Model 3940 are anti-aliasing, random noise
testing, sound measurements,
sound
recording, suppressing
interference in audio communications circuits and many
more.
SPECIFICATIONS
FUNCTIONS:
Two independent channels of
low-pass, high-pass or by-pass; one channel of
band-pass
or band-reject.
FILTER CHARACTERISTICS (Each Channel)
Type: 4-pole Butterworth (maximally flat) or
Bessel (linear phase).
Frequency Range (fc): 3Hz
to 2MHz.
Frequency Control: Keypad entry or increment,
decrement keys.
Frequency Resolution: 1Hz from 3Hz to 1kHz; 10Hz
to 2kHz; 100Hz to 100kHz;
1kHz to 1MHz;
10kHz to 2MHz.
Frequency Accuracy (fc):
±2% or least significant digit (which ever is greater)
20Hz to 500kHz;
±5% to 2MHz.
Relative Gain at fc:
Butterworth, –3dB; Bessel, –7.58dB.
Bandwidth: dc to fc, dc coupled; 0.2Hz
to fc, ac coupled (low-pass); fc to
10MHz (high-pass).
Attenuation: 24dB/octave per channel.
Stopband Attenuation: >95dB.
Insertion Loss (0dB, Input/ Output gain):
±0.5dB to 2MHz.
INPUT CHARACTERISTICS
Gain (pre-filter): 0dB or 20dB ±0.2dB.
Coupling: ac or dc.
Impedance: 1M ohm in parallel with 100pf.
Maximum Signal (at 0dB gain): ±4.5V peak at fc
<1MHz; ±4V peak at 2MHz.
Maximum DC Component: ±200V in ac coupled mode.
OUTPUT CHARACTERISTICS
Impedance: 50 ohms.
Gain (post-filter): 0dB or 20dB ±0.2dB.
Maximum Voltage: ±6.5V peak into ³ 500 ohms; ±1.3V peak into
greater than or equal to 50 ohms.
Maximum Current: ±25mA.
Distortion: –80dB at 1kHz at 1Vrms.
Noise: <200µV with 2MHz bandwidth detector.
DC Offset: adjustable to 0V.
DC Stability: ±0.5mV/°C typical; ±1mV/°C max.
GENERAL
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.
Storage Temperature: –20°C to 70°C.
Input/Output Connectors: BNC, front and rear.
Power Requirements: 90-132/180-264 volts ac,
50Hz-400Hz, 25 watts.
Dimensions: 3.5" (9cm) high, 8.5" (21.8cm)
wide, 18" (46.2cm) deep.
Weights: 12 lbs (5.4kg) net; 14 (6.3kg) lbs
shipping.
Accessories: 6 foot, 3 terminal line cord,
operating manual.
OPTIONS
002:
Lower frequency cutoff range to
0.3Hz to 200kHz.
Rack Mount
Kit: Part No. RK-37, permits installation of the
Model 3940 into a standard
19" rack
spacing.
Extended 1 Year Warranty: Part No. EW3940.
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.
Copyright ©
April 21, 2006
Krohn-Hite Corporation. All rights reserved.
15 Jonathan Drive, Unit 4, Brockton, MA 02301-5566 U.S.A.
Tel: (508) 580-1660; Fax: (508) 583-8989; info@krohn-hite.com
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