DESCRIPTION
The Krohn-Hite Model 38
Butterworth/Bessel, plug-in filter
card is one of a family of filter cards
used in Krohn-Hite Programmable Filter System Mainframes. It is
carefully designed with the user
in mind, providing ease
of operation, reliability and price competitiveness.
The 38
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 or complex filtering is
operator
selectable.
The 38 is
an 8-pole, wide range, low-pass/high-pass filter or an
amplifier providing gains to 70dB in
0.1dB steps. The 38
will accept input signals of ±10V 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.
APPLICATIONS
Applications of the Model 38
are ultra-sound measurements, random noise testing, sound recording, suppressing interference
in audio communications and related fields of medical,
geological,
geophysical, oceanographic, military and many
more.
MAINFRAMES
The 38 is
a plug-in card for two mainframes; Models 3905B/3905C and
3916B. The 3905B/C is a
3" high chassis, allowing up
to 5 filter/amplifier cards. The 3916B allows up to 16
cards.
SPECIFICATIONS
FUNCTION:
Low-pass filter, high-pass
filter; voltage gain amplifier.
FILTER
MODE
Type: 8-pole, Butterworth, Bessel.
Attenuation Slope: 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: >100dB.
Maximum Input: ±10V peak at 0dB gain reduced in proportion to gain
setting;
±7 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 (RTI): 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): 200µVrms min. gain; 25µVrms max.
gain.
DC Stability (RTI): Typically ±10mV/°C.
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.
Only for cards purchased at the same time.
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. Only cards
purchased at the same time.
Gain Match Between Channels: ±0.2dB max. to 100kHz.
Switch: For selection of Input, +(in phase), Differential or
–(inverted).
Input/Output Connectors: BNC.
Power: 15 watts.
Weights: 1.75 lbs (.79kg).
Accessories: Operating manual.
OPTIONS
002: extends low end cutoff
to 0.003Hz.
Extended 1 Year Warranty: Part No. EW38.
Specifications apply at 25°C, ±5°C.
Specifications subject to change without notice.
