170Hz
to 25.6MHz
2-Channel Low-Pass
Butterworth or Bessel
GPIB/Manual
---------------------------
Tunable Active Filter
Features Frequency
Range: 170Hz to 25.6MHz
Attenuation Slope: 24dB/Octave
Input Gain: Selectable up to 20dB
Output Gain: Selectable up to 26dB
Noise: Typically <250µV referred to input
Stopband Attenuation: >100dB
Remote Control: GPIB
Bessel Option
Options Rack
Mount Kit: Part No. RK-37, permits installation of the Model 3955
into a standard
19" rack spacing. 005: Replace Butterworth response to Bessel response. Extended 1 Year Warranty: Part No. EW3955.
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/HP/BP/BR - 3Hz to 25.6MHz - 3-Ch Butterworth &
Bessel
> 3955
- LP - 170Hz to 25.6MHz - 2-Ch Butterworth or Bessel 3988
- LP/HP/BP/BR - 0.03Hz to 1MHz - 2-Ch Butterworth &
Bessel
DESCRIPTION The Krohn-Hite
Model 3955 programmable, dual channel, low-pass filter is the first dual low-pass
programmable filter of its kind, covering the wide cutoff frequency range
from 170Hz to 25.6MHz with 2 digits of resolution. The 3955 is a 4-pole, maximally
flat (Butterworth) filter, with an attenuation slope of 24dB/octave and a
stopband attenuation of >100dB referred to 1Vrms input.
The filter has selectable
ac or dc coupling and selectable 1M or 50 ohm input impedance. Programmable
input gains to 20dB and output gains to 26dB are standard.
AMPLIFIER MODE The Model 3955
also has the capability to be configured in an “amplifier bypass” mode to
operate as an amplifier, bypassing the filter. This gives the user the ability
to amplify without filtering when so desired.
APPLICATIONS The Model 3955 fills
many applications such as high frequency anti-aliasing for digital signal
processing,
EMI testing, video recording and many more. It has been carefully designed
with the user in mind, providing ease of operation, reliability and price
competitiveness. All backed with the quality and workmanship which Krohn-Hite
has provided in filters since 1949.
SPECIFICATIONS
FUNCTION:
Two independent, low-pass filter
channels or amplified bypass.
FILTER MODE Filter Type: 4-Pole, Butterworth, low-pass. Attenuation Slope: 24dB/Octave. Tunable Frequency Range: 170Hz to 25.6MHz. Frequency Control: Keypad entry or increment, decrement keys. Cutoff Frequency Accuracy: ±2% to 2.56MHz, ±5% to 25.6MHz. Passband Response: ±0.2dB up to 2.56MHz, ±0.5dB to 25.6MHz. Stopband Attenuation: -100dB to 1MHz; -75dB at 10MHz; -55dB at 30MHz;
-50dB at 50MHz; -40dB to 100MHz. Pre-Filter Gain: 0dB, +10dB, +20dB ±0.1dB. Post-Filter Gain: 0dB, +6dB, +20dB, +26dB ±0.1dB. Input/Output Coupling: AC or DC. AC coupling cutoff is approximately
16Hz at the input and 10Hz at the output with a 50 ohms termination. Note
that the internal 50 ohms input termination is before the AC coupling. Noise Spectral Density (10kHz to 100MHz referred to input): Below –128dBm/Hz
into 50 ohms. This translates into a wideband noise power or voltage for a
30MHz BW of below –53dBm or 500µVrms referred to input. Harmonic Distortion (1Vrms sinewave): >–60dB below signal up
to 100kHz (0.1%). All harmonics below 50dB to 1MHz; below 40dB above 1MHz. Spurious Signals: Below –80dBm to 65MHz; below –75dBm to 100MHz. Referred
to input represented in voltage form: 22mV and 40mV respectively. DC Stability: ±0.5mV/°C referred to input.
AMPLIFIER MODE Bandwidth:
>50MHz. Rise and Fall Time: <7ns with 0dB input gain 6dB output gain; <10ns
with +20dB input or output gain. <5% ringing or overshoot. Input:
Impedance: Selectable 1M ohm or 50 ohms, ±2%, shunted by 65pF.
Maximum Signal: ±1.5V peak with 0dB input gain, reduced in proportion
to input gain selected.
Maximum Input Without Damage: 12Vrms with input terminator OFF, 7Vrms
with input terminator ON.
DC Blocking Voltage: 200V. Note that the internal input termination
is before the AC coupling and
can only tolerate 7Vrms when ON. Output:
Maximum Signal: ±3V peak open circuit; ±1.5V peak into 50 ohms.
Impedance: 50 ohms, ±2%.
DC Level: Adjustable to Zero.
GENERAL
Memory: 99 selectable groups; memory is non-volatile battery-backed CMOS. Overload Modes: Three selectable modes; non-latching, that monitors
all channels and displays the first channel to have an overload; latching,
that maintains the overload display until it is cleared; and no indications. Overload Indicators: LEDs for input and output. Gain display flashes
when overload occurs on displayed channel. 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 lbs (6.3kg) shipping. Accessories: 6 foot, 3 terminal line cord, operating manual.
OPTIONS Rack
Mount Kit: Part No. RK-37, permits installation of the Model 3955 into
a standard 19" rack spacing. 005: Replace Butterworth response to Bessel response. Extended 1 Year Warranty: Part No. EW3955.
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 ±10°C.
Specifications subject
to change without notice.
