FEATURES

• Frequency Range: 0.2Hz to 20kHz
• Passband Gain: 0dB or 20 dB
• Attenuation Slope: 24dB/octave
• Response Characteristics: Butterworth or Low Q
• Maximum Attenuation: 80dB
• Battery Operation
• Floating (Ungrounded) Operation

DESCRIPTION
The Model 3700 is a band-pass filter having attenuation slopes of 24dB/octave, with upper and lower cutoff frequencies independently adjustable from 0.2Hz to 20kHz.

RESPONSE
The frequency response characteristic is a 4th-order Butterworth with maximal flatness for cleanest filtering in the frequency domain. For pulse or transient signal filtering, a switch is provided to change the response to LOW Q, optimum for transient-free filtering.

BATTERY OPERATION
Battery operation capability is included on all instruments and batteries may be added at any future date. This consists of two rechargeable, nickel-cadmium batteries, with the recharging circuit built into all units. Battery operation makes this filter ideal for applications requiring complete isolation from line.

APPLICATIONS
This filter is designed primarily for low frequency operation and has many applications in the medical, geophysical, oceanographic and related fields.

FILTER CHARACTERISTICS
Functions: Band-Pass.
Frequency Range: Low cutoff and high cutoff frequencies are independently adjustable from 0.2Hz to 20kHz in five bands.

Frequency Dials: Separate low cutoff and high cutoff dials are individually calibrated with single logarithmic scales reading directly in Hz from 19 to 210. Total effective scale length for all five bands is approximately 30 inches.
Cutoff Frequency Calibrated Accuracy: ±5% with “RESPONSE” switch in “MAX FLAT” (Butterworth) position; less accurate in “LOW Q” (RC) position. Relative to mid-band level, the filter output is –3dB at cutoff in “MAX FLAT” position and approximately –12dB in “LOW Q” (RC) position.
Bandwidth: Continuously variable within the cutoff frequency limits of 0.2Hz to 20kHz. For minimum passband (Butterworth response) the two cutoffs are set to the same frequency, resulting in an insertion loss of 6dB at that frequency, with 3dB points at 0.8fc below and 1.25fc.
Attenuation Slope: Nominal 24dB/octave.
Maximum Attenuation: >80dB.
Insertion Loss: 0dB, ±1dB or 20dB, ±1dB.
Response Characteristics: Choice of 4-pole Butterworth (maximally flat response) for frequency domain operation and LOW Q (RC) for transient-free time domain operation, selected by means of a switch on the rear of chassis.

INPUT CHARACTERISTICS
Maximum Voltage: ±7V peak in the 0dB gain position, ±0.7V peak in the 20dB gain position.
Maximum DC Component: ±100V.
Input Impedance: 10M ohm in parallel with 50pF.

OUTPUT CHARACTERISTICS
Maximum Voltage: ±7V peak.
Maximum Current: ±1.5mA peak.
Internal Impedance: Approximately 50 ohms.
Hum and Noise: <200µV.

GENERAL
Operating Temperature Range: –10°C to 45°C.
Floating (ungrounded) Operation: A switch is provided on the rear of the chassis to disconnect signal ground from chassis ground.
Front Panel Controls: Low Cutoff Frequency dial and multiplier switch, High cutoff Frequency dial and multiplier switch, Power ON switch and gain switch.
Rear Panel Controls: Response switch, ground switch and 115/230V LINE switch.
Terminals: Front and rear panels, one BNC connector for Input, one for Output. One rear terminal for chassis grounding.
Power Requirements: 105-125 or 210-250 volts, single phase, 50-400Hz, 10 watts.
Dimensions And Weights: 3" (8.9cm) high, 8" (21.6cm) wide, 13" (34.8cm) deep; 11 lbs (4.9kg) net, 17 lbs (7.7kg) shipping.
Accessories: 3-terminal line cord; operating manual.

OPTIONS
Battery Kit: Part No. BK-370, battery option will operate up to 10 hours without recharging.
Rack Mounting Kit: Part No. RK-38 permits installation of the Model 3700 into a standard 19" rack spacing.
Extended 1 Year Warranty: Part No. EW3700.
Specifications subject to change without notice.