Model 3380 Series Tunable Active Filter Operating Manual 0.
Model 3380 Series 0.1Hz to 200kHz (0.005Hz Optional) 1, 2 or 4 Channels, 48dB/Octave Slope Low-Pass/High-Pass, Butterworth/Bessel Filter Operating Manual Copyright © 2004 Krohn-Hite Corporation. All rights reserved. Contents of this publication may not be reproduced in any form without the written permission of Krohn-Hite Corporation. Printed in USA - 9/2004. 15 Jonathan Drive, Unit 4, Brockton, MA 02301-5566 - Made in U.S.A. Tel: (508) 580-1660; Fax: (508) 583-8989 E-Mail: sales@krohnhite.
Ser vice and War ranty Krohn-Hite Instruments are designed and manufactured in accordance with sound engineering practices and should give long trouble-free service under normal operating conditions. If your instrument fails to provide satisfactory service and you are unable to locate the source of trouble, contact our Service Department at (508) 580-1660, giving all the information available concerning the failure. DO NOT return the instrument without our written or verbal authorization to do so.
Model 3380 Series Table of Contents Table of Contents 1.0 GENERAL DESCRIPTION · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1-1 1.1 INTRODUCTION · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1-1 1.2 SPECIFICATIONS · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1-1 1.2.1 Functions (Each Channel) · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 1-1 1.2.
Table of Contents Model 3380 Series Table of Contents (Continued) 2.5 REAR PANEL DC LEVEL ADJUSTMENTS · · · · · · · · · · · · · · · · · · · · · · · · · · · 2-3 2.5.1 DC Level Adj (Rear Panel) Out · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 2-3 2.5.2 DC Level Adj (Rear Panel) HP · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 2-3 2.6 FILTER CHARACTERISTICS · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 2-4 2.6.
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Table of Contents iv Model 3380 Series
Model 3380 Series Section 1 - General Description SECTION 1 GENERAL DESCRIPTION 1.1 IN TRO DUC TION The Krohn-Hite Model 3380 Filter Series (3381, 3382 and 3384) are one, two or four channel filters providing a tunable frequency range from 0.1Hz to 200kHz; and with the 002 option, the range is extended to 0.005Hz.
Section 1 - General Description Model 3380 Series Passband Gain: ±0.2dB. High-Pass Bandwidth (0dB Gain): >2MHz. Stopband Attenuation: >100dB. Maximum Input: ±10V peak at 0dB gain, reduced in proportion to gain setting. Pre-Filter Gain: 0dB, 10dB, 20dB, 30dB, 40dB, 50dB, ±0.2dB. Post-Filter Gain: 0dB to 20dB selectable in 0.1dB steps, ±0.2dB. Wideband Noise (2MHz bandwidth detector): 0dB gain, <400µVrms; Max input gain, <5µVrms RTI; Max. gain <25µVrms RTI. Harmonic Distortion (1V output): –60dB (0.
Model 3380 Series Section 1 - General Description Rack Mount Kit: Part No. RK-314, permits installation of the Model 3380 Series into a standard 19" rack spacing. Extended 1 Year Warranty: Part No. EX3380. Specifications apply at 25°C, ±5°C.
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Model 3380 Series Section 2 - Operation SECTION 2 OPERATION 2.1 IN TRO DUC TION The Model 3381, 3382 and 3384 Filters are one, two or four channel filters respectively, providing a tunable frequency range of 0.1Hz to 200kHz (0.005Hz with option 002). Each channel is selectable low-pass or high-pass, 8-pole with input gain from 0dB to 50dB, selectable in 10dB steps; and output gain from 0dB to 20dB, selectable in 0.1dB steps.
Section 2 - Operation Model 3380 Series Model 3382 Filters Note: On early models, a 120V/240V switch was provided next to the Norm/Low line switch. 120V 240V Jumper 120V 240V Norm Low Line Switch Input Voltage Range (rms) Norm 108-132 Low 90-110 Norm 216-264 Low 180-220 Install Fuse Model 3381 Model 3382 Model 3384 .15A 1/4A 1/2A .
Model 3380 Series 2.3 Section 2 - Operation SELF TEST When the Model 3380 is turned on, the microprocessor performs a self-test routine whereby the entire RAM and ROM operation is verified. If there is a malfunction, such as a defective RAM or ROM, the word “bad” will appear in the DISPLAY followed by a number 1 or 2. “bad 1” indicates U16, microprocessor is defective and a “bad 2” indicates U17, EPROM is defective.
Section 2 - Operation Model 3380 Series 2.4.1.7 Low-Pass and High-Pass Op er a tion – [MODE] When [MODE] is pressed once, DISPLAY indicates the present filter type, “h.P.” (high-pass) and “L.P.” (low-pass). When pressed again, the type will change (if the type was “L.P.” , the change will be to “h.P.”). 2.4.1.
Model 3380 Series Section 2 - Operation 2.4.1.13 Re call ing a Fil ter Setup – [RECLL] When [RECLL] is preceded by a number, it will recall the filter set-up which was stored in the memory location selected. Selectable locations are 0 to 8. When first pressed, the DISPLAY indicates the number of the memory location to be recalled. For example, the DISPLAY will indicate the following: “n=05”. Pressing the [RCLL] key again will recall the entire filter set-up from memory location “05”.
Section 2 - Operation 2.6 Model 3380 Series FIL TER CHAR AC TER IS TICS 2.6.1 Am pli tude Re sponse Each channel of the Model 3380 can operate in either the low-pass or high-pass mode at 48dB/octave attenuation and provide either maximally flat (Butterworth) amplitude response or linear phase (Bessel) operation. Comparative amplitude response characteristics in both modes are shown in Figure 2.2A and 2.2B. Figure 2.2A Low-Pass Amplitude Response Figure 2.2B High-Pass Amplitude Response 2.6.
Model 3380 Series Section 2 - Operation Figure 2.3 Phase Response 2.6.3 Group De lay Group delay1 , shown in Figure 2.4, on opposite page, is defined as the derivative of radian phase with respect to radian frequency, which is the slope of the phase curve. A flat group delay is considered a linear phase response which corresponds to a constant slope of the phase curve.
Section 2 - Operation Model 3380 Series 2.6.4 Tran sient Re sponse The normalized response for a unit step voltage applied to the input of the Model 3380 operating in the low-pass mode with both Butterworth and Bessel response is shown in Figure 2.5, on page 2-12. Figure 2.
Model 3380 Section 3 - Incoming Acceptance SECTION 3 INCOMING ACCEPTANCE 3.1 IN TRO DUC TION The following procedure should be used to verify that the Model 3380 filter is operating within specifications. These checks may be used for incoming acceptance and periodic performance checks. Tests must be made with all covers in place and operating for a minimum of 30 minutes to reach operating temperature.
Section 3 - Incoming Acceptance Model 3380 Connect the frequency counter to the oscillator, the oscillator to the filter `+’ input, and the AC meter to the filter input. Set the filter to butterworth with the `TYPE’ key, lowpass with the ‘MODE’ key, 0dB input gain, 0dB output gain and 5kHz with the `FREQ’ key . Set the oscillator to 5kHz, 1VRMS. Set the meter to read 0dB (dB and REL mode on the Fluke 8920). Connect the meter to the filter output; adjust the oscillator frequency to get –3.01dB.
Model 3380 Section 3 - Incoming Acceptance Figure 3.2 3.6 Passive 2MHz Low-Pass Filter NOISE CHECK Short the `+’ inputs of both filter channels and set the channel being tested to 0dB input gain, 0dB output gain, lowpass (mode key), butterworth (type key), DC coupled (press shift then type, if display shows `AC’ press shift type again; display will show `DC’). Connect a 2MHz lowpass, passive filter, shown in Fig 3.
Section 3 - Incoming Acceptance 3.9 Model 3380 AC/DC COU PLING CHECK Apply a 1Vdc signal to the INPUT of the filter. Set the filter to low-pass mode with 0dB Input and Output gain. In the DC COUPLED mode, the OUTPUT of the filter should be approximately 1Vdc and approximately 0Vdc in the AC COUPLED mode.
