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Krohn-Hite 3945, Руководство по эксплуатации

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2.5.5

Power

Receptacle: Standard 3 pin.

Fuse: 3/8 amp slow-blow for 120V operation; 3/16 amp slow-blow for 230V operation. To change this
setting, refer to Section 2.2.

2.5.6

GPIB Connector

Standard IEEE-488 interface. Subsets are SH1, AH1, T6, L4, SR1, RL1, PP1, DC1, DT0, C0 and E1.

2 . 6

FILTER OPERATION

2.6.1

Introduction

The Model 3945 is a Multichannel filter with three channels that can function independently. Each chan-
nel can operate in either the low-pass mode or high-pass mode and provide 24dB/octave attenuation, or
channels 1.1 and 1.2 can be set to the same mode and connected in series, externally, to obtain 48dB/oc-
tave attenuation. The interconnection of two channels, by front panel data key entry, will provide
band-pass or band-reject (null) operation and no external connections are needed.

2.6.2

Variable Band-Pass and Band-Reject Operation

2.6.2.1 Band-Pass

Variable band-pass response is obtained by applying the input signal to channel 1.1. With the Channel
Display on 1.1, set the filter to the band-pass mode by pressing the [MODE] key until “b.P.” appears in the
DISPLAY. Enter the desired low-cutoff (high-pass) frequency, then set the filter to channel 1.2 and enter
the desired high-cutoff (low-pass) frequency. The band-pass response will appear at the output BNC con-
nector of channel 1.1 simultaneously.

2.6.2.2 High Frequency Band-Pass

When a high frequency band-pass response above 2MHz is desired, the Model 3945 can be configured by
connecting, externally, the output of channel 1.1 or 1.2 (set to high-pass) to the input channel 2.1 (set to
low-pass, 50 ohm input impedance and 6dB output gain for 0dB insertion loss).

This provides a band-pass filter that has a low cutoff (high-pass) that is adjustable between 3Hz to 2MHz
and a high cutoff (low-pass) that is adjustable between 170Hz and 10MHz.

Note: At high cutoff settings above 10MHz, 3945 passband response will deteriorate.

2.6.2.3 Band-Reject

Variable band-reject response is obtained by applying the signal to channel 1.1. With the Channel Display
on 1.1, set the filter to the band-reject mode by pressing the [MODE] key until “b.r.” appears in the display.
Enter the desired low-cutoff (low-pass) frequency into channel 1.1, then set the filter to channel 1.2 and
enter the desired high-cutoff (high-pass) frequency. A null can be obtained by setting the low cutoff fre-
quency to approximately 0.58 of the desired null frequency, the high cutoff frequency to approximately
1.7 of the null frequency. Fine tuning of both cutoff frequencies can be accomplished by varying the cut-
off frequency using the increment/decrement feature of the DIGIT SELECT described in paragraph 2.4.7.
The resolution of the Model 3945 will limit the extent of the null.

Section 2 - Operation

2-5

Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com

Содержание 3945

Страница 1: ...service in house repair center WE BUY USED EQUIPMENT Sell your excess underutilized and idle used equipment We also offer credit for buy backs and trade ins www artisantg com WeBuyEquipment REMOTE IN...

Страница 2: ...MODEL 3945 170Hz to 25 6MHz Dual Low Pass Programmable Butterworth Filter Operating Manual Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 3: ...tion problems and costs When it becomes necessary to return the instrument to the factory kindly pack it carefully and ship it to us prepaid All Krohn Hite products are warranted against defective mat...

Страница 4: ...of this publication may not be repro duced in any form without written permission of Krohn Hite Corporation Printed in U S A Ver 021507 Krohn Hite Corporation 15 Jonathan Drive Unit 4 Brockton MA 023...

Страница 5: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 6: ...URN ON PROCEDURE 2 1 2 3 SELF TEST 2 1 2 4 FRONT PANEL CONTROLS AND DISPLAY 2 1 2 4 1 Data Keys and Display 2 1 2 4 2 Parameter and Control Keys 2 2 2 4 3 Channel Selection 2 3 2 4 4 Cutoff Frequency...

Страница 7: ...3 2 3 3 ASCII DATA COMMANDS 3 2 3 3 1 Format 3 2 3 3 2 Types of Data Commands 3 2 3 3 3 Table of ASCII Commands 3 3 3 3 4 Examples 3 4 3 3 4 1 Example 1 3 4 3 3 4 2 Example 2 3 4 3 3 4 3 Example 3 3...

Страница 8: ...3 Band Pass Band Reject Response 4 2 4 1 3 4 Stopband Attenuation 4 4 4 1 3 5 Pre Filter and Post Filter Gain Accuracy 4 4 4 1 3 6 Noise Check 4 5 4 2 CHANNEL 2 1 4 5 4 2 1 Introduction 4 5 4 2 2 Req...

Страница 9: ...Model 3945 Filter IV Table of Contents Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 10: ...band rejectfilter with gains up to 40dB per channel The filter is controlled by the front panel keyboard or over the IEEE 488 bus Provided are LED displays and indicators for input and output gain cut...

Страница 11: ...Noise referred to input 200mV with 2MHz bandwidth detector Input Pre Filter Gain 0dB or 20dB 0 2dB Coupling ac or dc Impedance 1 megohm in parallel with 100pf Maximum Signal at 0dB gain 4 5V peak at f...

Страница 12: ...input Harmonic Distortion 1Vrmssinewave 60dB below signal up to 100kHz 0 1 All harmonics be low 50dB to 1mHz below 40dB above 1MHz Spurious Signals Below 80dBm to 65MHz below 75dBm to 100MHz Referred...

Страница 13: ...e 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 Overlo...

Страница 14: ...on of the Model 3945 into a standard 19 rack spac ing Specifications apply at 25 C 10 C Specifications subject to change without notice Section 1 General Description 1 5 Artisan Technology Group Quali...

Страница 15: ...This page intentionally left blank Section 1 General Description 1 6 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 16: ...he unit After reading the Self Test feature described next turn on the Model 3945 2 3 SELF TEST When the Model 3945 is turned on the microprocessor performs a self test routine whereby the entire RAM...

Страница 17: ...ed again the MODE will change to the next in the order explained above RECLL When preceded by a number it will recall the entire instru ment set up from the memory location selected When first pressed...

Страница 18: ...from 0 to 30 and press the SHIFT and MEGA keys see Section 3 2 1 for GPIB addressing information GPIB Line Termination When the SHIFT key followed by the ALL CH key are pressed the DISPLAY will indic...

Страница 19: ...essing the SHIFT key and either D or key again will toggle the setting Key Click Feature On Off When the SHIFT key is pressed followed by the D key under the CHANNEL display the key click feature will...

Страница 20: ...sly 2 6 2 2 High Frequency Band Pass When a high frequency band pass response above 2MHz is desired the Model 3945 can be configured by connecting externally the output of channel 1 1 or 1 2 set to hi...

Страница 21: ...either maximally flat Butterworth amplitude response or linear response Bessel operation Comparative amplitude response characteristics are shown in Figure 2 1A and 2 1B Section 2 Operation 2 6 Figur...

Страница 22: ...ith respect to radian fre quency which is the slop of the phase curve A flat group delay is considered a linear phase response which corresponds to a constant slope of the phase curve With linear phas...

Страница 23: ...2p timesgreater in Hz for a cutoff of 1 radian sec or 940 7 Hz and 1152 4 Hz respectively Dividing by 360 converts Hz to radians radi ans per sec yields a group delay time of 2 61s for Butterworth an...

Страница 24: ...ied to the input of the Model 3945 operating in the low pass mode with both Butterworth and Bessel response is shown in Figure 2 4 Section 2 Operation 2 9 Figure 2 4 Transient Response Artisan Technol...

Страница 25: ...This page intentionally left blank Section 2 Operation 2 10 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 26: ...d on The LTCS affects the GPIB in the TALKER mode only data output from the 3945 to the GPIB After the printable characters have been sent non printable characters such as carriage return CR and line...

Страница 27: ...E3 2 7 X 103 2E3 2 X 103 2E 3 2 X 103 2 Multiplier KILO MEGA 3 Parameter Parameter frequency gain channel etc is included in Section 3 3 3 b Delimiters which may separate commands are the following c...

Страница 28: ...channel down Output Gain OG OU OD set output gain increase output gain up decrease output gain down Type Channels 1 1 and 1 2 TY1 TY2 Butterworth Bessel Type Channel 2 1 TY1 Butterworth Mode Channels...

Страница 29: ...those parameters that change all others remain unaffected 3 3 4 2 Example 2 To change frequency to 150Hz 150H or 150bHZ or 150F or 15K or F150 or H150 or HZ150 or K0 15 or 1 5E2HZ or F1 5E2 or etc b...

Страница 30: ...s IEEE 488 Command Mnemonic Result My listen address MLA Enables unit to receive data Unlisten UNL Disables unit from receiv ing data My talk Address MTA Designates unit to send data Untalk UNT Disabl...

Страница 31: ...ed to be remote Selection of the local or local with lockout and remote and remote with lockout is done in several ways When the unit is ad dressed to talk MTA or listen MLA it will enter into remote...

Страница 32: ...8 Command Mneonic Result Configure PPC Places unit into a state where it expects par allel poll enable and disable commands to establish which bits should be set or selected in response to a parallel...

Страница 33: ...rmation The Model 3940 3944 service request capability is enabled or disabled with the SRQON and SRQOFF commands see Section 3 3 3 The unit turns on with service request disabled This is an extension...

Страница 34: ...esponse to an error when a command came from the bus and ser vice request is enabled by the SRQON command Remote enable REN When true allows the 3940 3944 to re spond to remote messages When this line...

Страница 35: ...C if dc coupled 7 if all channel mode otherwise a space see Section 3 3 4 3 for example 3 5 2 Model Number and Software Version Format Aftersending the V commands the next line of data read fromthe Mo...

Страница 36: ...____________ Set to 500 Hz 500Hz 0dB input gain 0IG 0db output gain 00G DC coupled re display the frequency F so it will be read over the bus CALL IBWRT D39XX 500HZ 0IG 0OG DC F IF IBSTA 0 THEN GOT0...

Страница 37: ...sumes the name of the device at address 1 hasn t been changed in IBCONFIG it s still called DEV1 which is the default The status variables IBSTA IBERR and IBCNT are defined in DECL H Each bit of IBSTA...

Страница 38: ...msg char rd 255 read data buffer int GpibDev GpibBoard device handles void main printf nSending data to the Krohn Hite model 39xx n printf n Assign a unique identifier a handle to the K H 39XX and st...

Страница 39: ...ror Append the null character to mark the end of the data rd ibcnt 0 do this BEFORE calling ibcmd because ibcnt will be printf Read s n rd changed by any ib calls ibcmd GpibBoard _ 2L send unt unl if...

Страница 40: ...IBCNT will be printed in decimal The NI 488 function IBONL is called to disable the hardware and software The EXIT function will terminate this program void gpiberr char msg Unsigned int I Table of ib...

Страница 41: ...rovides the primary information about the cause o the error print it s value and mnemonic for each bit set printf ibsta H X ibsta for i 0 i 15 i if ibsta ibstaMsg i bit printf s ibstaMsg i msg printf...

Страница 42: ...ogram to access the de vice at GPIB address 1 dev1 ibwrt 5 1K Set the unit to 5 1kHz dev1 ibrd 50 Read the unit 50 characters is ade quate dev1 set gpib0 The ibrd command does not unaddress the unit i...

Страница 43: ...This page intentionally left blank Section 3 GPIB Programming 3 18 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com...

Страница 44: ...requency Counter e Distortion Analyzer Krohn Hite Model 6900B or equivalent 4 1 3 Procedure 4 1 3 1 Low Pass High Pass Response Channels 1 1 and 1 2 can be either low pass high pass or by pass modes o...

Страница 45: ...utput gain Monitor the output of the filter with a freuqncy counter and an ac voltmeter referenced to 0dB Set the oscillator to 1kHz and adjust the frequency so the output voltage is 3dB The oscillato...

Страница 46: ...gure 4 2 is obtained by applying the input signal to channel 1 1 input Set the CHANNEL display to 1 1 Set the filter to band reject mode b r and Butterworth response Apply 1Vrms at 100Hz to the input...

Страница 47: ...as shown in Figure 4 3 to the ac voltmeter Set the filter to the low pass mode The filter output should be 80dB 300uVrms Figure 4 3 High Pass Filter 4 1 3 5 Pre Filter and Post Filter Gain Accuracy Se...

Страница 48: ...excessive verify that the distortion of the oscilaltor being used is less than 0 005 4 2 2 Required Test Equipment The test equipment below is required to performa the following tests a DC Voltmeter D...

Страница 49: ...Set the filter output gain to 0dB Set the Fluke 8920A for ac referenced to 0dB Check each input and output gain setting by switching each one up from 0dB independently All dB read ings should be with...

Страница 50: ...he output of the filter with a 50 ohm cable Set the Fluke for relative dB operation Set the filter for a cutoff frequency of 1kHz and Gain mode Zero reference the Fluke Set the filter for Low Pass mod...

Страница 51: ...nput Set the spectrumanalyzer to measurethe 3Vp p 1MHz signal into a50 ohmtermination at the filter output and connect ther filter output to the analyzer Adjust the analyzer for 0dB referencing level...

Страница 52: ...service in house repair center WE BUY USED EQUIPMENT Sell your excess underutilized and idle used equipment We also offer credit for buy backs and trade ins www artisantg com WeBuyEquipment REMOTE IN...

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