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Operation

3-4

3.2.5 Preamplifier filtering

The Model 1801 has three analog filters with FAST,
MEDIUM, and SLOW responses respectively. These fil-
ters are in addition to the Model 2001 filter, which can
also be used with the preamplifier. See paragraph 3.9 of
the Model 2001 Operator’s Manual for details on Model
2001 filtering.

The following paragraphs discuss selecting the filter
response and also cover filter frequency response curves.
See the specifications in Appendix A for filter settling
times.

Selecting filter response

1. Press the CHAN key to bring up the preamplifier

configuration menu. The instrument will display the
following:

CONFIGURE PREAMP

CONTROL

FILTER

CALIBRATION

2. Select FILTER, then press ENTER. The unit will dis-

play filter response selections:

SELECT PREAMP FILTER

FAST

MEDIUM

SLOW

3. Select the desired filter response, then press ENTER.

The FAST response filter provides the least noise
reduction and fastest response, while the SLOW
response filter gives the most noise reduction and
slowest response. Note that only the FAST response
filter is available with the ACV and FREQ functions.

4. Press EXIT to return to normal display.

Filter frequency response curves

Each of the preamplifier filters exhibits single-pole, low-
pass response. In addition to the filter selection, filter
response also depends on the selected range, as summa-
rized in Table 3-4. The table includes the -3dB response
point for each set of operating conditions, as well as a fil-
ter response number. The filter frequency response num-
ber corresponds to the equivalent curve number shown in
Figure 3-1. Note that the filter response curves shown are
for the preamplifier only and do not include Model 2001
response, which is affected by its own filter parameters as
well as the selected integration period.

Table 3-4
Filter response parameters

Function and Range

Filter response

FAST

MEDIUM

SLOW

-3dB
bandwidth

Filter
number

-3dB
bandwidth

Filter
number

-3dB
bandwidth

Filter
number

DCV:

20µV

Ω

4W

None

40Hz

3

0.32Hz

6

0.032Hz

7

DCV:

200µV

Ω

4W: 2m

Ω

185Hz

2

3.2Hz

5

0.32Hz

6

DCV:

2mV

Ω

4W: 20m

Ω

–200

Ω

700Hz

1

32Hz

4

3.2Hz

5

NOTE: Filter numbers correspond to curves shown in Figure 3-1. FAST filter only for ACV and FREQ functions.

10%-90% risetime = 0.35/Bandwidth (Hz)

τ

(s) = 0.15/Bandwidth (Hz)

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Содержание 1801

Страница 1: ...Model 1801Nanovolt Preamp Instruction Manual A G R E A T E R M E A S U R E O F C O N F I D E N C E...

Страница 2: ...NSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS INC HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES SUCH EXCLUDED DAMAGES SHALL I...

Страница 3: ...Model 1801 Nanovolt Preamp Instruction Manual 1993 Keithley Instruments Inc All rights reserved Third Printing April 1999 Cleveland Ohio U S A Document Number 1801 901 01 Rev C...

Страница 4: ...new Revision is created all Addenda associated with the previous Revision of the manual are incorporated into the new Revision of the manual Each new Revi sion includes a revised copy of this print h...

Страница 5: ...s that a shock hazard exists when voltage levels greater than 30V RMS 42 4V peak or 60VDC are present A good safety practice is to expect that hazardous voltage is present in any unknown circuit befor...

Страница 6: ...nt components in mains circuits including the power transformer test leads and input jacks must be purchased from Keithley Instru ments Standard fuses with applicable national safety approvals may be...

Страница 7: ...mpatibility 1 3 1 10 Optional accessories 1 3 2 Installation 2 1 Introduction 2 1 2 2 Card configuration 2 2 2 2 1 Preamplifier module 2 2 2 2 2 Power supply card 2 3 2 3 Power supply card preparation...

Страница 8: ...entials 3 18 3 4 2 Source resistance noise 3 20 3 4 3 Magnetic fields 3 21 3 4 4 Electromagnetic interference EMI 3 22 3 4 5 Ground loops 3 22 3 4 6 Shielding 3 22 4 Performance Verification 4 1 Intro...

Страница 9: ...g 5 12 5 5 1 Troubleshooting equipment 5 12 5 5 2 Troubleshooting access 5 12 5 5 3 Troubleshooting procedure 5 12 6 Replaceable Parts 6 1 Introduction 6 1 6 2 Parts lists 6 1 6 3 Ordering information...

Страница 10: ...ons for AC voltage measurements 3 10 Figure 3 4 Connections for 4 wire resistance measurements 3 12 Figure 3 5 Connections for frequency measurements 3 13 Figure 3 6 Connections for differential tempe...

Страница 11: ...rformance Verification Table 4 1 Recommended test equipment for performance verification 4 2 Table 4 2 Limits for DC volts verification 4 5 Table 4 3 Limits for AC voltage verification 4 6 5 Service I...

Страница 12: ...el 2001 by a factor of 10 000 Low noise Excellent noise rejection ensures minimal noise effects on the measurement Low thermal input connections Copper to copper input connections are used to minimize...

Страница 13: ...pping carton and inspect for physical damage Report any such damage to the shipping agent immediately Save the packing carton in case the unit must be shipped in the future NOTE Be careful not to thro...

Страница 14: ...ision level may also be displayed by using the front panel MENU GENERAL SERIAL selection If an earlier version is displayed Ann contact your Keithley sales representative regarding an upgrade to your...

Страница 15: ...ation Covers connect ing the power supply cable to the card and routing the output leads through the cable clamp 2 4 Card installation and removal Gives the proce dure to install the power supply card...

Страница 16: ...en LO and chassis ground is 41V peak Exceeding these limits may result in damage Offset Adjustments V ZERO and I ZERO are externally accessible adjustments for nulling voltage and current offsets resp...

Страница 17: ...p provides a strain relief for the output leads and power cable Output Leads The two output leads are terminated with banana plugs intended to connect to the multimeter input jacks Red is HI and black...

Страница 18: ...ded to that of the Model 1801 2001 Typ ical common mode current levels for a DMM or chart recorder are several micro amps or higher Power Connections Output Connections To Preamp Figure 2 3 Power and...

Страница 19: ...Figure 2 4 Typical analog output connections so pry out the two fasteners then remove the cover plate 2 Slide the power supply card edges into the guide rails inside the multimeter 3 With the ejector...

Страница 20: ...le to the power supply card and multimeter Lock card Ejector Arms 2 Unlock card Figure 2 5 Power supply card installation 2 5 1 Power supply connections After installing the power supply in the multim...

Страница 21: ...ut connection information specific to the type of measure ment function refer to paragraph 3 3 in Section 3 CAUTION Turn off the Model 2001 Multimeter power before connecting or discon necting the cab...

Страница 22: ...panel switch 1801 NANOVOLT PREAMP INPUTS HI LO 41V PEAK V ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK DUT HI LO Low Thermal Input...

Страница 23: ...one hour to achieve rated accuracy 2 6 2 Minimum operating distance The Model 1801 preamplifier module should be kept a minimum of two feet away from the Model 2001 Multi meter and other instrumentati...

Страница 24: ...he presence of the Model 1801 by display ing the following message if the preamplifier is disabled Preamp OFF If however the preamplifier is enabled at power on the unit will display the following mes...

Страница 25: ...llowing message to indicate that the preamplifier is enabled Preamp ON 5 To disable the preamplifier repeat steps 1 through 4 but select DISABLE in the PREAMP CONTROL menu The unit will display the fo...

Страница 26: ...eamplifier Input calibration constants NOTE Press CHAN key to access CONFIGURE PREAMP menu See Section 5 for calibration information Table 3 3 Preamp ON OFF states Mode Preamp ON Preamp OFF DCV Range...

Страница 27: ...te that only the FAST response filter is available with the ACV and FREQ functions 4 Press EXIT to return to normal display Filter frequency response curves Each of the preamplifier filters exhibits s...

Страница 28: ...curves 0 10 20 30 40 50 60 70 80 90 100 0 001 0 01 0 1 1 10 100 1k 10k 100k dB Gain Frequency Hz NOTE Response curves are for preamplifier only Number corresponds to conditions listed in Table 3 4 1 2...

Страница 29: ...setup is recalled the Model 1801 operating state assumes the condition dictated by the recalled setup If the setup was stored with the Model 1801 disabled the preamplifier will be disabled when the s...

Страница 30: ...preamplifier state SLOW MED or FAST Notes 1 Angle brackets are used to indicate parameter type Do not include brackets in programming message 2 Upper case letters indicate command short form Example...

Страница 31: ...ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTE Use only clean copper to copper connect...

Страница 32: ...the ends of the leads together Allow suffi cient time for thermal offsets and noise to stabilize 4 Press the REL key The display will read zero 5 Remove the short and connect the input leads to the si...

Страница 33: ...ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTE Use only clean copper to copper connect...

Страница 34: ...es in ambient temperature given in Appendix A To zero rel the Model 1801 follow the steps below 1 Disable rel if presently enabled by pressing the REL key The REL annunciator should be off 2 Select th...

Страница 35: ...TERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTES 1 Use only clean copper to copper connections 2 Sense voltage i...

Страница 36: ...VZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK HI LO Low Thermal Input Cable Noise Shield NOTE Use only clean copper to copper connec...

Страница 37: ...eady known Note that differential thermocouples can only be mea sured with the Model 1801 installed and enabled other wise pertinent setup menus will not be available Also a differential thermocouple...

Страница 38: ...nge and cursor keys then press ENTER and go on to step 11 8 If you selected USER SPECIFIED SLOPE in step 6 the instrument will prompt you to enter the thermo couple slope in V C as follows SLOPE 00020...

Страница 39: ...CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK a Input Connections T1 T2 Thermocouples connected in differential configuration Note Connect leads...

Страница 40: ...abled the temperature bar graph display limits are reduced to reflect the 50 C tem perature range of the Model 1801 regardless of the normal range of the selected thermocouple type Otherwise the tempe...

Страница 41: ...ucer Sense subsystem Temperature path Differential path Select thermocouple type type J K T E R S B USER Return thermocouple type J K T R R S B USER Select thermocouple slope value slope in V C 0 is i...

Страница 42: ...ns are taken Figure 3 7 Thermal EMF generation Nanovolt Preamplifier T2 HI LO T1 A B A EAB QAB T1 T2 The thermal EMF developed by dissimilar metals A and B in a series circuit is Temperature of the A...

Страница 43: ...fsets can be minimized by using the Model 2001 relative feature to null them out To do so place the instrument on the range to be used for the measurement and short the end of the connecting cable nea...

Страница 44: ...of the connecting cables 2 mini mize the exposed circuit area and 3 keep test leads and magnetic field sources stationary As shown in Figure 3 9a a large loop area generates a relatively large voltag...

Страница 45: ...to other instrumentation with more than one signal return path such as power line ground As shown in Figure 3 10 the resulting ground loop causes current to flow through the instrument LO signal leads...

Страница 46: ...d bus VG Input voltage to the preamplifier is EIN ES I R Resistance of input LO connection typically around 100m Current passing through input LO connection due to ground voltages VG in the ground bus...

Страница 47: ...Ground Ground bus VG Input voltage to the preamplifier is EIN ES I R Resistance of input LO connection typically around 100m Current passing through ZCM M or G due to VG and currents in the source mag...

Страница 48: ...Covers the tempera ture and humidity limits for verification 4 3 Warm up period Describes the length of time the Model 1801 should be allowed to warm up before testing 4 4 Line power Covers power lin...

Страница 49: ...on limits The verification limits stated in this section have been calculated using only Model 1801 one year specifications and they do not include test equipment tolerance If a particular measurement...

Страница 50: ...automatically confirmed by verifying the accuracy of the 2mV DC range which is used for temper ature measurements If the Model 1801 is out of specifications and not under warranty refer to the calibra...

Страница 51: ...mode and use 2 2V range 262 Low thermal Voltage Divider Input HI HI Red Input LO LO Black b Output Connections 1801 NANOVOLT PREAMP INPUTS 41V PEAK V ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEA...

Страница 52: ...ading to settle 11 Verify that the Model 2001 reading is within the lim its summarized in Table 4 2 12 Repeat steps 8 through 11 for the remaining ranges voltages and divider ratios listed in Table 4...

Страница 53: ...and make sure that REL is disabled NOTE Do not use REL to null offsets when per forming AC volts tests 6 Set the calibrator output to 450 000 V AC RMS at a frequency of 100Hz and allow the reading to...

Страница 54: ...ed Input LO LO Black b Output Connections 1801 NANOVOLT PREAMP INPUTS 41V PEAK V ZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK a Inpu...

Страница 55: ...the Model 1801 preampli fier power supply card and Model 2001 are cali brated together as a unit The normal calibration method should be used in most cases Gain constants calibration where preamplifi...

Страница 56: ...follows A Press the CHAN key B Select CONTROL then press ENTER C Select ENABLE then press ENTER 4 Select the 20 V DC range and allow a two hour warm up period before proceeding with the offset adjust...

Страница 57: ...LO 41V PEAK VZERO I ZERO CAUTION NO INTERNAL OPERATOR SERVICEABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY KEITHLEY 2mV PEAK Low thermal Shorting Strap 1801 NANOVOLT PREAMP Offset Voltage Adjustment...

Страница 58: ...n in Figure 5 3 Be sure that the preamplifier module is installed in the thermal isolation enclosure and that the lid is firmly in place 3 Turn on the Model 2001 and the calibrator and allow a two hou...

Страница 59: ...tput to 0 20000V DC Output HI Output LO 5700A Calibrator Output DC Volts Sense LO Sense HI Sense HI LO Input Output NOTE Put calibrator in external sense mode and use 2 2V range 262 Low thermal Voltag...

Страница 60: ...the process without saving calibration constants press EXIT instead 22 Press EXIT to return to normal display NOTE If an error occurs an appropriate error message will be displayed See the dis cussio...

Страница 61: ...end calibration date Request calibration date Send calibration due date Request calibration due date Calculate calibration constants test if they are valid valid range 0 98 to 1 2 Save calibration con...

Страница 62: ...on error messages 5 Use the GPIB MENU to set the Model 2001 primary address to the value used in the controller program default 16 6 Set the calibrator to the external sense mode and lock the unit on...

Страница 63: ...ts in the new power supply card The basic procedures for reading and storing constants are explained in the following paragraphs Reading gain constants There are three gain constants that are derived...

Страница 64: ...nstants are only tempo rary and will be lost when power is cycled unless the CAL UNPR PRE SAVE command is sent to permanently save them 5 3 Principles of operation The following paragraphs discuss the...

Страница 65: ...ost regulation filter ing is provided by C102 and C103 To 2001 Gain Filter Switching Memory Supply 2 Preamp Power Supply 1 Common Mode Current Cancellation Circuit LO To 2001 Input HI Power Supply Car...

Страница 66: ...ile working with these devices 3 Handle the devices only by the body do not touch the pins or terminals 4 Any printed circuit board into which the device is to be inserted must first be grounded to th...

Страница 67: ...le square wave Referenced to digital common P1034 pin 1 2 T102 pin 6 0 2V p p rounded square wave Referenced to 3 U104 pin 1 8 5V DC 10 Referenced to 4 U105 pin 2 8 5V DC 10 Referenced to 5 U108 pin 7...

Страница 68: ...number 1801 Serial number Part description Circuit description if applicable Keithley part number 6 4 Factory service If the preamplifier is to be returned to Keithley Instru ments for repair perform...

Страница 69: ...R FILM RES 470 5 1 4W COMPOSITION OR FILM RES 4 7K 5 1 4W COMPOSITION OR FILM RES 26 7K 1 1 8W METAL FILM RES 649K 1 1 8W METAL FILM RES 110K 1 1 8W METAL FILM RES 1K 5 1 4W COMPOSITION OR FILM RES 33...

Страница 70: ...R BOTTOM CABLE CLAMP SHIELDED COVER BOTTOM STRIP POLYURETHANE SHIELDED COVER TOP SHIELDED COVER TOP SHIELD SCANNER BOTTOM INSULATOR BOTTOM SHIELD TOP CARD EJECTOR PLASTIC THERMAL ENCLOSURE W PACKING M...

Страница 71: ......

Страница 72: ......

Страница 73: ...A Specifications A 1...

Страница 74: ......

Страница 75: ......

Страница 76: ......

Страница 77: ...5700A calibrator connect the calibrator to the IEEE 488 bus as well Be sure to use shielded IEEE 488 cables for bus connections 2 Turn on the computer the Model 2001 and the cali brator Allow the Mod...

Страница 78: ...tor to external sense 0V DC output PRINT Place calibrator in operate mode PRINT PRINT Set 262 polarity to POS position PRINT Wait two minutes for thermals to settle GOSUB KeyCheck FOR I 1 TO 7 Loop fo...

Страница 79: ...INPUT 2 E Err IF E 0 THEN PRINT If error is detected error PRINT Err is displayed and program PRINT Calibration aborted is halted BEEP CLOSE 1 CLOSE 2 END END IF RETURN Dly Delay routine T TIMER Lp I...

Страница 80: ...s10k 200e 6 cal unpr pre fs1k 2e 3 cal unpr pre calc void keypress errcheck checkopt char date 10 int i calend if ieeeinit 1 printf Cannot initialize interface n exit 1 ieeewt remote 16 n Put 2001 in...

Страница 81: ...printf Calibration completed n void keypress Wait for keypress printf Press any key to continue n while kbhit 0 getch int calend n Check for cal end int n char status 40 int stat printf Waiting for ca...

Страница 82: ...tion Programs B 6 Program B 2 Calibration Program for Use with Any Suitable Calibrator Turbo C Version Continued ieeerd buf if strstr buf 1801 NULL printf Model 1801 is not installed program aborted n...

Страница 83: ...range PRINT 1 OUTPUT 04 RANGELCK ON Lock range PRINT 1 OUTPUT 04 OUT 0V 0 HZ Output 0V PRINT 1 OUTPUT 04 OPER Put calibrator in operate PRINT 1 OUTPUT 04 EXTSENSE ON Enable external sense PRINT PRINT...

Страница 84: ...6 SYST ERR Query error queue PRINT 1 ENTER 16 INPUT 2 E Err IF E 0 THEN PRINT If error is detected error PRINT Err is displayed and program PRINT Calibration aborted is halted BEEP CLOSE 1 CLOSE 2 END...

Страница 85: ...date 10 int i calend if ieeeinit 1 printf Cannot initialize interface n exit 1 ieeewt remote 16 n Put 2001 in remote ieeewt remote 04 n Put 5700A in remote ieeewt clear n Send DCL ieeewt term lf eoi n...

Страница 86: ...output 16 cal unpr pre ndue s n date ieeewt output 16 cal unpr pre save n printf Calibration completed n void keypress Wait for keypress printf Press any key to continue n while kbhit 0 getch int cal...

Страница 87: ...B 4 Calibration Program for Use with Fluke 5700A Calibrator Turbo C Version Continued char buf 40 ieeewt output 16 opt n ieeewt enter 16 n ieeerd buf if strstr buf 1801 NULL printf Model 1801 is not i...

Страница 88: ...preamp lter response Name SLOW MEDium FAST Returns preamp lter state SLOW MED or FAST SENSe 1 TEMPerature DTCouple TYPE type TYPE USLope value USLope RTEMperature value RTEMperature TRANsducer DTC TR...

Страница 89: ...o Measure 20 V range zero Measure 2mV range full scale value 1E 3 to 2E 3 Measure 200 V range full scale value 100E 6 to 200E 6 Measure 20 V range full scale value 10E 6 to 20E 6 Send calibration date...

Страница 90: ...2 Introduction 1 1 2 1 3 1 4 1 5 1 6 1 B 1 L Line power 4 2 5 2 M Magnetic fields 3 21 Manual addenda 1 2 Measurement considerations 3 18 Measurements 3 7 Minimum operating distance 2 9 Model 2001 com...

Страница 91: ...ve devices 5 12 Specifications 1 2 A 1 T Thermoelectric potentials 3 18 Troubleshooting 5 12 Troubleshooting access 5 12 Troubleshooting equipment 5 12 Troubleshooting procedure 5 12 U Unpacking and i...

Страница 92: ...nstable Will not read applied input Overload Calibration only Certi cate of calibration required Data required attach any additional sheets as necessary Show a block diagram of your measurement system...

Страница 93: ...se 65 82110 Germering 089 84 93 07 40 Fax 089 84 93 07 34 GREAT BRITAIN Unit 2 Commerce Park Brunel Road Theale Berkshire RG7 4AB 0118 929 7500 Fax 0118 929 7519 INDIA Flat 2B Willocrissa 14 Rest Hous...

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