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Lake Shore 420 User Manual

Gaussmeter
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Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc.
No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary
rights of Lake Shore Cryotronics, Inc. in these developments. Methods and apparatus disclosed herein may be subject to U.S. Patents
existing or applied for. Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design
modifications, or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or
consequential damages in connection with furnishing, performance, or use of this material.
Rev. 1.0
User's Manual
Model 420
Model 420
Model 420
Model 420
Gaussmeter
Lake Shore Cryotronics, Inc.
575 McCorkle Blvd.
Westerville, Ohio 43082-8888 USA
Internet Addresses:
sales@lakeshore.com
service@lakeshore.com
Fax: (614) 891-1392
Telephone: (614) 891-2243
21 August 1997

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  • Page 1 Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design modifications, or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing, performance, or use of this material.
  • Page 2 DuPont De Nemours. Copyright © 1993 – 1997 by Lake Shore Cryotronics, Inc. All rights reserved. No portion of this manual may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic,...

  • Page 3: Table Of Contents

    Lake Shore Model 420 Gaussmeter User’s Manual TABLE OF CONTENTS Chapter/Paragraph Title Page INTRODUCTION ..........................General........................Model 420 Gaussmeter System Description............... Electrostatic Discharge....................1.2.1 Identification of Electrostatic Discharge Sensitive Components......1.2.2 Handling of Electrostatic Discharge Sensitive Components........Safety Summary......................Safety Symbols......................
  • Page 4 B2.1 Active Area ....................... B2.2 Orientation ........................ B2.3 Handling........................B2.4 Polarity........................B2.5 Lead Configurations....................B3.0 Hall Generator Generic Hookup .................. B4.0 Using a Hall Generator with the Model 420 ..............B5.0 Specifications ....................... B6.0 HALLCAL.EXE Program ....................Table of Contents...
  • Page 5 Lake Shore Model 420 Gaussmeter User’s Manual LIST OF ILLUSTRATIONS Figure No. Title Page Model 420 Rear Panel..........................Model 420 Front Panel..........................Front Panel Display Definition ......................... Maximum Flexible Probe Bend Radius ....................Probe Orientation For Positive Measurement ..................Effect Of Angle On Measurements......................
  • Page 6 Lake Shore Model 420 Gaussmeter User’s Manual This Page Intentionally Left Blank Table of Contents...

  • Page 7: Introduction

    The display has a resolution of 4-characters. The Model 420 measures fields from 3 mG (0.3 µT) to 300 kG (30 T), in either gauss or tesla. Set field ranges either manually or with auto ranging. The Range key displays the full scale value and cycles through allowable ranges for the probe installed.

  • Page 8: Electrostatic Discharge

    Lake Shore Model 420 Gaussmeter User’s Manual Table 1-1 Model 420 Specifications Measurement: Number of Inputs: One Update Rate: Three Per Second Autorange: Yes Field Ranges/Resolutions: High Stability Probe High Sensitivity Probe Ultra-High Sensitivity Probe Gauss tesla Gauss tesla Gauss...

  • Page 9: Identification Of Electrostatic Discharge Sensitive Components

    Lake Shore Cryotronics, Inc. assumes no liability for Customer failure to comply with these requirements. The Model 420 protects the operator and surrounding area from electric shock or burn, mechanical hazards, excessive temperature, and spread of fire from the instrument. Environmental conditions outside of the conditions below may pose a hazard to the operator and surrounding area.

  • Page 10: Safety Symbols

    Do Not Substitute Parts Or Modify Instrument Do not install substitute parts or perform any unauthorized modification to the instrument. Return the instrument to an authorized Lake Shore Cryotronics, Inc. representative for service and repair to ensure that safety features are maintained.

  • Page 11: Installation

    Inspect shipping containers for external damage. Make all claims for damage (apparent or concealed) or partial loss of shipment in writing to Lake Shore within five (5) days from receipt of goods. If damage or loss is apparent, please notify the shipping agent immediately.

  • Page 12: Definition Of Rear Panel Connections

    Figure 2-1 Model 420 Rear Panel DEFINITION OF REAR PANEL CONNECTIONS The Model 420 rear panel consists of the power and fuse assembly, Serial I/O Connector, Corrected and Monitor Analog Output BNCs, and a DA-15 Probe Input Connector. See Chapter 5 for rear panel connector pin-out details.

  • Page 13: Initial Setup And System Checkout Procedure

    Some Lake Shore probes come with a clear plastic sleeve to protect the probe tip when not in use. The sleeve slides up and down the probe cable. To place the probe in the zero gauss chamber, slide the protective sleeve back, exposing the probe tip, before placing the tip in the chamber.
  • Page 14 Lake Shore Model 420 Gaussmeter User’s Manual This Page Intentionally Left Blank Installation...

  • Page 15: Operation

    OPERATION GENERAL This chapter covers aspects of Model 420 operation: Front Panel Controls (Paragraph 3.1), Front Panel Functions (Paragraphs 3.2 thru 3.10), Default Settings (Paragraph 3.11), and Probe Handling Considerations (Paragraph 3.12). See Chapter 4 for remote serial interface operation.

  • Page 16: Front Panel Display

    Lake Shore Model 420 Gaussmeter User’s Manual 3.1.2 Front Panel Display In normal operation, the two row by sixteen character LCD provides magnetic readings on the top row and special information or readings on the bottom row. Other information displays when using the various keypad functions.

  • Page 17: Range

    SELECT RANGE AND AUTO RANGE The Model 420 reads each Lake Shore probe type: High Stability, High Sensitivity, or Ultra-High Sensitivity. These probes sense fields as low as 0.2 mG and as high as 300 kG. The tables below list full scale ranges for each probe sensitivity, along with fixed display resolution.

  • Page 18: Gauss/Tesla

    The Corrected and Monitor Analog Outputs are not affected by a change in units. When tesla is selected, the Model 420 displays AC or DC field values followed by T for tesla, mT for millitesla, or uT for microtesla and formats field values over the Serial Interface accordingly.

  • Page 19: 3.10 Locking And Unlocking The Keypad

    45° from the base (see Figure 3-3). Never apply force to the tip of the probe. On all probes, do not pinch or allow cables to be struck by heavy or sharp objects. Although Lake Shore repairs damaged or severed cables that are returned, probes are not always repairable.

  • Page 20: 3.12.3 Probe Operation

    To help offset the effects of temperature on the Hall sensor, a thermistor may be included in the Lake Shore High Sensitivity and Ultra-High Sensitivity Probes. The High Stability Probe requires no temperature correction due to inherent thermal stability of materials used in its construction.

  • Page 21: Effect Of Angle On Measurements

    Lake Shore Model 420 Gaussmeter User’s Manual Consider gaussmeter, probe, and 29.3% magnet tolerances before making critical measurements. The 45° accuracy of the gaussmeter 13.4% reading is better than ±0.1% of 30° reading and ±0.005% of range. An 6.0% absolute accuracy reading for 20°...
  • Page 22 Lake Shore Model 420 Gaussmeter User’s Manual This Page Intentionally Left Blank Operation...

  • Page 23: Remote Operation

    The Customer supplied computer must have a Serial Interface port. The Model 420 Serial Interface complies with the electrical format of the RS-232C Interface Standard. A Serial Interface between the computer and the Model 420 permits remote monitoring and control of Model 420 control functions, which in turn controls Model 420 operation.

  • Page 24: Serial Interface Hardware Configuration

    Sample BASIC Serial Interface Program The program in Table 4-2 is a sample interactive serial poll routine for the Model 420 Serial Interface written in QuickBASIC V4.0. The following are typical examples using this BASIC program. Input provided by the user is shown in bold type.
  • Page 25 Add a query to the end of a command string to confirm command execution. For example, UNIT G;UNIT? commands the Model 420 to set units to gauss then requests the Model 420 return the units to confirm the change. •...
  • Page 26 Lake Shore Model 420 Gaussmeter User’s Manual Table 4-2 Sample BASIC Serial Interface Program SEREXAM.BAS EXAMPLE PROGRAM FOR SERIAL INTERFACE This program works with QuickBasic 4.0/4.5 or Qbasic on an IBM PC or compatible with a serial interface. It uses the COM1 communication port at 9600 BAUD. Enter an instrument command or query at the prompt.

  • Page 27: Serial Interface Command Summary

    Lake Shore Model 420 Gaussmeter User’s Manual SERIAL INTERFACE COMMAND SUMMARY There are two command groups: Interface Commands (Paragraph 4.2.2) and Device Specific Commands (Paragraph 4.2.3). Command Function Page Command Function Page Interface Commands MAXC Initiate Max Clear (Reset)......4-6 MAXR? Max Reading Query .........
  • Page 28 Lake Shore Model 420 Gaussmeter User’s Manual 4.2.3 Device Specific Commands ACDC Set AC or DC Magnetic Field Reading Status. Input: ACDC 0 or ACDC 1 Returned: Nothing Remarks: Configures the unit for AC or DC measurements: 0 = DC, 1 = AC.
  • Page 29 Lake Shore Model 420 Gaussmeter User’s Manual MAXC Initiate Max Clear (Reset). Input: MAXC Returned: Nothing Remarks: Initiate a Max Clear (or reset). Upon entry, Max Hold zeros out and captures a new peak. MAXR? Max Reading Query. Input: MAXR? Returned: ±XXX.XX...
  • Page 30 Lake Shore Model 420 Gaussmeter User’s Manual RELS? Relative Mode Setpoint Query. Input: RELS? Returned: ±XXX.XX Remarks: Returns sign, up to 5 digits, and decimal point. Places decimal appropriate to range. SNUM? Probe Serial Number Query. Input: SNUM? Returned: XXXXXXXXXX Remarks: Queries probe serial number.
  • Page 31 Lake Shore Model 420 Gaussmeter User’s Manual This Page Intentionally Left Blank Remote Operation...

  • Page 33: Service

    (Paragraph 5.4), and Operating Software EPROM Replacement (Paragraph 5.5). GENERAL TROUBLESHOOTING If the keyboard locks up, hold Escape for about 20 seconds to reset the Model 420 to factory defaults. The gaussmeter then requires the user to re-enter setpoints and zero the probe.

  • Page 34: Rear Panel Connector Definitions

    Lake Shore Model 420 Gaussmeter User’s Manual REAR PANEL CONNECTOR DEFINITIONS DESCRIPTION PROBE INPUT Input + ITEMP + ITEMP – VIEW FROM MATING SIDE OF CONNECTOR I c + DA-15 Connector INPUT – C-450-U-5-2 GND 1 A/D CLK EE-DATA I c –...

  • Page 35: Serial Interface Cable And Adapters

    Lake Shore Model 420 Gaussmeter User’s Manual SERIAL INTERFACE CABLE AND ADAPTERS To aid in Serial Interface troubleshooting, Figures 5-6 through 5-8 show wiring information for the cable assembly and the two mating adapters. YELLOW GREEN BLACK Figure 5-6 Model 2001 RJ-11 Cable Assembly Wiring Details...

  • Page 36: Operating Software Eprom Replacement

    Lake Shore Model 420 Gaussmeter User’s Manual OPERATING SOFTWARE EPROM REPLACEMENT The operating software for the Model 420 is contained on one Erasable Programmable Read Only Memory (EPROM) Integrated Circuit (IC). The EPROM is numbered U36 and located just behind the microprocessor IC (U31).

  • Page 37: Accessories And Probes

    4502 Hall Generator Cable Assembly . The MCBL-6 Cable Assembly connects a discrete Hall generator to the Model 420 Gaussmeter. Cable is 2 meters (79 inches) long. The cable ships with the MCBL-6 HALLCAL.EXE program on a 3.5 inch diskette which permits cable PROM programming through an IBM PC or compatible computer serial port.

  • Page 38: Model 4001 Rj-11 Cable Assembly

    Lake Shore Model 420 Gaussmeter User’s Manual Cable Length: 4.3 meters (14 feet) C-450-U-6-1 Figure 6-1 Model 4001 RJ-11 Cable Assembly 43 mm (1.69 inches) 15.8 mm (0.63 inches) C-450-U-6-2 Figure 6-2 Model 4002 RJ-11 to DB-25 Adapter 60.3 mm (2.37 inches) 15.9 mm...

  • Page 39: Model 4022 Rack-Mount Kit

    Lake Shore Model 420 Gaussmeter User’s Manual NOTE: Remove four Model 450 side screws with 5/64" Refer to (2 mm) hex key. “Note” Drawing shows right side mounting. Left side mounting also possible. Item Description Rack Mount Ear 107-430 Rack Mount Support...

  • Page 40: Model 4060 Standard Zero Gauss Chamber

    Lake Shore Model 420 Gaussmeter User’s Manual NOTE: Periodically de-magnetize (degauss) the chamber. Using a magnetized chamber to zero a probe can lead to erroneous field readings. If no professional degausser is available, use a bulk tape degausser (Radio Shack P/N 44-232 or equivalent).
  • Page 41 Transverse (Figure 6-10), and Gamma (Figure 6-11) - each named by its Hall sensor orientation. Because the Model 420 covers such a wide magnetic field range (0.01 mG to 300 kG), three probe ranges are available: High Stability (HST), High Sensitivity (HSE), and Ultra-High Sensitivity (UHS). Consult the factory for availability of probe types not detailed in these figures.

  • Page 42: Definition Of Lake Shore Transverse Probes

    Lake Shore Model 420 Gaussmeter User’s Manual Probe Table Definitions: Usable Full-Scale Ranges vs Probe Type = Distance from tip of probe to center line of active area. Type HST-1 HST-2 HSE-1 UHS-1 = Magnetic flux density vector 300 G...

  • Page 43: Definition Of Lake Shore Axial Probes

    Lake Shore Model 420 Gaussmeter User’s Manual 2.5" 0.35 ±0.030" dia. Cable Length = 6.6 feet Corrected Temp. Coefficient Active Stem Freq. Accuracy Model (Maximum) Temp. Type Area Material Range (% of Number Range Zero Calibration Reading) MMA-0602-TH 2 ±0.125"...

  • Page 44: Definition Of Lake Shore Flexible Transverse Probes

    30 kG C-450-U-6-10 Figure 6-10 Definition of Lake Shore Flexible Transverse Probes Around large solenoids, measure small variations or low values of large volume magnetic fields such as that of the earth, or fringe fields with ultra-high sensitivity probes.

  • Page 45: Appendix A - Units For Magnetic Properties

    Lake Shore Model 420 Gaussmeter User’s Manual APPENDIX A UNITS FOR MAGNETIC PROPERTIES Conversion from CGS to SI Units Gaussian Conversion SI & Quantity Symbol & CGS emu Factor, C Rationalized mks Magnetic flux density, tesla (T), Wb/m gauss (G)
  • Page 46 Lake Shore Model 420 Gaussmeter User’s Manual This Page Intentionally Left Blank Appendix A...

  • Page 47: Appendix Bhall Generators

    B1.0 GENERAL This chapter covers useful information about Hall Generators including: Theory of Operation (Paragraph B2.0), Generic Hall Generator Hookup (Paragraph B3.0), Hookup to a Model 420 Gaussmeter (Paragraph B4.0), Specifications (Paragraph B5.0), and the HALLCAL.EXE Program (Paragraph B6.0). Obtain additional installation and calibration information in Lake Shore Document Number C2S001.

  • Page 48: B2.2 Orientation

    The Hall voltage leads may connect directly to a readout instrument, such as a high impedance voltmeter, or to electronic circuitry for amplification or conditioning. Device signal levels are in the range of microvolts to hundreds of millivolts. In this case, a separate precision current source (Lake Shore Model 120CS or equivalent) is necessary. See Figure B-3.

  • Page 49: Typical Hall Generator Hookup

    30 Ω . 2. Because the Model 420 input impedance is 420 Ω , there is a voltage drop due to lead resistance in series with the gaussmeter input. The Lake Shore Hall generator sensitivity given on the data sheet includes no lead resistance.

  • Page 50: Active Area

    Lake Shore Model 420 Gaussmeter User’s Manual B5.0 SPECIFICATIONS This section covers three types of Hall generators available from Lake Shore: HGCA & HGCT Series Cryogenic Hall generators (Figures B-5 and B-6) with specifications (Table B-1), HGA Series Axial Hall generators (Figures B-5 and B-7) with specifications (Table B-2), and HGT Series Transverse Hall generators (Figures B-8 thru B-10) with specifications (Table B-3).

  • Page 51: Axial Hall Generator Hga-2010 Dimensions

    Lake Shore Model 420 Gaussmeter User’s Manual 0.09 in. (max.) 5 ±0.5 in. (Lead Length) 1.25 in. 0.175 in. (max.) Active Area Figure B-7 Axial Hall Generator HGA-2010 Dimensions Table B-2 Axial Hall Generator Specifications Axial HGA-2010 HGA-3010 HGA-3030 Description General purpose axial;...

  • Page 52: Transverse Hall Generator Hgt-1010 Dimensions

    Lake Shore Model 420 Gaussmeter User’s Manual 0.50 in. 9.5 in. (min.) 0.125 in. Center of Active Area 0.130 in. (max.) 0.020 in. (max.) over Hall plate 0.028 in. (max.) over leads Figure B-8 Transverse Hall Generator HGT-1010 Dimensions 0.060 in. (max.) 5 ±0.5 in.
  • Page 53 Lake Shore Model 420 Gaussmeter User’s Manual Table B-3 Transverse Hall Generator Specifications Transverse HGT-1010 HGT-2010 HGT-2100 HGT-3010 HGT-3030 Description General purpose General purpose Low cost; high Instrumentation Instrumentation transverse; 0.020 transverse; high sensitivity; quality quality transverse inch thick sensitivity surface mount transverse;...

  • Page 54: B6.0 Hallcal.exe Program

    (@ 100 mA current). 6. The program prompts for the Calibration Constant. Enter the magnetic sensitivity in mV/kG at a control current of 100 mA. Remember to account for the Gaussmeter 420 Ω input impedance when calculating the proper load resistor to install.

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