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Model DRC-7_1975 - Lake Shore Cryotronics, Inc.

1. O 00 ON O ON BURN Introduction Test Equipment and Accessories General Remarks Operational Checks Nominal Operating Voltages and Gains Initial Adjustments Final Adjustments Alignment of Controller Section Model DRC 7C Model DRC 70C Troubleshooting Panel Meter Circuit Board Removal Panel Meter Removal Parts List Printed Circuit Board Component Locator and Schematic Appendixes Table of Illustrations Reference Description Figure 1 1 Figure 2 1 Table 3 1 Figure 3 1 Figure 3 2 Table 3 2 Table 3 3 Figure 4 Figure 4 Figure 5 m Figure 5 2 Figure 5 3 Figure 5 4 Figure 5 5 Table 6 1 Model DRC 70 Digital Cryogenic Thermometer Sensor and Heater Cables Entry Number Correlation Rear Panel Front Panel Pin Designation for Model DRC 7 BCD Pin Designation for Models DRC 7C DRC 70 DRC 70C Timing Diagram for Ts Greater Than Tp Timing Diagram for Ts Less Than Tp Circuit Schematic Diagram Models DRC 7 and DRC 7C TEMPERATURE INDICATOR SECTION Circuit Schematic Diagram Models DRC 70 and DRC 70C TEMPERATURE INDICATOR SECTION Circuit Schematic Diagram Model DRC 7C TEMPERATURE CONTROLLER SECTION Circuit Schematic Diagram Model DRC 70C TEMPERATURE CONTROLLER SECTION Printed Circuit Board Components Locator DRC 7 Series Standard Silicon Diode Table 4 400 K iii Page 39 40 4l 42 43 45 WARRANTY Lake Shore Cryotronics
2. User s Manual Model DRC 7 70 Digital Cryogenic Thermometer Model DRC 7C 70C Digital Cryogenic Controller Obsolete Notice This manual describes an obsolete Lake Shore product This manual is a copy from our archives and may not exactly match your instrument Lake Shore assumes no responsibility for this manual matching your exact hardware revision or operational procedures Lake Shore is not responsible for any repairs made to the instrument based on information from this manual E1 akeShore Lake Shore Cryotronics Inc 575 McCorkle Blvd Westerville Ohio 43082 8888 USA E Mail Addresses sales lakeshore com service lakeshore com Visit Our Website www lakeshore com Fax 614 891 1392 Telephone 614 891 2243 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 performa
3. 14 EMEN 25 The bandwidth circuit adds its output to the input from the BCD output of the temperature display allowing the comparators to see an artificial value of real temperature The bandwidth circuit adds the artificial temperature units to the counter Z16 by way of additional counts with each additional count equivalent to 0 1 degree The artificial temperature is constantly adjusting for changes between actual temperature and set point temperature to arrive at a controlled temperature approximately equal to the displayed temperature Assume the artificial temperature TA is 1 2 5 counts above the actual display temperature Tp and that the temperature set point Tg is equal to Tp then as in Section 4 4 1 the control circuit will provide a logic state 0 to prevent power from being applied except for a small amount of residual power which increases linearity from O K 0 power to 400 K 15 power Assume the temperature set point Tg is greater than the temperature display Tp Since the counter circuit is modified to count 5 counts 1 2 K above the display the display will actually be 5 counts 5 K below the artificial temperature TA When the display is 5 counts below the temperature set point setting then the latch circuit Z17 allows the bandwidth counter 216 to register the number of counts above the set point and transfer these to comparison circuit 710 218 219 and Z20 The comparison number is con
4. f S r t z N 2 L i 0 100 200 300 400 0 100 200 300 Temperature K Temperature K 1 Figure 2 Figure 3 Comparison of typical forward voltage versus Typical capacitance temperature characteristics 1 temperature characteristics for the gallium arsenide for SrTiO capacitance thermometers GaAs and silicon Si diode thermometers M FOR BULLETIN INSTALLATION AND 10 5 1 gt 2 D 0 01 1 10 100 Temperature K Figure 4 Temperature sensitivity of voltage dV dT as a function of temperature for silicon Si and gallium arsenide GaAs diode solid and dotted line ther mometers and carbon glass CG solid line ger manium Ge dotted line and platinum Pt R 470 ohms resistors Numbers for resistors indicate current in microamperes Diode thermometer is at 10 microamperes Magnetic 2 5 5 10 15 TG 100 GaAs 2 7 2 3K N R DT 900 1 4K 2 4K N R Silicon CS 400 CGR Carbon Glass GR 200 Germanium Figure 6 Typical Magnetic Field Induced Temperature Errors at Selected Field Levels at 4 2 K N R Not Recommended 100 APPLICATION NOTES FOR CRYOGENIC SENSORS I Temperature Figure 5 Relative sensitivity data dinR dInT versus temperature for carbon glass
5. Vacuum Source SERIES DRC F DIGITAL THERMOMETERS Technical Specification DRC 7 e to 400 Range e Silicon Diode Sensor Recorder Output e BCD Output e Optional 10 Sensor Input e 115 or 230 VAC Power The Model DRC 7 Digital Cryogenic Thermometer is designed to cover the range from 1 to 400 K utilizing the Lake Shore Cryotronics DT 500 Silicon diode sensor Six segments of digital linearization are used to achieve 0 5 K conformity accuracy to the Lake Shore Cryotronics DRC 7 standard DT 500 Silicon diode table from 4 to 300 K In addition to a TTL compatible BCD output an analog 0 100 mV recorder output is provided and is proportioned to the actual diode forward voltage drop and thus gives a 0 1 K resolution capability The temperature sensor is excited by a 10 uA constant current source with 0 1 regulation The thermometer is designed to connect to the sensor in a 2 or 3 wire configuration or a four lead potentiometric configuration which significantly reduces errors due to lead wire resistance A selector switch is available as an option which allows one to select and read out up to 10 separate sensors TECHNICAL SPECIFICATIONS TEMPERATURE RANGE 1 to 400 K SENSING MATERIAL Silicon RESOLUTION OPERATING Digital 1 kelvin ENVIRONMENT 0 45 C Analog 0 1 kelvin or better CONFORMITY TO LSCI STANDARD DRC 7 SILICON DIODE TABLE 0 5 K 4 300 K TTL compa
6. The adjustment procedure is divided into several small sections Care should be taken not to touch integrated circuits 4016 Z6 and Z8 since any static charge on the body might cause permanent damage to the integrated circuits Turn the POWER to the instrument and allow one hour warmup time Connect the positive lead of Voltmeter 1 to test point 9 Rgg and the negative lead to test point 10 R27 Adjust potentiometer R71 until the DVM reads 7 000 volts 0 001 volts With Voltmeter 4 indicating the voltage across adjust until a reading of 100 00 millivolts is obtained Connect the positive lead of Voltmeter 2 to test point 3 Z4 pin 14 Connect the negative lead of Voltmeter 2 to test point 10 Set the voltage standard to 1 6884 volts and adjust the potentiometer Rg2 until Voltmeter 2 indicates 0 977 volts 30 Now connect the positive lead of Voltmeter 2 to test point 4 24 1 retaining the negative lead at test point 10 Adjust Rgg until the voltmeter indicates 1 527 volts Connect the positive lead of Voltmeter 1 to test point 5 Z4 pin 3 retaining the negative lead at test point 10 Set the voltage standard to 1 1390 volts Voltmeter f1 should indicate positive saturation voltage approximately 6 volts Set the voltage standard to 1 1395 volts and observe the reading on Voltmeter fl is a negative saturation voltage approximately 6 volts If necessary adjust Rog until th
7. 914 eremo 2045522 gt 277772255 PHIL tsP v0 NOWNSD A LY Xs son a TN 09 03 Merlo 440001 x1 4000 122 9 24 w A 183 xm 3842 yos mg 40 NOILOAS Wu3TIOHLNOO O 24G T3dON WVYOVIG OILVWSHOS 1100812 S MINDI riporta 00 ANOJ 374849 t RM amp o RERS RERS LIT 2 ts amp t 8 8 lt L4 9 724 465 k k sesame w om XC ARAR Tra woa A 5e dal 48 o 002 Y 3148892 ZU Tg 2 5 2 41 01153 YATIOULNOD JANLVYAdWIL 204 2ud TAGOW DILVWAHOS 1102412 v S 14 9 44 i ae vua sare W ane yams stay R f 44 s s 5 WEES ME NEES Yeri Veri VEE M 50 H4 PO M PRO i p 4 o 4 2 Mess wee NEES 7 44 111 SONU 60d ll o ver gt sia 91 appe eoo 826 0002098 42 YOLVIOT SINSNOdWOO GuVOd 1100412 GHLNIYd S S HSHfloId 7 H r C H Fine eni 01 sis 1 qum Es T 5 Aq LA m T db IPSE RR AMBAS 3 43
8. e Rhodium lron Resistor e Platinum Resistor e Nickel Resistor Available Configuration See Pages 6 and 7 Sensing Element Material Diode Thermometry Gallium Arsenide Silicon Capacitance Thermometry Strontium Titanate Resistance Thermometry Carbon Glass Germanium Copper Rhodium with 0 5 atomic Iron Platinum Nickel Heat Dissipation at 4 2K and recommended Operating current Useful Temperature Range 15 uW to at 10 uA 400 K 25 uW at 10 uA 400 K 12 lt 10 mk lt 10 W to at1 K Hz 60 K and 50 mv 70 K excitation 400 K CGR 1 2000 0 2 uW 10 uA 0 31 to 100K uW 300K 3 0 uA CGR 1 10 000 lt 0 03 K GR 200 1000 to 0 1 uw 100 K at 10 uA with several Elements 70K N A f to 475 K 2K to 300 K Output Signal or Nominal Value at 4 2k at 295 K 50 mV K 250 pF K d at 4 2 K 40 nF 4 2K 160 pF K FP only See Fig 3 See Fig 3 250 ohm 1000 ohm See 2000 ohm Figures 5000 ohm 4 5 7 10 000 ohm 30 ohm See 100 ohm Figures 1000 ohm 4 5 7 2340 ohms at 10 1 K 273 2 0 C 20 47 BU 90 uV K 100 ohms at4 2 K at 273 2 K OC and 500 uA Sensitivity 0 6 mV K at at 4 2 K 7K 2 75 mV K See Fig 2 4 at 4 2 K 7K at 2 75 mV K See Fig 1 4 Inter changeability N A 0 1K 4 2K HK 77K 300 K see remarks N
9. 430 1970 3 Brown M A Reliable Low Thermal Resistance Bond Between Dielectrics and Metals for Use at Low Temperatures Cryogenics 10 p 439 1970 4 Anderson A C and Rauch B Low Temperature Thermal Conductivity of a Suspension of Copper Particles Jour App Physics 41 p 3648 1970 5 Kreitman M M Low Temperature Thermal Conductivity of Several Greases Rev of Sci Instr 40 p 1562 1969 6 Anderson A C Rauch R B and Kreitman M M Another Comparison of Thermal Bonding Agents Rev of Sci Instr 41 p 469 1970 1JULY 74 7 Hust J G Thermal Anchoring of Wires in Cryogenic Appartus Rev of Sci Instr 41 p 622 1970 9 8 Kopp J and Slack G A Thermal Contact Problems in Low Temperature Thermocouple Thermometry Cryogenics 11 22 1971 10 Platinum sensor leads can be easily soldered to if a flux is used Care should be taken to remove all flux after making the joint One suitable flux is Stay Clean Solder and Tinning Flux from the J W Harris Co 433 W 9th Cincinnati 3 Ohio Because of the many varied installations for temperature sensors many are supplied without strain relief at the stem lead interface strain relief however is recommended particularly when the sensor l is not permanently installed A satisfactory material is RTV silicone This material is waterproof dries quickly and is soft at
10. As a further check an independent voltmeter equivalent to Voltmeter 1 may be used to monitor directly the voltage drop developed across the test resistor Comparison of this voltage to the standard DRC 7 silicon diode table determines the temperature value expected as well as the accuracy of the factory adjusted internal current source 29 Adjust the temperature set point switch to equal the temperature value displayed With the set point switch equal to or less than the display the power heater ON light will illuminate indicating the power being applied to the heater load With the set point value greater than the display value the controller s ON light should be off indicating no power applied to the heater load For operation of the Model DRC 70C the ON will not shut off until the display temperature is greater than the set point temperature by 0 5 K If the instrument responds to the tests outlined above as indicated either the trouble lies elsewhere in the system or the malfunction in the controller is of a subtle nature aid in troubleshooting in the latter case typical voltages and gains are given in Section 5 5 5 5 Nominal Operating Voltages and Gains 5 5 1 Initial Adjustments Connect the voltage standard such as EDN MV 100N as listed in Section 5 2 across the input terminals and input voltage terminals and Voltmeter 4 across positive terminal to test point 1 and negative terminal to test point 2
11. Inc warrants each instru ment of its own manufacture to be free from defects in material and workmanship Obligations under this Warranty shall be limited to replacing repairing or giving credit for the purchase price at our op tion of any instrument returned shipment prepaid to our factory for that purpose within ONE year of delivery to the original purchaser provided prior authorization for such return has been given by an authorized representative of Lake Shore Cryotronics Inc This Warranty shall not apply to any instrument which our inspection shall disclose to our satis faction to have become defective or unworkable due to abuse mishandling misuse accident alteration negligence improper installation or other causes beyond our control This Warranty likewise shall not apply to any instrument or component not man ufactured by others and included in Lake Shore Cry otronics Inc equipment the original manufacturer s warranty is extended to Lake Shore Cryotronics Inc customers Lake Shore Cryotronics reserves the right to make changes in design at any time without incurring any obligation to install same on units previously pur chased THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THE DES CRIPTION ON THE FACE HEREOF THIS WARRANTY IS IN LIEU OF AND EXCLUDES ANY AND ALL OTHER WARRANTIES OR RE PRESENTATIONS EXPRESSED IMPLIED OR STATUTORY IN CLUDING MERCHANTABILITY AND FITNESS AS WE
12. SECTION VI APPENDIXES 44 Temp K Voltage V 2 46200 2 45000 2 40200 2 34200 2 28964 2 23727 2 18491 2 13255 2 08018 2 02782 1 97545 1 92309 1 86442 1 80574 1 74707 1 68839 1 61309 1 53778 1 46248 1 38717 1 31187 1 26000 1 20813 1 17357 1 13900 1 12833 1 11769 1 10705 1 09375 1 08045 1 06715 1 05385 1 04055 1 02725 TABLE 6 1 K 45 Voltage V 1 01595 1 00065 0 98755 0 98113 0 97405 0 96017 0 94630 0 93242 0 91855 0 90467 0 89079 0 87692 0 86304 0 84917 0 83529 0 82141 0 80754 0 79366 0 77979 0 76591 0 75203 0 73816 0 72428 0 71041 0 69653 0 68265 0 66378 0 65490 0 64103 0 62715 0 61327 0 59940 0 58552 0 57165 DRC 7 SERIES STANDARD SILICON DIODE TABLE 4 400 K A 020 009 Temp K 230 235 240 245 250 255 260 270 275 280 285 290 295 300 305 310 315 320 325 330 335 340 345 350 355 360 365 370 375 380 385 390 395 400 Voltage V 0 55777 0 54389 0 53002 0 51614 0 50227 0 48839 0 47451 0 46064 0 44676 0 43289 0 41901 0 40513 0 39126 0 37738 0 36351 0 34963 0 33575 0 32188 0 30800 0 29413 0 28025 0 26637 0 25250 0 23862 0 22475 0 21087 0 19699 0 18312 0 16924 0 15537 0 14149 0 12761 0 11574 0 09986 0 08599 CONTENTS Page No General Considerations 1 Diode Temperature Sensors 2 Capacitance Temperature Sensors 3 Resistance Temperature Sensors 4 While certain thermometers
13. A Consult Factory Limited with Bridge Techniques Yes with Current Adjustment ASK FOR BULLETIN CRYOGENIC INSTRUMENTATION Magnetic Field Effect Data taken 1 to field at 5 Tesla and 4 2K Thermal Response Repeatability at 4 2K at 4 2K Configuration Dependent 0 7 K 100 K sec 100 uV See Fig 6 2 4 K 100 K sec 50 uV See Fig 6 No 100 K sec Effect See Fig 6 0 5 mK lt 0 05K at 4 2 K See Fig 6 0 5 mK at x Not 42K Recommended N A N A N A O 3 at 0 3 K 4 2 K FROM LAKE SHORE CRYOTRONICS INC Reliability Typical cycling life 300K to 4 2K 200 to 300 Cycles Nominally Excellent Excellent Excellent Excellent Excellent Excellent Suggested Temperature Accuracy REMARKS Useful modest 100 V magnetic fields Sensors of same config can be matched at LHe LN and 100 uV i room temperature i If quantites to be matched exceed 5 discuss applicaton with factory Unaffected by magnetic fields to 18 T 3 pF Recommended Tor control purposes Request detailed information from factory i D Useful in Magnetic Fields Large useful range essentially no piezo resistance monotonic vs T and dR dT curves 250 ohm 0 3 4 2 1000 ohm 1 5 100 300K 2000 ohm 2 100K 300K 5000 ohm 2 5 100K 300K D 10 000 ohm 3 100K 300K Recognized secondary
14. ANALOG 0 1 kelvin or better DIGITAL 0 1 kelvin CONFORMITY TO LSCI STANDARD DRC 7 SILICON DIODE TABLE 0 3K 4 400K MAXIMUM SENSOR POWER DISSIPATION 25uWat 4 2K MAXIMUM DIGITIZING ERROR 8 HRS at 25 0 5K TEMPERATURE COEFFICIENT ERROR 0 06K C REPEATABILITY 0 1K INPUT RESISTANCE Greater than 100 megohms ISOLATION 300V OUTPUTS ANALOG 10mV Kat 1000 ohms output impedance Tracking to digital display of 0 3K DIGITAL Optional TTL compatible non isolated DISPLAY 4 digits 14mm 0 55 high 7 segment non blinking RESPONSE TIME 2secondsto rated accuracy NORMAL MODE REJECTION 50 at 60 Hz and above COMMON MODE REJECTION 120 min at 60 Hz and above CRYOGENIC TEMPERATURE SENGING ELEMENTS FROM CAPACITANCE TEMPERATURE SENSORS CS 400 e Strontium Titanate e Unaffected by Magnetic Fields e 005 K to 400 K m CRUD NEE DIODE TEMPERATURE SENSORS TG 100 e Gallium Arsenide e 1 K to 400 K Full Range Useful in Modest Magnetic Fields DT 500 e Silicon e 1 K to 400 K Full Range s Highest Sensitivity e Interchangeable RESISTANCE SENSORS CGR e Carbon Glass e 1K to 300 e Monotonic Tempera ture Response Useful in Magnetic Fields GR 200 e Germanium Repeatability 030 K to 100 K Secondary Standard LR 700 e Copper e 70K to 475 K e Essentially Linear with Temp Coeff 4396 K MISCELLANEOUS
15. CG and germanium Ge resistors Resistance Ohms Y 102 is r EN 1 10 100 Temperature K Figure 7 Resistance temperature characteristics of the ger manium Ge platinum Pt R 1380 ohms and carbon glass CG resistors 1 SENSOR LEAD IDENT SERIES AND CONFIGURATION DESIGNATION i ISOLATION Cathode is at TG 100K case potential DT 500K Tab index DT 500K DE is anode isolated Tab index is anode DT 500KL DT 500KL DE Both leads isolated Tab index is anode TG 100KL Cathode is at case potential anode is shorter lead TG 100P DT 500P Cathode is at 632 A TG 100K T05 case potential x ST 5 9 272 DT 500K T05 Tab index 000000109 Hr DT 500K T05 DE is anode B Both leads 5314 A gt TG 100KL T05 6 isolated x c 2 QM DT 500KL T05 Tab index 000000089 z DT 500KL T05 DE is anode B Standard version TG 100P TO5 TG 100P T05 7 1 Same as Ref 4 DT 500P TO5 designates DT 500P T05 1 both leads isolated TG 100P GR TG 100P GR I DT 500P GR DT 500P GR 1 DT 500P GR MIN Standard version designates both leads isolated Short le
16. K 3 0 to 4 2 K 0 4 K 5 0 to 30 K 1 0 K Computer printouts are provided where applicable All diode and resistor calibrations are performed with a 4 wire potentiometric configuration Capacitance temperature sensors are calibrated with a 3 wire bridge configuration Resistor calibration currents are selected to produce a potential difference between 1 and 15 mV for the desired temperature Diodes are calibrated with a 10 uA excitation current Capacitors are calibrated with a 50 mV rms excitation signal at 5 kilohertz Note Consult factory for special printouts M MM P M M M M 9631 SANDROCK ROAD e EDEN NEW YORK 14057 U S A e 716 992 3411 TELEX 91 396 CRYOTRON EDNE 742 REV 1 MAY 75 Printed in U S A
17. Meg 1 8W 1 RN60D1004F R2 100 K 1 8W 1 RN60D1003F R3 324 1 8W 1 RN60D3240F R4 511 K 1 8W 1 RN60D5113F R5 100 K 1 8W 1 RN60D1003F R6 513 1 8W 1 RN60D5130F R7 634 K 1 8W 1 RN60D6343F R8 388 1 8W 1 RN60D3880F R9 100 K 1 8W 1 RN60D1003F R10 634 K 1 8W 1 RN60D6343F R11 100 K 1 8W 1 RN60D1003F R12 931 1 8W 1 RN60D9310F R13 475 K 1 8W 1 RN60DA753F R14 100 K 1 8W 1 RN60D1003F R15 1004 1 8W 1 RN60D10040F R16 63 4 K 1 8W 1 RN60D6342F R17 100 K 1 8W 1 RN60D1003F R18 1 02 K 1 8W 1 RN60D1021F R19 50 ohm VARIABLE 3006 1 500 R20 13 3 K 1 8W 1 RN60D1332F R21 100 K 1 8W 1 RN60D1003F R22 98 8 K 1 8W 1 RN60D9882F R23 8 47 K 1 8W 1 RN60D8471F R24 100 1 8W 1 RN60D1003F R25 1 05 1 8W 1 RN60D1051F R26 50 ohm VARIABLE 3006P 1 500 R27 100 1 4W 5 RCR07G101JS R28 90 9 K 1 8W 1 RN60D9092F R29 5 11 K 1 8W 1 RN60D5111F R30 51 1 1 8W 1 RN60D51R1F R31 6 49 1 8W 1 RN60D6491F R32 100 K 1 8W 1 RN60D1003F R33 10 K VARIABLE 3006 1 103 R34 50 ohm VARIABLE 3006P 1 500 R35 1 1 Meg 1 8W 1 RN65D1104F 34 REF DESIG R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R51 R52 R69 R70 R71 R72 R73 R74 R75 R76 amp R77 R78 R79 R80 R81 R82 R83 R84 85 R86 87 R88 R89 R90 91 R92 MODEL DESCRIPTION DESIG 324 1 8W 15 419 1 8W 1 234 1 8W 1 377 1 8W 1
18. VAC add K to model number DRC 70 K PRINTED IN U S A OCTOBER 1975 Temperature Control SET POINT CONTROLLABILITY REPEATABILITY SETTABILITY HEATER OUTPUT CONTROL MODE Temperature Readout RESOLUTION ANALOG DIGITAL CONFORMITY TO LSCI STANDARD DRC 7 SILICON DIODE TABLE MAXIMUM SENSOR POWER DISSIPATION MAXIMUM DIGITISING ERROR 8 HRS at 25 O TEMPERATURE COEFFICIENT ERROR REPEATABILITY INPUT RESISTANCE ISOLATION OUTPUTS ANALOG DIGITAL Optional DISPLAY RESPONSE TIME NORMAL MODE REJECTION COMMON MODE REJECTION Digital thumbwheel selection directly in kelvin temperature units 0 5 K with a properly designed System 1K 1K Standard 0 50 watts 0 1A 0 50 VAC Time proportional thyristor with continuously adjustable variac output 0 1 kelvin or better 1 kelvin 0 5 K 4 400K 25 uW at 4 2 K 0 5 K 0 06K C 1K Greater than 100 megohms 300V 10 mV K at 1 K output impedance Tracking to digital display of 0 3K TTL compatible non isolated 3 digits 14mm 0 55 high 7 segment non blinking 2 seconds to rated accuracy 50db min at 60 Hz and above 120db min at 60 Hz and above Technical Specification DRC 70 SERIES DRC DIGITAL THERMOMETERS Dm TS MODEL DRC 70 DIGITAL CRYOGENIC THERMOMETER e 0 1K Resolution 9 1 to 400K Range e Silicon Diode Sensor Model DT 500 DRC e Recorder Outp
19. be considered where the power is the sum of the DC current times the equivalent voltage plus the square of the DC current times the DC dynamic resistance Diode thermometer construction techniques allow a wide and diverse variety of envelope configurations Because of this character istic it is important that the user assure himself that the material in the package does not affect his experiment For example several configurations utilize gold plated Kovar or Rodar material nominal 50 50 Ni Fe This material will not effect the sensing element in a magnetic field but its presence will certainly affect the homogenity of the field adjacent to the sensor TO 5 headers have been designed to withstand no more than 16 inch ounces of torque Capacitance Temperature Sensors Capacitance sensors Figure 4 may be connected to terminal points outside the cryostat with two unshielded insulated fine wires alongside the other wires leading to the sample area No appreciable change in the measured capacitance arising from the leads should result provided changes in lead capacitance due to mechanical movement are avoided When the mechanical stability is not assured each sensor lead should be connected to a thin coaxial cable brought out to the external terminal points with the shield of each cable electrically insulated from the cryostat Two coaxial cables one for each lead with the shield insulated from each other shoul
20. by observing a continuous switching between ON and OFF of the heater ON light 3 4 3 Model DRC 70 The sensor should be connected to both the sample area and instrument following the suggestions noted in Section 3 4 2 The sensor and readout display should follow Table 6 1 which illustrates typical values expected of the standard DT 500 DRC sensors If the instrument or sensor does not agree with values listed in the table consult sections on installation and or section on troubleshooting to determine cause and cure of malfunction For those units equipped with BCD output the following Table 3 3 illustrates the function of each pin designation Table 3 3 BCD Pin Designation for Models DRC 7C DRC 70 and DRC 70C PIN NO FUNCTION 1 N A 2 N A 3 Print command 4 Polarity 5 BCD 8 6 BCD 2 7 BCD 80 8 BCD 20 9 BCD 800 10 N A 11 BCD 400 12 BCD 200 13 N A 14 BCD 1000 15 Hold 16 BCD 1 17 BCD 4 18 BCD 10 19 BCD 40 20 BCD 100 21 Digital GND BCD GND 22 BCD 2000 23 N A 24 Overload 25 Shift All terminations for above signals are located at the connector Key No 10 type 17 10250 by Amphenol 15 3 4 4 Model DRC 70C Connect the sensor following the procedure outlined in Section 3 4 2 Before applying power the fine tuning control Key 7 should be rotated full counterclockwise to minimum power output and the set point switch Key No 6 to 002 0 K Note If 000 0 K is set in the thumbwheel s
21. end by a sensitive lip and the other end by a rolling diaphragm This poppet is driven by a diaphragm The reference side of the diaphragm is gas loaded by means of two orifices in series with an absolute pressure aneroid which controls a frictionless lever and inboard bleed valving system Vacuum is applied to the vacuum pump port Since the main valve is balanced it doesn t want to move in either direction If the poppet is open the regulated side of the regulator will start to lower in pressure This decrease in pressure will be sensed through the poppet will lower the pressure under the diaphragm and pull the valve closed This same vacuum is applied to the dome volume through an orifice This will lower the reference pressure dome pressure and cause the main valve to open When the dome pressure gets to the set point the aneroid expands allowing ambient air into the dome through the second orifice and maintains dome pressure at set point Inboard Bleed Orifice Absolute Pressure Aneroid Controls Control Reference Pressure Handle Reference Pressure Diaphrege Operated Reference Pressure Vacuum Source for Regulated Uttraminiature Coaxial Cable Construction Detait Center Conductor Drain Wire Dielectric Jacket Figure 5 Main Valve Remote Sensing Port Poppet Valve Controlled Vacuum Poppet Valve Seat
22. standard at h 010 1 5k 4 2k For 100001 30 ohm 0 010 1 5 4 2k at 4 2 K 1 100 ohm 0 3 4 2K 1000 ohm 1 5 40K 100K Essentially linear 0 1 in response over 9r most of the useful better temperature range Model RF 802 Perf 0 008K is a perforated Or i can version for gas or liquid use better i ersion 9 i 1 i d H Request detailed information from factory Data sheet available on request Wissen IMS SES Sensor Diode Thermometry DT 500 Capacitance Thermometry Resistance Thermometry CGR GR 200 LR 700 RF 800 2 EE EEC LOE Figure 1 DT 500 Cryogenic Sensor Typical Response Curve Excitation Current 10 vA NERA m N Secs hems Osan S ZS RO lt Vg Volts lt SEE SOME SERA 0 20 40 60 80 100 500 Temperature K d Figure 1 Detailed Response of DT 500 Silicon Diode Temperature Sensor 15 20 H H l i H i 2 5 3 2 E x 5 am E S 8 P 219 6 gt L amp gt L DIE 5 8 L a 2 P 1 E o r F age 5
23. system is critical the 10 uA current should be used The power dissipated at helium temperatures by the sensor is approximately 15 micro watts for gallium arsenide and 21 micro watts for silicon for this current If power input is not critical then the 100 uA current may be preferred The static impedance of the silicon diode is 210 K ohms at helium temperatures with 10 microamperes excitation current and 21 K ohms with 100 microampere excitation current The static impedance of the gallium arsenide sensor at helium temperatures is approximately 150 K ohms at 10 microamperes and 15 K ohms at 10 microamperes i e R V I 1 JULY 74 To accurately measure the forward voltage to 100 microvolts or better consideration must be given to the input impedance of the voltage measurement system being used For example a digital voltmeter with a ten megohm input impedance will have an 7 effect the 10 millivolt position for current of 10 microamperes For the 100 microampere current source the loading effect will be seen in the one millivolt position Therefore for a calibrated device readings must be taken with a very high input impedance voltage measurement system If however a sensor is calibrated with a voltmeter of less than infinite impedance as long as the same system is used i e the loading is not changed accurate temperature measurement should be possible 8 Insufficient evaluation of an
24. the use of a variac control 8 PWR A C line switch ON OFF 9 NO LABEL Heater ON light indicates power is applied to heater load 10 BCD BCD output optional 3 3 Initial Checks Initial checks calibration checks and servicing procedures are described in Section V Maintenance 3 4 Temperature Readout Control 3 4 1 Model DRC 7 The digital panel meter has provisions to accept a connector at the rear of the case connector package is supplied which consists of a connector ELCO No 00 6007 030 980 002 and two screws No 4 40 thd by inch long binding head Table 3 2 provides the necessary pin designation for input and output signals Table 3 2 Pin Designation for Model DRC 7 PIN NO FUNCTION PIN NO FUNCTION 1 4 8 volts A 9 volts 2 Analog Current Test 3 Print Command C Overrange 4 Polarity D Hold 5 BCD 8 BCD 1 6 BCD 2 F BCD 4 7 BCD 80 H BCD 10 8 BCD 20 J BCD 40 9 Sensor Input K BCD 100 10 Analog Signal Ground L N C 12 PIN NO FUNCTION PIN NO FUNCTION 11 BCD 400 M Trip Point 12 BCD 200 N Digital Gnd BCD Gnd 13 Current Test P N C 14 Sensor Input R Shield 15 115 230 VAC Line 1 S 115 230 VAC Line 2 The sensor is connected to the instrument via pins 9 and 14 The internal current source can be checked by placing a 100 K ohm 01 resistor between pins 13 and and measuring the voltage drop with a voltmeter having an accuracy of 0 01
25. 100 1 4W 5 10 K 1 8W 1 10 K 1 8W 1 104 1 8W 1 69 8 1 8W 1 115 1 8W 1 5 11 K 1 8W 15 147 1 8W 1 487 K 1 8W 1 634 K 1 8W 15 100 1 4W 55 100 1 4W 5 TRIM 1 8W 15 100 ohm VARIABLE 2 K 1 8W 1 100 K 1 8W 15 100 K 1 8W 15 51 1 K 1 8W 15 402 K 1 8W 1 50 K VARIABLE 10 K 0 15 TEL LABS 22 1 K 1 8W 1 500 ohm VARIABLE 13 3 K 1 8W 1 100 1 4W 5 100 K 0 15 TEL LABS 100 K 1 8W 15 100 ohm VARIABLE 10 1 8W 15 100 K 1 8W 1 35 LAKE SHORE PART NO RN60D3240F RN60D4190F RN60D2 340F RN60D3770F RCR076101JS RN60D1002F RN60D1002F RN60D1040F RN60DG69R8F RN60D1150F RN60DS11F RN60D147 3F RN60D4873F RN60D634 3F RCR07G101JS RCRO7G101JS RN60D 3006P 1 101 RN60D1003F RN60D1003F RN60D5112F RN60D4023F 3006 1 503 SA1 RN60D2212F 3006P 1 501 RN60D1332F RCR07G101JS SA1 RN60D1003F CTSX201R101B RN60D10ROF RN60D1003F C12 MODEL DESCRIPTION DESIG 10 K 1 8W 1 200 K 1 8W 1 10 K 1 8W 1 50 ohm VARIABLE 500 ohm VARIABLE 47 K 1 4W 5 300 1 4W 5 22 K 1 4W 5 82 5 K 1 8W 1 40 2 K 1 8W 1 20 K 1 8W 1 10 K 1 8W 1 22 K 1 4W 5 820 1 4W 5 6 8 K 1 4W 5 22 K 1 4W 5 330 1 4W 5 150 K 1 8W 1 10 K 1 8W 1 22 1 K 1 8W 1 5000 VARIABLE 100 K 1 4W 5 6 8 1 4W 5 100 K 1 4W 5 22 K 1 4W 5 39 K 1 4W 5 100 1 4W 5 2 2 MFD 100 PFD 0 05 MFD 500 V 2 2 MFD LAKE SHORE PA
26. 9 remains off Advance the set point 2 K and observe that the heater power light turns ON Return the set point to its original value and check that the heater power light shuts OFF If light does not shut off check to see if display is indicating a different temperature The heater power light will remain ON as long as the set point is less than the display by at least 1 K Increase the set point switch until the desired value is set If the temperature set point is larger than the temperature being displayed the heater ON light will illuminate indicating power is being applied to the heater Observe the display and if the temperature being displayed does not show signs of heating then increase the maximum power out by rotating clockwise the fine tuning control knob Key No 7 The knob Should be rotated in 1 4 turn increments until the proper rate of heating is observed on the temperature display If the increase in temperature is slow or the temperature does not increase and is still below the temperature set point rotate the fine tuning knob another 1 4 turn Repeat above procedure until the desired rate or temperature is achieved When the readout is equal to or greater than the temperature set point the heater ON light will switch OFF The maximum controllability will be achieved with the minimum value of amplitude pulse height applied to the heater controlled by the fine tuning knob Key No 7 This condition can be detected
27. E 1 NORMAL 2 3 or 4 wire MODE REJECTION constant current COMMON MODE REJECTION 25 uW at 4 2 POWER REQUIREMENTS 0 5 0 06K C DIMENSIONS 0 1K Greater than 100 megohms 300V 10 45 10m VIK at 1K output impedance Tracking to digital display of 0 3K TTL compatible non isolated 4 digits 1 4 cm 0 55 high 7 segment non blinking 2 seconds to rated accuracy 50 db min at 60 Hz and up 120 db at 60 Hz and above 115 or 230 VAC 10 50 60 Hz 8 9 cm 3 5 high x 20 3 8 wide x 30 5 cm 12 deep For 230 VAC add K to model number DRC 70 K PRINTED IN U S A OCTOBER 1975 EEE SERIES DIGITAL THERMOMETERS Technical Specification DRC 70C MODEL DRC 70C DIGITAL CRYOGENIC THERMOMETER CONTROLLER e 1 400K Range 0 1 K Resolution e Silicon Diode Sensor Model DT 500 DRC e 0 to 50 Watt Heater Output Recorder Output and Optional BCD Output e 115 or 230 VAC Power The Model DRC 70C goes a step beyond the Model DRC 7C and provides 0 1 K readout and setpoint resolution with controllability of 0 3 K in a properly designed system As with other members of the DRC instrument family the DRC 70C utilizes the latest state of the art id electronics to achieve stable operation and long term reliability over the range from 1 to 400K In addition to an analog output with 0 1K resolution an optional BCD output is available T
28. K The Model DRC 7C utilizes the proven DT 500 silicon diode sensor Model DT 500 DRC as the temperature sensor All DT 500 As sensors are interchangeable and can be used with any of the DRC 7 DRC 7C DRC 70 or DRC 70C instruments In addition to direct digital display the DRC 7C provides an analog output with 0 1K resolution and an optional BCD output Separate zero and span adjustments are provided which enable the user to calibrate his system for increased accuracies The temperature control portion of the DRC 7C is actuated by internal digital comparison of the BCD output to a digital thumbwheel setpoint switch The BCD comparison signal provides an error value equivalent to the temperature deviation to a time proportional thyristor control circuit The thyristor circuit controls the ON time of the powered output available from a continuously adjustable variac with an adjustable power output of 0 to 50 watts TECHNICAL SPECIFICATIONS General TEMPERATURE RANGE 1 400 SENSOR Silicon Model DT 500 DRC SENSORINPUT 4terminal connection with constant current exitation of 100 ohms ina 2 wire system SENSOR CURRENT 10microamps SENSOR CURRENT REGULATION 0 1 VOLTAGEINPUT 115 or 230 VAG 10 50 60 Hz POWER COMSUMPTION 60VA CONSTRUCTION Solid State Electronics OPERATING ENVIRONMENT 10 45 WEIGHT 3 6 Kg 8 Ibs DIMENSIONS 8 9 cm 3 5 high x 20 3 cm 8 wide x 30 5 cm 12 deep For 230
29. LATOR RESISTANCE NETWORK BOURNS DIGITAL PANEL METER WESTON DIGITAL PANEL METER GRALEX TRANSFORMER GRAND RELAY HAMLIN INDICATOR LED HEWLETT PACKARD SWITCH FUSE CLIPS 2 each FUSE 1 amp FUSE 1 8 amp CONNECTOR FLAT CABLE CONNECTOR 14 PIN SOCKET For 24 8 10 13 17 22 16 PIN SOCKET For Z14 16 Printed Circuit Board Schematic Diagram Schematic Diagram Schematic Diagram Schematic Diagram LAKE SHORE PART NO CD4030AE LF355H CD4011AE CD4001AE CD4029AE CD4518BE CD4013AE CD4030AE CD4011 AE CA3747 LM305 4116R 1230 37 5332 701 11 5 5082 4684 7101 AV2 798 AGC AGC 3428 2002 ISMISDRAS 14MSLSC 16MSLSC D60109 D270276 D270275 D270274 D270279 Except where noted under column labeled MODEL DESIGN all parts listed are for all units 4 Model DRC 70C 1 Model DRC 7 2 Model DRC 7C 3 Model DRC 70 and NOLLOSS YOLVOIGNI JANLVYAdWIL 2 24q pue 2 44 STAGOW WVYOVIG OILVWYHOS 1102410 175 quf9Id 5 Ab 0 202170 a 252 IH 1 USIM XIA KID Lond T wewaos eoeseTil owoww uw vo ns kutamakuna 2 See AN wu Ol PAA 04553 OFID 955 259 Hawn amp A ma ae A rowno 4 ow Sas 12 o 39 NOILO3S WOLVOIGNI JYNLVAJdWIL 20 2 4 PUB 0 2 4 STAGOW WVNOVIG OILVWSHOS 1119415 Z S
30. LL AS ANY AND ALL OTHER OBLIGATIONS OR LIABILITIES OF LAKE SHORE CRYOTRONICS INC INCLUDING BUT NOT LIMITED TO SPECIAL OR CONSEQUENTIAL DAMAGES NO PERSON FIRM OR CORPORATION IS AUTHORIZED TO ASSUME FOR LAKE SHORE CRYOTRONICS INC ANY ADDITIONAL OBLIGATION OR LIA BILITY NOT EXPRESSLY PROVIDED FOR HEREIN EXCEPT IN WRITING DULY EXECUTED BY AN OFFICER OF LAKE SHORE CRYOTRONICS INC iv W3L3WONSdHL 2IN350XA92 TVLII9IG 0 24G TIGON T I 34914 SECTION I General Information 1 1 Introduction This section contains a description for the DRC 7 series digital temperature readout controller instruments which include the Models DRC 7 DRC 7C DRC 70 and DRC 70C for use with the Model DT 500 DRC standard silicon diode sensor 1 2 Description General The series DRC 7 is a completely self contained unit providing the capability of both direct digital readout in kelvin temperature units and temperature control DRC 7C and DRC 70C by direct digital comparison to the displayed temperature The useful range of operation is 1 to 400 K utilizing the standard DT 500 DRC sensor which has been pre selected to provide uniform characteristics Pre selection allows the series DRC 7 to be used with standard sensors without adjustment of any kind Since the standard sensors are completely interchangeable the series DRC 7 may be used to read out any number of sensors with equal accuracy when selected through an appropriate external swit
31. RT NO RN60D1002F RN60D2003F RN60D1002F 3006P 1 500 3006P 1 501 RCR07G473JS RCR07G301JS RCR07G223F RN60D8252F RN60D4022F RN60D2002F RN60D1002F RCR07G223F RCR07G821JS RCR07G682JS RCR07G223F RCR07G330JS RN60D1503F RN60D1002F RN60D2212F 3006P 1 502 RCR07G104JS RCR07G682JS RCR07G104JS RCR07G223F RCR07G393JS RCR07G101JS 196D2250025 DD101 5GA amp 50 196D2250025 REF DESIG C13 14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C27 C28 29 C32 34 MODEL DESCRIPTION DESIG 0 05 MFD 500 V 0 1 MFD 500 V 50 100 MFD 25 V 0 05 MFD 500 V 0 1 MFD 500 V 22 MFD 15 V 220 MFD 35 V 0 05 MFD 500 V 100 MFD 10 V 1000 PFD 10 MFD 25 V 1000 PFD 2 2 25 V 10 MFD 25 V 0 05 MFD 500 V 2 2 MFD 25 V SILICON RECTIFIER SILICON DIODE TRANSISTOR TRANSISTOR I C AMPLIFIER AMPLIFIER I C AMPLIFIER I C ANALOG SWITCH I C AMPLIFIER I C ANALOG SWITCH 37 LAKE SHORE PART NO SGAS50 DD104 DDS00 TE1211 SGAS50 DD104 196D226X0015 196D2250035 SGAS50 196D107V0010 DD102 196D106X0025 DD102 196D2250025 196D106X0025 SGAS50 196D2250025 IN 4004 IN 914 2N4124 2N2905 LF355H LM308A RC4136 CD4016AE RC41 36 CD4016AE 1 2 MODEL DESCRIPTION DESIG COMPARATOR AMPLIFIER NANDGATE NORGATE COUNTER COUNTER FLIP FLOP COMPARATOR NANDGATE AMPLIFIER 9 nn O0000000n0020 VOLTAGE REGU
32. able cause of system malfunction is an improperly connected temperature sensing diode If the display blanks or a negative temperature is displayed carefully examine the cable diode assembly to insure that the diode polarity is correct that the sensor is connected to the proper terminals and that there are good solder joints at the interface connection Because of the highly reliable solid state design of the readout controller it is most unlikely that the readout controller will be a source of difficulty For this reason it is advisable to examine other portions of the cryogenic system before testing the readout controller proper Some suggested checks are 1 Open or shorted sensor and heater leads particularly in the vicinity of the sample holder if it is subject to frequent disassembly 2 Leakage paths between heater and sensor leads giving rise to electrical feedback in addition to thermal feedback 3 Poor thermal lagging of sensor input leads normally results in an indicated temperature several degrees higher than the actual temperature 4 Extraneous resistance in the sensor s voltage leads which increases the apparent sensor s voltage proportional to the voltage drop I times R across extraneous lead resistance This normally manifests itself as an indicated temperature which is lower then the actual temperature 28 5 Premature loss of cryogens due to thermal shorts in dewar ice blocks in lines sample holder im
33. ad Anode TG 100FP Gold lead anode DT 500FP 9 Platlead cathode DT 500FP MIN Min short lead Anode es SS H White 1 D Yellow V Green V Black L Interchangeable 11 Leads have no polarity 2 ers s E _ Interchangeable P CS 400FP 12 d Leads have no polarity 1 T Interchangeable CS 400 Basic 13 1 Leads have no polarity Pairs are D E interchangeable LR 700GR 14 see instructions with sensor ls OTHER CONFIGURATIONS ENGINEERED ON REQUEST DIMENSIONS INCHES MM LEADS LEAD WEIGHT DIAM ENCAPSULATION gt MATERIALS REMARKS 125 3 18 Min 16 Ultra a 05 1 27 030 Min 76 125 3 18 08 1 5 2 38 08 1 5 2 38 21 1 5 5 3 38 065 1 0 1 65 25 4 09 1 5 2 8 38 09 1 5 2 9 38 09 1 0 2 8 25 4 35 8 9 1 0 Min 2 16 25 4 Ultra J 4 1 M 1 5 38 3328 6 8 5 152 335 6 8 5 152 340 1 0 8 6 25 4 1 0 340 25 4 8 6 1 5 38 320 2 8 1 51 07 1 8 07 1 8 06 1 5 10 2 5 07 1 8 06 1 5 06 1 5 pud 01 Ultra J 254 2 5 2 5 06 1 5 06 1 5 Gold Plated Ni Fe 3 DE Gold Plated Ni Fe 3 DE Gold Plated Ni Fe 2 Plat 10 Ir 2 G
34. and out through the vacuum pump port There is little chance of air from the bleed entering the controlled vacuum even if the vacuum system fails as this condition will cause the bleed to be shut off completely Controller Heater Installation For a non permanent surface mount secure the substrate against the surface with a l foam padded mounting jig The jig should apply only light pressure Fillet the plate and secure the leads with Sylgard 186 or a similar material After the Hall generator has been mounted check the misalignment voltage per the proper specification A large misalign ment voltage shift 100 uV or more is a sign of Hall generator physical damage Vacuum Regulator Valve l The 329 Valve was offered initially as a vacuum control for vacuum pumped cryostats In this application it is necessary to ensure that the temperature of the gas entering the valve is not lower than 175 K 100 C Generally this means that the piping between the cryostat and the valve will be 2 3 feet or more For the most sensitive and stable operation the remote sensing port should be used This allows the valve to see the controlled vacuum through a static line as opposed to a line with flow Product of the Dow Corning Corporation Most cryogenic temperature controllers utilize the thermal relaxation method for control That is heat is continually added to provide the proper balance between the payload whose t
35. andled The aluminum oxide substrate is brittle and very sensitive to bending stress Use the leads to move and locate it Do not handle the substrate The lead to substrate bond strength is on the order of several ounces Avoid tension on the leads and avoid bending them close to the substrate The leads may be bent at any angle as long as the bend is at least 1 8 away from the substrate connection The preferred mounting procedure is to locate the chip in a slot that is any depth 003 inch wider and 010 inch longer than the substrate Tack the leads outside the slot with Sylgard 186 or a similar substance Don t get Sylgard 186 inside the slot If an extreme temperature range is expected check the coefficients of thermal expansion to be certain that the slot will always have clearance for the chip This procedure is not recommended for installations that will be subject to any acceleration greater than 10 G Surface mounting is acceptable when 3 necessary The mounting surface may be any non flexible solid with flat smooth 001 surface at least the size of the substrate The substrate must not overhang the mounting surface Steel ferrite ceramic and glass are 4 examples of mounting surfaces For extended temperature ranges choose a material with a coefficient of thermal expansion no greater than a factor of three different from that of the aluminum oxide substrate 27x10 5IN IN C For a permanent mount spari
36. anel meter does not require calibration However Should the reading on the panel meter differ by more than 2 K from the analog output calibration of the panel meter is indicated At this point consult manufacturer If it is indicated that the panel meter is SEHE the following procedure should be followed for removal 32 5 8 Circuit Board Removal Disconnect all electrical connections to the terminal strip at the rear of the instrument Remove the six screws located at the rear of the instrument and slide the board gently out of the case On Models DRC 7C and DRC 70C to remove the circuit board slide the board out of the case approximately 1 disconnect the three single wires connect by pulling the pins down The connectors are of different sizes to facilitate their correct replacement Slide the board until it is approximately half way out of the case Disconnect the connector tied to the flat ribbon cable by pulling downward on the flat cable Slide the circuit board all the way out 5 9 Panel Meter Removal Removal of the panel meter is accomplished after the printed circuit board is removed Unscrew two screws in the front section of the piggy back panel meter board from the main readout controller mother board Slide the meter forward out of the connector 33 5 10 Parts List Printed Circuit Board Component Locator and Schematic Table 5 1 PARTS LIST REF MODEL LAKE SHORE DESIG DESCRIPTION DESIG PART NO R1 1
37. ase and is still below the temper ature set point rotate the fine tuning knob another 1 4 turn Repeat the above procedure until the desired rate of increase or the set temperature is achieved When the readout display is within 0 5 K of the temperature set point the heater ON light Key No 9 will begin to blink proportionally to the difference between the set point temperature and the display temperature If the overshoot drives the temperature 0 5 K beyond the set point the heater ON light will switch off The maximum controllability will be achieved with minimum value of amplitude pulse height applied to the heater controlled by the fine tuning knob Key No 7 This condition is detected by observing a 50 proportional duty cycle switching between ON and OFF of the heater ON light 16 3 5 Customer Calibration The procedure outlined below is applicable to Table 6 1 for aligning all series DRC 7 instruments 3 5 1 Model DRC 7 A Ten Microamp Sensor Current Adjustment 1 2 3 4 Remove the front panel cover on the meter Turn the power ON to the instrument and allow about 10 minutes warm up Connect a voltmeter with a 0 01 accuracy and a 100 megohm minimum resistance between pins B and 13 the positive terminal of the voltmeter should be connected to pin B Connect a 10 uF capacitor across pins B and 13 if the connector leads are long Adjust the potentiometer marked 1 located at the back of t
38. ce shock absorbing material around all sides of the instrument to prevent damage to protruding controls Place the inner container in a second heavy carton and seal with tape Affix mailing labels and FRAGILE warnings SECTION III Operating Instructions 3 1 Introduction This section contains a description of the operating controls and their adjustment under normal operating conditions These instructions are predicated upon the instrument having been installed as outlined in Section II The diode polarity as shown in Fig 2 1 a in particular must be correct 2 2 Controls Indicators and Connectors The operating controls indicators and connectors on the instrument s front and rear panels are shown in Figures 3 1 and 3 2 The numbers with leaders to various controls in the figures are keyed to the entries in Table 3 1 Table 5 1 Entry Number Correlation NO KEY NAME FUNCTION 1 Heater Heater element terminals 2 Analog Hi amp Lo Recorder output 3 Input Sensor input lead terminals plus I plus V minus V and minus I 4 NO LABEL A C line cord 5 NO LABEL Digital temperature display located behind filter panel Maximum range 1 400 K 6 NO LABEL Digital set point switch Selects desired temperature to be controlled to directly in kelvin units Adjustable from 2 to 399 K NO KEY NAME FUNCTION 7 NO LABEL Fine tuning power control Adjusts the maximum power available from 0 50 VRMS Infinite resolution through
39. ch or multiplexer The series DRC 7 units contain an internal constant current source which is preset at the factory for 10 microamps As a standard feature all units are equipped with a recorder output providing 0 4 volts in increments of 10 millivolts per degree with a linearity error of 0 5 K DRC 7 and DRC 7C and 0 3 K DRC 70 and DRC 70C Both the DRC 7C and DRC 70C readout controller units have an adjustable fine tuning control for peak output power adjustment The fine tuning control is continuously adjustable to allow infinite resolution and minimizing of the overshoot value 1 3 Description Specific The following provides a description for each specific instruments in the DRC 7 series digital cryogenic thermometers and controllers 1 3 1 Model DRC 7 The Model DRC 7 provides direct temperature readout in kelvin temperature units with 1 degree resolution The error of linearization conformity is factory set at 0 5 degrees 1 3 2 Model DRC 7C The Model DRC 7C combines the electronics contained in the Model DRC 7 with a time proportional thyristor temperature controller The control portion is actuated by an internal digital comparison of the BCD output to a digital thumbwheel set point switch The BCD comparison signal provides an error value equivalent to the temperature deviation to a time proportional thyristor control circuit The thyristor circuit controls the ON time of the powered output available from a continuou
40. corresponding to the various linearizer segment break points from the standard DRC 7 voltage versus temperature table The attenuated output of the input amplifier is fed into two stages of amplifiers 23 and Z5 whose gain is variable as a function of the sensor temperature The gain changing networks are switched by means of analog Switches set to close when the voltage output of the sensor amplifier 22 is equal to the predetermined voltage reference corresponding to each break point of the DRC 7 standard table The voltage output of the linearizer is a linear function of the sensor temperature This output is converted to a linearized output of 10 mV K and the digital voltmeter reads and displays this output 4 3 Detailed Description A detailed description of the voltage temperature conversion is outlined below 4 5 1 Power Supply and System Common The output of transformer Tl is rectified and filtered to 22 VDC by means of a full wave bridge CR1 4 and a capacitor C24 filter The line filter C19 C20 and C25 on the power line bypasses the high frequency noise signal in the power line The filtered but unregulated 22 VDC is regulated to 14 VDC by a precision voltage regulator 224 19 The voltages at various parts of the circuit are referred to the System Common which is the output of the amplifier Z7 The common is located 7 VDC below the positive regulated voltage This voltage can be adjusted to within 0 001 volts with
41. d attention to this feature can result in serious temperature measurement errors For this reason 10 megohm input impedance DPM s or DVM s at 10 uA diode excitation are not recommended Fortunately there is no dearth of DVM s l or DPM s with the desired characteristics i e 1 Volt range with 100 or 200 overrange and input in the 10 to 1010 range Differential voltmeters are also a proper choice The dynamic impedance of the sensor is approximately 1000 ohms at 10 uA and 100 ohms at 100 uA This is extremely fortunate since it reduces the requirements on the constant current source by nearly two orders of magnitude over that of the voltage measure ment system For example a current source regulated to 0 1 will cause a change in the 100 microvolt position The required temperature accuracy vs the instrumentation current regulation and 2 voltmeter resolution is Required Current Voltmeter Temperature Source Resolution Accuracy Resolution 1 0 K 5 1 mV 1 K 5 100 uV 01 K 05 10 uV Epoxy encased sensors should not be used in vacuum as self heating as a result of the epoxy acting as an insulator can cause large temperature errors below 10 K Heat dissipation in diode thermometers can be calculated two ways both yielding the same result In the first case the power dissipated is the product of the DC voltage across the diode and the DC current through the diode In the second case an equivalent circuit can
42. d be used to complete the wiring The total length of coaxial cable internal plus external is not critical i e 100 feet is not unreasonable An increasingly popular lead material is a family of ultraminiature coaxial cables This coax has a diameter of less than 020 To prepare the ultraminiature coax for termination the inexpensive Miller wire stripper available at any radio supply store is ideally suited Care should be taken to set the opening on the wire stripper to remove just the outer two wraps of aluminized Mylar and Vylex thus exposing the drain wire and the insulated center conductor similar Miller wire stripper set for the appropriate opening will strip the dielectric cleanly from the center conductor These sensors may be depended upon for 1 or 2 mK stability during many hours even days of consecutive operation as long 1 as a settling period of up to an hour is allowed after the device is thermally cycled defined a cooldown from liquid N temp erature or higher to some lower temperature such as 4 2 K In its present state of development the sensor should not be expected to reproduce to better than 2 0 2 0 4 K from one thermal cycle to the next Depending on the extent and rate of cooldown a shift in dC dT of as much as 2 may also be observed However it should be recognized that none of the above constraints limits the primary function of the thermometer viz as a contro
43. eads isolated from case No ferromagnetic materials are utilized in the construction of these sensors TG 100K or DT 500K set into the top of a copper alloy hex head cap screw DE Dual Eiement w Common Cathodes TG 100KL or DT 500KL set into the top of a copper alloy hex head cap screw DE Dual Element w Common anodes TG 100P or DT 500P set into the top of a copper alloy hex head cap screw DE Dual Element w Common Cathodes TG 100P or DT 500P set into a gold plated copper cylinder except Min amp Ultra No ferromagnetic materials are utilized in the construction of these sensors Sensor has He in can to act as a heat transfer medium 3He and other gases are avail for GR 200 Sensor can is completely filled with sensor element and glass No ferromagnetic materials are utilized in the construction of CS 400 sensors This is unencapsulated CS 400 GR element Leads are polyimide insulated oN The equipment shown is utilized for temperature calibrations from 1 3 to 400 K Other available equip ment includes cryostat for 3 to 1 5 calibrations and a dilution refrigerator for lower temperatures SES Standard calibrations are supplied according to the following table unless otherwise specified Temperature Maximum Interval Temperature Maximum Interval 0 3 to 1 3 K 0 05 K 30 to 40 K 2 0 K 1 8 to 2 0 K 0 1 K 40 to 80 K 5 0 K 2 0 to 3 0 K 0 2 K 80 to 400 K 10 0
44. ed by the linearizer For long lead runs it is suggested that shield cables be used to minimize noise pickup 4 3 4 Linearizer The series DRC 7 utilizes straight line segments over the range of 1 to 400 kelvin with break points at 6 K 14 K 18 K 23 K 25 K 27 K 30 K and 80 K The slope between 18 and 23 K is the largest 75 3 mV K and hence the gain of the linearizer is the lowest between these points Similarly the linearizer has its highest gain between 30 and 80 K where the diode has the smallest slope of 2 66 mV K 20 4 3 5 Comparators and Voltage References The reference voltages are formed in steps of ascending order corresponding to the voltage output of the input amplifier at the various break points A ladder network connected between V and common provide these voltages The reference voltages are compared with the respective output voltages of the input amplifier and analog switches SW4 through SW7 are closed when the amplifier voltage is equal to the reference voltage The analog switches SW1 SW2 and SW3 are set to open when the amplifier voltage exceeds the reference voltage This occurs when the initial gain of the linearizer is lower than the lowest gain which occurs between 18 and 23 K Analog switch SW8 opens at 80 K since the gain over the temperature range 80 to 400 K is lower than the gain between 30 and 80 K Due to the sharp increase in gain between 27 30 K and 30 80 K the analog switches should be clo
45. emperature is to be controlled and the surrounding environment Therefore the optimum balance is best achieved with both the source of refrigeration and heat emanating from the same direction with as large an area and as even a source of each as possible The cryogenic temperature controller system including control sensor heater controller lead in wiring etc can all perform perfectly and the system be an abject failure if the total system integration is not adequate considerations include Some a The heater area should be as large as possible For this reason wire heaters of several feet wound on the payload are preferred to point source heaters such as carbon resistors etc b To prevent hunting within a closed loop thermal control system thermal contact between heater and load should be as close as possible This can be accomplished by utilizing insulation materials such as formvar or bicalex Both offer a good thermal short with an electrical open circuit to the load The heater may then be appropriately cemented by Glyptal or G E 7051 varnish to mechanically hold and thermally anchor the heat input system to the load The controller heater output circuit sees the total heater load e g heater plus lead wires Therefore the heater proper should be designed for as close to 100 of the heater lead in wire heater resistance total as possible to avoid heat leaks to the system 12R from the lead in wir
46. er Assume the temperature set point Ts is less than the temperature display Tp Fig 4 2 then the BCD output of the counters 214 715 and 716 is greater than the BCD code generated by the thumbwheel switch setting A comparison is made utilizing comparators Z10 Z18 Z19 and Z20 resulting in an equal or greater than condition which drives the comparator output to a logic state 0 This condition is latched with Z13 and remains latched until a reset occurs The latched condition will occur for both Ts lt Tp and Ts To prevent full power from being applied during the reset cycle transistors Q4 and 05 are equipped with RC networks R123 Css and R131 C30 for a short time delay 4 4 2 Model DRC 70C The digital proportional controller with fixed bandwidth utilizes a new concept for control The digital proportional circuit samples the temperature display and temperature set point to determine the magnitude of difference and adds a proportionally greater number of signal pulses to the heater output circuit for successively larger deviations between temperature display and temperature set point The circuit is factory adjusted 216 for a bandwidth of K about the temperature set point 23 NVHL SL 304 WVHOVIG ONIWIL I t 914 HEO ssIsassass ee ee ee pied ee 295 OST FUE 24 a OL ANY NVHL 537 S 403 9NINIL 277
47. error For those units having the optional BCD output a binary coded decimal BCD is provided as listed in Table 3 2 The decade counters provide a 1 2 4 8 code using positive logic with standard TTL levels of 0 4 volts and 2 4 volts for the 0 and 1 state respectively The drive is sufficient to sink two standard loads 3 2 mA in the low state For additional usage a switch or TTL microcircuit connected to the hold terminal Pin D can be used to keep the voltage level low and defeat the synchronizing signal applied to the synchronizing divider This will prevent the generation of a reset pulse 3 4 2 Model DRC 7C The sensor and heater should be installed following the suggestions listed in the Installation and Application Notes for Cryogenic Sensors brochure in Section VI Connect the sensor and heater to the instrument following the diagrams in Fig 2 1 Rotate the fine tuning power control Key No 7 full counter clockwise to minimum power output Adjust the digital thumbwheel switch Key No 6 to 001 Turn the power switch Key No 8 to ON and observe that the display Key No 5 shows the proper temperature relative to the sample temperature If the display reads 1800 1090 or blanks the diode is connected backwards The heater ON light Key No 9 should be off 13 Adjust the set point Key No 6 to one degree below the value being displayed Key No 5 and observe that the heater power light Key No
48. es and to assure proper thermal control at the heater Germanium Resistor Construction 124 lt S NN 5 Hermetically sealed Atmosphere Secondary Thermal Approximate Mass ZZ Cu 2 gm N N conduction path 20 Pt 07 gm Normal Ge M gm Helium 4 u 01 om ial Glass 01 gm Pee 3 Nitrogen Vacuum External leads normaily supplied are 6 32 stranded Cu silver plated Teflon insulated For use below 1 K Solid copper Formvar insulated leads are available Copper Au plated Germanium sensing element Epoxy protects the conneclion to avoid breakage of the Pt leads 22222222202020020000020000000020000000000000000002 Gold wire V t KC CCM I o to 7ZZZZZZ7 N w N Glass y N N N N Au Sn solder N 7 280 C MP N ii H Platinum White pri Yell rimary thermal Sree conduction path 80 Black to the sensor is through the leads Figure 1 Gold plated Kovar base 005 Au lead 0 210 Si or GaAs Chip gt 2 Kovar leads 019 diam epoxy bali H Glass 060 diam Gold ptated Plat base Plat Cap Kovar base Kovar 2 Plat leads 2 Kovar leads 010 diam 019 diam Glass TYPICAL DIODE THERMOMETERS Figure 3 The heater heater lead wire combined resistance should be accurately matched to the controller For example a 20 ohm heater matched to a 10 ohm controller output wi
49. ess than 0 1 temperature readout and control errors due to these variables can be held to 1 mK Hall Resistance Thermometers These thermometers are normally used as secondary standards and should be treated in the same manner as any precision instrument It is recommended that they not be subjected to any unnecessary shock or rough mechanical treatment Copper wires as well as other types of wire positioned in a thermal gradient will develop small EMF s due to inhomogenieties along the wire These defects may be slight differences in crystal structure may be due to work hardening mechanical strains etc which behave as small parasitic thermocouples These EMF s change with the thermal gradient and can be a source of serious error in those temperature measurements where sub microvolt levels are involved To overcome this error it is good practice to inspect each wire by connecting each end to a suitable measuring instrument and then pull it through a liquid nitrogen bath observing the EMF readings Any voltages greater than 1 microvolt are sufficient to cause an error in the measurement of temperature unless such effects are averaged by taking resistance readings on the thermometer with reverse polarity of the excitation current Of course another possibility is the use of AC measuring techniques Generator The Hall generator is fragile It cannot be handled the same way most other electronic components are h
50. have specific 3 LAKE SHORE CRYOTRONICS INC 9631 SANDROCK RD EDEN N Y 14057 716 992 3411 TELEX 91 396 CRYOTRON EDNE INSTALLATION And APPLICATION NOTES For Cryogenic Sensors characteristics which must be considered during installation generally all thermometers have common installation constraints Many of these general constraints and specific application and installation notes are listed below General 1 Always heat sink the temperature sensor and sensor leads when soldering or otherwise attaching the lead wires Thermal heat sink of diode thermometry is not as critical as it is for example for resistance thermometers For most resistance thermometers construction of the sensor is such that the sensing element is both thermally and usually electrically isolated from its case Figures 1 and 2 The result is that the main thermal input to the device is through the electrical leads Therefore the resistors have a tendency to read the lead temperature rather than the case temperature To solve this problem considerable care must be taken to properly heat sink these leads The opposite is true for diode sensors where the temperature sensing element is mounted directly on its header case with the cathode lead directly connected to the case Figure 3 The positive anode lead is electrically isolated and makes electrical contact to the sensor through a short two mil gold wire The sensor t
51. he instrument until the voltmeter reads 100 0 millivolts B Calibration of the Instrument Between 0 300 K 1 2 3 4 5 6 Connect a voltage standard such as EDC Model MV 100N to the probe input terminals and set the value of 2 81586 volts on the voltage standard Set the ZERO adjust potentiometer until the meter displays 000 The ZERO potentiometer is located on the front panel at the right hand side of display Set the voltage standard to the value of 0 37721 volts and adjust the SPAN potentiometer until the meter displays 300 The SPAN potentiometer is located to the left of the display Repeat steps 1 through 3 until the respective readings are displayed Set the voltage standard to the value of 1 09471 volts and adjust the potentiometer labeled 7 until the meter displays 035 This potentiometer is located at the back of the meter Repeat above steps if necessary Note For DRC 7 units having a serialized number greater than 2000 use calibration procedure under Section 3 5 2 17 3 5 2 Models DRC 7C DRC 70 and DRC 70C 1 2 3 4 7 8 Connect the input terminals to a voltage standard such as EDN Model MV 100N or equivalent and a voltmeter input 199 99 mV resolution 10 uV 0 05 accuracy and an input impedance of not less than 1000 megohms across resistor The positive terminal of the voltmeter should be connected to the test point 1 and the negative ter
52. he temperature control portion of the DRC 70C is actuated by internal digital comparison of the BCD output to a digital thumbwheel set point switch The BCD comparison signal provides an error value equivalent to the temperature deviation to a digital proportional thyristor control circuit The thyristor circuit controls the ON time of the powered output available from a continuously adjustable variac with an adjustable power output of 0 to 50 watts TECHNICAL SPECIFICATIONS General TEMPERATURE RANGE SENSOR SENSOR INPUT SENSOR CURRENT SENSOR CURRENT REGULATION VOLTAGE INPUT POWER CONSUMPTION CONSTRUCTION OPERATING ENVIRONMENT WEIGHT DIMENSIONS 1 400K Silicon Model DT 500 DRC 4 terminal connection with constant current exitation ora 3 wire system 10 microamperes x 0 196 115 or 230 VAC 10 50 60 Hz 60VA Solid State Electronics 10 45 3 6 kg 8 Ibs 8 9 3 5 high x 20 3 cm 8 wide x 30 5 cm 12 deep For 230 VAC add K to model number DRC 70C K PRINTED IN U S A OCTOBER 1975 1 Temperature Control SETPOINT Digital thumbwheel selection directly in kelvin temperature units CONTROLLABILITY 0 3 with a properly designed system REPEATABILITY 0 1 SETTABILITY 0 1 HEATER OUTPUT Standard 0 50 watts 0 1 A 0 50 VAC CONTROL MODE Isolated digital proportional with continuously adjustable variac output Temperature Readout RESOLUTION
53. herefore measures the case temperature and thermal heat sinking of the electrical leads is of secondary importance The direct thermal connection to its case for the diode thermometers results in a substantial decrease in the thermal time constant for its sensor Due to the low heat capacity at or near 4 K the sensor follows relatively fast temperature changes Within this range under appropriate conditions it can control at better than 8 K sec Page No Hall Generators 4 Controller Heater Installation 5 Vacuum Regulator Valve 587 Construction Details 657 Although varnish heat sink compound such as CryCon grease see reference 5 6 may be used to heat sink the device somewhat more satisfactory results may be obtained if the sensor is mounted with low melting temperature solder Woods Metal may be an appropriate choice for most applications However due to its super conductive characteristics at low temperatures it may be preferable to use a substitute For example 26 Sn 54 Bi 20 Cd by weight melts at 1039 C with a Tc 3 69 K Useful references which provide data on heat sinking and heat sinking materials are 1 Warren Jr and Bader W Superconductivity Measurements in Solders Commonly Used in Low Temperature Research Rev of Sci Instr 40 p 180 1969 2 Anderson A C and Peterson R E Selection of a Thermal Bonding Agent for Temperatures Below 1 K Cryogenics 10 p
54. ier Z5 will be negligible 4 3 8 Output Stage and Digital Display The output amplifier Z5 provides the necessary offset and gain to yield an overall output of 4 000 volts corresponding to 400 0 kelvin with a linear response of 10 mV K as indicated by the digital voltmeter DVM display 4 4 Temperature Controller The function of the controller is to apply power to the heater when the reading on the digital display is below the value set by the digital set point control switch The full power condition of the heater is indicated by a red light emitting diode LED Key No 9 The maximum full power heater voltage is continuously adjustable via fine tuning power control Key No 7 between 0 and 50 VAC and can supply a maximum output current of 1 amp 22 4 4 1 Model DRC 7C The following description of the controller system refers to Figures 4 1 4 2 and 5 3 Assume the temperature set point Ts is greater than the temperature display Tp Fig 4 1 then the BCD output of the counters 214 Z15 and 716 is below the BCD code generated by the thumbwheel switch setting A comparison is attempted with 710 218 219 and 720 However due to the inequality a comparison cannot be made and a logic 1 is provided which latches 213 and full power is applied to the heater and the power ON light Key No 9 is turned ON indicating full power for a fixed number of timing cycles determined by updating signal contained in the digital panel met
55. is condition is achieved This guarantees that the comparator changes its state both above and below the set point Connect the positive lead of Voltmeter 2 to test point 6 27 1 and adjust Rog for an indication of 1 559 volts on Voltmeter 2 Connect the positive lead of Voltmeter 1 to test point 7 Z4 pin 4 and set the voltage standard to 1 1071 volts Voltmeter 1 should indicate a positive saturation voltage approximately 6 volts Set the voltage standard to 1 1075 volts and verify the Voltmeter 1 now indicates negative saturation voltage approximately 6 volts Readjust Rog until the above conditions are achieved The comparator is now set for proper switching levels For setting the amplifier gain adjust the voltage standard to 1 6884 volts Adjust 9 for a reading of 46 5 millivolts as indicated on Voltmeter 3 when connected between test point 8 R49 and test point 10 5 5 2 Final Adjustments Set the voltage standard to 1 9755 volts and adjust the potentiometer labeled ZERO on front panel for a reading of 013 1 kelvin 013 for the Models DRC 7 and DRC 7C on the readout controller display Set the voltage standard to 1 1736 volts and adjust the potentiometer labeled FS for a front panel display reading of 026 0 kelvin 026 for Models DRC 7 and DRC 7C Set the voltage standard to 1 1283 volts and adjust potentiometer Rjg for a reading of 028 0 kelvin 028 for Models DRC 7 and DRC 7C Finally
56. l device to hold temperature at some preset level while a magnetic field is being applied Large and erratic error signals will result from the presence of water vapor and or ice contacting the sensor leads and lead in cabling particularly when the sensor is used at temperatures over 200 K or when bare unshielded lead wires are used Presence of the water greatly increases the loss tangent of the measuring system and hence the capacitance readings are erroneous It should be noted that the excitation of capacitance sensors utilized in cryostats below 0 1 K will cause most resistance thermometers to self heat and become 1 effectively useless unless the capacitance sensor leads are fully shielded Due to a very small amount of ferro electric phase or interfacially polarized phase a large surge voltage for example from the measuring field will induce time dependent dielectric phenomena which will appear as a drifting or instability in the capacitive signal of the sensor Such effects have been observed immediately following the brief application of a five fold increase in AC sensor voltage An example is a 2 capacitance bridge umbalance produced by the accidental switching of the bridge switch Excitation frequency and amplitude must not change during temperature readout or control For example with the recommended 50 mV rms amplitude excitation signal held to 0 1 and with the frequency variation l
57. lications the wiring scheme in Fig 2 1 b and c may be used The heating element should be floated to preclude the possibility of any of the heater current being conducted into the diode sensor Electrical feedback in addition to the desired thermal feedback may cause oscillations and certainly erroneous temperature readings 2 5 Repackaging for Shipment Before returning an instrument to the factory for repair please discuss the malfunction with a factory representative He may be able to suggest several field tests which will preclude returning a satisfactory instrument to the factory when the malfunction is elsewhere If it is indicated that the fault is in the instrument after these tests the representative will send shipping instructions and labels for returning it When returning an instrument please attach a tag securely to the instrument itself not on the shipping carton clearly stating 1 Owner and address 2 Instrument Model and Serial Number 3 Malfunction symptoms 4 Description of external connections and cryostats If the original carton is available repack the instrument in a plastic bag place in carton using original styrafoam popcorn to protect protruding controls and close carton Seal lid with paper or nylon tape Affix mailing labels and FRAGILE warnings If the original carton is not available wrap the instrument in protective plastic wrapping material before placing in an inner container Pla
58. ll halve the useful heat available Control sensor preferred mounting is as near to the test specimen as practical and always between the heater and the test specimen Carbon Glass Resistor Construction 124 Gold Plated Kovar cap Approximate Mass lt Hermetically sealed Atmosphere Secondary Thermal Cu 21 gm gt conduction path 20 Pt 07 gm N Normal C G 204 gm N Helium 4 Au 01 gm N Special Glass 01 gm Helium 3 N Nitrogen N Vacuum External leads normally N n supplied are 6 32 335 stranded Cu silver plated Tetlon insulated For use below 1 Solid copper Formvar insulated leads are available Epoxy protects the connection to avoid breakage of the Pt leads Copper Au plated Carbon Glass sensing element Mn P 22 Gold wire a t PEELS w 5 Glass Y N N NS N solder N N 280 C MP N N G N N B Platinum Primary thermal conduction path 80 to the sensor is through the leads Figure 2 TFE Insulated Copper Leads Epoxy Strain Relief Cu Ag solder joint Ag Lead Ag Lead High Conductivity Ag Paste Glaze Capacitance Element PT Can Capacitance Temperature Sensor Figure 4 1 JULY 74 Encapsulation Glass Description of Operation for Model 329 Vacuum Regulator Valve The Model 329 Vacuum Regulator Valve consists of a balanced poppet main valve which is sealed at one
59. ll parts should be inventoried before discarding any shipping material If there is damage to the instrument in transit be sure to file appropriate claims with the carrier and or insurance company Please advise the company of such filings case of parts shortages please advise company The standard Lake Shore Cryotronics warranty is given on page ii 2 3 Power and Grounding Requirements To protect operating personnel the National Electrical Manufacturers Association NEMA recommends and some local codes require instruments to be grounded This instrument is equipped with a three conductor power cable which when plugged into an appropriate receptacle grounds the instrument The standard unit is set for 115 VAC 10 50 60 Hertz operation with the designated K units set for 230 VAC 10 50 60 Hertz The standard 115 VAC unit may be converted to 230 VAC by requesting the conversion procedure from the company 6 A RECOMMENDED SENSOR AND HEATER CABLING B ALTERNATE TWO WIRE HOOK UP UP C ALTERNATE THREE WIRE HOOK FIGURE 2 1 SENSOR AND HEATER CABLES 2 4 Installation The recommended cable diagrams for the sensor diode and heater element are given in Fig 2 1 a The use of a four wire diode connection is highly recommended to avoid introducing lead IR drops in the voltage sensing pair The indicated shielding connections are the recommended standard practice to avoid ground loops For less critical app
60. lways make ample allowance for thermal contractions when sizing hookup wire lead length and thus prevent possible lead fractures Because most cryogenic sensors are small and their lead wires are of negligible diameter it is sometimes difficult to find an optimum tie down material that will maintain strength at cryogenic temperatures and not lose its adherence One good choice is wax impregnated dacron thread commonly known as dental floss Diode Temperature Sensors Forward voltage measurements should be made at a constant current of 10 or 100 micro amperes The silicon diode can withstand 200 Volts in the reverse direction and up to five milliamperes in the forward direction In the case of the gallium arsenide diode do not apply a current of greater than one milliampere in the forward direction or a voltage of greater than five volts in the reverse direction Either condition can result in permanent damage to the temperature sensor This dangerous condition can be generated specifically with the use of a multimeter type ohmmeter The solution is straight forward however For the Simpson 260 types use the Rx100 ohm scale with a 2 K resistor in series with one lead for Triplett 630 types do the same with either the Rx100 or Rx1000 ohm scales This will limit the back voltage to 1 5 volts and the forward current to less than 1 mA yet the forward reverse difference can easily be seen If power input to your cryogenic
61. mersed in cryogen directly sample holder in vapor whose temperature is above the controller set point temperature etc 6 Excessive thermal path phase lags will cause the control loop to be unstable due to large internal gain values Physical separation between the diode and heater particularly by paths of small thermal cross section should be avoided If it is indicated that the controller is malfunctioning after performing the tests to be described below it is recommended that the instrument be returned to the factory or to an authorized factory repair representative for repair The components used in the instrument are costly and may be permanently damaged if subjected to inappropriate test voltages or excessive soldering iron heat Although premium materials and techniques have been used to fabricate the instrument circuit board there is always the risk of lifting a connection pad or cracking the board when unsoldering a component 5 4 Operational Checks Replace the sensor diode with a test fixture containing a precision resistor or resistance decade box and a 100 ohm 20 watt resistor The precision resistor replaces the diode sensor and the high wattage resistor replaces the cryostat heater With 10 microamperes flowing through the test resistor a 1 0 volt potential should develop across a 100 K ohm resistor This test condition should provide a temperature display of 70 K and a corresponding analog output value of 0 70 V
62. minal to test point 2 Turn the power on and allow approximately 60 minutes warm up time Adjust potentiometer R7g until the voltmeter reads 100 0 mV Set the voltage standard to 1 9755 volts Adjust the ZERO potentiometer R54 until the panel meter reads 013 1 013 for Model DRC 7C Set the voltage standard to 1 1283 volts Adjust potentiometer Rio to a value of 028 0 on the panel meter display Set the voltage standard to 0 9811 volts and adjust potentiometer R26 to a value of 077 3 077 for Model DRC 7C on the panel meter display Set the voltage standard to 0 099 volts and adjust potentiometer labeled FS R33 to a value of 395 2 395 for Model DRC 7C on the panel meter Repeat above steps if necessary bes LJ SECTION IV Theory of Operation 4 1 Introduction This section contains the theory of operation of the series DRC 7 Digital Readout Controller to aid the system engineer in designing stable thermal system Refer to Figures 4 1 4 2 5 1 5 2 5 3 5 4 and 5 5 as an aid in the following discussion 4 2 General Description The diode sensor Model DT 500 DRC is excited by an adjustable R79 constant current source and forms the feedback element of the input amplifier 22 The output of this amplifier is a voltage referred to the system common 10 and is proportional to the voltage output of the sensor The amplifier output voltage is compared with a predetermined voltage reference
63. nce or use of this material Obsolete Manual 1975 II III 3 5 2 Table of Contents eral Information Introduction Description General Description Specific Model DRC 7 Model DRC 7C Model DRC 70 Model DRC 70C General Specifications Accessory Equipment and Custom Options tallation Introduction Initial Inspection Power and Grounding Requirements Installation Repackaging for Shipment rating Instructions Introduction Controls Indicators and Connectors Initial Checks Temperature Readout Control Model DRC 7 Model DRC 7C Model DRC 70 Model DRC 70C Customer Calibration Model DRC 7 A Ten Microamp Sensor Current Adjustment B Calibration of Instrument Between 0 300 K Models DRC 7C DRC 70 and DRC 70C Page CQ NN N N b m 000 ON Section IV VI e 1 2 3 3 3 3 3 cdi 3 45 4 4 1 4 2 gt amp Pp Pb D Pp PD gt HH AHS D O Ui DWN heory of Operation Introduction General Description Detailed Description Power Supply and System Common Two Wire Input Four Wire Input Linearizer Comparators and Voltage References Amplifier Stage I Amplifier Stage II Output Stage and Digital Display Temperature Controller Model DRC 7C Model DRC 70C Maintenance and Troubleshooting 5 1 N b N e o Qn
64. ngly coat the mounting surface with Eastman 910 contact cement or other similar cement The ceramic side of the substrate is visible as non red or as opposite the Hall element Locate the ceramic side on the clean degreased surface and apply extremely light pressure with a foam pad until the bond is made Wipe off the excess contact cement Use an epoxy such as Bacon Industries FA8 or Emerson and Cuming 2850FT to form a fillet around the plate and to secure the leads Don t get epoxy on top of the chip If encapsulation is absolutely necessary use a light coating of Sylgard 186 or a similar soft material If tight shut off is necessary in the system a separate shut off valve should be used in series with the valve and should be placed between the vacuum chamber and the valve A small inboard bleed from atmosphere is necessary for the proper operation of the valve This bleed is through the small recessed screen in the end of the valve near the control handle The most probable cause of problems with the 329 Valve is restricted flow through the screen This part of the valve should be inspected periodically to ensure that plugging has not occurred When flush panel mounted the shallow channel from the circumference of the valve to the bleed port ensures that sufficient air is available and no special provisions need be made in the panel During normal operation the bleed flow is approximately 1 5 SCFH through the valve
65. old Plated Ni Fe 3 DE 2 Gold Plated Ni Fe 3 DE 2 Plat 10 Ir 2 Plat 1096 Ir 1 gold 1 plat 10 Ir Min 2 pt 1096 Ir Copper 2 Copper 2 Silver 2 Silver Copper 2 3 gr 019 15 5 gr pa 18 gr us 1 24 gr 19 1 24 ot 1 24 gr e 42 gr ns Min 45 mg Ua Ultra 35mg 002 Anode 05 25 005 mg Cathode 13 Win 17 mg 2 005 13 32 AWG teflon 13 gr insulated 32 AWG 55 gr 05 1 gr a 15 gr 32 AWG 6 gr Gold Plated Kovar TO 46 Package Gold Plated Kovar TO 46 Package Gold Plated Kovar TO 18 Package Platinum amp Glass Gold Plated Kovar TO 46 base set in 6 32 x 38 copper alloy hex head cap screw Gold Plated Kovar TO 46 base set in 6 32 x 3 4 copper alloy hex head cap screw Platinum and glass header set in a 6 32 x 38 copper alloy hex head cap screw Platinum and glass header set into a gold plated copper cylinder Min amp Ultra Platinum Brass amp Epoxy Platinum Gold and Epoxy Min Platinum amp Epoxy Platinum and glass header set into a gold plated copper cylinder amp an epoxy lead strain relief Platinum Glass and Epoxy Glass Glass Gold plated copper can and high tempera ture epoxy Thermal transfer thru body of unit one lead grounded DE Dual Element w Common Cathodes Both leads isolated from case DE Dual Element w Common anodes Both l
66. or break point 23 K providing a gain of Z3 equivalent to the gain for segment 18 to 23 As the input voltage increases current proportional to the input voltage flows through Rio and the gain of amplifier 25 is modified accordingly 21 The gain network t the negative input of amplifier 23 is divided into 1 3 R and 2 3 R in order to keep the value of R7 and RA respectively within 1 3 megohms It is also necessary to keep the value of R29 above 10 K ohms so that the resistance of the analog switch will be negligible compared to Rog At break points 27 and 30 K the value of Vig and Vig and Vos and V26 should be exactly equal to the voltage at the negative input terminal of Z3 through adjustable potentiometers R26 and R19 Since the gain between 4 and 6 K is lower than that between 6 and 14 K resistor Rss is switched across R49 feedback resistor to provide the lower gain required In the temperature range 18 to 23 K all switches SWl through SW7 are open to provide the proper slope and gain for conformity to standard DRC 7 table 4 5 7 Amplifier Stage II Operation between 80 to 400 K is accomplished with the break point set for 80 K which triggers the comparator to operate switch SW8 into an open state The comparator switches when the voltage at the input to Z5 exceeds 0 97405 volts With the gain change in this stage only 1 28th of the highest gain any error introduced by resistor R22 and the voltage offset in amplif
67. owatts at 4 2 K 0 5 K 0 06 1 2 3 4 1 kelvin 0 1 kelvin 10 mV K at 1 K output impedance Tracking to digital display of 0 3 K TTL compatible non isolated 3 digits 14 mm 0 55 high 7 segment non blinking 2 seconds to rated accuracy Digital thumbwheel selection directly in kelvin temperature units 0 5 K 0 3 K with a properly designed system 2 1 kelvin 0 1 K 1 kelvin 0 1 Standard 0 50 watts 0 1 A 0 50 VAC Time proportional thyristor with continuously adjustable variac output Isolated digital proportional with continuously adjustable variac output 1 5 Accessory Equipment and Custom Options Available The following accessory equipment and custom options are available from the factory SECTION II Installation 2 1 Introduction This section contains information and instructions necessary for the installation and shipping of the series DRC 7 Digital Readout Controller Included are inspection instructions power and grounding requirements installation information and instructions for repackaging for shipment 2 2 Initial Inspection This instrument was electronically and mechanically inspected prior to shipment It should be free from mechanical damages and in perfect working order upon receipt To confirm this the instrument should be inspected visually for obvious damage upon receipt and tested electronically by use to detect concealed damage A
68. potentiometer R71 The amplifiers comparators and the analog switches in this system are operated between V and V 14 volts and the networks for the bias and gain controls work between V and common Therefore the output of all amplifiers is referred to the System Common 4 3 2 Two Wire Input This diode sensor is supplied by a constant current of 10 micro amperes which is adjustable R79 to provide the current excitation The sensor forms the feedback element of the amplifier Z2 The offset adjust potentiometer R89 provides the exact voltage required by the linearizer The two wire input is subject to voltage errors produced by the IR drops along the lead wires with 10 microamps flowing 4 5 3 Four Wire Input Since the sensor forms the feedback element of amplifier Z2 the lead resistance will have an appreciable effect on the accuracy as noted in Section 4 3 2 This effect is reduced by utilizing a four wire input as follows The output of amplifier Z2 is connected to the negative input of the unity gain amplifier Z11 The positive input of amplifier Z11 is referred to the cathode of the sensor through lead 3 pin 11 The variation of the output of amplifier Z2 due to the lead resistance of lead 1 pin 9 and lead 2 pin 10 is equal and opposite to the variation of the voltage of lead f3 pin 11 Due to the equality they cancel at the output of the amplifier 211 which provides the exact voltages equal to sensor requir
69. room temperature A small amount carefully placed at the base of the sensor leads will protect them from sharp bends and possible fracture Special care must be given in mounting sensors or thermocouples with gold leads Gold wire will dissolve in the solder if ordinary soldering techniques are used Extreme care must be used in soldering this lead to another lead It is suggested that the other lead be pretinned Then the gold lead should be wrapped around the pretinned lead and heat applied above the tinned region As soon as the solder starts to melt the soldering iron should be removed from the pretinned lead low power microscope may be of use here A second equally satisfactory approach is to use pure Indium as the solder 2 In either instance great care must be taken to insure the sensor is properly heat sinked as described above In addition to properly heat sinking the temperature sensor and sensor leads at the site to be measured it is most important that the lead wires be carefully 3 lagged to the equipment surface sometimes called thermally tempered at regular intervals as they are brought out to room temperature In this manner thermal loads to both the equipment and the temperature sensor are minimized Specific care should be taken in mounting epoxy encased sensors to assure no inter action with solvents overheating etc Ge 7031 varnish with its xylene solvent is particularly dangerous A
70. sed exactly at the amplifier voltage corres ponding to break points 27 K and 30 K The adjustments for these two break points are accomplished with potentiometers R99 and R98 respectively The high slope below 27 K guarantees that the error resulting from the set point accuracy of this break point will not have any significant effect on the overall accuracy The set point accuracy at the break point for 80 K is not very critical since the overall gain between 80 and 400 K is reduced only by 1 28th of the maximum gain 4 5 6 Amplifier Stage I The characteristics of the Model DT 500 DRC see standard table of DRC 7 shows that the ratio of the highest gain to the lowest gain is 28 Therefore to operate amplifier 23 within its linear region it is necessary to attenuate the signal of the input amplifier Z2 to approximately 1 20 of its actual level This signal is fed into the positive terminal of unity gain amplifier Z3 to maintain the proper sign with the negative input terminal following the positive input terminal and with the difference being only the offset voltage of the amplifier Therefore when the comparator closes the analog switch a reference voltage equal to the voltage at the negative terminal is switched At the point of switching no current flows through Rswitch For example if analog switch SW4 is closed the reference voltage V12 is applied and is equivalent to the voltage at break point 23 K No current will flow through Rio f
71. series are applicable when used with the standard DT 500 DRC temperature sensor General Temperature Range Sensing Material Sensor Excitation Sensor Current Regulation Sensor Input Connection Imput Resistance Isolation Operating Environment Normal Mode Rejection Common Mode Rejection Power Requirements Dimensions Power Consumption Circuit Design Weight 1 to 400 K Silicon Model DT 500 DRC 10 microamps t l ge 2 3 or 4 wire constant current Greater than 100 megohms 300V 10 459 SO db min at 60 Hz and up 120 db at 60 Hz and above 115 or 230 VAC 10 50 60 Hz 8 9 cm 3 5 high x 20 3 cm 8 wide x 30 5 cm 12 deep 15 VAS 60 vA2 4 Solid State Electronics 3 6 Kg 8 1 3 5 4 Kg 12 pounds 2 4 For 230 VAC add K to model number i e DRC 70 K 1 Model DRC 7 only 2 Model DRC 7C only 3 Model DRC 70 only 4 Model DRC 70C only Temperature Readout Resolution Digital Analog Conformity to LSCI Standard DRC 7 Silicon Diode Table Maximum Sensor Power Dissipation Maximum Digitizing Error 8 hours at 25 C Temperature Coefficient Error Repeatability Outputs Analog Digital optional Display Response Time Temperature Control Set Point Controllability Repeatability Settability Heater Output Control Mode 4 1 kelvinb 0 1 kelvin Better than 0 1 kglvin all units 0 5 K 4 400 SPP 0 3 K 4 400 25 micr
72. set the voltage standard to 0 9811 volts and adjust potentiometer R26 for a reading of 077 4 kelvin 077 on Models DRC 7 and DRC 7C on the front panel display The final calibration is the same as outlined under Customer Calibration in Section 3 31 5 6 Alignment of Controller Section 5 6 1 Model DRC 7C No alignment or adjustments are required for this section 5 6 2 Model DRC 70C With the circuit board removed following instructions in Section 5 8 connect the flat ribbon cable connector and three single wire connectors to their appropriate spots on the printed circuit board using clip leads Connect a 100 ohm 20 watt load across the heater terminals Set the fine tuning control to minimum Connect an oscilloscope across the 100 ohm load as follows a Time setting at 50 m sec div b Voltage setting to 5 volts div using times 1 probe c Set coupling to Auto d Select trigger mode for line Set the thumbwheel switch to 150 0 and turn power ON Adjust the sensor input voltage such that the meter display reads 149 0 and increase the fine tuning control until 10 volts AC is indicated across the 100 ohm resistor The AC waveform will appear throughout the time sweep Adjust the sensor voltage such that the digital display indicates 149 6 Set R129 until 9 cycles of the AC waveform appears on the screen The proportional bandwidth has now been adjusted for proper cycling 5 7 Troubleshooting Panel Meter In normal use the p
73. sly adjustable variac with an adjustable power output of 0 to 50 watts 1 3 3 Model DRC 70 The Model DRC 70 like the DRC 7 provides temperature readout only However the resolution has been improved to 0 1 degree and the conformity error has been reduced to 0 3 degrees Both the Models DRC 7 and DRC 70 have a standard analog output to compliment the digital display providing a 0 4 volt output with a slope of 10 millivolts degree with their respective linearity error 1 3 4 Model DRC 70C The Model DRC 70C as the DRC 7C provides both temperature readout and control over the useable range of 1 to 400 K The DRC 70C combines the DRC 70 with a revolutionary new digital proportional thyristor control unit having an internal factory set bandwidth of 0 5 kelvin The digital proportion control provides for maximum agreement between the set point temperature and the actual temperature A fine tuning control is provided on the front panel which allows the maximum peak voltage to be adjusted between 0 and 50 volts rms The bandwidth is fixed about the set point value and is equal to 0 5 Operation within the bandwidth zone allows the controller to work in a proportional mode The proportional mode operation is detectable by a pulsating or blinking heater power ON light Operation below the proportional zone allows the controller to work in a continuously ON condition 1 4 General Specifications The following specifications for the DRC 7
74. tible non isolated 0 100 mV at 1 K output impedance DISPLAY 31 digits 1 4 cm 0 55 high DIGITAL LINEARIZATION 6 segments Sperry 7 segment non blinking SENSOR EXCITATION 10 microamps RESPONSE TIME 2 seconds to rated accuracy SENSOR CURRENT NORMAL REGULATION 1 MODE REJECTION 50 db min at 60 Hz and up SENSOR INPUT CONNECTION 2 or 3 wire or 4 wire MODE REJECTION 120 db at 60 Hz and above potentiometric POWER 115 V C 10 at 50 60 Hz MAXIMUM SENSOR POWER DISSIPATION MAXIMUM DIGITIZING ERROR 25 uW at 4 2 K REQUIREMENTS Optional 230 VAC 10 at 50 60 Hz 8hrs at25 C 0 5 K ae i 1 ase 4 3 1 7 high x 10 2 TEMPERATURE X 4 wide x 11 4 4 deep COEFFICIENT ERROR 0 05 K C instrument Case 8 9 cm 31 2 high x 22 9 REPEATABILITY 1 9 wide x 22 9 cm 9 deep PRINTED IN U S A AO PT SAAT SERIES DRC DIGITAL THERMOMETERS Technical Specification DRC 7C MODEL DRC 7C DIGITAL THERMOMETERICONTROLLER 2 1 400 e 1K Resolution Silicon Diode Sensor Model DT 500 DRC 0 to 50 Watt Heater Output Recorder Output and Optional BCD Output e 115 or 230 VAC Power readout and control over the 1 400 kelvin range with a resolution of 1
75. ut and Optional BCD Output Optional 10 Sensor Input e 115 or 230 VAC Power The Model DRC 70 Digital Cryogenic Thermometer is designed to cover the range from 1 to 400K utilizing the Lake Shore Cryotronics Model DT 500 DRC Silicon diode sensor The DRC 70 linearization circuit combined with the completely interchangeable model DT 500 DRC sensor allows the DRC 70 to achieve 0 3K conformity to the standard DRC 7 Silicon Diode table from 4 to 400 K In addition to an analog output with 0 1K resolution an optional BCD output is available The temperature sensor is excited by a 10 uA constant current source with 0 196 regulation The thermometer is designed to connect to the sensor in a 2 3 or 4 wire configuration A push button selector switch is available as an option which allows one to select and read out up to 10 separate sensors TEMPERATURE RANGE SENSING MATERIAL RESOLUTION ANALOG DIGITAL CONFORMITY TO LSCI STANDARD DRC 7 SILICON DIODE TABLE SENSOR EXCITATION SENSOR CURRENT REGULATION SENSOR INPUT CONNECTION MAXIMUM SENSOR POWER DISSIPATION MAXIMUM DIGITIZING ERROR 8 hrs at 25 C TEMPERATURE COEFFICIENT ERROR REPEATABILITY TECHNICAL SPECIFICATIONS 1 to 400K INPUT RESISTANCE Silicon Model ISOLATION DT 500 DRC OPERATING ENVIRONMENT OUTPUTS ANALOG 0 1 or better 0 1 DIGITAL Optional kelvin 0 3K 4 400K 10 microamps DISPLAY RESPONSE TIM
76. verted to a proportional voltage which drives a ramp generator 222 to provide an adjustable time period R128 proportional to the count The proportional time period drives transistors 03 and Q4 to provide power to the heater 26 SECTION V Maintenance and Trouble Shooting 5 1 Imtroduction This section contains instructions for maintaining and calibrating the series DRC 7 instrument nominal voltage values and gains circuit schematic diagrams printed circuit board component diagram and parts list 5 2 Test Equipment and Accessories The following test equipment is required to perform the necessary adjustments a b Voltage Standard Electronic Development Corporation Model MV 100N or equivalent Voltmeter 1 Input 9 999 volts Resolution 1 mV Accuracy 0 05 Reading Input Impedance Not less Voltmeter 2 Input 1 999 volts Resolution 1 mV Accuracy 0 05 Reading Input Impedance Not less Voltmeter 3 Input 199 9 mV Resolution 100 uV Accuracy 0 05 Reading Input Impedance Not less 27 0 05 F S than 100 megohms 0 05 F S than 100 megohms 0 05 F S than 1000 megohms Voltmeter 4 Input 199 99 mV Resolution 10 uV Accuracy 0 05 Reading 0 05 F S Input Impedance Not less than 1000 megohms All voltmeters should have their leads with E Z hook terminals 5 3 General Remarks Upon initial installation the single most prob
77. witch the unit will apply full power to the heater Observe the temperature display Key No 5 and if it is greater than the set point by 0 5 K Key 6 the heater ON light Key No 9 should be off illustrating zero power being applied to heater load Adjust the set point to a value equal to 0 5 K less than the value being displayed and observe that the power ON light just begins to illuminate Adjust in 0 1 K increments the set point towards the value being displayed and observe the power ON light begins to appear more frequently When the set point value equals the display value the power ON light should be on 50 of the time Note This test should be performed with a displayed value less than 150 K Continue to increase set point in 0 1 K increments and note that the power ON light continues to increase in frequency With the set point equal to 0 5 K plus the value on display the power ON light will be on continuously 100 of the time If the above observances are met the unit is functioning properly If not see sections on installation and section on troubleshooting for correcting malfunction With the unit functioning properly adjust set point switch to the desired temperature value Increase the maximum output power by rotating the fine tuning control Key No 7 turn and observe the rate of heating indicated by the readout display s rate of change If the increase in temperature is slow or the temperature does not incre

Model DRC-7_1975 - Lake Shore Cryotronics, Inc.

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