150B(Model150BMicroAmmeter) 电路图.pdf

INSTRUCTION MANUAL MODEL 15OB MICROVOLT AMMETER RadioFans.CN 收音机爱 好者资料库 WARRANTY We warrant each of our products to be free from defects in material and workmanship. Our obligation under this warranty is to repair or replace any instrument or part thereof (except tubes and batteries) which, within a year after shipment, proves defective upon examination. We,will pay domestic surface freight costs. To exercise this warranty, call your local field representative or the Cleveland factory, DDD 216-248-0400. You will be given assist- ance and shipping instructions. REPAIRS AND RECALIBRATION Keithley instruments maintains a complete re- pair service and standards laboratory in Cleve- land, and has an authorized field repair facility in Los Angeles. To insure prompt repair or recalibration serv- ice, please contact your local field representa- tive or the plant directly before returning the instrument. Estimates for repairs, normal recalibrations, and calibrations traceable to the National Bu- reau of Standards are available upon request. RadioFans.CN 收音机爱 好者资料库 MODEL 150B MICROVOLT AMMETER TABLE OF CONTENTS TABLE OF CONTENTS Section Page Section Page MODEL 150B SPECIFICATIONS. . .ii 4. MAINTENANCE. . . . . . . . . . . 19 1. GENERAL DESCRIPTION. . 1 l-1. General. . 1 l-2. As a Microvoltmeter. . 1 l-3. As a Null Detector . 1 l-4 . As an Ammeter. . 1 2. OPERATION. . 3 4,-l. General. . . . . . . . . . . 19 4-2. Parts Replacement. . . . . . 19 4,-3. Mechanical Chopper Replacement. . . . . . . . . 19 4,-4,. Troubleshooting. . . . . . . 20 4-5. Preliminary Troubleshooting Procedures . . . . . . . . . 20 4,-6. Check Out and Calibration Procedures . . . . . . . . . 20 4-7. Power Supply Check Out and Calibration. . . . . . . 22 4,-a. Amplifier Check Out and Calibration. . . . . . . 25 3. 2-1. 2-2. 2-3. 2-4,. 2-5. 2-6. 2e7. 2-8. 2-9. 2-10. 2-11. 2-12. 2-13. Z-14,. 2-15. 2-16. Mode of Operation. . . . . . Battery Operation. . . . . . Microvolt and Null Detector Operating Procedures . . . . Ammeter Operating Procedures . . . . . . . . . Zero Suppress Operation. . . Filter Switch. . . . . . . . Recorder Outputs . . . . . . Synchronizing Terminals. . . Differential (Floating) Measurements . . , . F . . . Accuracy Consideration . . . Thermal Noise. . . . . . . . Input Resistance . . . . . . Therinal Emfs. . . . . . . . Shielding. . . . . . . . . . Operating From Source Other Than 117 Volts, 60 cps . . . Accessories For Input .3 .3 . 4, .6 .6 7 : 7 .7 .8 .8 0 : 9 . 9 .lO .ll Connections. . . . . . . . . .ll CIRCUIT DESCRIPTION. ., . . . . . . .13 3-1. General. . . . . , . 13 3-2. Input Circuit. . . 13 3-3. AC Amplifier . . . . .14. 3-4. Demodulator. . . . * . .15 3-5. DC Amplifier . . . .15 3-6. Zero Suppression . . .15 3-7. Power Supplies . . . .15 3-8. Battery Charging Circuit . .17 5. ACCESSORIES. . . . . . . . . . . . 35 5-l. Model 4,006 Rack Mounting.Kit . . . . . . . . 37 5-2. Model 4007 Dual Rack Mounting Kit . . . . . . . . 37 5-3. Model 370 Recorder . . . . . 39 6. REPLACEABLE PARTS. . . . . . . . . 41 6-l. Replaceable Parts List . , . 41 6-2. How to Order Parts . . . . . 41 Model 150B Replaceable Parts List . . . . . . . . . 42 Models 14,83, 14.84 Replaceable Parts List . . . 50 Schematic Diagram 20350E . . 53 Schematic Diagram 20357D . . 55 * Change Notice Last page * Yellow Change Notice sheet is included only for instrument modFfications affect- ing the Instrument Manual. 0667R i RadioFans.CN 收音机爱 好者资料库 GENERAL DESCRIPTION MODEL 150B MICROVOLT AMMETER TABLE 1. Model 1SOB Specifications. AS A VOLTMETER AND NULL DETECTOR: RANGE: 0.3 microvolt (3 x 10- volt) full scale to 1 volt on a Zero-centw meter. 14 overlapping ranges in Ix and 3x steps. ACCURACY: Meter: *2g Of full scale on all ranges. I-Volt Output Terminals: *I%. 100.Millivolt Output Terminals: Adjustable to 1%. Note: Accuracy specifications excluie noise and drift. ZERO DRIFT: Less than 0.1 microvolt per 24 hours after I- hour warmup with reasonably constant ambient tempera. ture. Long-term d!ift is ncwcumulatlve. INPUT NOISE: With input shorted, less than 5 nanovolts rms (25 nanovolts peak-to-peak) on the most sensitive range. With a 10,000.ohm source resistance. lessthan 14 nanovolts rms (70 nanovalts peak-to-peak) on the most sensitive range. INPUT RESISTANCE: Input Resistance Maximum Source* Range Greater than, Resistance, ohms Ohms 0.3 IN 1M 10 k 1 P” 3M 30 k 3, 10 M 100 k 10 pv 30 M 300 k 30 IN 100 M 1M 100 #v and above 100 M IM Note: Source resistances higher than the recommended maximum will increase noise and rise time. ZERO SHIFf WITH SOURCE RESISTANCE: Less than 1o-o volt per ohm. LINE FREQUENCY RUECTION: A voltage of power line frequency which is 75 db (p.p/dc) greater than full scale affects reading less than 2% on the most sensitive range (decreasing to 60 db on the 10.microvolt range and to 20 db on the l-volt range). COMMON MODE RLIECTIDN*: Greater than 180 db at line frequencv or dc. RISE TIME (10% to 90?stabi; net weight, 16 pounds. ACCESSORIES SUPPLIED: Model 1506 Low.Therma, Input Cable (4 feet, low-thermal triaxial cable, alligator clips). Mating output connector. Length of lowthermal solder. Internally mounted nickel.cadmium battery pack. Model 1499. ii 0267R MODEL 150B MICROVOLT AMMETER GENERAL DESCRIPTION ._ SECTION 1. GENERAL DESCRIPTION l-l. GENERAL. The Keithley Model 150B Microvolt Ammeter is an extremely sensitive instrument which measures voltages from 0.3 microvolt to 1 volt and currents from 0.3 nanoampere to 1 milliampere. It can be used as a voltmeter, null detector or an ammeter with either battery or line power operation. l-2. AS A MICROVOLTMETER. a. The Model 150B is ideal as a microvoltmeter for measuring semiconductor resistivity, thermopile and thermocouple potentials, Hall effect, contact resistances, biologically generated emfs, electrochemical potentials and strain guages emfs. b. The Model 15OB has input noise less than 25 na,novolts peak-to-peak; high input re- sistance and loti zero shift; excellent zero stability; very high line-frequency rejection and common mode rejection; battery operation; zero suppression; special low-thermal input circuitry; two available outputs. c. With these features, the Model 150B permits excellent resolution; maintains measure- ment accuracy even from high resistance sources; is ideal for long-term measurements; de- tects dc signals in the presence of large ac voltages and is virtually insensitive to nc or dc voltages applied between circuit and chassis ground; disconnects from power lines for improved isolation; measures small changes in dc signals: reduces temperature and shield- ing problems; provides outputs where either filtering is needed or fast response or greater output power is needed. l-3. AS A NULL DETECTOR. a. As a null detector the Model 15OB is excellent for use in ratio measurements and in potentiometer and bridge circuits. b. The Microvolt Ammeters outstanding features as a null detector are: very good re- solution; high line frequency and cormnon mode rejection; isolation from chassis ground to input terminals; battery operation; high input resistance; floating capability; low zero shift; zercl suppression. C. Because of these features the Model 150B has resolution comparable to the maximum usable resolution of most potentiometers and bridges; may be simply connected to the ter- minals of a null circuit; is very insensitive to commnn mode voltages developed in the null circuit; can be used in most potentiometer and bridge circuits without off-null load- ing; accurately detects a null regardless of the setting on most potentiometers and bridges; compensates for thermal emfs generated in the null circuit. 1-4. AS AN AMMETER. a. The Model 150B has general use in research, design and production test facilities. It is useful for making low voltage drop, in-circuit measurements as well as measuring the output of radiation detectors, phototubes and other current generating transducers. b. The instrument has low voltage drop for measuring currents in very low-voltage circuits; low zero drift for measuring long-term current; excellent floating capabilities for measur- ing ungrounded sources; and low input noise,giving excellent resolution. 0667R 1 . OPERATION MODEL 150B MICROVOLT AMMETER Control JEER SUPPLY Switch 4NGE Swi.tch Functional Description Controls mode of operation for power supply Se.lects the full scale voltage or current which is to be measured Par. 2-1,2- 2-3,2- UNCTION Switch Determines whether the Model 150B measures voltage or 2-3,2- current; selects input resistance on voltage ranges. ERO SUPPRESS Controls Determines the amount of zero suppression 2-5 LLTER Switch Connects or disconnects a lfne frequency filter 2-6 at the input gPLIT Receptacle Connection for input cable 2-16 TABLE 2. Model 150B Front Panel Controls. The table briefely describes each control, and indicates the paragraph which contains instructions on the use of the control. Control Functional Descriotion Par. LINE VOLTAGE Switch BATTERY FUSE Line Fuse Power Cord 1V OUTPUT Receptacle 1OOMV OUTPUT Receptacle 1OOMV ADJUST GND Terminal LO Terminal SYNCHRONIZING Jacks Sets Model 150B for 117 or 234-volt ac power line 2-16 Quick-Acting, .3/4 amp 3AG or MDL fuse _ 117-volt: Slow-Blow l/4 amp 3AG or MDL fuse - 234-volt: Slow-Blow l/8 amp 3AG or MDL fuse Provides ground connection for cabinet; 3-wire power - cord with NEMA approved 3-pronged plug Power output; provides ?l volt at up to one.milliampere 2-7 for a full-scale meter deflection. Fast response. Recorder output; provides OOmv, adjustable within 2-7 1Omv span, for full-scale meter deflection. Filtered. Adjusts 1OOMV OUTPUT within 1Omv span 2-7 Connection to chassis ground 2-3,2-9,2-14 Connection to circuit low; circuit low will not 2-3,2-9,2-14 be at chassis ground unless LO is linked to GND Eliminates any interaction between two adjacent 2-8 TABLE 3. Model 150B Rear Panel Controls. The table briefly describes each control, and indicates the paragraph which contains instructions on the use of the control. 2 0567K MODEL 150B MICROVOLT AMMETER OPERATION SECTION 2. OPERATION 2-l. MODE OF OPERATION, a. When the POWER SUPPLY Switch is in the OFF position, the Model 150B will not operate, and the red dot cannot be seen through the switch knob. b. The Model 150B operates either from an ac power line when the POWER SUPPLY Switch is in the AC position, or from its battery with the Switch in BATTERY position. In either po- sition the red dot can be seen. For most uses the instrument functions well from ac. use battery operation, however, if the ac power line will create ground loop or isolation prob- lems. Isolation from low to ground is complete for battery operation when the power cord isdisconnected; it is greater than 101 ohms shunted by .OOl microfarad with the power cord connected. Also, battery operation is useful to reduce modulation products (usually 8 cps) which may appear at the output for certain low-level measurements. (See paragraph 2-14,.) NOTE Before using the battery operation, thoroughly read paragraph 2-2. Improper battery operation can damage the battery pack and lead to inaccurate measurements. 2-2. BATTERY OPERATION. The Model 150B is supplied with a rechargeable 6-volt, 4, ampere-hour nickel-cadmium battery pack. Do not use the battery more than seven consncutive hours without recharging. ,FIGURE 1. Model 150B Front Panel Controls. FIGURE 2. Model 150B Rear Panel Controls. Circuit designations refer to Replaceable Circuit designations refer to Replaceable Parts List and schematic diagram. Parts List and schematic diagram. 0667R 3 OPERATION MODEL 150B MICROVOLT AMMETER NOTE Permanent damage to the battery pack may occur if it is used for more than 8 con- secutive hours witbout recharging. At this discharge rate, the number of recharge gycles is greatly reduced. Before using the Model 150B, check the state of the battery charge. b. Check the battery charge before making a measurement. Hold the POWER SUPPLY Switch in the BATT. TEST position; the red dot will show. In this position the Model 150B shows the state of the battery charge directly on the meter. The minimum acceptable charge is a meter indication of approximately +6 on the upper meter scale. 1. Tine terminal voltage of a nickel-cadmium battery changes very little from full charge to almost crmplete discharge. The +6 meter indication for minimum charged ter- minal voltage will vary a few minor divisions for different batteries. After a few charge-discharge cycles, the exact value of the charged terminal voltage for any in- dividual battery wil.1 be apparent. 2. Recharge the battery if needed. Otherwise, battery operation is the same as for the ac power line operating mode; refer to paragraph 2-3. NOTE When the battery is used beyond its capacity, two effects are seen. There is a large shift in zero offset from ac to battery operation. Also, the power supplies do not regulate and high ripple voltages appear at the supply outputs. C. To recharge the battery, connect the power cord to an ac power line. Turn the POWER SUPPLY Switch t,o AC or OFF. The battery will be automatically charged in either of these positions. The charging circuit is such that the battery cannot be overcharged. d. It is suggested that the battery be used during the day and be recharge then turn the POWER SUPPLY _ . Switch to OFF at night. After a fully charged battery is used icor seven ConseCutiVe Hours, . it will recharge within 16 hours. Leaving the power cord connected has little effect on the isolation: loLo ohms with the low-ground link disconnected. If the battery is used longer than eight hours, it may take considerably longer than 16 hours to recharge. -., 2-3. MICROVOLT AND NULL DETECTOR OPERATING PROCEDURES. a. Set the front panel controls as follows: -. POWER SUPPLY Switch OFF RANGE Switch 1oooMV .- FUNCTION Switch INPUT R lOOK ZERO SUPPRESS COARSE Control OFF FILTER Switch -IN - NOTE Make sure rha ZERO SUPPRESS COARSE Control is OFF. If it is not, a suppression voltage is introduced, which may cause an error in measurements. See paragraph 2-5 for zero suppression. 4 0667R MODEL 150B MICROVOLT AElMETER OPERATION b. Check the voltage shown on the rear panel LINE VOLTAGE Switch; connect the Model 150B to the ac power line. The battery will now be charging. c. If the circuit low is to be at ground, put the low-ground link between the LO and GND terminals on the rear panel. The ground terminal (GND) is connected to the chassis and the third wire of the power cord. The low terminal (LO) is connected to circuit ground and the low side of the INPUT Connector. d. Turn the POWER SUPPLYSwitch to the desired mode of operation, AC or BATTERY. For moat stable operation,