Keithley 151, Instruction Manual

Page 1: ...INSTRUCTION MANUAL MODEL 151 MICROVOLTMETER...

Page 2: ...Tube Complement power Connector3 Accessories Supplied Dimension3 OPERATION Operating Control3 Preliminary Set Up Operation CIRCUIT DESCRIPTION Input Circuit AC Amplifier Demodulator Circuit DC Amplif...

Page 3: ...s the linear ranges but are compressed in a quasi logarithmi way to three decade3 on each range The3 e range3 permit speedier null searching th3 n the l inear scales without sncrlfizing sensitivity at...

Page 4: ...sis ground Approximately 109 ohins ijllillted 5 ll i L microfarad Circuit ground may be floated up to 500 volts dc or p ak i il rcspcc KC chassis ground RISE TIME 10 to 90 Approximately L second on al...

Page 5: ...seconds the meter will zero Short the input and turn to the 1 millivolt range Zero the meter with the SHORTCIXCUIT ZERO Open the input and zero the meter with the OPEN CIRCUIT ZERO In the first 30 mi...

Page 6: ...fication for 60 cps rejection are given in Section II The rejection is high enough so that usually no precautions are necessary with regard to 60 cps pick up While the input filter is specially peaked...

Page 7: ...eedback factor Above 10 millivolts an input divider is used The l nput divider is formed by R153 through Rl59 The total resistance of this divider is 10 megohms which is always across the input The ze...

Page 8: ...it is conventional and consists of V3 connected as a differential amplifier Vb used as a dc an 7lifier and the output cathode follow r Rl28 DC AMP BAL adjusts the balance of the dc amplifier Once set...

Page 9: ...n 7 of Q2 to ground with a small value of resistance 167 F POWER SUPPLY Despite the high sensitivity no regulation is employed in the power supply The plus and minus supplies are derived from standard...

Page 10: ...ove V h the 12AT7 from its socket sh crt the clltcut terminals and the input termi nals 5 Connec an oscillosope to the plate of W B pin 6 Rotate the SHORTCIRCLTIT ZERO to one end of its travels If the...

Page 11: ...r V2 is not amplifying To check this place the oscilloscope at high sensitivity at the plate of Vl pin 6 and rotate the short circuit ZCI O control If the signal appears and is capable of being nulled...

Page 12: ...Finally check pin 7 of VU Since this is the cutput cathode follower it should swing both plus and minus at least 20 volts upon ma ipu1ati0 of Rl28 If it does not either V B is defective or FU3h is op...

Page 13: ...pacitor c47 l l mfd Mylar 200 v 20 Capacitor C6G l Same as C 104 40 mfd Dry Electrolytic capacitor 200 mfd Electrolytic Upright Capacitor C27 40 C48 200 l mfd Paper Metalized 02 mfd Ceramic Disc 2 0 m...

Page 14: ...1 C 1510 Light Modulator 1510 Light Modulator Pilot Light 25K Deposited Carbon 4 watt 1 Resistor m 4 ha 21 ME 22 ME 32 cv 4 cv 4 PL 8 For 50 cycle Operation RlOl is 30K 10K Composition Slotted Shaft P...

Page 15: ...R 121 R 124 R 125 R 126 R 127 R 128 15 K ohm Composition fw 1 Resistor Rl 15K 470 K ohm Composition kw 10 Resistor Rl 470K 5M ohm Deposited Carbon w 1 Resistor RlZ 500K 50 K ohm Deposited Carbon w 1...

Page 16: ...sited Carbon w 1 96 ohms Deposited Carbon fw 1 10 ohms Deposited Carbon 4 1 100 ohms Carbon Printed Circuit Resistor ill 94 5K Potentiometer RP17 15K Resistor R37 10g Resistor R12 66K Resistor R12 10K...

Page 17: ...ohma Composition 1 w 10 Same as R 121 RF 101 Rectifier RF 102 RF 103 RF 104 RF 105 RF 106 RF 107 RF 108 RF 109 RF 110 SW 1 SW 2 T l Same PS RF 101 Same LI RF 101 Same aa RF 101 Recfifisr matched with...

Page 18: ...REPLACEABLEPARTS LIST MODEL 15L Circuit I f Desig Dercription Part NO Ef fi V l Vacuum Tube EV 3iM I 24 v 2 6 Vicuum Tube EV F v 3 v 4 same v 2 l AT7 Vacuum Tube EV 12 AT7 VI 6 0564R...

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