Tektronix 262 Instruction Manual
Model 262
Instruction Manual
Low Thermal Voltage Divider
WARRANTY
Keithley Inslrumenls. Inc. warrants this producl to be free from defects in material
and workmanship for a period of I year from date of shipmem.
Keithley Inslrumen&. Inc. warranls the following items for 90 days from the date
of shipment: probes, cables, rechargeable batteries, diskettes, and documentation.
During the warranty period, we will, at our option. either repair or replace any
product Ihal proves to be defecrive.
To exercise [his warranty, write or call your local Keithley representative. or con-
lacr Keithley headquarrers in Cleveland, Ohio. You will be given prompt assistance
and return inslructions. Send lhe product, lransportation prepaid, to rhe indicated
service facilily. Repairs will be made and the product returned, transportation prepaid. Repaired or replaced producls are warranted for the balance of the original
warranty period, or al leas1 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modilication withoul
Keithley’s express wrilten consem, or misuse of any producl or pan. This warranty
also does not apply to fuses. sofware. non-rechargeable batteries, damage from bal-
tery leakage. or problems arising from normal wear or failure 10 follow instructions.
THIS WARRANTY IS IN LIEU OFALL OTHER WARRANTIES, EXPRESSED
OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PRO-
VIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOY-
EES SHALL BE L1ABI.E FOR ANY DIRECT, INDIRECT, SPECIAL, INCI-
DENTAL OR CONSEQIJENTIAL DAMAGES ARISING OUT OF THE USE OF
ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRU-
MENTS, INC.. HAS BEEN ADVISED IN ADVANCE OF THE POSSlBlLITY
OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE,
BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION,
LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR
DAMAGETO PROPERTY.
Model 262 Low Thermal Voltage Divider
Instruction Manual
@1982, Keithley Instruments, Inc.
All rights rcservcd.
Cleveland, Ohio, U.S.A.
Fourth Printing, May 2000
Document Number: 262-901-01 Rev. D
Safety Precautions
The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used
with non-hazardous voltages, there arc situations where hazardous conditions may bc present.
This product is intended for use by qualified personnel who recognize shock hazards and are
familiar with the safety precautions required to avoid possible injury. Read the upcrating information carefully before using the product.
The types of product users are:
Responsible body is the individual or group responsible for the use and maintenance of
equipment, for cnsuring that the equipment is operated within its specifications and operating limits, and for ensuring that operators are adequately trained.
Operators use the product for its intended function. They must be vained in electrical safety
procedures and proper use of the inatmment. They must be protected from elec(nc shock and
contact with hazardous live circuits.
Maintenance personnel perform routine procedures on the product to keep it operating, for
example, setting the line voltage or replacing consumable materials. Maintenance procedures
arc described in the manual. The procedures explicitly state if the operator may perform them.
Otherwise, they should be performed only by service personnel.
Service personnel are trained to work on live circuits, and perform safe installations and rc-
pairs of products. Only properly trained service personnel may perform installation and ser-
vice procedures.
Exercise extreme caution when a shock hazard is present. Lethal voltage may be present on
cable connector jacks or test lixtures. The American National Standards Institute (ANSI)
sratcs that a shock hazard exists when voltage levels greater than 30V RMS, 42.4V peak, or
60VDC are present. A good safety practice is to expect that hazardous voltage is present
in any unknown circuit befure measuring.
Users of this pmduct must be protected from elecaic shock at all times. The responsible body
mustenwe tidt users are prevented access and/or insulated fromevery connection point. In some
cases, connections must be exlxxd to potential human confacf. Product users in these circun-
stances must be trained to pro&t themselves from the risk of electric shock. If the circuit is capable of operating at or above loo0 volts, no conductive part of the circuit may be exposed.
As described in the International Electrotechnical Commission (IEC) Standard IEC 664, dig-
ital multimeter measuring circuits (e.g.. Keitbley Models l75A, 199,2OOO, 2001, 2002, and
2010) are Installation Category II. All other instruments’ signal terminals are installation Cat-
egory I and must not be connected to mains.
Do not connect switching cards directly to unlimited power circuits. They arc intended to be
used with impedance limited sources. NEVER connect switching cards directly to AC mains.
When connecting sources to switching cards. install protective devices to limit fault currcnt
and voltage to the card.
Before operating an insuument, make sure the line cord is connected to a properly grounded
power receptacle. Inspect the connecdng cables, test leads, and jumpers for possible wear,
cracks. or breaks before each use.
For maximum safety, do not touch the product, test cables. or any other instmments while pow-
er is applied to the circuit under test. ALWAYS remove power from the entire test system and
discharge any capacitors beforo: connecting or disconnecting cables or jumpers, installing or
removing switching cards, or making internal changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the common side of the circuit
under test or power line (earth) ground. Always make measurements with dry hands while
standing on a dry, insulated surface capable of withstanding the voltage being measured.
The instrument and accessories must he used in accordance with its specifications and operating instructions or the safety of the equipment may he impaired.
Do not excwd the maximum signal levels of the instruments and accessories, as de6ned in
the specifications and operating information, and as shown on the instrument or test fixture
panels, or switching card.
When fuses are used in a product, replace with same type and rating for continued protection
against fire hazard.
Chassis connections must only he used ns shield connections for measuring circuits, NGT as
safety earth ground connections.
If you are using a test lixture. keep the lid closed while power is applied to the device under
test. Safe operation requires the use of a lid interlock.
Ifa @ screw is present, connect it to safety earth ground using the wire recommended in
the user documentation.
The A symbol on 8.n instrument indicates that the user should refer to the operating in-
structions located in the manual.
Then. symbol on an insbument shows that it can source or measure 10X volts or more, in-
cluding the combined effect of normal and common mode voltages. Use standard safety precnutions to avoid personal contact with these voltages.
The WARNING heading in a manual explains dangers that might result in personal injury or
death. Always read the associated information very carefully before performing the indicated
procedure.
The CAUTION heading in a manual explains hazards that could damage the instrument.
Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and all test cables.
To maintain protection from electric shock and fire, replacement components in mains cir-
cuits, including the pnwer transformer, test leads, and input jacks, must be purchased from
I-&id&y Insh’uments. Standard fuses, with applicable national safety approvals, may be used
if the rnting and type are the same. Other components that are not safety related may he purchased from other suppliers as long as they nre equivalent to the original component. (Note
that selected parts should he purchased only through Keitbley Instruments to maintain nccuracy and functionnlity of the product.) If you are unsure about the applicability of a replacement component, call a Keithley Instruments office for information.
To clean an instrument, use a damp cloth or mild, writer based cleaner. Clean the exterior
of the instrument only. Do not apply cleaner directly to the instruiuent or allow liquids to
enter or spill on the instrument. Products that consist of a circuit board with no case or chas-
sis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled according to instructions. If the board becomes contaminated and operation
is affected, the board should be returned to the factory for proper cleaning/servicing.
Rc”. 10199
SPECIFICATIONS
ACCURACY TEMI’ARATURE OUTPUT
DIVIDER (1 Year)* COEFFICIENT NOISE THERMAL
RATIO
220-24’C W280C
(O.lHz Bw) DRIFT**
101 : 1
103 : 1
10’ : 1
105 : 1
* 35ppm
* 35ppm
*lOOppm
*lOOppm
2ppmPC 1onv p-p
2ppmPC 1onv p-p 1onv
10ppmPC 1nv p-p 3nV
lOppm/Yz 1nv p-p 3nv
1onv
*Referenced to output terminals.
**br ambient temperature changes ~1”Clhour. Includes effects of sup-
plied cable.
INPUT RESISTANCE:
20khl for divider ratios of lo?1 and 1O’:l; 200kn
for divider ratios of lo’:1 and 105:1.
OUTPUT RESISTANCE:
261 for divider ratios of lo’:1 and 10s:l; 2000
for divider ratios of lo’:1 and lO?l.
OVERLOAD PROTECHON:
Maximum operating input voltage is 20V.
Input is protected against 1OOOV overloads from calibrators with current limits up to 150mA.
CONTROLS:
CONNECTORS: Input: 5.~3~
ground.
Polarity and divider ratio.
binding posts for input, sense, and case
Output:
Special low thermal female connector; mates with
Models 1506, 1507, 1481, and 1482.
ENVIRONMENTAL LIMITS: Operating:
humidity.
DIMENSIONS, WEIGHT:
Storage: -25”
to 65°C.
114mm high x 165mm wide x 184mm deep
18%28’C, 0 to 60% relative
(4’/2 in. x 6% in. x 7’/a in.). Net weight 2kg (4% Ibs.).
ACCESSORY SUPPLIED:
Low thermal male-to-male cable (3 ft.) for
connecting to Models 148 and 181.
ACCESSORIES AVAILABLE:
Model 1481 Low Thermal Twin Lead Shielded Input Cable (4 ft. with
clips)
Model 1482: Low Thermal Twin Lead Shielded Input Cable (10 ft. bare
copper leads)
Model 1483: Low Thermal Connection Kit
Model 1484: Refill Kit for 1483 Kit
Model 1485: Female Low Thermal Input Connector
Model 1486: Male Low Thermal Input Connector
Model 1503: Low Thermal Solder and Flux
Model 1506: Low Thermal Triax Cable (4 ft. with clips)
Model 1507: Low Thermal Triax Cable (4 ft. with lugs)
OUTPUT NOISE:
Source noise is measured over a 30 second interval.
Use supplied cable when making measurements. When measuring
noise of the Model 262 using the Model 148 (which has 1nV p-p noise
spec), the total noise will not exceed 1.4nV p-p for 98.76% of the time.
THERMAL DRIFT!
Thermal drift is measured with the Model 26’2’s
polarity switch set to zero. Specifications apply to the Model 262 and
supplied cable only. Thermal drift is a function of the rate of change
of ambient temperature. Using a two channel chart recorder, monitor
the rate of change of ambient temperature versus drift due to ther-
mal EMR. See example below:
At=t>-t,=0.5hr
t2
AVlt,=l5nV
ATT;;,=2.5’C
AV/AT/At=3nVPClhr
TABLE OF, CONTENTS
GENERAL INFORMATION.. . . . . . . . . . . . . . . . . . . 1
INTRODUCTION ..........................................
OPTIONAL ACCESSORIES.,
WARRANTY INFORMATION
MANUAL ADDENDA ...............................
SAFETY SYMBOLS AND TERMS
UNPACKING AND INSPECTION
REPACKING FOR SHIPMENT
...............................
............................... 2
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1
1
..... 2
2
3
..
3
OPERATION
INTRODUCTION ...............
ENVIRONMENTAL CONDITIONS
MODEL 262 CONTROL AND CONNECTORS
MODEL 181 VERIFICATION AND CALIBRATION
(2mV, 20mV and 200mV Ranges)
MODEL 148 NANOVOLT VERIFICATION
DMM CALIBRATION .....................................
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.......... 5
..
........ 5
5
5
7
9
10
CALIBRATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
INTRODUCTION .........................................
ENVIRONMENTAL CONDITIONS
INITIAL EQUIPMENT CONDITIONS
ADIUSTMENTONE
ADjUSTMENTTWO
ADJUSTMENT THREE ....................................
......................................
......................................
SERVICING INFORMATION
CLEANING INSTRUCTIONS
LOW THERMAL CONNECTIONS
THEORY OF OPERATION
DISASSEMBLY INSTRUCTIONS
REPLACEABLE PARTS
PARTS LlST.. ............................................
ORDERING INFORMATION
FACTORY SERVICE .......................................
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l3
14
15
16
26
26
29
29
30
32
32
35
35
35
35
OPERATION
Figure 1. Digital Nanovoltmeter Calibration.
Figure 2. Analog Nanovoltmeter Calibration
Figure 3. DMM Calibration.
................................ 11
.................. 7
.................
CALIBRATION
Figure 4. Calibration Configuration Schematic
Figure 5A. LO Lead Compensation Schematic
Figure 5B. LO Lead Compensation Connection Diagram
Figure 6A. HI Lead Compensation Schematic.,
Figure 6B. HI Lead Compensation Connection Diagram
Figure 7A. Pot Adjustment Set Up Schematic
Figure 7B. Pot Adjustment Connection Diagram
Figure 8. Calibration Adjustments
..........................
............... 14
...............
..............
................
.............
SERVICING INFORMATION
Figure 9. Model 262 Mechanical Parts
Figure 10. Divider Ratio Switch
....................... 36
.............................
REPLACEABLE PARTS
Figure 11. Model 262, Component Location Drawing,
Dwg. No. 262-100
Figure 12. Model 262, Schematic Diagram,
Dwg. No. 262-106,
.......................................
.......................................
10
18
...... 19
20
...... 21
24
25
28
37
39
40
ii
OPERATION
Table 1. Model 181 Verification (2mV, 20mV and 200mV) 8
Table 2. Model 181 Calibration (2mV, 20mV and 204lmV) 8
Table 3. Model 148 Verification. 9
Table 4. DMM Calibration 11
CALIBRATION
Table 5. Recommended Equipment 16
Table 6. Calibration Limits. 27
REPLACEABLE PARTS
Table 7. Model 262, Parts List.. 38
iii/iv
GENERAL INFORMATION
INTRODUCTION
The Model 262 is a precision low thermal divider with divider ratios
of lO’:l, lO’:l, lo’:1 and 105:1. The Model 262 is designed to calibrate
nanovoltmeters and 1pV sensitive DMMs. A low thermal male-to-male
output cable is included with the Model 262.
OPTIONAL ACCESSORIES
Model 1481 Low Thermal Input Cable is useful for making temporary
connections in low voltage circuits. The 1.2m (4’) cable is terminated
with two alligator clips and a male low thermal connector. Recommended for use with the Model 148 Nanovoltmeter.
Model 1482 Low Thermal Input Cable allows a user to make his own
special, low thermal input connections for the Model 148. The 3m (10’)
cable is terminated with a male, low thermal connector and two bare
copper leads.
Model 1483 Law Thermal Connection Kit is useful for making low thermal connections in experimental setups. The kit contains a crimp tool,
pure copper lugs, alligator clips, low thermal cadmium solder and
assorted hardware.
Model 1484 Refill Kit contains replacement parts for the Model 1483
Low Thermal Connection Kit.
Model 1485 Female Low Thermal Input Connector is the connector for
Models 148, 181, and 262.
Model 1486 Male Low Thermal Connector mates with the input connector for Models 148, 181 and 262. It allows the user to make a custom
length input cable.
Model 1503 Low Thermal Solder is useful when making connections
to low voltage circuits.
Model I506 Low Thermal Input Cable is a triaxial1.2m (4’) cable specially designed to provide excellent shielding for input connections to the
Model 181. It has a mating connector and two copper alligator clips.
Recommended for use with the Model 262.
Model I5W Low Thermal Input Cable is a triaxial cable, 1.2m (4’),
similar to the Model W06, but has two copper spade lugs instead of
clips. Recommended for use with the Model 262.
WARRANTY INFORMATION
Warranty information is provided on the inside, front cover of this
manual. If there is a need to exercise the warranty, contact the Keithley
representative in your area to determine the proper action to be taken.
Information concerning the applicaton, operation or service of your instrument may be directed to the applications engineer. Check the inside front cover of this manual for addresses.
MANUAL ADDENDA
Improvements or changes to this manual will be explained on an addendum included with this manual.
SAFETY SYMBOLS AND TERMS
Safety symbols used in this manual are as follows:
The symbol A on the instrument denotes that the user should refer
to the operating instructions.
The symbol & on the mstrument denotes that 1OOOV or more may
be present on the terminal(s).
2
The WARNING used in this manual explains dangers that could result
in personal injury or death.
The CAUTION used in this manual explains hazards that could damage
the instrument.
UNPACKING AND INSPECTION
The Model 262 is inspected both mechanically and electrically before
shipment, Upon receiving the Model 262 unpack all items from the
shipping container and check for any obvious damage that may have
occurred during transit. Report any damage to the shipping agent. Retam and use the original packaging materials if reshipment is necessary.
The following items are shipped with all Model 262 orders:
l
Model 262 Low Thermal Voltage Divider
l
Model 262 Instruction Manual
l
Low Thermal Male-to-Male Cable (part number 262-315)
l
Optional accessories as ordered.
REPACKING FOR SHIPMENT
The Model 262 should be packed in its original carton. Before packaging, wrap the instrument in plastic. After it is placed in the box, surround the instrument with Styrofoam packaging material.
314
OPERATION
lNTRODUCTlON
To operate the Model 262, connect the unit to a DC calibrator and the
nanovoltmeter or DMM that is to be calibrated, and select the desired
output. See Figures 1 and 2.
NOTE
The Model 262 is designed to be used with a DC voltage
calibrator equipped with remote sensing.
NOTE
The user should be familiar with low thermal measuring
techniques.
ENVIRONMENTAL CONDITIONS
All measurements should be made at an ambient temperature within
the range of WC to 28’C, and 0 to 60% relative humidity. Environmental
conditions for storage are from -25°C to 65’C.
If the instrument has been subjected to temperature extremes, allow
sufficient time for internal temperatures to reach environmental conditions. Typically, it takes one to four hours to stabilize a unit that is
10°C (18°F) out of specified temperature range.
MODEL 262 CONTROLS AND CONNECTORS
The POLARITY switch settings are as follows:
0 Position-In
removed from the Model 262 divider. Use this position when zeroing
the nanovoltmeter or DMM.
this standby position the DC calibrator input voltage is
5
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