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 factory, DDD 216.
795-2666. You will be given assistance and
shipping instructions.
REPAIRS AND RECALIBRATION
Keithley Instruments maintains a complete repair service and standards laboratory in Cleveland, and has an authorized field repair
facility in Los Angeles.
To insure prompt repair or recalibration serv-
ice, please contact your local field representatkve or the plant directly before returning the
instrument.
Estimates for repairs, normal recalibrations,
and calibrations traceable to the National Bureau
of Standards are available upon request.
MODEL 660A DIFFERENTIAL VOLTMETER
TABLE OF CONTENTS
CONTENTS
Section
GENERAL DESCRIPTION
1.
1-1.
1-2.
l-3.
l-4.
1-5.
1-6.
OPERATION.
2.
2-l.
2-2.
2-3.
2-4.
2-5.
2-6.
2-7.
2-8.
2-9.
APPLICATIONS . . . . . . . . . .lL
3.
3-1.
3-2.
CIRCUIT DESCRIPTION . . . . . . . .13
4.
4-l.
4-2.
4-3.
4-4.
4-5. Guarding . . . . . , . .15
Description .........
Operating Modes .......
Applications ........
Specifications .......
Accessories .........
Equipment Shipped ... ...
............
Front Panel Controls
and Terminals . . . . . . . 5
Rear Controls and
Terminals . . . . . . . . . 5
Preliminary Procedures . . 6
Operating Procedures . . . . 6
Recorder Output . . . . . . . 8
Effects Due to Kelvin-
Varley Divider Out-
put Resistance . . . . . . . 9
Loading and Off-Null
Resistance . . . . . . . . . 9
Thermal EMF Precau-
tions . . . . . , . . . . .lO
AC Effects on Measurement . .lO
Procedures for Measuring
Resistances . , . . . . .
Theory of Measuring Resis-
tances . . . . . I . . . . .ll
General . . . . , . . . . .13
Reference Voltage Supply . .13
Kelvin-Varley Divider . . . .14
Null Detector . . . . . . . .14
........
Page
1
1
1
1
2
3
3
5
.lL
Section
5-5.
5-6.
5-7. Meter Adjustment . . . . . 19
6. CALIBRATION . . . . . . . . . 21
6-l.
6-2.
6-3.
6-4. Range Calibration , . . . . 23
6-5.
6-6.
7.
ACCESSORIES , . . . . . , . . . . 35
7-L. Model 660LA High Voltage
7-2. Rack Mounting . . . . . . . 35
7-3.
8.
REPLACEABLE PARTS , . . . . . . : 37
8-l. Replaceable Parts List . . 37
8-2. How to Order Parts . . . . 37
$0 Change Notice
Adjusting Hum Bal Control . 19
Zener Diode Replacement . . 19
General . . . . . . . . . . 21
Calibration Schedule . . . 22
Kelvin-Varley Divider
Verification . . . . . . . 22
Reference Voltage Supply
Stability Test . . . . . . 25
Oscillator Adjustment . . . 27
Divider . , . . . . , , . 35
Placing in Rack . . . . . 36
Model 660A Replaceable
Parts List . . . . . . . . 38
Model 6601A Replaceable
Parts List . . . . . . . . 44
Model 66OA Schematic Diagram
182693. . . . . . . . . . 47
Model 6601A Schematic Diagram
1632LB . . . . . . . . . 49
Page
SERVICING . . . . . . . . . . . .17
5.
5-l.
5-2.
5-3.
5-4.
1065R
General . , . . . . . .17
Servicing Schedule . . , . .17
Parts Replacement . . . , . .17
Troubleshooting . . . , . .L7
-'- Yellow Change Notice sheet is included only for instrument modifications affecting the Instruction
Manual.
MODEL 660A DIFFERENTIAL VOLTMETER
GENERAL DESCRIPTION
SECTION 1.
l-1.
contained potentiometer. It measures from 100 millivolts to 500 volts with 0.02% limit
of error, and below 100 millivolts within 20 microvolts. Since the limit of error includes
all stability considerations, the unit need not be periodically calibrated or manually
restandardized for a full year. The 500-volt reference supply permits infinite impedance
at null for measurements from 0 to 500 volts.
lighted decimal points; 10 to 25-millivolt recorder output; input polarity switch; floating
operation up to 500 volts off chassis ground; line frequency rejection greater than 45 db.
Also, full guarding minimizes leakage problems.
L-2.
vacuum tube voltmeter.
to 500 volts with i-0.02% limit of error and from 100 microvolts full scale to LOO milli-
volts within 20 microvolts. As a VTVM, the Model 660A measures from 1 millivolt full
scale to 500 volts with an accuracy of -f3% of full scale.
tances from 10 megohms to 100,000 megohms within i-5%.
DESCRIPTION.
The Keithley Model 660A Guarded dc Differential Voltmeter is a convenient, self-
a.
Features for convenient use include:
b.
OPERATING MODES, The Model 660A can be used as a potentiometer or as a conventional
As a potentiometer,
GENERAL DESCRIPTION
five in-line readout dials with automatically
it can measure from 100 millivolts full scale
It can also measure resis-
1-3. APPLICATIONS.
The Model 660A is used for measurements over a wide range.
a.
the microvolt region are the matching of semiconductors and the monitoring of noise, transients and drift. High level voltage applications include power supply and meter calibra-
tion, and tube potential measurements.
Typical applications in
1.065R
FIGURE I..
Keithley Instruments Model 660A Guarded dc Differential Voltmeter.
1
GENERAL DESCRIPTION
Its Long-term stability makes the Model 660A useful in measurements of extended
b.
duration.
Measurements of Long-term power supply stability, Long-term drift runs, and
MODEL 660A DIFFERENTIAL VOLTMETER
monitoring during environmental and reliability tests are possible uses.
c. The null-detector output permits use with potentiometric recorders and digital volt-
meters equipped with automatic print-out.
product development,
Floating operation to 500 volts is provided for measurements such as plate potential
d.
inspection and production.
The Model 660A is useful in quality control,
differences of balanced amplifiers.
l-4. SPECIFICATIONS.
AS A POTENTIOMETER:
LIMIT OF ERROR:
+0.02% of reading or 20 microvolts,
warm-up.
LONG-TERM STABILITY:
TFXPERATURE COEFFICIENT:
Will operate within stated Limit of error for one year.
Does not exceed 0.002% per OC.
REPEATABILITY: Within 0.005%.
MAXIMUM NULL SENSITIVITY:
INPUT RESISTANCE:
FLOATING OPERATION:
INPUT ISOLATION:
Infinite at null, from 0 to 500,voLts.
500 volts maximum off chassis ground.
Circuit ground to chassis ground: LOS ohms shunted by 0.05 microfarad.
LOO microvoltb full scale with 2-microvolt resolution.
RESOLUTION CHART:
Input Voltage
Range >
volts
- 500
50
5 - 50
0.5- 5
0 - 0.5
i
Maximum Dial
Resolution,
millivolts
whichever is greater, after 30-minute
Maximum Usable
Full-Scale Null
Sensitivity,
millivolts
10
1
0.1
0.1
Meter
Resolution,
I
microvoLts
LOO
LO
2
2
AS A VACUUM TUBE VOLTMETER:
VOLTAGE RANGES:
NULL RANGES:
100 microvolts full scale to 100 volts in seven decade ranges.
VTVM ACCURACY:
0.5 volt full
t3% of full scale on all ranges, exclusive of noise and drift.
scale
to 500 volts in four decade ranges.
ZERO DRIFT: Less than 10 microvolts per 24 hours, non-cumulative, after 30-minute warm-up.
2
0665R
MODEL 660A DIFFERENTIAL VOLTMETER
GENEPaL DESCRIPTION
INPUT RESISTANCE:
50 megohms, 0.5 to 500-volt ranges;
10 megohms, O.l-volt range;
1 megohm, 0.1 to lo-millivolt ranges.
LINE FREQUENCY REJECTION:
Greater than 45 db.
GENERAL:
LINE STABILITY:
Better than 5 ppm for 10% change in Line voltage.
RECORDER OUTPUT:
output:
Output Resistance:
Noise:
Note:
Adjustable 10 to 25 millivolts dc for full-scale meter deflection.
300 ohms maximum.
2 microvolts peak-to-peak referred to input up to 1 cps.
Recorder used must have fully isolated input, 1010 ohms minimum to ground.
POLARITY: Positive or negative, selectable by switch.
CONNECTORS:
POWER:
Input:
105-125 or 210-250 volts (switch selected), 50-400 cps, 45
DIMENSIONS, WEIGHT:
Binding posts.
Output:
5-l/2 inches high x 17-l/2 inches wide x 13-l/2 inches deep; net
Banana jacks
weight, 24 pounds.
watts.
l-5. ACCESSORIES.
a. Model 6601A High Voltage Divider is a LOO:L divider which extends the range of the
Model 660A to 5000 volts. The divider accuracy is ?O.Ol% and its input resistance is
10 megohms.
The overall limit of error of the Model 660A with the Model 660lA is ?0.03%.
Section 7 gives operating instructions and Section 8 contains the Replaceable Parts List
and the Schematic Diagram for the Divider.
Model 4000 Rack Mounting Kit,
b.
Model 660A to fit standard 19-inch racks,
high x 19 inches wide x 13-l/2 inches deep.
1-6.
EQUIPMENT SHIPPED.
The Model 660A Guarded dc Differential Voltmeter is factorycalibrated and is shipped with all components in place.
use.
Model 4000 Kit may be ordered for rack mounting; refer to Section 7 for assembly
containing two brackets and a top cover, converts the
Rack mounted, the Model 660A is 5-l/4 inches
Section 7 has assembly instructions.
All units are shipped for bench
instructions. The shipping carton also contains the Instruction Manual.
1066R
3
GENERAL DESCRIPTION
MODEL 660A DIFFERENTIAL VOLTMETER
PIGURE 2.
to Replaceable Parts List and the Schematic Diagram.
Model 660A Front Panel Controls and Terminals.
Circuit Designations refer
4
FIGURE 3.
Model 660A Rear Controls and Terminals.
J
1065R
MODEL 660A DIFFERENTIAL VOLTMETER
SECTION 2. OPERATION
OPERATION
2-1.
a.
FRONT PANEL CONTROLS AND TERMINALS.
Power Switch. A toggle switch turns the instrument on when it is set to the ON
(See Figure 2.)
position.
POLARITY Switch.
b.
The POLARITY Switch selects the input polarity.
The Switch reverses the polarity of the internal reference voltage supply so both positive and negative
voltages may be measured;
c. NULL Switch.
The NULL Switch sets the null detector sensitivity for seven decade
ranges from 0.1 millivolt full scale
the Model 660A operates as a conventional
it does not reverse the meter polarity.
to
100 volts.
vacuum
When the Switch is in the VTVM position,
tube
voltmeter
for the four ranges of the
RANGE Switch.
d. RANGE Switch. The RANGE Switch adjusts the sensitivity of the VTVM in four steps:
0.5, 5, 50 and 500 volts full scale.
Varley divider and the position of the decimal point light -
It also determines the voltage across the Kelvin-
which also serves as a pilot
light - between the five Reference Voltage Dials.
e. Reference Voltage Dials.
reference voltage when the Model 660A is used as a potentiometer.
Five in-line dials at the top of the front panel set the
The last dial is con-
tinuously variable.
METER ZERO Control. The METER ZERO Control adjusts the meter needle to zero. The
f.
Control is needed on only the 0.1 and l.O-millivolt null ranges; on the other ranges, the
needle will normally be on zero without adjustment.
The Control has a range of approx-
imately i30 microvolts.
Input Terminals. At the lower left front panel, the black LO Post is for connections
25.
to the low impedance terminal of the unknown voltage and the red HI Post is for connections
to the high impedance terminal. A second set of binding posts marked LO and GND is provided
for grounding the LO input terminal to the chassis when desired. The LO terminals are
connected together internally.
2-2.
a.
REAR CONTROLS AND TERMINALS.
Fuse. For 105-125 volt operation, the Model 660A uses a l-ampere 3 AG fuse. FOK
(See Figure 3.)
210-250 volt operation, the Model 660A uses a 0.5-ampere 3 AG fuse.
Power Cord.
b.
unless otherwise specified on the rear panel.
The Model 66OR is designed for a 105-125 volt, SO-&O0 cps line source,
The 3-wire power cord with the NEMA approved
3-prong plug provides a ground connection for the cabinet. An adapter for operation from
2-terminal outlets is provided.
c. NULL DETECTOR OUTPUT.
Two terminals, marked + and -, supply a dc signal from the
null detector.
d. OUTPUT
ADJUST.
+4 screwdriver control next to the OUTPUT terminals adjusts the null
detector output between 10 and 25 millivolts full scale.
1066R
5
OPERATION
MODEL 660A DIFFERENTIAL VOLTMETER
e. 117-234 Switch.
or 234-volt ac power
2-3.
power cord.
The decimal light between the third and fourth Dials will light.
warm up for 30 minutes to meet the specified accuracy on all ranges.
the METER ZERO Control.
660A is such that no adjustment should be required in eight hours after a 30-minute warm-up.
2-4.
PRELIMINARY PROCEDURES.
Check the 117-234 Switch and the Fuse for the proper ac line voltage.
a.
b. Set the Model 660A as follows:
Power Switch
RANGE Switch 500
NULL Switch
POLARITY Switch
Reference Voltage Dials
c. With the input terminals open,
OPERATING PROCEDURES.
The screwdriver-operated slide switch sets the Model 660A for 117
lines.
Connect the
ON
VTVM
+
zero
Allow the instrument to
set the NULL Switch to 0.1 MV and zero the meter with
Then return the NULL Switch to VTVM.
The stability of the Model
The Model 66OA is used first as a VTVM to determine the approximate value of the un-
a.
known voltage. It is then used in the potentiometric mode to determine the voltage to iO.OZ"/,.
LH LG
A
I
FIGURE 4.
measuring at ground and ,for floating.
In A, the unknown voltage has one terminal
LO and GND Posts of the Model 660A.
In 13,
or off-ground potential
used.
Input Connections to Model 660A.
the unknown voltage has both terminals
must
be less than 500 volts. Also note the shorting link is not
0
I
I
Unknown
Voltage -
The two diagrams show the input circuit for
at
ground. The shorting link is between the
off
ground potential. Note this floating
0000
Off-Ground,
Potential -
B
,
m
-
6
1066R
MODEL 660A DIFFERENTIAL VOLTMETER
The Model 6601A High Voltage Divider extends the Model 660A range to 5000 volts.
Refer to Section 7 for operation instructions.
b. VTVM Operating Procedures.
OPERATION
NOTE
Eleven full-scale ranges are available for VTVM operation.
1.
is at VTVM, the RANGE Switch determines one of four full-scale ranges.
five Reference Voltage Dials at zero,
seven null ranges.
Connect the unknown voltage to the input terminals,
2.
impedance terminal of the unknown.
Switch the RANGE Switch to the most sensitive range for an on-scale meter deflection
3.
c. Potentiometric Operating Prbcedures.
Avoid large overload voltages on the null detector. No permanent damage will
occur even with 500-volt overloads, but some open circuit offset will be caused
in the null detector.
capacitors, will disappear after about 5 minutes.
1. Leave the RANGE Switch at the last setting used in the VTVM operation.
VTVM reading is negative,
Set the first two Reference Voltage
2.
Dials to the first two digits of the unknown voltage found in the VTVM operation.
The offset, due to the polarization of the input filter
reverse the POLARITY Switch position.
the Model 660A can then operate as a VTVM on the
using the LO Post for the low
Refer to Figure 4.
NOTE
Initial Most Sensitive
NULL Switch NULL Switch
When the NULL Switch
BY putting the
Setting
If the
3. Set the NULL Switch to the initial
null setting shown in Table 1.
the Voltage Reference Dials progressively
for zero meter deflection while increasing
the null detector's sensitivity with the
NULL Switch. Deflections to the right TABLE 1.
indicate the voltage being measured is and Settings.
more positive than the Reference Voltage
Dial setting.
The most accurate resistors in the Kelvin-Varley divider are in the first two
Reference Voltage Dials. Therefore, to obtain the most accurate readings, use
the first two dials as much as possible.
4. The value of the unknwon voltage is read directly from the Reference Voltage Dials.
a) The Dial reading will be within the specified limit of error if the NULL Switch
is at the most sensitive setting (Table 1) for the range used and if the meter indi-
cates as close to null as possible.
1066R
Adjust
Recommended Null Sensitivities
NOTE
Null does not have to be reached.
7
OPERATION
MODEL 660A DIFFERENTIAL VOLTMETER
b) When the first Reference Voltage Dial is used,
to be within specifications (fO.OZ% of reading or 20 microvolts).
may be read as an approximation of a sixth digit.
c) When the first Reference Voltage Dial is not used, read the voltage directly
from the remaining four Dials.
d) Use the meter as a null indicator when balancing voltages. When the first
Reference Voltage Dial is
However,
tative inaccuracies when the meter
2-5. RECORDER OUTPUT.
Recommended recorders for use with the Model 660A are the F. L. Moseley Autograf
a.
680 series recorder and the Minneapolis Honeywell recorder (lOmv-O-10mv scale, 50 kilohms
input resistance).
input must be fully isolated (lOlo
Before attaching the recorder, set all Reference Voltage Dials to zero.
b.
the unknown voltage and short both Model 660A input terminals.
10 MV.
c.
potential to the null detector on the LO-millivolt null range.
scale recorder output which can be matched to the recorder’s range between 10 and 25 milli-
volts by adjusting the OUTPUT ADJUST Control.
Connect the recorder to the OUTPUT terminals on the Model 660A rear panel.
Set the Reference Voltage Dials to 10 millivolts to apply an accurate lo-millivolt
the loading effect of Kelvin-Varley divider on the meter causes some quanti-
Any recorder used must be able to float 500 volts off ground and its
not
used,
ohm minimum leakage resistance to ground).
the meter approximates a fifth dial reading.
is
off null.
only the five Dials need be read
HOWeVer,
(See paragraph Z-6.)
Set the NULL Switch
This will provide a full-
the meter
Disconnect
to
To obtain accurate results and/or to prevent damage to the instruments, the recorder
d.
must be ablt to float off-ground with the
Model 660A. Leakage and pickup between the
two instruments should also be minimized.
Make sure neither recorder terminal
1.
is grounded. Use a 3-wire grounded power
line for the recorder. If a Z-wire line
is used,
the Model 660A chassis with a separate lead.
2.
tween the output terminals, the recorder
and ground. Use polystyrene or Teflon-
insulated wire where possible. If the
connecting wires are shielded, connect
the shield to the LO Post.
3. Avoid long leads between the Model the Model 660A and the recorder may be neces660A and the recorder.
4.
cauwct a lo-microfarad capacitor between the LO and GND terminals on the Model 660A
front panel.
connect the recorder chassis and
Minimize all sources of leakage be-
I
FIGURE 5.
sary when using the O.l-millivolt null detector range.
If difficulty is encountered in off-ground measurements, such as unstable readings,
Model ;
660A ’
Null :
Detector I
output ’
TBlack
Recorder Filter. A filter between
10 pf
i
1
1
T
1
Recorder
Terminals
4
9
MODEL 660A DIFFERENTIAL VOLmTER
NOTE
Do not short either Model 660A output terminal to the case; this may damage the
Kelvin-Varley divider.
If there is substantial recorder jitter on the O.l-millivolt null range, place a
e.
filter between the Model 660A and the recorder.
Note the filter must also be insulated from ground.
Refer to Figure 5 for this connection.
OPERATION
2-6.
ence Voltage Dial may appear to be inaccurate.
across the Kelvin-Varley divider.
and not the accuracy of the Dial setting.
sible, the Reference Voltage Dial setting is correct within the instrument's specifications.
There is no effect present at null.
on the O.l-millivolt range a O.l-millivolt off-null setting of the reference voltage will
not produce a full-scale meter deflection. This is because the Kelvin-Varley divider out-
put resistance is significant compared to the shunt resistance across the null detector
meter. The LR drop across the divider will cause the meter to be off up to 6%, depending
upon the Reference Voltage Dial settings. On the lOO-millivolt range the maximum error
is 1%. The effect cannot be observed on the other null ranges of the Model 660A.
where R, is the shunt resistance across the meter (50 megohms for the 100 to l-volt null
EFFECTS DUE TO IaLVIN-VARLEY OUTPUT RESISTANCE.
When the Model 660A is used for nulling on the O.l-millivolt range, the last Refer-
a.
The apparent error is due to a voltage drop
This effect involves only the null detector sensitivity
When the Model 66OA is as near to null as pos-
b. The effect is most apparent on the 0.1,
The amount of deflection on the meter is equal to the ratio
c.
ranges, 10 megohms for the 100~millivolt range,
millivolt ranges);
1 and lo-millivolt null ranges. For example,
and 1 megohm for the 10 to O.l-
Rkv is rhe output resistance of the Kelvin-Varley divider, which is a maximum of
62.4 kilohms at Reference Voltage Dial settings of 2 4 5 4 5 and 2 5 4 5 5 and
a minimum of 100 ohms at settings of 4 9 9 9 8 and 0 0 0 0 2.
2-7. LOADING AND OFF-NULL RESISTANCE.
a. The input resistance of the voltmeter for the seven null ranges varies from 50 to
1 megohm as given in Table 2.
tance of the Model 660A. Its input resistance is considerably higher due to the potentiometric principle of operation.
Where Rin
1066R
is the effective input resistance of the Model 660A;
Ed is the setting of the Reference Voltage Dials in volts;
R, is the shunt or input resistance of the null detector meter in ohms;
V is the null detector meter reading in volts.
This resistance, however, is not the effective input resis-
The value is given by
Rin = Ed Rn
V
Equation 1
9
OPERATION
MODEL 660A DIFFERENT,IAL VOLTMETER
b. To find the loading effect the Model
660A will have on a circuit, "se Equation 1
to compute the effective input resistance.
At null, the input resistance is infinite.
Off null, the input resistance is usually
high compared to the internal resistance
of the unknown voltage, and loading will
not be enough to affect the measurement
.XC"iZXY.
Voltage Dials are set at 1.0000 volt on the
l-millivolt null range for a reading off
null by 10% of full scale, the Model 660A
input resistance is lolo ohms.
2-S.
standard thermocouple techniques to reduce
thermal emf errors for measurements using
the most sensitive null ranges.
Model 660A can read to 2 microvolts, thermal
emf's can introduce considerable errors
into the measurements.
pure copper leads throughout the system
when measuring in the microvolt range.
extensive measurements in the microvolt region, request the article, DC Microvolt
Measurements, from Keithley Instruments,
Inc., or its representative.
THERMAL EMF PRECAUTIONS. Observe
For example, if the Reference
Since the
In general, use
FO??
Voltage
Range
500 volts
50 volts
5 volts
0.5 volts
Null
Range
100 volts
10 volts
1 volt
100 millivolts
10 millivolts
1 millivolt
0.1 millivolt
TABLE 2. Model 660A VTVM Input Resistanct
by Ranges. Resistance for Null Ranges is
when the Reference Voltage Dials are set
to zero.
Input
Resistance
50 megohms
50 megohms
50 megohms
50 megohms
Input
Resistance
(Slewing)
50 megohms
50 megohms
50 megohms
10 megohms
1 megohm
1 megohm
1 megohm
2-9.
known voltage, the Model 660A employs a chopper-stabilized null detector operating at a
42-cps chopping rate with a 3-section R-C filter at the input. Very large ac components
on the measuring lines, however,
pick-up will be observed as needle quiver.
Model 660A, additional filtering is required.
filter is effective.
AC EFFECTS ON MEASUREMENTS. To minimize errors from ac signals present in thq un-
may reduce off-null sensitivity.
If ac components affect measurements by the
For a single-frequency ac signal, a twin-T
For a variable frequency signal, "se an ordinary low-pass filter.
Also, heavy 60-cps
10
106611
MODEL 660A DIFFERENTIAL VOLTMETER
APPLICATIONS
SECTION 3.
3-1.
resistances from 1 megohm to 100.000 megohms with an accuracy of is%.
tance,
isolated lead to the HI terminal to prevent measuring leakage between the leads.
RANGE Switch to 500.
adjust the Reference Voltage Dials to obtain a full-scale meter deflection
10.000 from the Dial setting and multiply the difference by 5 to obtain the value of the
resistor in megohms.
volt;
tract 1.0000 from the dial setting and multiply the difference by 50 to obtain the value
of the resistor in megohms.
volt; adjust the Reference Voltage Dials to obtain a convenient deflection on the meter.
Calculate the value of the resistor using,
PROCEDURES FOR MEASURING RESISTANCES. The Model 660A can be used to rapidly measure
connect the unknown resistor across the Model 660A HI and LO terminals.
Then determine the value of the resistor as follows:
For resistances between 1 megohm and 1000 megohms,
a.
For resistances between 1000 megohms and 10,000 megohms,
b. set the NULL Switch to 1
adjust the Reference Voltage Dials to obtain a full-scale meter deflection.
For resistances between 10,000 megohms and 100,000 megohms,
c.
Rx =
50 Ed
V
APPLICATIONS
To measure resis-
Use a short
Set the
set the NULL Switch to 10 volts;
Subtract
*
Sub-
set the NULL Switch to 1
megohms Equation 2
Where & is the unknown resistance;
Ed is the Reference Voltage Dial setting in volts;
V is the meter reading in volts.
3-2. THEORY OF MEASURING RESISTANCES. The
above method for determining the value of an
unknown resistor is based upon the equation
for the circuit.(See Figure 6). If an unknown resistance is across the Model 660A
input terminals, then
Ed = i (Rx + Rn) Equation 3
Where Ed is the Reference Voltage Dial set-
ting in volts;
i is the current in the circuit;
Rx is the unknown resistance;
R, is the i'nput resistance of the null
detector meter in ohms.
The current can be written i = V/R,, where
V is the null detector meter reading in
volts.
Equation 3 now becomes
Equation 4
Ed
Measuring Resistances. Rx is the unknown
resistance. R, is the input resistance of
the null detector; V is the null detector;
Ed is the buckout voltage.
1065R
11
APPLICATIONS
If measurements are made on the 1 to loo-volt null ranges, the input resistance, R,,, is
50 megohms. Equation 4 becomes
MODEL 660A DIFFERENTIAL VOLTMETER
Rx = 5~10~ ( 7 -1)
This is thebasis for simplified calculations in paragraph 3-l.
Equation 5
12
1065R
MODEL 660A DIFFERENTIAL VOLTMETER
CIRCUIT DESCRIPTION
SECTION 4.
4-1.
GENERAL.
metric (null) method.
supply used in conjunction with a precision multi-dial Kelvin-Varley divider.
The Model 660A Differential Voltmeter measures voltage by the potentiw
The variable known voltage is an ultra-stable 500-volt reference
CIRCUIT DESCRIPTION
Electronic
referencing of the 500volt output to a zener diode standard maintains the reference supply's stability and accuracy.
This method eliminates repeated manual standardization.
The difference between the divider output and the unknown voltage is indicated by the
null detector,
a chopper-stabilized vacuum-tube voltmeter.
can be read directly from the in-line dials of the Kelvin-Varley divider.
null detector are fully guarded
to
avoid leakage.
At null the unknown voltage
The input and
NOTE
Refer to Schematic Diagram 18269E for cir&it designations.
INPUT GUARDED
TERMINALS NULL
DETECTCIR
KELVIN-VARLEV
DlVlDER
REFERENCE
VOLTAGE
SUPPLY
Simplified Model 660A Circuit Diagram.
4-2.
FIGURE 7.
REFERENCE VOLTAGE SUPPLY.
a. Unregulated voltage from transformer T3001 is rectified by a silicon half-wave
rectifier, D3001, and is filtered by capacitors C3001 and C3002.
applied to the regulator series pass tube, V3004.
Regulator tube V3005 is used to keep
The voltage then is
the screen of V3004 at a constant potential.
To obtain a stable, accurate voltage,
b.
divider network of wirewound resistors, R3023 to R3028.
justed with potentiometer R3025 to better than 0.01%.
sample voltage from the divider network to the voltage across zener diode, D3003.
the 500-volt output of V3004 is sampled by a
The divider network ratio is ad-
Light modulator E3002 compares the
Any dif-
ference between the two voltages is chopped by E3002 and amplified by a 2-stage ac-coupled
1065R 13
CIRCUIT DESCRIPTION MODEL 660A DIFFERENTIAL VOLTMETER
amplifier, V3001.
The amplified output of V3001 is converted to a dc signal by light
modulator E3001 and then is amplified by the two-stage differential dc amplifier, V3002
and V3003.
The amplifier output is applied to the grid of the series tube, V3004, to
nullify input variations. Capacitor C3004 is used in the ac feedback circuit.
The temperature-compensated zener diode,
C.
D3003, is used as the basic reference since
typical variations are limited to less than 20 ppm par year and 5 ppm per OC. Thus, a
highly stable reference which eliminates manual standardization is provided with respect
to both time and temperature, The zener diode will also withstand shock and vibration.
The regulated 500-volt output of V3004 is either applied directly to the Kelvin-
d.
Varley divider or it is divided to 50,
networks.
The WGE Switch, 53008, determines which network is used.
5 or 0.5 volts by very stable wirewound resistor
The 50-volt range
divider consists of resistors R3030, R3032 and R3033; the 'j-volt, of R3030, R3035 and
R3036; and the 0.5-volt of R3030, R3038 and R3039. Using potentiometers R3032, R3035
and R3038 accurately sets the voltage division on each range.
4-3. KELVIN-VARLEY DIVIDER.
a. The Kelvin-Varley divider precisely divides the reference voltage for nulling an
unknown voltage.
It is, in effect, a constant input impedance decade potentiometer, consisting of resistors R3040 through R3088. The resistors within each decade are matched;
the decades are matched for each instrument.
Each decade of the Kelvin-Varley divider, except the first, R3040 through R3045,
b.
parallels two resistors of the preceeding string. Between the two contacts of the first
Reference Voltage Switch, S3003, the total resistance is 40 kilohms (80 kilohms in para-
llel with the 80 kilohms total resistance of the four remaining strings). With the
RANGE Switch set at 500, 100 volts dc will appear across the contacts of Reference Voltage
Switch S3004, 10 volts across 53005, 1 volt across 53006, and 0.1 volt across 53007.
4-4. NULL DETECTOR. The Model 660A uses a null detector with a chopper stabilized,
feedback amplifier. The input signal is attenuated, if necessary, and sent through a
three-stage R-C filter. The signal is then amplified and applied to the meter.
a. The null detector has three full-scale sensitivities, 0.1, 1 and 10 millivolts.
Above the lo-millivolt range,
the 10 millivolts.
back resistors, R1040
The full-scale sensitivities are determined by one of three feed-
to
R1042, in the circuit. A three-stage R-C filter, consisting of
the input is divided by resistors R1004 through R1009 to
RlOlO, RlOll, 61003, R1012, C1004, Rl018 and C1005, is used to decrease the ac input
components.
The light modulators El001 and El002 convert the difference between the filtered
b.
input voltage and the output of the Kelvin-Varley divider into an ac voltage, which is
fed to a four-stage ac coupled amplifier, VlOOl and V1002. The amplifier output is then
demodulated by light modulator El003 and filtered by capacitor C1019. The null detector
meter, MlOOl, indicates the value of the filtered signal. A 42-cps oscillator drives
the light modulators.
Using a drive source harmonically unrelated to the standard line
frequency minimizes 60-cps pickup effects.
One arm of the feedback network is formed by resistors R1043 to R1046, and one of
c.
the feedback range resistors, R1040 to R1042. Resistor R1039 forms the second shunt arm.
The feedback is applied
to
light modulator E1002.
14
0665
MODEL 660A DIFFERENTIAL VOLTMETER
A zero-control network is used to buck out thermal emf's at the input on the two
d.
most sensitive ranges.
resistors R1013 through R1016.
The network consists of a 1.34-volt mercury battery, BTlOOl, and
The zero control on the front panel, R1016, has approxi-
CIRCUIT DESCRIPTION
mately a 60-microvolt span.
a. The null detector output is obtained across resistors R1045 and R1046, which are
in the feedback network.
at full scale.
The output voltage is proportional to the full-scale meter reading.
Potentiometer R1045 adjusts the output from 10 to 25 millivolts
4-5. GUARDING.
circuitry at a voltage equal to the input voltage from a low impedance source.
guarding eliminates leakage between the input terminal and ground.
unguarded circuit is difficult to avoid,
in sizeable errors.
of 108
ohms will introduce 1% error.
Guarding is accomplished by floating the null detector and the input
This full
Such leakage in an
under laboratory conditions, and can result
For example,
in an unguarded circuit with a 1-megohm source, leakage
A guarded circuit eliminates this element of error.
The effectiveness of guarding in the Model 660A is demonstrated by setting the null det-
ector on the O.l-millivolt range, with the input circuit open, and Reference Voltage
Dials set to 500 volts.
Even at this extreme condition there is no deflection on the meter,
demonstrating there is no leakage.
0665
15
MODEL 660A DIFFERENTIAL VOLTMETER
SERVICING
SERVICING
5-l. GENERAL.
Model 660A.
Follow these procedures as closely as possible to maintain the accuracy and
SECTION 5.
Section 5 contains the maintenance and troubleshooting procedures for the
stability of the instrument.
5-2. SERVICING SCHEDULE.
care required of high-quality electronic equipment.
The Model 660A needs no periodic maintenance beyond the normal
No part should need replacement un-
der ordinary use except a pilot lamp, fuse or, occasionally, a vacuum tube.
5-3. PARTS REPLACEMENT.
The Replaceable Parts List in Section 8 describes the electrical components in the
a.
Model 660A.
Replace components only as necessary,
and use only reliable replacements
which meet the specifications.
Replace resistors within any one of the first three Kelvin-Varley divider decades
b.
only as an assembly.
R3040 to R3067.
assemblies.
Reorder using the Keithley part number (see Section 8) and replace all resis-
tors in the assembly.
Refer to the Replaceable Parts List for the part number for resistors
Resistors R3023, R3024, R3026, R3033, R3036 and R3039 are also parts of
Because of its importance in maintaining the power supply stability,
order aener diode D3003 only from Keithley Instruments, Inc., or its representative.
fer to paragraph 5-6 for instructions to replace the zener.
Re-
5-4. TROUBLESHOOTING.
a. The following procedures are for repairing troubles which might occur in the Model
660A.
Table 3 lists equipment recommended for troubleshooting.
ly located or repaired,
b.
the troubleshooting,
difficulty.
cing
Use these procedures to troubleshoot and use only specified replacement parts.
If the trouble cannot be readi-
contact Keithley Instruments, Inc., or its representative.
Paragraph 7-2 describes how to remove the Model 660A cover.
check the vacuum tubes.
Normally, replacing tubes will clear up the
All tubes can be readily tested on a grid-modulated tube
a
tube does not correct the trouble, continue the procedures.
Before proceeding with
tester.
If repla-
Replacing tubes does
not necessitate recalibration of the instrument.
c. Table 4 contains the more common troubles which might occur.
ted in the Table do not clear up the trouble,
the difficulty will have to be found through
Instrument
Tektronix Type 503 Oscilloscope
dc voltmeter, 10% accuracy, minimum lOO-
Check wave forms
Circuit checking
USI2
If the repairs indica-
megohm input resistance, 1 volt to 500 volts
Grid-modulated tube tester
Test vacuum
tubes
TABLE 3.
Equipment Recommended for Model 660A Troubleshooting.
their equivalents.
0665
Use these instruments or
17
SERVICING
MODEL 660A DIFFERENTIAL VOLTMETER
Difficulty Probable Cause
eedle quiver
eter rattle, drift or er-
R1048 is out of adjustment
Tube VlOOl, V1002 or V2001
or is observed on all null is faulty
Adjust per paragraph 5-5
Check tubes; replace if faultY
Solution
anges
ine voltage variations Tube V3005 is defective Check tube; replace if faul-
ause measurements
to
be
tY
ut of specifications
,eference voltage supply
rifts after 30-minute
arm-up,
requiring frequent
V3001, V3002, V3003 or Check tubes; replace if fualV3007 is defective
tY
djusting of the range con- One of the divider resis- Return the instrument for
rols, R3025, R3032, R3035, tars, R3023 to R3028, is
,3038
changing value rapidly dur-
factory check-out
ing warm-up.
Zener diode, D3003, is un- Return the instrument for
stable factory check-out
Light modulator E3002 is Check light modulator by re-
defective placing
easurements out of toler- Out of calibration Refer to paragraph 6-4 for
nce on all ranges
recalibration
One of the divider resistors, Return the Instrument for
factory check-out
Paragraph 4-2 d points out
range. Try to bring the ran-
ges within specifications by
easurements are out of
pecifications on one
ange other than 500olt range
R3023 to R3028, is faulty
Resistor in the range divider network is faulty the resistors used for each
calibrating with the potentiometers in the network. See
paragraph 6-4.
If this does
not work, check individual
resistors.
easurements are out of
Resistor R3030 is faulty
Replace the faulty resistor
pecifications on all ranes other than 500-volt
ange
18
TABLE 4 (Sheet 1).
Model 660A Troubleshooting.
1065R
MODEL 660A DIFFERENTIAL VOLTMETER
SERVICING
Difficulty
Probable Cause Solution
Measurements are out of One of the Kelvin-Varley di- See paragraph 6-3
specifications on any vider resistors is faulty
range when the Reference
Voltage Dials are
at
any
setting other than
499910
Instrument is out of spec- Resistor R1003 is faulty Check resistor; replace i
ifications on all null faulty
ranges above 10 millivolts
TABLE 4 (Sheet 2).
a point-by-point check of the circuits.
find the more crucial components and to determine their function in the circuit.
Model 660A Troubleshooting.
Refer to the circuit description in Section 4 to
The
complete circuit schematic, 182693, is found in Section 8.
5-5.
ADJUSTING HUM BAL CONTROL.
a.
Potentiometer ~1048 (Figure 18) min-
imizes 60-cps pickup in the null detector.
Misadjustment will reduce sensitivity and
cause needle quiver.
b. To adjust the potentiometer, set the
Reference Voltage Dials to zero and short
the input terminals. Attach an oscilloscope to the junction of capacitor Cl016
and resistor R1035 (from pin 6 of V1002).
Figure 8 shows the wave form if potentiometer R1048 is adjusted for minimum output.
5-6.
D3003, is a reference for the voltage divide]
resistors R3023 to R3028. The values of resistors R3027 and R3028 (Figure 20) are determined by the reference voltage across di-
ode D3003.
ZENER DIODE REPLACEMENT. Zener diode,
When the zener is replaced, the
FIGURE 8. Wave Form with R1048 Adjusted.
I,
A Type 503 Oscilloscope was used; horizon-
tal sweep was 20 msec/cm; vertical, 500
mv/cm.
value of these two resistors may have to be
changed.
5-7. MXTER ADJUSTMENT.
a. Potentiometer R1043 (Figure 18) is the internal meter sensitivity adjustment. It
sets the current through the
meter to
indicate a full-scale deflection for a full-scale
applied voltage.
b. Warm up the Model 660A for 30 minutes.
range, and set the Reference Voltage Dials to .OOOlO.
Set the NULL Switch on the 0.1 millivolt
Adjust potentiometer R1043 until
the meter reads full scale.
1066R
19
MODEL 660A DIFFERENTIAL VOLTMETER
SERVICING
SECTION 6.
6-l.
equipment recommended in Table 5. If proper facilities - especially important for calibrating an +0.02% instrument - are not available or if difficulty is encountered, contact Keithley Instruments or its representative to arrange for factory calibration.
calibration, reference voltage supply stability test and oscillator adjustment.
troubleshooting procedures or contact Keithley Instruments, Inc., or its representative,
GENERAL.
a. The following procedures are recommended for calibrating the Model 660A. Use the
Four procedures are covered: Kelvin-Varley divider verification, voltage range
b.
c. If the Model 660A is not within specifications after the calibration, follow the
Instrument
Electra Scientific Industries Model SV194B Range voltage calibration
Joltage Calibrator, *0.005% accuracy with
corrections on certificate
Electra Scientific Industries Model RV7'22 Voltage divider for range calibration
)ecade Voltage Divider; terminal linearity,
hl ppm; certificate corrected to *0.2 ppm
CALIBRATION
Use
Slectro Scientific Industries Model LC875B
Lead Compensator
Hewlett-Packard Model 200CD Oscillator
(eithley Instruments Model 150A MicroJoltmeter
(eithley Instruments Model 241 Regulated
$igh Voltage Supply
(eithley Instruments Model 662 Guarded dc
Xfferential Voltmeter
losley Instruments Model 680 Direct Reading
&corder bility
Cektronix Type 503 Oscilloscope Check wave forms
jeston Instruments Model 3 Type 7 Saturated
;tandard Cell
Jeston Instruments Model 66 Oil Bath Range calibration and reference voltage
Range voltage calibration
Monitor oscillator frequency
Null detector for range calibration
Voltage supply for range calibration
Check voltages in Kelvin-Varley divider
Recorder for reference voltage supply sta.
Range calibration and reference voltage
supply stability
supply stability
CABLE 5. Equipment Recommended for Model 660A Calibration.
equivalents.
1065R
Use these instruments or tht
21
r
CALIBRATION
MODEL 660A DIFFERENTIAL VOLTMETER
Circuit
I
/(
0.5-volt Hum Oscillator 500-volt 50-volt 5-volt eter Balance Calibrate Calibrate Calibrate Calibrate Calibrate
TABLE 6. Model 660A Internal Controls. The Table lists all internal controls, the fig-
ure picturing the location and the paragraph describing the adjustment,
6-2.
ca?tibration (paragraph 6-4).
b.
or if components in the divider have been replaced.
tion after verifying the divider accuracy.
Control Desig.
R1048 R2007 R3025 R3032 R3035 R3038 R1043
CALIBRATION SCHEDULE.
Recalibrate the Model 660A yearly.
The other verifications need not be done.
Verify the Kelvin-Varley divider (paragraph 6-3) only if trouble is suspected in iti
This normally means performing the voltage range
Also make the voltage range calibra-
Fig. Refer to
Ref.
20 20 20 20 20 18 18
Paranrauh
5-7 5-5 6-4 6-4 6-6 6-4 6-4
Check the reference voltage supply stability (paragraph 6-5) only if trouble is
c.
suspected in the supply or if some of its components have been replaced.
6-3. KELVIN-VARLEY DIVIDER VERIFICATION.
a. There is no in-field calibration for the Kelvin-Varley divider; its accuracy can
only be verified. The divider accuracy depends upon matching resistors and switches. At
manufacture,
S3004, is matched to 0.005%.
accuracy of better than 0.005%.
the string
Kelvin-Varley Divider Accuracy Verification Procedures.
b.
Use the Model 662 Differential Voltmeter or equipment with better limit of error
1.
to match the Model 660A under test.
strument under test to the HI terminal of the Model 662.
Be careful of high voltages when working within the Model 660A.
volts dc is present at various points.
Set the dials to random settings on both instruments.
2.
?0.02%.
The errors of the two instruments may be additive,
most accurate way is to use standard procedures for checking a Kelvin-Varley divider
or to return the Model 660A to Keithley Instruments, Inc., for checking.
each resistor within the first two Reference Voltage switches, 53003 and
The resistors in the switches are checked as a set to an
Individual resistors cannot be replaced without rematching
at
Keithley Instruments,
Connect the wiper arm of Switch S3007 of the in-
Connect both LO terminals.
up to 800
Settings should match to
This procedure, however, only indicates the Kelvin-Varley divider accuracy.
causing a false verification.
The
22 1065R
MODEL 660A DIFFERENTIAL VOLTMETER
CALIBRATION
If any resistor fails to test out,
3.
matched at the factory,
6-4. RANGE CALIBRATION.
The reference voltage supply has a 500-volt output which can be attenuated to 50, 5
a.
or 0.5 volts.
accurate buckout voltage.
potentiometers R3025, R3032, R3035 and R3038 (Figure '20).
The ranges are calibrated by applying an accurate voltage to the Model 660A for each
b.
setting of the RANGE Switch.
tage, and the internal range potentiometer is adusted until the voltmeter indicates a null.
The accuracy of the Model 660A calibration will be no greater than the
accuracy of the voltage source used for calibrating.
familiar with techniques for obtaining accuracy greater than 0.002%
(20 ppm), it is better to return the Model 660A to the factory for range
calibration.
c. The most critical part in range calibration is establishing a reference source
whose accuracy exceeds 0.002%.
5 and 0.5-volt outputs.
This voltage is then divided by the Kelvin-Varley divider to provide the
Each of the four voltage ranges is set by internally adjusting
The Model 660A is set to furnish the equivalent buckout vol-
Use the Model SV194B Voltage Calibrator for the 500, 50:
Establish the accuracy 3f these outputs by determining the cor-
the tintire divider string will have to be re-
NOTP
Unless the user is
Model LC 875B
r’
9.9 m
Extender
(5 and 0.5 v
on1
P
Model RV722
FIGURE 9.
Fully guard the entire system to prevent leakage errors.
to shunt the null detector.
0665
Block Diagram to Establish System Accuracy for Model 660A Range Calibration.
See Table 5 for recommended equipment.
Use a 1-kilollm copper resistor
23
CALIBRATION MODEL 660A DIFFERENTIAL VOLTMETER
rections for the calibrator's CALIBRATION and OUTPUT dials at these outputs.
tem's accuracy can be determined to approximately 10 ppm.
Added to the accuracy of the
The sys-
standard cell, total accuracy should be approximately 12 ppm. Note that this depends
upon properly executed procedures.
Procedures to Establish System Accuracy.
d.
Set up the system shown in Figure 9. Use the 9.9-megohm extender for only the
1.
0.5 and 5-volt outputs.
Establish the corrections for the CALIBRATION dial setting for Model SV194B out-
2.
puts of 500, 50, 5 and 0.5 volts.
Set the Model 241 Voltage Supply to 500 volts.
the Model RV772 Divider to a voltage equal to that of the standard cell. Adjust the
Model SV194B ratio dial until the null detector indicates a null. The difference be-
tween the settings of the Model RV772 Divider and the ratio dial is the Model SV194B
correction factor at 500 volts. With this correction, the 500 volts may be set to
within approximately 12 ppm.
Connect the null detector to the 50,
3.
ibrator in that order.
Set the Model RV722 Divider to corresponding voltages.
9.9-megohm extender for the 5 and 0.5-volt outputs.
5 and 0.5-volt taps of the Model SV194B Cal-
Use the
(See Figure 9.) The difference
read on the null detector is the correction factor for each of the three voltages.
These voltage may also be set to within 12 ppm.
Use the four correction factors for calibrating the Model 660A range settings,
4.
set
Procedures for Range Calibration.
e.
Set up the system shown in Figure 10. The standard cell should be certified to
1.
10 ppm.
Use the dial correction factors found for each output.
was properly determined,
500-volt Range Calibration:
2.
RANGE Switch
the input voltage to the Model 660A should be correct to 20 ppm.
Set
the Model 660A controls
500
If the system accuracy
as
follows:
Reference Voltage Dials 4 9 9.9 10
NULL Switch VTVM
POLARITY Switch
Adjust the Voltage Calibrator to apply 500 volts dc
+
to
the Model 660A. Turn the Model
660A NULL Switch to 10 MV and adjust the 500 V CAL potentiometer, R3025 (Figure 20),
for null on the Differential Voltmeter.
50-volt Range Calibration:
3.
RANGE Switch
Set the Model 660A controls as follows:
50
Reference Voltage Dials 4 9.9 9 10
NULL Switch 10 Mv
POLARITY
Adjust the Voltage Calibrator to apply 50 volts dc
+
to
the Model 660A. Adjust the 50 v
CAL potentiometer, R3032 (Figure 20), for an off-null reading on the Model 660A equal to
the correction factor at 50 volts.
MODEL 660A DIFFERENTIAL VOLTMETER
CALIBRATION
FIGURE IU. Block Diagram for Model 660A Range Calibration.
to prevent leakage errors.
4. 5-volt Range Calibration:
RANGE Switch
Reference Voltage Dials
NULL Switch
See Table 5 for recommended equipment.
Set the Model 660A controls as follows:
5
4 .9 9 9 1.0
1 MV
Fully guard the entire system
POLARITY Switch +
Adjust the Voltage Calibrator
CAL potentiometer, R3035 (Figure ZO),
to
apply 5 volts dc to the Model 660A.
for an off-null reading on the Model 660A equal
to the correction factor at 5 volts.
5. 0.5-volt Range Calibration:
RANGE Switch
Reference Voltage Dials
Set the Model 660A controls as follows:
0.5
.4 9 9 9 10
NULL Switch 0.1 MV
POLARITY Switch
+
Adjust the Voltage Calibrator to apply 0.5 volt dc to the Model 660A.
CAL potentiometer, R3038 (Figure ZO),
for an off-null reading on the Model 660A equal
to the correction factor at 0.5 volt.
L
Adjust the 5 V
Adjust the 0.5 V
6-5. REFERENCE VOLTAGE SUPPLY STABILITY TEST.
The reference voltage supply,
pl;*(printed circuit PC92),
is factory calibrated i-or an output of 500 volts dc f0.002%.
consisting of the power transformer and the main sup-
The 500-volt output is adjustable to meet specifications.
1066~
If the stability of the supply
25
CALIBRATION
MODEL 660A DIFFERENTIAL VOLTMETER
; I
I
10
FIGURE 11.
voltage across the 530-ohm resistor is slightly higher than the standard cell. Use the
lo-kilohm potentiometer to shunt the divider voltage down.
See Table 5 for recommended equipment.
is not within specifications, then troubleshoot for a faulty component.
b. Routine calibration of the Model 660A does not require a stability test of the reference voltage supply. However, a stability test is recommended if one of the components
in the supply is replaced.
For the 24-hour test, the SOO-volt output of the reference voltage supply is divi-
c.
ded and compared to a 1.02-volt saturated standard cell using a sensitive null detector.
Variations between the reference voltage supply and the standard cell are detected by the
Model 150A and are recorded on a recorder. Refer to Figure 11 for the block diagram of
the test circuit.
Circuit Diagram for Model 660A Reference Voltage Supply Stability Test.
I I I I
I
I
Model 15OA
Null
Recorder
The
All resistors are wirewound.
d. In using the test circuit, the following points are important.
1. Saturated standard cells,
ture coefficient and require a controlled environment during use.
ton Oil Bath, which is maintained at +35OC *O.Ol%, is used for the test.
standard cells have a lower temperature coefficient, but they do not have the Long term
stability required for this test.
2.
The resistor divider network is constructed from wire of the same spool for an
extremely close temperature coefficient match (4 ppm, typically). Additional stability
results when the resistors are immersed in an oil bath to hold the ambient temperature
variations to ?O.Ol%.
Procedures for the Reference Voltage Supply Stability Test.
I?.
1.
After the saturated standard cell and the resistor divider network are placed in
the oil bath, allow sufficient time for the cell to stabilize at +35%.
26
though extremely stable with time, have a high tempera-
Therefore, the Wes-
Unsaturated
(Consult Keith-
1066R
MODEL 660A DIFFERENTIAL VOLTMETER CALIBRATION
ley Instruments, Inc., or its representative for details.) Connect the standard cell to
the circuit after turning on the 500-volt supply. Set the Model 660A controls as follows:
RANGE Switch 500
Reference Voltage Dials 4 9 9.9 10
NULL Switch LO MV
POLARITY Switch
Connect the resistor divider network across the Model 660A's reference voltage supply,
the positive side of the divider input to the wiper arm of the last Reference Voltage
Switch, 53007, and the negative side of the divider to the LO terminal on the Model 660A
front panel.
OFF
2. Connect the Model 150A and the recorder as shown in Figure 11.
to the 3-volt range.
the divider.
tages are improperly connected in series. If the circuit is correct, the Model 150A
will read zero.
it reads more than 20 microvolts,
shunting the divider.
Any adjustment of potentiometer R3025 requires all other ranges to be calibrated.
After a l-hour warm-up,
3.
volts in 24 hours (Figure 12).
6-6. OSCILLATOR ADJUSTMENT.
a. The oscillator circuit drives the light modulators.
make sure the reference voltage supply is operating correctly.
b. Connect the Type 503 Oscilloscope Vertical Input to the plate and low side of tube
V2001 (Figure 19) and the Horizontal Input to the Model ZOOCD Oscillator.
oscillator frequency to approximately 42 cps with potentiometer R2007 (Figure 20). The
Model 660A oscillator is then adjusted for minimum meter noise - normalLy.within a cycle
of 42 cps. Disconnect the Oscilloscope before adjusting potentiometer R2007. The Oscilloscope will cause a small loading error.
If the Model 150A reads two volts, the standard cell and the divider vol-
Advance the Model 660A POLARITY Switch to + to put 500 volts across
Increase the Model 150A's sensitivity to the O.l-millivolt range. If
adjust the 500 V CAL potentiometer, R3025 (Figure 20),
NOTE
the drift of the entire system should not exceed i-50 micro-
Before adjusting the oscillator,
Set the Model 150A
Adjust the
FIGURE 12.
ers over 15 hours. Fluctuations are well within -i-0.005%.
No compensation for variations of line voltage or other conditions was made.
1066R
Stability Strip Chart for Model 660A Reference Voltage Supply.
Note drift is non-cumulative.
The chart cov-
27
CALIBRATION
MODEL 660A DIFFERENTIAL VOLTMETER
FIGURE 13.
Top View of Model 660A Chassis.
Front panel faces to the right. Location of
components, printed circuits and switches is shown.
for circuit designations.
Figure 14 shows the bottom view.
28
Refer to the Replaceable Parts List
1065R
MODEL 660A DIFFERENTIAL VOLTMETER
CALIBRATION
FIGURE 14. Bottom View of Model 660A Chassis.
Front panel faces to the right.
Reference
A in the photograph designates the location of resistors R3031, R3033, R3034, R3036, R3037
and R3039.
1065R
Figure 13 shows the top view.
29
CALIBRATION
MODEL 660A DIFFERENTIAL VOLTMETER
FIGURE 15.
Circuit Board PC93-1.
Component Locations
on Printed
FIGURE 16.
Component Locations on Printed
Circuit Board PC105.
30 1066R
MODEL 660A DIFFERENTIAL VOLTMEJJER
CALIBRATION
FIGURE 17.
Capacitor, Modulator, Diode and Tube
Locations on Printed Circuit Board PC93-2.
to Figure 18 for resistor location.
Refer
1065R
FIGURE 18.
Board PC93-2.
Resistor Locations on Printed Circuit
Refer to Figure 17 for the location
of other components.
31
CALIBRATION
MODEL 660A DIFFERmTIAL VOLTMETER
FI( XJRE 19. Capacitor, Modulator, Diode and Tube Locations on Printed Circuit Board PC92.
Ref ier to Figure 20 for the resistor locations.
32
1065R
MODEL 660A DIFFERENTIAL VOLTMETER
CALIBRATION
F 1 'IGURF 20. Resistor Locations on Printed Circuit Board PC92.
,ocation of other components.
1065R
Refer to Figure 19 for
the
33
CALIBRATION
MODEL 660A DIFFERENTIAL VOLTMETER
34
GIJRE 21.
to Schematic Diagram 16321B.
Component Locations of Model 6601A.
Circuit designations refer
1065R
MODEL 660A DIFFERENTIAL VOLTMETER
SECTION 7. ACCESSORIES
ACCESSORIES
7-l.
MODEL 6601A HIGH VOLTAGE DIVIDER,
a. The Model 6601A extends the range of the Model 660A to 5000 volts full scale. The
ratio of the Divider is lOO:l,
?O.Ol%; the input resistance is 10 megohms.
The limit of
error using the Models 660A and 6601A is 20.03%. Section 8 contains the Replaceable Parts
List and Schematic Diagram 16321~ for the Divider.
NOTE
Maximum input into the Model 6601A is 5000 volts.
b. Set the Model 660A RANGE Switch to 50 volts.
SCEllE!.
tively.
Connect the HI and LO Divider terminals to the HI and LO Voltmeter terminals respec-
Connect the unknown voltage to the Divider INPUT, and use the Model 660A as out-
The meter will read to 5000 volts full
lined in paragraph 2-4.
NOTE
The input cable to the Model 6601A must be able to withstand 5000 volts.
Use of
normal leads will maintain the accuracy.
7-2.
40:; Rack Mounting Kit converts the instrument to rack mounting
RACK MOUNTING. (See Figure 23.)
The Model 660A is shipped for bench use with four feet and a tilt-bail
to
standard EIA "(RETMA)
the
The Model
19-inch width.
To convert the Model 660A, remove the four screws at the bottom of each side of the
b.
instrument case. Lift off the top cover assembly with the handles; save the four screws.
To remove the feet and tilt bail from the bottom cover assembly,
the back.
the
The two pawl-type
feet and
FIGURF 22.
Keithley Instruments Model 6601A High Voltage Divider.
fasteners will release the cover and allow it to drop off.
turn the two screws near
1066R
35
MODEL 660A DIFFERENTIAL VOLTMETER
Attach the pair of rack angles (3) to the cabinet with the four screws (4) previous-
c.
ly removed.
Insert the top cover assembly (1) in place and fasten to the chassis with the
two pawl-type fasteners at the rear. Store the top cover with handles, feet and tilt-bail
for future use.
7-3. PLACING IN RACK.
The Model 660A, once converted for rack mounting, easily fits
into the rack. It is recommended, however, that a blower be used in the rack enclosure
in which the Model 660A is mounted. The instrument specifications state a 0.002% per "C
temperature coefficient. A temperature rise of 5 "C (9 OF) will cause a 0.01% error.
Item
(See Fig. 23) Description
1 Cover Assembly
Keithley
Part No. Quantit:
14623B 1
2 Cover Assembly, Bottom (Supplied with
3
Model 660A)
Angle, Rack
14590B
14624B 2
1
4 Screw, Slot Head, lo-32 UNC-2 x l/4
(Supplied with Model 660A)
5 Front Panel (Supplied with Model 660A)
---
---
4
1
TABLE 7. Parts List for Model 4000 Rack Mounting Kit.
/oCOVER ASSEMBLY
36
FIGURE 23.
Exploded View for Rack Mounting with Model 4000 Kit.
Refer to Table 7 for parts list.
1066R
MODEL 660A DIFFERENTIAL VOLTMETER
REPLACEABLE PARTS
SECTION 8.
8-l. REPLACEABLE PARTS LIST.
Models 660A and 6601A.
suggested manufacturer,
last column indicates the figure picturing the part.
turers listed in the "Mfg. Code" column are in Table 9.
8-2. HOW TO ORDER PARTS.
For parts orders,
a.
Part Number,
and those parts coded for Keithley manufacture (80164) must be ordered from Keithley
Instruments, Inc.
describe the part,
Order parts through your nearest Keithley representative or the Sales Service Depart-
b.
ment, Keithley Instruments, Inc.
smp
the circuit designation and a description of the part.
ZtlllpC?re
The List gives the circuit designation, the part description, a
the manufacturer's part number and the Keithley Part Number.
include the instrument's model and serial number, the Keithley
In ordering a part not listed in the Replaceable Parts List, completely
its function and its location.
The Replaceable Parts List describes the components of the
REPLACEABLE PARTS
The name and address of the manufac-
All structural parts
MtF Metal Film
The
CbVar
CerD
camp
compv
DCb
EMC
ETB
ETT
f
k
!I or meg
n
Mfg.
Carbon Variable
Ceramic, Disc
Composition
Composition Variable
Deposited Carbon
Electrolytic, metal cased
Electrolytic, tubular
Electrolytic, tantalum
farad
kilo (103)
mega (106) or megohms
milli (10m3)
Manufacturer
TABLE 8.
Abbreviations and Symbols.
Mil. No.
MY
cl
Polv
P
I*
"
Var
w
ww
wwvar
Military Type Number
Mylar
ohm
Polystyrene
pica (10-12)
micro (10T6)
volt
Variable
watt
Wirewound
Wirewound Variable
0465
37
REPLACEABLE PARTS
(Refer to Schematic Diagram 182693 for circuit designations.)
MODEL 660A DIFFERENTIAL VOLTMETER
MODEL 660A REPLACEABLE PARTS LIST
CAPACITORS
Circuit
Desig. Value Rating
Cl001 .05 IJ.f
Cl002
.47 pf
Cl003 0.1 pf
Cl004 0.1 pf
Cl005
0.1 pf
Cl006 0.05 pf
Cl007 .05 pf
Cl008 10 IJ.f
Cl009
.0022 pf
600 v
600 v
100 v
100 v
100 v
100 v
600 v
15 v
1000 " CerD 72982 85125V222P
TYPO
MY
MY
Poly
Poly 00656 lPJ-104.J C129-.lM
Poly
Poly
MY
ETB 56289 TE1155 C3-10M
Mfg. Mfg.
Code
Part No. Part No. Ref.
56289 6~~-s50
14655
00656
00656
00656
WMF6P47 ClOl-.47M
lP.J-104.J C129-.lM 16
lP.J-104J Cl29-.lM 16
lP.J-503J C129-.05M 16
56289 CPS-s50
Cl010 10 pf 15 v ETB 56289 TEL155
Cl011 680 pf 1000 v
Cl012 40 wf
Cl013
Cl014
0.0022 pf
10 pf 15 "
450 v EMC 56289 TVL2762 C36-40/20M
1000 " CerD 72982 85125V222P C22-.0022M
CerD
ETB
72982
56289
801X5R681K C22-680P
TE1155 C3-10M
Cl015 .0047 iJ.f 1000 " CerD 72982 811Z5V472P
Cl016
Cl017
1.0 I.lf
4 Pf
600 v
MY
13050 24009
250 v ETB 14655 BBR4-250
Cl018 125 pf 15 " ETB 56289 TEL162
Cl019
600 IJ.f 6v
ETT 05079
TEZ600-6C2
Keithley
C62-.05M
C62-.05M 17
C22-.0022M 17
C3-10M 17
C22-.0047M
C12-1M
C27-4M
C3-125M
C133-600M
Cl020 20 IJ.f 450 v IBfC 56289 TVL2762 C36-40/20M
Fig.
14
14
16
17
17
17
17
17
17
17
17
17
17
17
c2001
c2002
c3001
C3002
c3003
c3004
c3005
C3006
c3007
C3008
c3009
c3010
c3011
.Ol pf
.Ol IJ.f
20 pf
20 pf
.OOl pf
1.0 kf
0.05 pf
4 Ilf
50 pf
.0047 IJ.f
.022 I*f
.05 IJ.f
40 pf
400 v Poly 14655
400 v Poly 14655
wMF4Sl Cl14-.OlM
W4Sl C114-.OlM
450 v EMC 37942 FP144
450 "
1000 "
1000 "
600 v
250 v
6v ETB 56289
1000 "
200 " ETB 13050
600 v
450 " EMC 56289
EMC 56289 TVL2762 C36-20/40M
CerD 72982 8OlZ5V102P
MY
MY
ETB
13050 Z4009B
56289 6PS-S50
14655
BBR4-250
TEllOO C17-50M
CerD 72982 811Z5V472P
MWlA C6-.022M
MY
56289
6PS-S50 C62-.05M
TVL2762 C36-20/40M
C36-20M
C22-.OOlM
C14-1M'
C62-.05M
C27-4M
C22-.0047M
19
19
19
19
19
19
19
19
19
19
19
19
19
38
1066R
MODEL 660A DIFFERENTIAL VOLTMETER
REPLACEABLE PARTS
DIODES
Circuit
Desig.
DlOOl Silicon lN645 01295 RF-14 17
D1002 Silicon lN3256 02735 RF-22 17
D3001 Silicon lN2378 08520 RF-25 19
D3002 Silicon 1~3256
D3003 Zellei? - 80164 DZ-8 (1) 19
Circuit
Desig. Description
BTlOOl
DSlOOl
DS2001
DS2002
DS2003
DS2004
El001
El002
El003
Type
MISCELLANEOUS PARTS
Battery, 1.34-v mercury (Mfg. No. PXl3T2) 37942 BA-16
Neon Lamp (Mfg. No. NE-81) 08804 PL-6 16
Neon Lamp (Mfg. No. NE-2P) 08804
Neon clamp (Mfg. No. NE-2P) 08804 PL-2
Neon Lamp (Mfg. No. NE-2P) 08804
Neon Lamp (Mfg. No. NE-2P) 08804 PL-2
Light Modulator
Light Modulator
Light Modulator
NUllIbEX
Mfg.
Code Part No. Ref.
02735
Mfg.
Code Part No. Ref.
80164 Model 1513 16
80164 Model 1513 16
80164
Keithley
RF-22 19
Keithley
PL-2 13
PL-2
Model 1514 17
Fig.
Fig.
16
13
13
13
E3001
E3002
FlOOl (117 v)
FlOOl (234 v)
-
JlOOl
51002
JlOO3
51004
-
J1005
51006
Ml001
PlOOl
SlOOl
-
-
Light Modulator 80164
Light Modulator 80164
Fuse, slow blow, 1 amp (Mfg. Type MDL) 71400 FU-10
Fuse, slow blow, 0.5 amp (Mfg. No. 312.500) 75915 FU-6
Fuse Holder (Mfg. No. 342012)
Binding Post, HI (Mfg. No. DF31RC)
Binding Post, LO (Mfg. No. DF31BC) 58474 BP-8B
Binding Post, LO (Mfg. No. DF31BC) 58474 BP-8B
Binding Post, GND (Mfg. No. DF31BC) 58474
Shorting Link (Mfg. No. 938-L) 24655
Banana Jack, + (Mfg. No. 108-745-l)
Banana Jack, - (Mfg. No. 108-745-2)
Meter
Power Cord, 6 feet (Mfg. No. 4638-13)
Rotary Switch less components, NULL
Knob Assembly, Null Switch
Knob Assembly, Meter Zero Potentiometer
75915
58474 BP-8R
74970 BJ-3
74970 BJ-4
80164
82879
80164
80164
80164
Model 1512
Model 1514
FH-3
BP-8B
BP-6
ME-38
co-5
SW-191
14838A
15110A
19
19
3
3
2
2
2
2
3
3
13
3
2
(1) Refer to paragraph 5-6.
1065R
39
REPLACEABLE PARTS
MODEL 660A DIFFERENTIAL VOLWTER
MISCELLANEOUS PARTS (Cont'd)
Circuit
Desig. Description
s3002
s3003
Slide Switch, 117-234 SW-151 3
Switch Assembly with components, Readout
Dial Assembly, Q-4 Readout
s3004
Switch Assembly with components, Readout
Dial Assembly, O-9 Readout
s3005
-----
S3006
Switch Assembly with components, Readout
Dial Assembly, O-9 Readout
Rotary Switch less components, Readout
Dial Assembly, O-9 Readout
_--_-
s3007
53008
Dial Assembly, O-10 Readout
Toggle Switch, SPST, ON (Mfg. No. 2099141)
Rotary Switch less components, RANGE
Knob Assembly, Range Switch
s3009
-----
Rotary Switch less components, POLARITY
Knob Assembly, Polarity Switch
Mfg.
Keithley
Fig.
Code Part No. Ref.
80164
80164
80164
80164
80164
80164
80164
80164
80164
80164
04009
80164
80164
80164
80164
18339B
14827A
15114B
14828A
15112B
14828A
~~-118
14828A
19185A
SW-4
~~-116
14838A
SW-203
14838A
2
2
2
2
2
2
2
T3001
Transformer
Circuit
Desig. Value Rating
RlOOl 100 MO
R1002 1 ka
R1003 50 MR
R1004 1.5 Ma
R1005 5 kfl
R1006 50 kfi
R1007 505 kfi
Rl008 12.5 Ma
R1009 1.14 MR
R1010 220 kfi
RlOll 220 ka
R1012' 220 kfi
R1013 3 kQ
R1014 3 kfi
R1015 900 kfi
20%, l/2 w
lo%, 112 W
l%, 2 W
l%,
l%,
I%,
112
l%,
l%, l W
l%, l/2 w
lO%, 112 W
lO%, l/2 w
lO%,
l%, l/2 W
l%, 112 w
l%,
l/2 w
112
w
l/2
w
w
112
w
l/2 W
80164
TR-67
RESISTORS
TYPO
Mfg.
Mfg.
Code Part No. Part No.
Keithley
Comp 75042 GBT R37-100M
Comp 01121
DCb 91637
EB Rl-1K
DC-2
R14-50M
DCb 79727 CFE-15 R12-1.5M
DCb 79727 CFE-15
DCb 79727 CFE-15
R12-51~ 15
R12-50K
DCb 79727 CFE-15 Rl2-505K
DCb 91637
DC-l
Rl3-12.5M
DCb 79727 CFE-15 R12-1.14M
Comp 01121
Comp 01121
Comp 01121
DCb 79727
EB Rl-220K 16
ED Rl-220K
ED Rl-220K
CFE-15
R12-3K
DCb 79727 CFE-15 Rl2-3K
DCb 79727 CFE-15 Rl2-900K
13
Fig.
Ref.
14
14
15
15
15
15
15
15
16
16
16
16
16
40
1066R
MODEL 660A DIFFERENTIAL VOLTMETER
REPLACEABLE PARTS
RESISTORS (Cont'd)
Circuit
Desig.
R1016
R1017
R1018
R1019
R1020
Ii1021
Rl022
R1023
R1024
Rl025
R1026
R1027
R1028
R1029
R1030
R1031
R1032
R1033
R1034
R1035
Value
15 kfi
200 kll
470 m
1MQ
22 m
1.5 m
10 kn
1.5 la
15 kc
10 m
70 kn
450 krl
4ia
10 wl
1.5 i%
8.2 ks2
100 kn
3.3 Mn
10 Ma
100 kQ
Rating
lO%, 5 w
l%, l/2 w
l%, l/2 w
lO%, I.12 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
l%, l/2 w
l%, l/2 w
l%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, u2 w
lO%, l/2 w
lO%, l/2 w
Mfg.
TYPO
wwvar
DCb
Code
71450
79727 CFE-15 R12-ZOOK 16
DCb 79727
Comp 01121
camp
01121
Comp 01121
Comp
Comp
01121
01121
Comp 01121
camp
01121
DCb 79727
DCb
79727 CFE-15 R12-450K 15
DCb 79727
camp 01121
Mfg.
Part No. Part No. Ref.
AW
CFE-15
EB
EB
EB
EB
EB
EB
EB
CFE-15
CFE-15
EB Rl-1OM 18
Keithley
Fig.
RP19-15K 2
R12-470K
Rl-1M
16
16
Rl-22M 18
Rl-1.5M
18
Rl-1OK 18
Rl-1.5M
Rl-15K
18
18
Rl-1OM 18
R12-70K
R12-4M
15
15
Comp 01121 EB Rl-1.5M 18
camp 01121
camp 01121
camp 01121
camp 01121
EB
EB
EB
EB
Rl-8.2K
Rl-100K
Rl-3.3M
Rl-1OM
18
18
18
18
Comp 01121 EB Rl-100K 18
R1036
R1037
R1038
R1039
R1040
R1041
R1042
R1043
R1044
R1045
R1046
R1047
R1048
R2001
R2002
R2003
R2004
R2005
R2006
R2007
R2008
1.2 kn
220 kn
10 kn
2k.G
*40 k.0
*400 kn
*4.7 m
500 n
1.5 kcl
200 n
80 R
lti
lkn
220 kQ
1.8 MO
100 kcl
150 Ia,
150 ko.
1.8 IQ
50 kn
40 krl
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
l%, l/2 w
l%, l/2 w
l%, l/2 w
l%, l/2 w
lO%, 5 w
l%, l/2 w
lO%, 2 w
l%, l/2 w
lO%, l/2 w
20%, .2 w
lO%, l/2 w
l%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
l%, l/2 w
30%, l/2 w
l%, l/2 w
camp oil21
Comp 01121
camp 01121
ww 01686
DCb 79727
DCb
DCb
wwvar
ww
wwvar
ww
camp
CompV
camp
DCb
Comp
Comp
camp
DCb
compv
DCb
79727
79727
71450
01686
71450
01686
01121
71450
01121
79727
01121
01121
01121
79727
71450
79727
ED
EB
EB
E-30
CFE-15
CFE-15
Rl-1.2K 18
Rl-220K 18
Rl-1OK 18
R58-2K 16
Rl2-40K
Rl2-400K
15
15
CFE-15 R12-4.7M 15
AW
E-30
P252 RP22-200
E-30
EB
70
EB
CFE-15
EB
EB
EB
CFE-15
VA-45
CFE-15
RP3-500 18
R58-1.5K 18
3
R58-80 18
Rl-1K 18
RP31-1K 18
Rl-220K
R12-1.8M
Rl-100K
Rl-150K
Rl-150K
R12-1.8M
RP16B-50K
R12-40K
20
20
20
20
20
20
20
20
K Nominal value, factory set.
1065R
41
REPLACEABLE PARTS MODEL 660A DIFFERENTIAL VOLTMETER
RESISTORS (Cont'd)
Circuit
Desig. Value Rating
R2009
R2010
R2011
R2012
R2013
R3001
R3002
R3003
R3004
R3005
R3006
R3007
R3008
R3009
R3010
R3011
R3012
R3013
R3014
R3015
150 kn
180 kn
100 kn
100 kn
220 kn
220 12
50 kn
820 kil
150 kn
1m
1Mfl
3.3 m
lH?
470 n
470 kn
1m
4.7 kn
1Mfl
10 Mn
330 kn
l%, l/2 w
l%, II2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, 2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
Keithley
TYPO
Mfg.
Mfg.
Code Part No. Part No.
DCb 79727 CFE-15 R12-150K
DCb 79727 CFE-15 R12-180K
camp 01121
EB
Rl-100K
Comp 01121 EB Rl-100K
Comp
01121
EB Rl-220K
camp 01121 EB Rl-220
Comp 01121
HB
R4A-50K
camp 01121 EB Rl-820K
camp 01121
EB
Rl-150K
Comp 01121 EB Rl-1M
camp
Comp
01121
01121
EB Rl-1M
EB Rl-3.3K
camp 01121 EB Rl-1M
Comp 01121 EB Rl-470
camp 01121 EB Rl-470K
Comp
Comp
camp
01121
EB
01121 EB Rl-4.7K
01121 EB
Rl-1M
Rl-1M
camp 01121 EB Rl-1OM
camp
01121
EB Rl-330K
Fig.
Ref.
20
20
20
20
20
20
20
20
20
20
14
20
20
20
20
20
20
20
20
20
R3016
R3017
R3018
R3019
R3020
R3021
R3022
R3023
R3024
R3025
R3026
R3027
R3028
R3029
R3030
R3031
R3032
680 kn
270 kn
2.2 i%
5.6 Icn
65.4 kQ
lM!J
220 kn
125 k~
125 kn
200 R
4.4 kn
*
A
lkfl
250 kn
91 kR
1Ul
lO%, l/2 w
lO%, II2 w
lO%, l/2 w
lO%, l/2 w
D
O.l/,, 50 w
lO%, l/2 w
lO%, l/2 w
O.l%, 2 w
O.l%, 2 w
lO%, 5 x.7
O.l%, l/4 w
0.1%. l/4 w
0.1%; l/4 w
l%, l/2 w
.l%, 2 w
l%, l/2 w
lO%, 5 w
Comp
camp
camp 01121 EB Rl-2.2M
camp 01121 EB Rl-5.6K
ww 91637 RR-50 R73-65.4K
Comp
Comp
ww 80164
ww
WWVar 71450
ww 80164
ww
ww
DCb 79727
ww
DCb 79727 CFE-15 R12-91K
WWVar 71450 AW
01121
01121
01121
01121
80164
01686
01686
01686
EB Rl-680K
EB Rl-270K
EB
EB
Rl-1M
Rl-220K
(1)
(1)
AW
RP34-200
(1)
7009
7009
CFE-15
7070
R95-+e
R95-9<
R12-1K
R93-250K
RP34-1K
>'I Nominal value, factory set. -Refer to paragraph-5-6.
(1) R3023, R3024 and R3926 comprise a matched set, Keithley Part No. 183708
20
20
20
20
13
20
20
20
20
20
20
20
20
13
20
14
20
42
1166R
MODEL 660~ DIFFERENTIAL VOLTMETER
REPLACEABLE PARTS
RESISTORS (Cont'd)
Circuit
Desig.
R3033
R3034
R3035
R3036
R3037
R3038
R3039
R3040 to
R3045
R3046 to
R3056
R3057 to
R3067
R3068 to
R3078
R3079
R3080
Value
Rating
Type
32.33 kc2 O.l%, l/2 w ww
91 kQ
lkn
2.563 kn
930 kfl l%, l/2 w
lb
l%, l/2 w DCb 79727
lO%, 5 w WWar 71450
O.l%, l/2 w ww 80164
DCb 79727
lO%, 5 w WWVar 71450
250.9 n O.l%, l/2 w ww
40 kfl
0.02%, 1 w ww
0.02%, 1 w ww
1.6
kn
320 n
*
750 cl
0.05%, l/2 w ww
O.l%, L/2 w ww
I%, l/2 w DCb 79277
lO%, 4 w
WWVsr 12697
Mfg.
Code
80164
80164
80164
80164
80164
01686
plfg.
Part No.
CFE-15
AW
CFE-15
AW
Keithley
Part No.
(2)
R12-91K
RP34-1K
(2)
R12-930K
RP34-1K
(2)
(3)
(4)
(5)
7044 R67-320
CFE-15 RlZ-Jr
58M RP49-750
Fig.
Ref.
14
14
20
14
14
20
14
13
13
13
13
13
13
VACUUM TUBES
Circuit
Desig.
NUmbCC
Mfg.
Code
VlOOl 7025 73445
v1002 6CM8 00011
v2001 12AU7 73445
v3001 7025 73445
V3002 7025 73445
v3003 7025 73445
v3004 6CM6 00011
v3005 OG3 73445
Keithley
Part No.
EV-7025 17
~v-6cM8 17
EV-12AU7 19
XV-7025 19
EV-7025 19
EV-7025 19
EV-6~~6 19
EV-OG3 19
* Nominal value, factory set.
(2) R3033, R3036 and R3039 comprise a matched set, Keithley Part No. 20019A.
(3) Part of assembly with 53003, Keithley Part No. 18339B.
(4) Part of assembly with S3004, Keithley Part No. 15114B.
(5) Part of assembly with S3005, Keithley Part NO. 15112B.
Fig.
Ref.
1066R
43
REPLACEABLE PARTS
(Refer to schematic Diagram 16321B for circuit designations)
MODEL 660A DIFFERENTIAL VOLTMETER
MODEL 6601A REPLACEABLE PARTS LIST
TERMINALS
Circuit
Desig.
x01
---
J102
J103
Description
Receptacle, hn modified
Plug, hn, Mate of JlOl, Mil No. UG-59A/U (Mfg.
No. 7908)
Binding Post, HI OUTPUT (Mfg. No. DF31RC)
Binding Post, LO OUTPUT (Mfg. No. DF31BC)
Mfg.
Code
80164 cs-79 22
91737 CS-80
58474 BP-8R 22
58474 BP-8B 22
RESISTORS
Circuit Mfg. Mfg.
Desig. Value Rating
RlOl
R102
R103
R104
R105
R106
R107
Rl08
* Nominal value. factnrv Set.
_ ,_... -..-- _---_, _- __.., ___.
2 Mfi
2 Mfi
2 Mfi
2 Ma
2 Mel
200 n
100 kfi
*l kfl
O.l%, 1 w
O.l%, 1 w
O.l%, 1 w
O.l%, 1 w
O.l%, 1 w
lO%, 2 w
O.l%, 1 w
l%,
112
w
TYPO
ww
ww
ww
ww
ww
WWVar
ww
DCb
Code
54294
54294
54294
54294
54294
71450
54294
79727
Part No. Part No. Ref
~116
P116
P116
~116
Pll6
AW
P-36
CFE-15
Keithley Fig.
Part No. Ref.
22
Keithley Fig
R91-2M 22
R91-2M
R91-2M
22
22
R91-2M 22
R91-2M
RP3-200
22
22
R90-100K 22
R12-1K 22
00011 Sylvania Electric Products, Inc.
Buffalo Operations of Sylvania
04009 Arrow-Hart and Hegeman Electric Co
Hartford, Corm.
Electronic Systems
Buffalo, N. Y.
04713 Motorola, Inc.
Semiconductor Products Division
00656 Aerovox Corp.
Phoenix, Arizona
New Bedford, Mass.
05079 Tansitor Electronics, Inc.
01121 Allen-Bradley Corp.
Bennington, Vt.
Milwaukee, Wis.
08520 Electronic Devices, Inc.
01295 Texas Instruments, Inc. North Ridgeville, Ohio
Semi-Conductor-Components Division
Dallas, Texas 08804 Lamp Metals and Components
Department G. E. Co.
01686 RCL Electronics, Inc. Cleveland, Ohio
Riverside, N. J.
12697 Clarostat Mfg. Co., Inc.
02735 RCA Semiconductor and Materials Dover, N. H.
Division of Radio Corp. of America
Somerville, N. J. 13050 potter co.
Wesson, Miss.
TABLE 9 (Sheet 1).
Code List of Suggested Manufacturers. (Based on Federal Supply Code
for Manufacturers, Cataloging Handbook H4-1.)
44
1066R
FR)DEL 660A DIFFERENTIAL VOLTMETER
REPLACEABLE PARTS
14655 Cornell-Dubilier Electric Corp.
Newark, N. J.
15YO9 Daven Co.
Livingston, N. J.
24655 General Radio Co.
West Concord, Mass.
37942 Mallory, P. R., and Co., Inc.
Indianapolis, Ind.
53021 Sangamo Electric Co.
Springfield, Ill.
54294 Shallcross Mfg. Co.
Selma, N. C.
56289 Sprague Electric Co.
North Adams, Mass.
58474 Superior Electric Co., The
Bristol, Corm.
71400 Bussmann Mfg. Div. of
McGraw-Edison Co.
St. Louis, MO.
73445 Amperex Electronic Co. Division
of North American Philips Co., Inc
Hicksville, N. Y.
74970 Johnson, E. F., Co.
Waseca, Minn.
75042 International Resistance Co.
Philadelphia, Pa.
75915 Littelfuse, Inc.
Des Plaines, 111.
79727 Continental-Wirt Electronics Corp.
Philadelphia, Pa.
80164 Keithley Instruments, IX.
Cleveland, Ohio
81483 International Rectifier Corp.
El Segundo, Calif.
82879 Royal Electric Corp.
Pawtucket, R. I.
85599 Tube Department G. E. Co.
Schenectady, N. Y.
71450 CTS Corp.
Elkhart, Ind.
71590 Centralab Division of
Globe-Union, Inc.
Milwaukee, Wis.
72982 Gudeman Co.
Chicago, 111.
TABLE 9 (Sheet 2).
for Manufacturers, Cataloging Handbook H4-1.)
Code List of Suggested Manufacturers.
91637 Dale Electronics, Inc.
Columbus, Nebr.
91737 G.remar Mfg. Co., Inc.
Wakefield, Mass.
(Based on Federal Supply Code
1066R
45
I II
!-
z
i
I
L
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