INSTRUCTION MANUAL
MODEL 300
ELECTROMETER
OPERATIONAL AMPLIFIER
MODEL 300 OPERATIONAL AMPLIFIER
TABLE OF CONTENTS
TABLE OF CONTENTS
Section
1. GENERAL DESCRIPTION . . . . . . . . 1
l-l.
l-2.
l-3.
l-4.
1-5.
l-6. Equipment Shipped . . . ,. . . 3
2. OPERATION . . . . . . . . . . . . . 5
2-l. Terminals . . . . . . . . . . 5
2-2.
2-3. power supply . . . . . . . . 6
2-4.
2-5. Output Connections . . . . . 8
2-6.
2-7.
2-E.
2-9. Current Integrator or
2-10. Impedance Matching Amplifier 15
2-11. Voltage Amplifier . . . . . . 17
2-12. Other Modes of Operation . . 18
2-13. Stability, Frequency Response,
Z-14. Remote Zero Control . . . . . 19
2-15. Connections and Use of
General . . . . . . . . . . . 1
Features . , . . . . . . . . 1
Specifications . , . . + . . 2
Operating Modes : , . . , . . 3
Accessories . . . . . . I . . 3
Mounting Instructions . . . 5
Input Connections . . . , . . 7
Modes of Operation . . . . . 8
Linear Current Amplifier . . 10
Logarithmic Current Amplifier 12
Charge Amplifier . . . . . . 14
Andy Oscillation . . . . . . 18
Reference Voltages . . . . . 20
Page
Section
MAINTENANCE . . . . . . . . . . . 23
4.
4-l.
4-2.
4-3.
4-4. Troubleshooting . . . . . . . 24
4-5.
4-6.
4-7.
ACCESSORIES . . . . . . . . . . 29
5.
5-l.
5-2.
6.
REPLACEABLE PARTS . . . . . . . . . 35
6-l. Replaceable Parts List . . . 35
6-2. How to Order Parts . . . . . 35
General . . . . . . , . . 23
Maintenance Schedule . . . . 23
Parts Replacement . . . . . 23
Troubleshooting Positive and
Negative Power Supply
Regulators . . . . . . . . . 25
Troubleshooting the Amplifier 26
Calibration . . . . . . . . . 26
Model 3012 Power Supply . . , 29
Model 3011 Shielded Switch . 31
Model 300 Replaceable
Parts List . . . . . . :. 36
Model 3012 Replaceable
Parts List . . . . . . . . 38
Model 300 Schematic
Diagram 195581) . . , . . . 4.1
Model 3012 Schematic
Diagram 20351B . . . . . . 43
Page
CIRCUIT DESCRIPTION . . . . . . . . 21
3.
3-l. General . . . . . . . . . . . 21
3-2. Electrometer Input . . . . . 21
3-3. &lid State
Differential Amplifier . . . 21
3-4.
3-5.
0167R
Positive Pkvar Supply
Regulator . . . . . . . . . 22
Negative Power Supply
Regulator . . . . . . . . . 22
* Change Notice , . . . . . . . .Last Page
* Yellow Change Notice Sheet is included
only for instrument modifications
affecting the Instruction Manual.
i
MODEL 300 OPERATIONAL AMPLIFIER
GENERAL DESCRIPTION
GENERAL DESCRIPTION
sing&-end-
lo-
l-l.
GENERAL.
a.
The Keithley Model 300 Electrometer Operational Amplifier is a compact,
ed amplifier.
SECTION 1.
It has greater than 1014 ohm input resistance and less than 5 x
ampere current offset. Its current drift is less than lo-l5 ampere/24 hours and its current noise is less than 5 x LO-l5 ampere peak-to-peak.
Primarily a current amplifier, the
Model 300 will operate with signals from LO-l4 to 10T2 ampere.
b.
Open
C.
The Model 300 is completely solid state except for the input stage.
input tubes are used because they have less noise, better
loop
dc voltage gain is 20,000; output is fll volts, 11 milliamperes.
stability,
Electrometer
and are less sensi-
tive to voltage transients than other high impedance devices now available.
l-2. FEATURES.
a. The Model 300 will operate from inexpensive power supplies or batteries.
ted supplies with outputs from +16
to
125 volts and -16 to -25 volts will power the Model
Unregula-
300. The Amplifier Will also operate from standard 15-volt regulated supplies.
An internal zero control is built into the Model 300.
b.
In addition, a potentiometer
can be connected externally to allow remote zeroing.
c. A regulated reference or polarizing potential of ~13.5 volts at 1 milliampere is
available.
d. Electrostatic and electromagnetic
shields are provided to insure minimum pick-
Therefore, input and feedback elements
UP.
can be mounted within the Model 300 case
with complete shielding.
e.
The Model 300 withstands input over-
loads up to 2400 volts and will not be dam-
aged by induced static voltages with the
input open.
f.
An internal compensation network
greatly reduces the possibility of oscil-
lation regardless of external circuitry.
The Amplifier is constructed on a
g.
3-l/2 inch by 4 inch prip.ted circuit board
that forms a 15-terminal card-edge connector.
coaxial connector,
The input is a Teflon-insulated
Space and mounting ter-
minals are provided for internally mounting
input,
dances.
feedback and output dividing impe-
FIGURE 1. Keithley Instruments Model 300
Electrometer Operational Amplifier.
0566R 1
GENERAL DESCRIPTION
MODEL 300 OPERATIONAL AMPLIFIER
l-3.
DC VOLTAGE GAIN,, OPEN LOOP:
INPUT CHARACTERISTICS:
FREQUENCY CHARACTERISTICS:
SPECIFICATIONS (Measured at 250C).
Unloaded:
lOOO-ohm load: Greater than 12,000.
Resistance:
Capacitance: Less than 10 picofarads.
Current Offset:
Drift: Less than lo-l5 ampere/24 hours.
Temperature Coefficient: Less than LO-15 ampere/OC.
Voltage Offset: Adjustable to zero.
Drift: Less than 500 microvolts/hour averaged over any 24-hour period after two-'
hour warm-up.*
Temperature Coefficient:
Input Voltage Noise:
(0.1-10 cps): Less than 5 microvolts rms.
(10 cps-100 kc): Less than 5 millivolts rms.
Current Noise (0.1-10 cps): Less than 5 x LO-15 ampere peak-to-peak.
Overload Limit: ?400 volts.**
Closed Loop Unity Gain, Small Signal: dc to 100 kc (-3db).
Slewing Rate: l'voltfmicrosecond minimum.
Gain Bandwidth Product: Greater than 150 kc.
Rolloff:
Greater than 20,000.
Greater than 1014 ohms.
Less than 5 x LO-l4 ampere.
Less than 500 microvoltsf°C.*
Approximately 6 db/octave.
OUTPUT:
Amplifier: rll volts at 11 milliamperes.
Reference Voltage:
input.
OPERATING TEMPERATURE: 0 to 5O'C.
CONNECTORS: Input: push-on coaxial receptacle, Amphenol 2175. All other connections:
15-terminal l/16 inch card-edge.
POWER REQUIREMENTS:
+16,to +25 volts unregulated, 35 milliamperes plus output current;
-16 to -25 volts unregulated,
Note: Model 300 will also operate to specifications with standard 15-volt fO.l%
regulated power supplies.
DIMENSIONS, WEIGHT:
13 ounces.
ACCESSORIES SUPPLIED: Mating card-edge connector and Teflon-insulated coaxial input
connector with shield (chassis mounting).
*With 100% feedback this drift as a percent of full output is less than O.O05%/hour (or/OC,)
*with a LO5 ohm or greater feedback resistor without a shunting capacitor.
several hours to recover to specified drift with severe overload.
+13.5 volts at 1 milliampere, regulated to *O.l% for 10% change in
8 milliamperes plus output current.
3-l/2 inches high x 4 inches wide x l-1/2 inches deep; net weight,
May require
2
0466R
MODEL 300 OPERATIONAL AMPLIFIER GENERAL DESCRIPTION
l-4.
veniently used in a number of operating modes:
current amplifier, current integrator and charge amplifier.
OPERATING MODES. The Model 300 is primarily a current amplifier.
linear current amplifier, logarithmic
Section 2 describes these and
It can be con-
other operating modes for the Model 300.
1-5. ACCESSORIES (See Section 5.)
Model 3011 Sheilded Switch can be used with the Model 300 where range switching is
a.
required. The Switch is a 3-pole, &position, adjustable stop switch. The Model 3011 is
constructed for low leakage and to provide shielding for the components.
Refer to Section
5 for complete description.
b. Model 3012 Power Supply is designed to power 1,2 or 3 Model 300s.
The Model 3012
delivers positive and negative outputs between 16 and 25 volts, which fill all the power
requirements of'the Model 300. The Power Supply can be floated up
to
500 volts off
chassis ground.
High megohm resistors are available for using'in the Model 300.
c.
These resistors may
be mounted internally within the Amplifier or in the Model 3011 Shielded Switch. The
values available are:
1. Model R20-109 High Megohm Resistor; log ohms +3%.
Model R20-lOlo High Megohm Resistor; 1010 ohms *3%
2.
Model R20-10'1 High Megohm Resistor; LOLL ohms ?3%.
3:
4. Model R20-lQl* High Megohm Resistor; 101' ohms ?3%.
Model R2O-10L3 High Megohm Resistor: 1013 ohms rlO%.
5.
1-6. EQUIPMENT SHIPPED.
open loop opefational amplifier.
Feedback and input resistors are not included.
The Model 300 is shipped factory calibrated and connected as an
The built-in zero potentiometer (R112) is connected.
Shipped with the Model 300 is a mating 15
terminal card-edge connector, and Teflon insulated input connector with shielding hood.
06678
3
OPERATION
MODEL 300 OPERATIONAL AMPLIFIER
Pin No.
Designation
INPUT INPUT
1
ALT. INPUT
2 GUARO
3 B
4
A
5 -REF
6 -16V to -25V
7 ---
8 OUTPUT
9
10
+REF
+16V to t25V
11 --12 ---
13
C
14 FEEDBACK
15 GROUND
Description Paragraph
Teflon Insulated Coaxial Input
May be used for large signals
Used with ALT. INPUT
For remote mounting zero control
For remdte mounting zero control
Negative Reference Voltage (-14 volt output)
Negative Voltage Supply Input
Not used
Output
Positive Reference Voltage (+13.5 volt output)
Positive Voltage Supply Input
Not used
Not used
For remote mounting zero control
For fractional feedback
Circuit Ground
TABLE 1. Model 300 Terminal Explanation.
Zero Adjust
(Rll2)
Reference
2-4
2-4
2-4
2-14
2-14
2-15
2-3
---
2-5
2-15
2-3
---
---
2-14
2-7
2-4
FIGURE 2.
terminals.
4
Model 300 Terminal Designations. Kerer to Table 1 tar explanation or the
0666R
MODEL 300 OPERATIONAL AMPLIFIER
~~~e~~~~~~~~~,i
OPERATION
SECTION 2.
2-l.
The 15-terminal card-edge is used for all other connections. The mating connector for
the 15-terminal card-edge is keyed to prevent improper insertion.
Table 1 for terminal identification and explanation.
2-2.
in a convenient location within a system.
Part No. CS-175-15) and shielded input mating connector (Keithley Part No. CS-179) with
the hooded shield (Keithley Part No. W-180) to a surface. Then plug the Model 300 into
the mating connectors. This mounting is acceptable for all positions except when the
mating connectors are above the Amplifier. Then, it may be necessary to use a bracket
or similar device to hold the Model 300.
TERMINALS.
MOUNTING INSTRUCTIONS.
a. The Model 300 is designed for use in various measurement systems. It easily mounts
b. To mount the Amplifier, attach the furnished card-edge mating connector (Keithley
c. Mounting the mating connectors CS-179 and CS-175-15. (See Figure 3 for dimensions.)
1. Select the desired surface for mounting.
The Model 300 input connector is a Teflon-insulated coaxial receptacle.
OPERATION
Refer to Figure 2 and
' 2. Drill two l/B-inch diameter holes 2-15/16 inches apart to mount the mating 15-
terminal card-edge connector.
3. Drill the 21/64,-inch diameter hole for the mating coaxial
to Figure 3 for exact positions.)
4,. Cut out 2-7116 inch x 3/B-inch plot in chassis.
r-
3-1/411
-
input connector.
(Refer
I
Mating Connector Outline
21/64" Dia.
for Coaxial Connector
FIGURE 3. Mounting Hole Diagram.
Keithley Part Nos. CS-175-15 and CS-179.
0167R
This gives dimensions for mounting
mating connectors,
5
OPERATION
Fasten the connectors in their proper positions.
5.
Attach the Model 300 to its mating connectors.
6.
The terminals of the mating connectors correspond exactly to,the terminals of the
d.
Model 300 shown in Figure 2.
and CS-175-15 is the mating connector for the card-edge connector.
2-3. POWER SUPPLY.
a. The instantaneous value of the supply voltages must be between 16 and 25 volts.
For example, even a power supply whose value varies
only exception is that a power supply with as low as a 15-volt output regulated to 0.1%
can be used. Connect the positive supply
to the +16V to +25V Terminal (pin 10,
Figure 2).
to the -16V
ure 2).
The Model 300 can operate from unre-
b.
gulated power supplies whose minimum instantaneous output falls below 16 volts.
However, the positive reference output must
be set below the normal 13.5 volts by ad-
justing the Regulator Adjust Potentiometer,
R209, (Figure 22). For example, to use a
power supply with a 15-volt minimum output,
set the positive reference output to 12.5
volts. Reducing the 13.5 volts of the
positive reference output reduces the max-
imum Amplifier output voltage by a 1:l
ratio; that is, reducing the reference
output one volt reduces the maximum output
voltage one volt.
R209 is not necessary for 15-volt supplies
with 0.1% regulation.
The graph in Figure 4. shows where the
C.
Model 300 operates satisfactorily. Re-
liable operation is obtained wherever the
slope of the positive reference output
voltage versus the supply voltage is approx-
imately 2 millivolts per volt or less.
Reliable operation is also obtained wherever
the slope of the negative reference voltage
output versus the supply voltage is approx-
imately 20 millivolts per volt or less.
The Keithley Model 3012 Power Supply
d.
provides all the power necessary to drive
up to 3 Model 300s (See Section 5). Or,
a power supply can be constructed using
the circuit shown in Figure 5.
Connect the negative supply
to
-25V Terminal (pin 6, Fig-
Adjusting potentiometer
CS-179 is the mating connector for the INPUT Receptacle,
from
FIGURE 4,.
Voltages for the Model 300. The Model 300
will operate satisfactorily for a given
supply voltage and reference output as long
as the slope of the curve is approximately
2 millivolts/volt. As long as the voltage
is between 16 and 25 volts, no adjustment
is necessary. For instantaneous voltages
below 16 volts,
ence voltage to remain within the zone of
reliable operation.
potentiometer R209,
output,
gulated power supply whose instantaneous
voltage falls to 15 volts.
apply for the negative supply voltage. The
only variation is that the slope is approx-
imately 20 millivolts/volt.
MODEL 300 OPERATIONAL AMPLIFIER
16 to 25 volts can be used.
Allowable Unregulated Supply
reduce the positive refer-
For example, adjust
the positive reference
to 12.5 volts when using an unre-
Similar curves
The
?
6
0167R
MODEL 300 OPERATIONAL AMPLIFIER
e. Change the positive reference output
by measuring the output at pin 9 with the
Keithley Model 153 and adjusting potentiometer R209 (Figure 22).
2-4.. INPUT CONNECTIONS.
a. Normally all input signals should be
through the INPUT Receptacle.
It is specially insulated and shielded to minimize
noise which will distort the input signal.
b. For high impedance measurements,
carefully shield the input connection and
the source being measured, since power line
frequencies are well within the pass band
of the Amplifier. Unless the shielding is
thorough, any alteration in the electrostatic field near the input circuitry will
cause extraneous signals to appear at the
output.
OPERATION
:
Circuit of a Power Supply for the
Model 300. Keithley Part No. TR-78 can be
used as the transformer in the circuit.
c. Use high resistance, low-loss materials - such as Teflon (recommended) and polyethylene - for insulation. The insulation leakage resistance of test fixtures and leads
should be several orders magnitude higher than the internal resistance of the source. If
it is not, leakage losses will cause inaccurate readings. Coaxial cables used should be
a low-noise type which employ a graphite or other, conductive coating between the dielectric and the surrounding shield braid.
Amphenol-Borg Electronics Corporation, Microdot,
Inc., and Simplex Wire and Cable Company make satisfactory types.
NOTE
Clean and dry connections and cables are very important to maintain the value
of all insulation materials. Use pure CH30H methyl alcohol to clean Teflon
insulation.
d. Any change in the capacitance of the measuring circuit to ground will cause extraneous disturbances.
ing cables to prevent their movement.
at the output as a signal;
Make the measuring setup as rigid as possible, and tie'down connect-
If a continuous vibration is present, it may appear
other precautions may be necessary to isolate the instrument
and the connecting cable from the vibration.
NOTE
Unless otherwise specified all instructions in this manual are for input signals
through the INPUT Receptacle.
e. If it .is more convenient,
larger input signals.
come less effective.
Note that input leakage current may increase and shielding will be-
However,
the ALT. INPUT Terminal (pin 1, Figure 2) can be used for
the input tape will still remain guarded.
the INPUT Receptacle to the card-edge ALT. INPUT:
Remove jumper Q-R (Figure 6).
1.
0167R
To change from
7
OPERATION
Connect terminal R to hole P (Figure 6) located,at the end of the ALT. INPUT tape.
2.
NOTE
Do not use the GUARD Terminal for GROUND, even though GUARD and GROUND are shown
connected in the schematic diagram.
The Model 300's input overload limit of f400 volts is for LO5 ohms or greater feed-
f.
back impedance.
feedback currents.
feedback impedance is acceptable.
pendent upon frequency. As frequency increases, impedance is reduced:
This ensures that the output stage will not be damaged by large transient
Any combination of resistance and capacitance with 105 ohms minimum
However, when using a capacitor, the impedance is de-
Severe ground loops may result.
MODEL 300 OPERATIONAL AMPLIFIER
1
zc = 2nfC
where ZC is the impedance in ohms;
f is the frequency in cps;
c is the capacitance in farads.
equation 1
Therefore,
greatly and the impedance decreases.
than 105 ohms.
2-5. OUTPUT CONNECTIONS.
a. The output voltage is through the OUTPUT Terminal (pin 8, Figure 2). Almost any
means of looking at the output voltage can be employed as long as the load on the output
is not less than 1000 ohms.
Excessive capacitance loading at the output (usually greater than 1000 picofarads) will cause oscillation.
pensation elsewhere in the circuit (paragraph 2-13).
Output overload protection is provided for the Model 300. Thus a temporary direct
b.
short to ground at the output is harmless.
with the Model 300 in a saturated or near saturated state, may damage the Amplifier.
2-6.
through simple adjustment of its circuitry. Paragraphs 2-7 through 2-12 describe the con-
struction and use of several of the modes.
each operating mode.
MODES OF OPERATION.
The Model 300 Operational Amplifier can be used in many different modes of operation
a.
if spikes or steps are present in the overload signal, the frequency increases
In this situation the feedback impedance is less
This can usually be stabilized through com-
However, extended periods of shorted output,
Refer to Table 2 for the paragraph describing
The Model 300 can be used in these different operating modes through the mounting
b.
of various elements in the feedback and input circuits.
within the Model 300 case with complete shielding. To connect multiple feedback or input
elements, use the Model 301lShielded Switch. The mode of operation is determined by the
type of component used and where it is placed in the circuit.
8
The components can be mounted
0666R
.~
MODEL 300 OPERATIONAL AMPLIFIER
OPERATION
FIGURE 6.
Within Model 300.
Circuit Points
Points are
used to construct various circuits referred to in Figures
8 through 15.
aegulaCar
I
H-
Ad,“It J
FIGURE 7.
Circuit Points
Within Model 300. Points ax
used to construct various
circuits referred to in Fig-
ures 8 through 15.
0666
E-
K-
OPERATION
MODEL 300 OPERATIONAL AMPLIFIER
Operating Mode
Linear Current Amplifier Without Fractional Feedback
Linear Current Amplifier With Fractional Feedback
Logarithmic Current Amplifier
Current Integrator or Charge Amplifier
Impedance Matching Amplifier 2-10
Voltage Amplifier Without Fractional Feedback 2-11
Voltage Amplifier With Fractional Feedback 2-11
Other Circuits 2-12
TABLE 2.
c.
minals in these figures refer to the lettered points in Figures 6 and 7.
figures to connect jumpers and to mount elements.
d.
voltage for no input signal. There is a hole in the cover (Figure 2) enabling this adjustment to be made without removing the cover. Refer to paragraph 2-14 for other adjustments.
2-7. LINEAR CURRENT AMPLIFIER (Figures 8 and 9).
a.
amplifier.
input current.
Model 300 Operating Modes and Paragraph Describing the Modes.
Figures 8 through 15 illustrate the various modes of operation.
Adjusting the Zero Adjust Potentiometer, R112 (Figure 7), sets the output to zero
Placing a resistor in the feedback loop converts the Model 300 to a linear current
The output voltage depends on the magnitude of the feedback resistor and the
Paragraph
2-7
2-7
2-8
2-9
The lettered ter-
Ref.er to the
"out = -Iink
where Vout is the output voltage in volts;
Ii,, is the input current in amperes;
Rfb is the feedback resistance in ohms.
For a given iriput current the output voltage can be chosen by selecting the, feedback resistor, Rfb,
resistor accessories), V,ut can be as much as fll volts.
sible results in a better signal-to-noise ratio at the output.
Using fractional feedback increases the output voltage gain although drift and noise
b.
also increase. Fractional feedback is useful for amplifying different current levels
while using only one high megohm resistor in the feedback loop.
Be careful when handling the high megohm resistors,
the ends of the leads; do not touch the glass.
resistor value,
Connections for a linear current amplifier without a fractional feedback (Figure 8):
=.
1. Connect ,jumpers across terminals Q-R, R-S,
By using the largest possible feedback resistor (such as the high megohm
Keeping V,,t as large as pos-
Hold these resistors by
Contamination will change the
S-D, E-H, and H-J (Figures 6 and 7)
equation 2
10
0666R
MODEL 300 OPERATIONAL AMPLIFIER
OPERATION
FIGURE 8.
out Fractional Feedback.
The Model 300 is shipped from the factory in the linear current amplifier mode
minus the element in the feedback loop.
connected across terminals Q-R, R-S, S-D, E-H and H-J.
2. Remove any element of jumper from across E-K (Figure 7).
3. Mount the feedback resistor, Rfb,
4. The output voltage for the Model 30.0 as a linear current amplifier without a
fractional feedback is given by equation 2.
d. Connections for a linear current amplifier with a fractional feedback (Figure 9):
1.
2. Mount the feedback resistor, Rfb,
3. Mount fractional resistors Rl
respectively.
Linear Current Amplifier With-
---
Connect jumpers across terminals Q-R, R-S, S-D and E-H (Figures 6 and 7).
and R2 (Figure 9) across terminals J-H and H-K
FIGURE 9. Linear Current Amplifier With
FractionaL Feedback.
NOTE
Therefore it is shipped with jumpers
in the feedback loop across terminals D and E.
--
in the feedback loop across terminals D and E
4. The output voltage for the Model 300 as a linear current ampiifier with fractional
feedback is
v
= -IinRfb
out
where V,ut is the output voltage in volts;
Iin is the.input current in amperes;
Rfb is the feedback resistance in ohms;
Rl and R2 are the divider resistances in ohms.
NOTE
The current through fractional resistors R1
that through the feedback resistor, Rfb,
R1 + R2 should be greater than 1 kilohm so as not to overload the output.
0766R
and R2 should be much greater than
to maintain proper amplification. Also,
equation 3
11
OPERATION
Feedback
Resistor
1olOn
1olCn
MODEL 300 OPERATIONAL AMPLIFIER
1012Sl
101*sl
% Feedback
Output Voltage
Input current
Resolution
100%
10%
10 v 10 v
10-9 amp 10-10 amp
10-11 imp 10-12 amp
100%
10 v
10-11 amp
10-13
amp
10%
10 v
10-12
amp
10-14 amp
Current Offset,
% of output
0.005%
0.05%
0.5%
5%
Drift/Hour
% of output
Ovserved Rise Time
,
0.005%
10 msec
0.05% 0.005%
20 msec
200 msec
0.05%
300 msec
TABLE 3. Typical Performance Values for the Model 300 Used as a Linear Current Amplifier.
Offset, drift and rise time are affected by the circuit used, but the above table shows
some of the Model 300's capabilities.
3;
100% is
e.
with
no fractional feedback.
To mount the divider outside the Model 300, do the following:
---
1. Connect jumpers across terminals Q-R, R-S,
"% Feedback" refers to fractional feedback equation
--- -S-D and E-H (Figures 6 and 7).
2.
Remove all elements from.J-H and H-K.
3. Mount the feedback resistor, Rfb,
in the feedback loop across terminals D and E.
Connect FEEDBACK (pin 14, Figure 2) or terminal H to the center of an external
dizider. (T
5. Connect one end of the divider to OUTPUT (pin 8, Figure 2) or terminal J.
minal 3 is connected to OUTPUT).
2-a.
LOGARITHMIC CURRENT AMPLIFIER (Figure 10).
erminal H is connected to FEEDBACK).
(Ter-
(See NOTE paragraph 2-7d).
a. Silicon diodes or transistors in the feedback loop make the Model 300 a logarithmic
current amplifier.
The log characteristic of the element used determines the amplifier
performance. lN459 diodes and silicon transistors usually provide 7 to 9 accurate decades.
The leakage current of the element should be at least two magnitudes less than the current
being measured.
b. The circuit for the logarithmic current amplifier is shown in Figure 10.
cuit uses a single diode and is for positive currents.
V
= -A log Iin
out
The output voltage is:
This cir-
equation 4
where Vout is the output voltage in volts;
Iin is the input current in amperes;
A is a positive constant, dependent upon the characteristic of the diode.
12
0766R
MODEL 300 OPERATIONAL AMPLIFIER
Amplify negative currents by reversing the diode polarity. Measure both positive and
negative polarities by mounting the diodes in parallel and in opposite directions in the
feedback circuit.
1. Adding diodes in series increases A. Therefore, Vout increases for a given input
current.
percentage of the output voltage.
2. Fractional feedback increases A and thus increases the output voltage, Vout.
However, this method increases the drift proportionally as the output is increased.
The proportionality constant, A, is increased by the amount (Rl + R2)/R2. Rl and R2
are the fractional feedback resistors as shown in Figure 9.
fractional feedback, see paragraphs 2-7d and 2-7e.
To zero the output,
c.
and the output is required. This variable voltage can be achieved by use of a biasing
network in the feedback loop.
parallel with a battery.
and the output.
Connect the Model 300 as in paragraph 2-8e except that any element or jumper should be
removed from H-J. Adjusting the potentiometer will select the required voltage drop needed to zero the output.
around this network must be much greater than the current through the diode in the feed-
back loop.
This approach reduces the effect of drift, since the drift becomes a smaller
Altering the circuit changes the value of A.
For construction of the
a variable voltage between the log element in the feedback loop
The biasing network should consist of a potentiometer in
Mount this network externally in series between the log element
The log element is available at the FEEDBACK Terminal (pin 14, Figure 2).
The only requirement of the biasing network is that the current
OPERATION
d. Silicon transistors are also useful as log elements and they have better response
speed.>\ Using the basic circuit of Figure 10, positive currents can be amplified by using
an NPN transistor in the feedback loop. Negative currents can be amplified by using a
PNP transistor in the feedback loop. In both operations the base of the transistor can
either be connected to the collector of the transistor or to ground. Connect the collector
to the input and the emitter to the output.
NOTE
For further information send for the Keithley Product Note “Using the Model 300
Operational Amplifier as a Logarithmic Current Amplifier.”
e. Connections for the Model 300 as a logarithmic current amplifier (Figure 10):
1. Connect jumpers across terminals Q-R, R-S,
2. Remove any element or jumper from H-K
3. Mount the logarithmic elements in the feedback circuit as needed to amplify posi-
tive or negative input currents.
4. The output voltage for the Model 300 as a logarithmic current amplifier is given
by equation 4.
-----S-D, E-H and H-J (Figures 6 and 7).
Figure 10 shows a diode mounted for positive currents,
g:For more information on Silicon transistors used as log elements see “A Circuit With
Logarithmic Transfer Response Over 9 Decades”, by J. F. Gibbons and H. S. Horn, IEEE
Traxactions on Circuit Theory, September, 1964.
0766R
13
OPERATION
MODEL 300 OPERATIONAL AMPLIFIER
IGURE 10.
Logarithmic Current Amplifier
Diode shown for positive currents
z-,9.
feedback circuit.
CURRENT INTEGRATOR OR CHARGE AMPLIFIER (Figure 11).
The current integrator mode and the charge amplifier mode use capacitors in the
a.
These two modes are essentially the same,
FIGURE 11.
Amplifier.
Current Integrator or Charge
the only difference being in
their purpose.
Connections for the Model 300 as a current integrator or charge amplifier (Fiwre 11):
b.
connect jumpers across terminals Q-R,
1.
R-S, S-D, E-H, and H-J (Figures 6 and 7).
2. mount a capacitor in the feedback c.ircuif between terminals D and E.
The output voltage for the
3.
v
out
as a current integrator is
Iin dt
where V,,t is the output voltage in volts;
Iin is the input current in amperes;
Cfb is the feedback capacitance in farads.
equation 5
The output voltage for the Model 300 as a charge amplifier is
4.
where Vout
Q is the applied charge in coulombs;
Cfb is the feedback capacitance in farads;
Iin is the input current in amperes;
t is the time in seconds.
An output divider network can be mounted as described in paragraphs 2-7d and 2-7e.
14
OUt = p = Iint
V
Cfb Cfb
is the output voltage in volts;
equation 6
NOTE
0666R
MODEL 300 OPERATIONAL AMPLIFIER
OPERATION
FIGURE 12. Impedance Matching Unity-Gain
Amplifier.
Z-10.
IMPEDANCE MATCHING AMPLIFIER (Figures 12 and 13).
a.
The Model 300 is an excellent impedance matching amplifier. This mode requires no
-- __.- - .^ _ . .._
FLti”KE LJ.
mpedance Matcnrng AmpLitier
with Divided Output.
elements in the feedback circuit. Use the Amplifier in this mode either for unity gain
or to obtain voltage gain. Achieve voltage gain using an internal or external dividing
network on the output (Figure 13). Use the Model 300 as an impedance matching amplifier
only with a floating power supply or a floating signal source from LO millivolts to LL
volts.
Insulate the Model 300 input connector in this mode.
b. Exercise care in grounding when using the Model 300 as an impedance matching ampli-
fier .
For the unity-gain amplifier (Figure 12): if the Low side of the signal source is
1.
grounded,
then the high side of the output is grounded. Therefore, the power supply
must be floating if the signal source is not.
For an amplifier with voltage gain (Figure 13):
2.
if the signal source is floating,
the power supply need not be floating. If the signal source is grounded, both the power
supply and the output monitoring deivce must float.
The Keithley Model 3012 Power Supply meets the floating requirements of the Model
3.
.300 (See Section 5). Also available for insulated mechanical support of the Models 300
or 3012 is the Model 3013 Insulated Hold-Down Bracket.
c. Connections for the Model 300 as an impedance matchinp amplifier (Figure 12):
------
1. Connect a power supply to the Model 300 (see paragraph Z-3).
2. Connect jumpers across terminals Q-R,
R-S and S-D (Figures 6 and 7).
3. Remove all elements from D-E, H-K and H-J.
4. Apply the signal between INPUT and OUTPUT. Monitor the output between OUTPUT and
GROUND.
0667R
15
OPERATION MODEL 300 OPERATIONAL AMPLIFIER
The output voltage for the Model 300 as an impedance matching amplifier is
5.
where Vout
"in
Connections for the Model 300 as an impedance matching amplifier with a. divided
d.
output (Figure 13):
1.
2.
3.
4..
5.
and GROUND.
6.
divided outwt is
is the output voltage in volts;
is the input voltage in volt?,.
Connect a power supply to the Model 300 (see paragraph 2-3).
Connect jumpers across terminals Q-R, R-S, S-D and E-H (Figures 6 and 7).
Remove all elements from D-E.
Mount,divider resistors across J-H and H-K.
Apply the signal between INPUT and FEEDBACK.
The output voltage for the Model 300 as an impedance matching amplifier with a
v
-- ---- --
= Vi* equation 7
out
Monitor the output between OUTPUT
equation 8
where Vout is the output voltage in volts;
Vi,, is the input voltage, in volts;
Rl and R2 are the divider resistances in ohms.
NOTE
The sum of the resistances of Rl and R2 must be at least 1 kilohm. The current
through Rl and R2 must be much greater than the grid current of the Amplifier.
IGURE 14.. Voltage Amplifier Without E
tional Feedback.
16
IGURE 15. Voltage Amplifier With Frac-
tional Feedback.
0167R
MODEL 300 OPERATIONAL AMPLIFIER
OPERATION
Z-11.
back resistor.
(equation 9).
source resistance to minimize loading the source.
in this mode is now the value of the input resistor, Rin.
(Figure 14~):
where V,ut
VOLTAGE AMPLIFIER (Figures 14, and 15).
a. As a voltage amplifier,
The ratio of the feedback and input resistors determines the voltage gain
Use an input resistor whose value is more than 100 times greater than the
Connections for the Model 300 as a voltage amplifier without 2 divided feedback
b.
1. Connect jumpers across terminals Q-R,
Mount feedback resistor, Rfb,
2.
Mount an input resistor, Rin, across terminals R-S.
3.
The output voltage for the Model 300 as a voltage amplifier without a divided
4..
feedback is
is the output voltage in volts;
is the input voltage in volts;
is the feedback resistance in ohms;
in is the input resistance in ohms.
the Model 300 uses an input resistor in addition to a feed-
The input resistance of the Model 300
----
S-D, E-H and H-J (Figures 6 and 7).
across terminals D-E in the feedback circuit.
v
out
equation 9
Connections for the Model 300 as a voltage amplifier with fractional feedback
c.
iFigure 15):
1. Connect jumpers across terminals Q-R, S-D and E-H (Figures 6 and 7).
Mount feedback resistor, Rfb, across terminals D-E in the feedback circuit.
2.
Mount input resistor, Rin, across terminals R-S.
3.
4,. Mount divider resistors, Rl and R2,
The output voltage for the Model 300 as a voltage amplifier with fractional feed-
5.
back is
where V,ut is the output voltage in volts;
Vin is the input voltage in volts;
Rfb is the feedback resistance in ohms;
Rin is the input resistance in ohms;
Rl and R2 are the divider resistances in ohms.
------
xtoss terminals J-H and H-K respectively
V
out = -"in ( z)(R1 z:)
equation 10
The current through fractional resistors Rl and R2
that through the feedback resistor, R
Also, Rl + R2 should be greater than kllohm so as to not overload the output.
0167R
to maintain proper amplification.
fb '
should be much greater than
17
OPERATION MODEL 300 OPERATIONAL AMPLIFIER
2-12.
the Model 300 can be used. These modes use basically the same circuit construction. The
main difference is the feedback element. Alterations permit many more uses with the Model
300. Some of these possibilities are as voltage integrator, voltage differentiator,
current differentiator, adder,
2-13.
a. A logarithmic plot of an amplifier's dc voltage gain versus the frequency is known
as a Bode plot.
the amplifier is unconditionally stable. An amplifier is conditionally stable when the
roll off is between 6 db/octave and 12 db/octave.
fore, will oscillate when its Bode plot rolls off at greater than 12 db/octave.
b. The Keithley Model 300 is a very stable amplifier. The Bode plot of the Model 300
approaches the ideal 6 db/octave through use of an internal roll-off network that sta-
bilizes the amplifier. If the Model 300 did not have a roll-off network, its Bode plot
would be similar to the many segmented dotted curve shown in Figure lb.
completely random at&uncontrollable. HOWeVer,
cuts off the high frequency response (moves the slope line to the left). Thus,
on the natural roll-off curve (dotted line) will never occur.
variables present, this 6 db/octave may not be present in every application.
C. The frequency bandwidth of the Model 300 is narrowed,
The gain-bandwidth product for a stabilized amplifier is 150 Kc, while for the unstabili-
zed amplifier it is about 1 MC. HOWeVer, a minor adjustment in the roll-off network can
increase the frequency response in the Model 300. In general, increasing the resistance
and decreasing the capacitance of the roll-off network (resistor R103, Figure 22, and
capacitor C102, Figure 23) will increase the frequency response, although it will also
decrease the stability of the amplifier.
OTHER MODES OF OPERATION.
STABILITY,.FRGQUENCY RESPONSE, AND OSCILLATION.
When the slope of the Bode plot of an amplifier rolls off at 6 dbloctave,
The preceding paragraphs describe several modes in which
open loop voltage comparator, and others.
An amplifier is unstable and, there-
This curve is
the Model 300's internal roll-off network
operation
However, due to the many
thus improving its stability.
d. Additional stability results from placing a very small damping capacitor (3 to 10
picofarads) across the feedback element.
reducing overshoot of square waves and reducing noise. However,
of reducing frequency response and increasing rise time.
6
dbloctave
This can be useful for stopping oscillation,
this also has the effect
1
A
Frequency
IGURE lb. Bode Plot for Model 300.
1 Mcps
'lc.URc. L,. nemore I",OUnLe(L ‘era L"ncrOI.
Letters refer to terminals in Figure 2.
B
18
0167R
MODEL 300 OPERATIONAL AMPLIFIER
OPERATION
A
FINE
I
COURSE
PANEL
FINE
C
10K
Rl12 INTERNAL
COURSE
B
d
A
A
iGURE 18.
Zero Control.
in Figure 2.
2-14..
The Zero Adjust Potentiometer, R112, is accessible without removing the cover. A
a.
simple modification
locating a zero control in a more convenient place or improving zeroing resolution.
ternal zeroing is possible with several circuits:
internal control; using the external control for fine zeroing and the internal control
for coarse zeroing; using external fine and coarse controls and disconnecting the inter-
nal control; or some other arbitrary configuration.
Remote Mounted Coarse and Fine
Letters refer to terminals
REMOTE ZERO CONTROL.
permits
finer zero control or external zeroing.
B
IGURE 19. Internal Coarse Zero and Remo
Mounted Fine Zero. Letters refer to termin-
als in Figure 2.
within the Model 300.
substituting an external control for the
10K
R112 is already connected
This allows remotely
EX-
The external control can be a IO-turn, 5-kilohm wirewound potentiometer manufactured
b.
by several companies.
turns.
External zero control connections (Figure 17).
c.
Disconnect jumpers F-G and L-M (Figures 6 and 7) to remove potentiometer RL12
1.
(Figure 22) from the circuit.
Connect the external potentiometer to terminals A, B and C (Figure 2).
2.
Figure 17.
External fine and coarse zero control connections (Figure 18).
d.
Disconnect jumpers F-G and L-M (Figures b and 7) to remove potentiometer RlL2
1.
(Figure 22) from the circuit.
Connect a coarse potentiometer and a resistor in series between pins A and B (Fig-
2.
ure 2) of the Model 300 card-edge connector. This potentiometer will become the coarse
zero control.
Connect a fine zero potentiometer as shown in Figure 18.
3.
OL67R
--
If greater resolution is desired, use a potentiometer with more
Refer to
19
OPERATION MODEL 300 OPERATIONAL AMPLIFIER
4,. The total resistance between A and B should be about 5 kilohms.
e. External fine and internal coarse zero control connections (
--
Figure 20).
1. Connect a potentiometer in series with a resistor of at least 10 kilohms between
terminals C and A or between terminals C and B, as in Figure 19.
2. Do not disconnect jumpers F-G and L-M.
2-15.
CONNECTIONS AND USE OF REFERENCE VOLTAGES.
a. The reference voltages are useful for polarizing voltages for ion chambers, for grid
current buckout and for log diode biasing, In normal operation the reference output voltages available are +13.5 volts and approximately -14 volts.
amount
of additional cur-
The
rent that can be drawn from the + REF Terminal depends on the amplifier output current, the
ambient temperature and the supply voltages.
+ REF under th’e worst conditions; i.e.,
a full output load, power supply voltage around
Around 8 milliamperes can be drawn from the
25 volts and an operating temperature at 50%. The negative regulator supplies about 1
milliampere at these conditions.
More current can be supplied under more favorable con-
ditions.
Access to Reference Voltages:
b.
1. The +13.5 volt reference is available through the + REF Terminal (pin 9, Figure 2).
It. is connected at all times and is protected from overloads.
A temporary direct short
to ground will not cause damage.
2.
The negative voltage reference, whose nominal value is approximately -14 volts,
is independent of the negative supply voltage and load.
is not connected to the Negative Supply terminal (pin 6, Figure 2).
The negative regulator output
It may be connected
by attaching a jumper from 0 to N, (Figure 6).
NOTE
Overload protection is not provided on the negative reference voltage.
Any over-
load could damage the pass transistor, Q203.
3. Paragraph 2-3 and Figure 4, show the response of reference outputs to changes in
power supplies.
20
0167R
MODEL 300 OPERATIONAL AMPLIFIER
CIRCUIT DESCRIPTION
SECTION 3.
3-1. GENERAL.
a. The Keithley Model 300 Operational Amplifier uses a pair of high impedance balanced
electrometer tubes at its input, followed by solid-state differential amplifier stages.
Positive and negative power supply regulators enable the Model 300 to operate from a var-
iety of inexpensive power supplies. Input and feedback elements are easily mounted within the case to provide shielding for the complete circuit, or they may be externally
mounted.
b. By using different components - such
as resistors, diodes, capacitors - in the
feedback circuit,, the Model 300 can operate
in various modes: linear current amplifier,
logarithmic current amplifier, current in-
tegrator and so forth.
NOTE
Circuit designations refer to
schematic diagram 19558D in Sec-
tion 6.
3-2. ELECTROMETER INPUT. Two balanced
electrometer tubes, VlOl and V102, are at
the Amplifier input.
applied to the grid of V101. The tube fila-
ments are operated in parallel from the re- shaded portion.
gulated +13.5 volt supply through dropping
resistors Rl04 and RlO6.
tects the control grid of the active tube,
cessive overload. The input capacitor, ClOl, is a high-frequency bypass.
grid of V102 is returned to ground.
The input signal is
Resistor RlOl pro-
CIRCUIT DESCRIPTION
I5 10 -.,I"
b
FIGURE 20.
circuit for the Model 300 is within the
VlOl, from excessive grid current due to ex-
Model 300 Block Diagram.
The control
The
3-3. SOLID STATE DIFFERENTIAL AMPLIFIER.
a. An emitter follower stage, transistors QlOl and Q102, matches the relatively high
output impedance of the input stage to the low input impedance of the next differential
amplifier stage, formed by transistors 4103 and Q104.
differential amplifier stage,
b. The final ~differential stage drives the complimentary pair output stage, transistors
Q107 and Q108. Resistors Rll9 and R120 eliminate any crossover distortion.
and diode DlOl are provided as an overload limit when the output voltage is negative.
Positive output overload protection is achieved by overload limiting the positive regulator.
The zero adjust.control. potentiometer Rl12,
c.
grid for tube V102.
ters of transistors 4103 and 4104.
potential and tube operating points.
0566~ 21
The screen grids of the tubes are returned, in effect, to the emit-
transistors Q105 and Q106.
This connection stabilizes the electrometer plate
This latter stage drives a second
Resistor R121
adjusts the dc voltage of the screen
CIRCUIT DESCRIPTION
MODEL 300 OPERATIONAL AMPLIFIER
3-4. POSITIVE POWER SUPPLY REGULATOR.
This circuit regulates the +16 to +25 volt unregulated power supply input to the
a.
Model 300.
It provides an output adjusted to +13.5 volts for the electrometer tube fila-
ments and for all amplifier stages.
To obtain a stable, accurate voltage, the output of the series transistor, 9203, is
b.
regulated by comparing a sample voltage from the output dividers, resistors R208 to R210,
to the zener reference diode, D205.
If a voltage difference exists, it is amplified by a
differential amplifier, transistors Q206 and Q207. The signal is further amplified by
transistor Q204 and applied to transistor Q201.
This transistor is an emitter follower
whose function is to increase the current gain of the series transistor, Q'2.03, with which
it forms a Darlington pair.
Capacitors C201 and C202 prevent high-frequency oscillations. The series resistor,
c.
R204, and diodes D201 to D203 provide overload protection. If excessive current is drawn,
the voltage drop across resistor R204 increases. This forward biases the diodes which
prevent the Darlington pair from supplying additional current.
3-5. NEGATIVE POWER SUPPLY REGULATOR.
a. This circuit regulates the -16 to -25 volt unregulated power supply input to the
Model 300. It provides an output of approximately -14 volts to the last three amplifier
stages.
Since these stages are less cnitical in the Amplifier operation, the voltage
supplied to them is not as well regulated as the positive voltage.
The series transistor, 9202, is controlled by sampling the variation of its output
b.
and comparing it to the regulated +13.5 volts. The difference is amplified by trans,istor
4205 and applied to the base of transistor Q202. There is no overload protection.
22
MODEL 300 OPERATIONAL AMPLIFIER
MAINTENANCE
SECTION 4.
4-1. GENERAL.
cedures for the Model 300. Follow these procedures as closely as possible to maintain reliable operation for the Amplifier.
4-2. MAINTENANCE SCHEDULE. The Model 300 requires no periodic maintenance beyond the nor-
mal care required of high-quality electronic equipment. The most useful check is to make
sure the positive reference output (pin 9,
4-3. PARTS REPLACEMENT.
The Replaceable Parts List in Section 6 describes the electrical components of the
a.
Model 300.
meet the specifications.
The electrometer tubes, VlOl and V102, are specially matched and aged; order these
b.
only from Keithley Instruments, Inc., or its representative.
not need replacement before 10,000 hours of operation. They can be checked only by re-
placement. Standard 5886 tubes could be used in an emergency, but the drift, noise and
grid current specifications may not be met.
This Section contains the maintenance, troubleshooting and calibrating pro-
Replace components only as necessary. Use only reliable replacements which
MAINTENANCE
Figure 2) is +13.5 volts ?l%.
In normal use, they should
NOTE
When replacing the electrometer tubes,' do not touch the glass base where the
leads converge. Increased leakage will result from any contamination.
Transistor pairs QlOl, Q102 and 9103, 4104 are matched for dc current gain (hFB).
c.
Order only from Keithley Instruments, Inc., or its representative.
Transistor 4105, QlO6 and 4206
d.
Order only from Keithley Instruments, Inc., or its representative.
Instrument
Keithley Instruments Model 153 Microvolt-
Ammeter; 10 (iv to 1000 v, 200 M'2 input re-
sistance, ?l% accuracy, float 2500 " off
ground
Keithley Instruments Model 610B Electro-
meter; lo-14 to 0.3 ampere, 1 mv to 100 v
ranges; il% accuracy, 1014 0 input resistance
Voltage Supply; minimum 10 to 30-volt out-
positive and negative; O.Ol-volt
put,
steps; minimum 35 milliampere output
are selected for minimum current gain (hFE) of 50.
~~11 detector to check amplifier stages
Check currents and circuit
Source for checking regulators
Replace only as pairs.
Use
TABLE 4. Equipment Recommended for Model 300 Troubleshooting.
lent.
0866R
Use these or their equiva-
23
MAINTENANCE MODEL 300 OPERATIONAL AMPLIFIER
NOTE
The
accuracy.of the Amplifier depends almost exclusively on the accuracy of the
associated circuitry.
Impedance elements and output monitoring devices determine this. Therefore, use extreme care in selecting and handling these items
to minimize leakage and noise.
4-4. TROUBLESHOOTING.
The following procedures are for repairing troubles which might occur in the Model
30::
Use the procedures outlined and use only specified replacement parts.
Table 4 lists
equipment recommended for troubleshooting. If the problem cannot be readily located or
repaired, Keithley Instruments, Inc., can service the Amplifier at its complete service
facilities.
Contact your nearest representative.
Table 5 contains the more common troubles which might occur.
b.
If the repairs indi-
cated do not clear up the trouble, find the difficulty through a circuit-by-circuit check,
The schematic diagram contains typical voltages at various points. A properly operating
Difficulty Probable Cause
:xcessive zero drift Electrometer tubes defective
Solution
Check VlOl and V102; replace if faulty
Regulator(s) defective
Zxcessive grid current Excessive humidity or defective
electrometer tubes
Jnable to zero output
Amplifier not functioning
Electrometer tubes have aged and
drifted
Jumpers F-G and L-M may be dis-
Check per paragraph 4-5
Check VlOl and V102; re-
place if faulty
Check per paragraph 4-6
Check VlOl and V102; re-
place if faulty
Connect F-G and L-M
connected (Figur&b and 7)
:ll volt output not Faulty regulator operation
Check par paragraph 4-5
obtainable
Output overloaded
Remove excessive load
<eference output vol- Regulator out of adjustment Adjust potentiometer RZO'
:age not correct
tegulators do not
iunction
:xcrssive 60 cps in
Supply voltages may be dropping
Increase supply voltage
below 1~6-volt minimum (paragraph 2-3)
Defective regulator circuits
Regulators not functioning
Check per paragraph 4-5
Cheek per paragraph 4-5
>utput
TABLE 5. Model 300 Troubleshooting.
See paragraph 4-3 for checking electrometer tubes.
Also refer to paragraph 4-4 for step-by-step procedures.
24
05661~
MODEL 300 OPERATIONAL AMPLIFIER
MAINTENANCE
Amplifier will have these values ilO%/,.
to the Circuit Description in Section 3 to find the more critical components and to deter-
mine their function in the circuit.
4-5. TROUBLESHOOTING POSITIVE AND NEGATIVE POWER SUPPLY REGULATORS.
a. Check both the positive and negative power supplies to the Model 300 to make sure
they provide between 16 and 25 volts.
Model 153 or 610B: with no output load,
-1-35 milliamperes and the negative power supply approximately -8 milliamperes.
put currents indicate one or more transistor has shorted in the regulator or the amplifier.
Check the positive regulator output by measuring for 113.5 volts "1% with the Model
b.
153 at the positive reference output (pin 9, Figure 2). Internally check the negative
regulator output by measuring for -14 volts f5% with the Model 153 at the Negative Regu-
lator Check (Figure 7).
c. Check the regulation of the positive regulator by varying the input voltage. CO*-
nect the Voltage Supply to the positive supply (pin 10, Figure 2). Use the Model 153 to
monitor the output at pin 9, Figure 2.
positive reference voltage will change no more than 2 millivolts for every l-volt change
to the input between +16 and +25 volts.
d. Check the regulation of the negative regulator similarly. Connect the Voltage sup-
ply to the negative supply (pin 6, Figure 2).
Negative Regulator Check (Figure 7).
Model 153 will show less than 20 millivolts change for every l-volt change to the input
between -16 and -25 volts.
Voltages were measured with the Model 153.
Check the input power supply currents with the
the positive power supply should be approximately
Higher in-
If the regulator is operating satisfactorily, the
Use the Model 153 to monitor the signal at the
If the regulator is operating satisfactorily, the
Refer
If either regulator is not operating (zero regulation), the series transistor is
e.
probably shorted and should be replaced.
ure 23). For the negative regulator, replace Q202 (Figure 23).
f. If the positive regulator has poor regulation, use the following procedure:
1. Remove the positive power supply from the Amplifier.
2. Apply +13.5 volts to the iREF Terminal (pin 9, Figure 2).
Measure the voltage at the wiper of potentiometer R209 (Figure 22). The voltage
3.
should be about 9 volts. If 113.5 volts is present, then resistor RZLO (Figure 22) is
either faulty or it is not connected.
2,2) is either faulty or it is not connected.
sent and if the voltage is not about 9 volts, then potentiometer R209 is faulty.
4. If the voltage is about 9 volts,
sure that this voltage varies.
23). This voltage should be between 8.55 volts and 9.45 volts.
either resistor R205 (Figure 22) or diode D204 (Figure '23) is faulty. Next, check the
collector of transistor Q206 to see if the voltage here varies when potentiometer R209
is adjusted.
5. Finally, check the voltage at the collector of transistor Q204 (Figure 23) and
make sure that there is a response to adjusting R209. If there is no response at the
If it does not vary,
Then check the base voltage of transistor Q206 (Figure
For the positive regulator, replace Q203 (Fig-
If 0 volt is present then resistor ~208 (Figure
If neither +13.5 volts nor 0 volts is pre-
adjust potentiometer R209 a few turns to make
If it is not, then
then either transistors Q206 or Q207 or both are faulty.
0866R
25
MAINTENANCE
MODEL 300 OPERATIONAL AMPLIFIER
collector,
If there is a response, then either Q201
or Q203 is faulty.
For the negative regulator, repair is easiest by replacing transistors 4202 and Q205
(Figure 23).
4-6. TROUBLESHOOTING THE AMPLIFIER
Disconnect all feedback elements and
a.
short the input to ground. This allows
each stage of the amplifier to be individually checked.
b. Connect the Model 153 between the
plates (Figure 21) of VlOl and V102 (Figure
24).
(Figure
reached, check the tubes, the zero control meter Tube.
circuit, and transistors QlOl and Q102
(Figure 23).
placing them and adjusting for null again.
tor pair with a new pair.
Adjust the zero potentiometer, R112
then transistor Q204 is faulty.
i2),
for null. If null cannot be
Check the transistors by re-
FIGURE 21. Base Connections for Electro-
If null is now reached, replace the transis-
-7
rted Dot
Check the next stage by connecting the Model 153 acr0s.s the emitters of transis-
to:: QlOl and Q102 (Figure 23) and adjusting the 'zero potentiometer, Rll2 (Figure 22),
for null. If null is not reached, check this stage and the base circuit of the next
stage.
again adjusting for null. If null is now reached, replace Q103 and Q104 with a new pair.
d.
Q104 (Figure 23) and adjusting for null. If null is not reached, check this stage and
check for shorts in the circuit of QlO5 and Q106 (Figure 23).
e. Check transistors QlO5 and Q106 by measuring the potential of the collector of QlO5
with respect to ground. Note that as adjusting potentiometer R112 (Figure 22) carries
the other stages through null,
volts to at least +ll volts.
moving transistor Q107 and resistor R119. Now repeat adjusting potentiometer Rl12. If
the collector of QlO5 still does not swing 211 volts, replace transistor QlO5 or Q106 or
both.
output stage and replace transistor Q107 or QlOS (Figure 23) or both.
4-7. CALIBRATION.
adjustments are required under normal use.
paragraphs 4-5 and 4-6 will calibrate the Model 300.
Check the base circuit by removing transistors Q103 and Q104 (Figure 23) and
Check the next stage by connecting the Model 153 across the collectors of Q103 and
the voltage at the collector should swing from at least -11
If this does not occur, disconnect the output stage by re-
If transistors QlO5 and QlO6 were operating properly,
All calibration adjustments are made at the factory and no periodic
Checking for proper operation as given in
then the defect is in the
26
0666R
MODEL 300 OPERATIONAL AMPLIFIER
MAINTENANCE
FIGURE 22.
PC-110, HO
locations,
ponents on
see Figure
Resistor Locations on
de1 300.
see Figure 23.
For component
For com-
other side of PC-110,
24.
FIGURE 23. Component Locations on
PC-110, Model 300.
see Figure 22.
For resistors
For components on
other side of PC-110, see Figure 24
0666
MAINTENANCE
MODEL 300 OPERATIONAL AMPLUTE
28
FIGURE 24.
For components on other side of PC-110, see Figures 22
and 23.
Component Locations on PC-110, Model 300.
0666
MODEL 300 OPERATIONAL AMPLIFIER
ACCESSORIES
SECTION 5.
5-l. MODEL 3012 POWER SUPPLY
a. General.
1. The Keithley Model 3012 is a line-operated unregulated power supply.
dual supply with positive and negative outputs of 20 volts ?25%. The Power Supply can
be operated from a line source of 105-125 volts or 210-250 volts.
2. The Model 3012 is for powering the
Keithley Model 300 Operational Amplifier.
Up to three Model 300s can be driven by
the Power Supply without sacrificing performance. It can be floated at up to 500
volts off chassis ground. The Power Supply
is a completely self-contained unit and
has nearly the same exterior appearance
as the Model 300.
3. The Model 3013 Insulated Hold-Down
Bracket provides rigid mechanical support
for the Model 3012 or Model 300.
Bracket is insulated for use with the
Model 300 during floating operation.
The
ACCESSORIES
It is a
Specifications.
b.
OUTPUT: As required for 1, 2 or 3 Keithley
Model 300 Electrometer Operational Ampli-
fiers.
FIGURE 25.
ISOLATION :
ground;
than 50 picofarads. Circuit ground may be floated up to 500 volts off chassis ground,
CONNECTOR: 15 terminal l/16-inch card-edge.
POWER REQUIRED:
OPERATING TEMPERATURE: With one or two Model 300 Amplifiers; 50°C Maximum ambient.
DIMENSIONS, WEIGHT:
17 ounces.
ACCESSORIES SUPPLIED: Mating card-edge connector.
ACCESSORIES AVAILABLE:
Model 3013 Insulated Hold-Down Bracket: Provides rigid support for Models 300 or 3012.
Circguit ground to chassis
over 10
ohms shunted by less
105-125 volts or 210-250 volts, 50-60 cps, 10 watts.
With three Model 300 Amplifiers; 4,O'C Maximum ambient.
3-l/2 inches high x 4~ inches wide x l-1/2 inches deep; net weight,
Keithley Model 3012 Power Supp
0167~
29
ACCESSORIES MODEL 300 OPERATIONAL AMPLIFIER
c. Operation.
The Model 3012 has a 15-terminal card-edge connector, which is part of the pc
1.
board, that is used for all connections.
the Model 3012.
The mating connector is keyed so that the Model 3012 cannot be reverse
A mating card-edge connector is supplied with
connected to its mating connector.
NOTE
The Model 3012 can power up to three Model 300 Amplifiers. If more than three
Model 300's are used with one Model 3012, then the Power Supply will provide
less than the required voltages to each Model 300.
2. To secure the Model 3012 in operating position, first mount the input mating con-
'nectar on an appropriate surface. See Figure 3 for mounting hole diagram.
The mounting
procedure for the Model 3012 is the same as for the Model 300 except that the 3012 does
not have a coaxial connector.
the power line to the Model 3012 mating connector.
Check the power line voltage and frequency. Next, wire
The method of wiring the power line
to the Model 3012 mating connector terminals is different for the 105-125 volt source
than it is for the 210-250 volt source.
Refer to Figure 26 for wiring instructions.
For a 105-125 volt source,
a.
connect one lead from the power cord to terminals
1 and 2, and connect the other lead to terminals 3 and 4,. See Figure 26a.
For a 210-250 volt source,
b.
4 and connect terminals 2 and 3 together.
Connect the +16 to +25V Terminal on the Model 3012 mating connector to the +16 to
3.
+25V Terminal on the Model 300 mating connector.
connect one lead to terminal 1, one lead to terminal
Se'e Figure 26b.
Connect the -16 to -25V Terminal on
the Model 3012 mating connector to the -16 to -25V Terminal on the Model 300 mating
connector.
Connect the GROUND Terminal on the Model 3012 to the GROUND Terminal on the
Model 300.
4..
system.
In floating operation,
In normal
operation,
connect the Model 3012 CASE to the circuit ground of the
connect the Model 3012 CASE and GROUND Terminals to the
GLJRE 26.
Diagrams for Wiring the Power Line to the Model 3012 Connector. Diagram 26a
for a 105-125 volt source and diagram 26b is for a 210-250 volt source.
30
0667R
MODEL 300 OPERATIONAL AMPLIFIER
In floating operation one Model 3012 should not be used to power more than one
Model 300 unless they have a common ground. -
Plug the Model 3012 into its mating connector.
5.
ACCESSORIES
NOTE
Circuit Description.
d.
which is connected in parallel from a 105-125 volt ac power source and in series from a
210-250 volt ac power source.
the primary transformer.
wave rectification by a diode bridge configuration, DlOl through D104.
put of the diode bridge is filtered by capacitor ClOl,
by capacitor ~102.
output.
Maintenance.
e.
1. The Keithley Model 3012 Power Supply has no adjustments or controls.
tion adjustments are made at the factory and no periodic adjustments are required under
normal "se.
No trouble should occur under normal use.
2.
the following procedures:
If there is no output from the Model 3012, check for a blown fuse.
a.
b.
If there is a low or high voltage output of the Model 3012, chech the line voltage
and make sure that the power cord is wired to the mating connector correctly,
5-2. MODEL 3011 SHIELDED SWITCH.
A bleeder resistor, R101, improves load regulation for the negative
The Model 3012 Power Supply has a dual-primary transformer
This is a result of the wiring from the ac power cord to
The transformer secondary winding is center tapped for dual full-
The positive out-
and the negative supply is filtered
All calibra-
However,
if problems arise, tnen "se
a. General.
Shielded Switch is a 3-pole, &?-position
adjustable stop switch.
constructed for low leakage and to provide
shielding for the components.
which accommodates the feedback or input
resistors,
than 1014 ohms insulation ,resistance between terminals and ground.
contains two additional decks for these or
other components,
ing networks.
connectors provide electrical access to
the Model 3011.
Mounting (Figure 28).
b.
For best results mount high megohm
1.
resistors in the four clockwise positions
The hole in the Teflon insulated deck (4.)
has Teflon insulated bushings in these
four positions.
0667R
The Keithley Model 3011
The Model 3011 is
One deck,
is Teflon insulated with greater
The switch
such as divider or damp-
Three Teflon-insulated bnc
The extra deck (2) can be
FIGURE 27.
Model 3011 Shielded Switch.
31
ACCESSORIES MODEL 300 OPERATIONAL AMPLIFIER
less than l/4 inch less than l/4 inch
-I I- -I I-
6 6
4
I 4
I
11 11 I I I I
1
used for mounting divider or damping components.
The panel (9) should be less than l/4 inch thick and should have holes drilled
i.
into it for the bushing and lug (Figure 29). The panel,
ing and lug, physically stabilizes the Model 3011 Switch.
Insert the short lug (6) into the desired hole in the front plate (12) of the
3.
Switch.
the first lug.
This adjusts switch stopping. Insert the larger lug over the bushing against
;I_' .., .,
1 1 .., .,
I I
10
;I_'
10 5 / /
9 8 9 8
FIGURE 28. Model 3011 Shielded FIGURE 28. Model 3011 Shielded Switch Switch Diagram. Diagram.
This second lug should face opposite the first lug.
d d
5
I 3
4 4
in conjunction with the bush-
Insert the Switch into its shield. Make sure the bushing (5) and the larger lug
4. .
(6) are fitted into the proper holes on the front panel of the shield.
Insert the bushing and lug into the panel (9).
5.
Secure the Switch and panel with the nut and lockwasher (10).
6.
Attach the knob (11) to the Switch.
7.
c. Installation and Hook-up for Switching Feedback (Figure 30).
One INPUT Receptacle on the Model 3011 is used as the input to the system.
1.
other INPUT Receptacle is used as the input to the Model 300 INPUT Receptacle.
connectors and coaxial cables with the Model 3011 INPUT Terminals.
Connect the Model 3011 FEEDBACK Terminal to the Model 300 OUTPUT Terminal.
2.
unshielded cable may be used for the Feedback. Use bnc connectors with the FEEDBACK
Terminal.
32
Use bnc
The
Single
0167R
MODEL 300 OPERATIONAL AMPLIFIER
Item
(See Figure 28)
Description
ACCESSORIES
1
2
3 Component Mounting Decks
4,
5 Threaded Bushing
6
7
8 Shield (No. 194,02A)
9 Panel (not furnished with
10
11
12
ABLE 6.
tion
3.
and the solder lug connected to the wiper on the Teflon insulated deck (4,, Figure 28).
rear component mounting decks (Figure 30).
Model 3011 Callout and Descrip-
To use the Model 3011 for switching feedback elements:
Inside the Model 3011 Switch, connect a wire between the two INPUT Terminals
a.
b. Connect a second wire from the FEEDBACK Terminal to the wiper on one of the
Rear Cover (No. 19487B)
Extra Deck
Teflon Insulated Deck
Lugs (2 required)
Component positions
Switch)
Nut and lockwasher
Knob (No. 16338A)
Front Plate
.390 in.
Dia.
-- ---_
A
--.---_
.094 in.
Dia.
--
38 in.
-_
1:
'IGUW 29. Required Dimensions of Model
,011 Front Panel (used to physically sta-
ilize the Switch).
1
-
I
NOTE
Make sure that the input wires,
in contact with any part of the switch except the necessary points of connection.
unless they are Teflon insulated, do not come
0167R
33
ACCESSORIES
INPUT
MODEL 300 OPERATIONAL AMPLIFIER
SWITCH
SHIELD
/
t3z-E
r INPUT
-===I
FIGURE 30.
INSULATED
DECK
I
J FEEDBACK
8
MODEL
300
Model 3011 Installation and Hook-up Diagram.
L < OUTPUT
34
0167R
MODEL 300 OPERATIONAL AMPLIFIER
REPLACEABLE PARTS
SECTION 6.
6-l. REPLACEABLE PARTS LIST. The Replaceable Parts List describes the components of the
Model 300 and its accessories.
tion,
ber. The last column indicates the figure picturing the part.
the manufacturers listed in the "Mfg. Code" column are in Table 8.
6-2. HOW TO ORDER PARTS.
Part Number, the circuit designation and a description of the part.
are those parts coded for Keithley manufacture (80164) must be ordered through Keithley
Instruments, Inc. or its representatives. In ordering a part not listed in the Replaceable Parts List, completely describe the part, its function and its location.
partment, Keithley Instruments, Inc.
amp
CerD
camp
a suggested manufacturer, the manufacturer's part number and, the Keithley Part Num-
For parts orders,
a.
b. Order parts through your nearest Keithley representative or the Sales Service De-
include the instrument's model and serial number, the Keithley
ampere
Ceramic Disc
Composition
The List gives the circuit designation, the part descrip-
REPLACEABLE PARTS
The name and address of
MtF
MY
n
All structual parts
Metal Film
Mylar
ohm
DCb
ETB
f
Fig.
c
3
tfg.
Deposited Carbon
Electrolytic Tubular
farad
Figure
kilo (103) ww
Megohms (106)
Manufacturer
TABLE 7.
Abbreviations and Symbols
P
)J
"
w
wwvar
pica (10-12)
micro (lo-$
volt
watt
Wirewound
Wirewound Variable
0167R
35
REPLACEABLE PARTS
(Refer
MODEL 300 REPLACEABLE PARTS LIST
to
Schematic Diagram 195581) for circuit
CAPACITORS
MODEL 300 OPERATIONAL AMPLIFIER
designation)
Circuit
Desig. Value Rating
Cl01
Cl02
c201
c202
Circuit
Desig.
DlOl
D201
D202
D203
D204
0205
Circuit
Desig.
22 pf 600 v
k.068 IJ.f 100 v
330 pf 600 v
125 pf 15 v
Type
Silicon lN645
Silicon lN645
Silicon lN645
Silicon lN645
Silicon lN645
Zener lN936
Description
Mfg.
Type
CerD 72982
MY
CerD 72982
ETB 56289
DIODES
Number
MISCELLANEOUS PARTS
Code
88480
Mfg.
Code
01295
01295
01295
01295
01295
04713
Mfg. Keithley
Part No.
ED-22
3FR 683-1E
ED-330
TE 1162
Mfg.
Code
Part No.
c22-22P 24
Cl46-.068M 23
C22-330P 23
C3-125M 24
Keithley
Part No.
RF-14
RF-14
RF-14
RF-14
RF-14
DZ-5 23
Keithley
Part No.
Fig.
Ref.
Fig.
Ref.
23
23
23
23
23
Fig.
Ref.
JlOl Coaxial Receptacle (Mfg. No. FXR 2175
--_
---
---
VlOl
v102
Circuit
Desig. Value Rating
RlOl 10 Ma
R102 150 kfl
R103 "68 R
R104
R105 150 n
:cNominal value, factory set
(F)Furnished accessory
36
(F)Plug, Mate of JlOl (Mfg. No. FXR 30775)
(F)Hooded Shield for CS-179 (Mfg. No. FXR2273 02660
(F)Connector, 15 pin card-edge (Mfg. No.
PSC4SS15-12)
Electrometer tube
Electrometer tube
RESISTORS
Mfg.
Code
01121 EB
02985 400TS-1W R81-91
91 n
Type
lO%, l/2 w Comp
l%, l/2 w MtF 07716
lo%, l/2 w camp 01121 EB
3%, 1 w
l%, l/2 w MtF 07716
ww
02660 CS-178
02660 cs-179
CS-180
03612 cs-175-15 -80164
80164 EV-5886-5
Mfg.
Part No. Part No.
CEC R94-150K 22
CEC
EV-5886-5
Keithley
Rl-1OM
R1-$<68 22
R94-150K 22
24
-_
-_
24
24
Fig.
Ref.
24
22
0167R
MODEL 300 OPERATIONAL AMPLIFIER
REPLACEABLE PARTS
RESISTORS (Con't)
Circuit
Desig.
Rl06
R107
Rl08
R109
RllO
Rlll
R112
R113
R114
R115
R116
R117
Rll8
R119
R120
R121
R201
R202
R203
R204
R205
Value Rating
500 *
10 kn
100 kn
10 kn
100 kn
8.2 kfi
5 kn
2.1 kn
2.7 kn
33 kn
8.2 kn
680 n
22 kn
39 n
220 kfl
10 12
15 kn
10 kn
22 kn
6.8 n
I&
3%, 1 w
10x, l/2 w
lo%, l/2 w
lO%, l/2 w
lO%, 112 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, 112 w
lO%, l/4 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/2 w
lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
Mfg.
TYPO
ww
camp
Comp
Comp 01121 EB
Comp 01121 EB
camp
wwvar
camp
Comp
Comp
camp 01121 EB Rl-8.2K
Comp 01121 CB R76-680
Comp
Comp
Comp 01121 EB Rl-220K
Comp 01121 EB Rl-10
Camp
Comp
Comp 01121 CB
Comp
Comp
Code Part No.
02985 400TS-1W R81-500
01121 EB Rl-1OK
01121 EB Rl-100K
01121
80294
01121
01121
01121
01121 EB Rl-22K
01121
01121 CB R76-15K
01121
01121
01121
Mfg.
EB Rl-8.2K
3067P-l-502 RP39-5K
EB
EB
EB Rl-39
CB
CB R76-6.8 22
CB R76-1K
Keithley
Part No.
Rl-1OK
Rl-100K
Rl-2.7K EB
Rl-2.7K
Rl-33K
R76-10K
R76-22K 22
Fig.
Ref.
22
22
22
22
22
22
22
22
22
22
22
22
22
22
22
2.2
22
22
22
R206
R207
R208
R209
R210
R211
R212
Circuit
Desig.
QlOl A1380 80164 ~~~~18548A 23
Q102 A1380 80164 >'*:18548A 23
Q103 A1380 80164
Q104 A1380 80164 "~*18548A 23
Q105 517638 07263 TG-33 23
>+ QlOl, Q102 and 4103, 4104 are matched pairs. Order only from Keithley Instruments,
Inc.
3.3 kn
4.7 m
3.3 kn
2hl
8.2 m
9kn
8.6 kfl
lO%, l/4 w
lO%, l/4 w
lO%, l/4 w
lO%, l/2 w
lO%, l/4 w
l%, l/2 w
l%, l/2 w
Number Code Part No. Ref.
Comp
Comp
camp 01121 CB
wwvar
Comp
DCb 79727
DCb
TRANSISTORS
Mfg.
01121
01121 CB
80294 3067-l-502
01121
79727 CFE-15
CB R76-3.3K
CB
CFE-15
Keithley
%?‘18548A
R76-4.7K
R76-3.3K
RP39-ZK
R76-8.2K
R12-9K
RLZ-8.6K
22
22
22
22
22
24
22
Fig.
23
0167R 37
REPLACEABLE PARTS
MODEL 300 OPERATIONAL AMPLIFIER
TRANSISTORS (Cont'd)
Circuit
Des&.
Q106
Q107
QlO8
9201
Q202
Q203
Q204,
Q205
~206
Q207
Circuit
Desig.
Cl01
Cl02
Number
S17638
2N2430
2N2706
2N1605
2N2431
2N2270
A1380
517638
A1380
A1380
Mfg.
Code
07263
734,45
734.4,5
93332
734,4~5
02735
734'4.5
07263
734.4.5
734.4,5
Keithley
Part No.
TG-33
TG-36
TG-35 23
TG-22 23
TG-37
TG-25
TG-32
TG-33
MODEL 3012 REPLACEABLE PARTS LIST
(Refer to Schematic Diagram 20351B for circuit designations)
Mfg.
Description
Capacitor, Electrolytic aluminum, 400 vf
code
734,4,5
4,O " (Mfg. No. C4,37AR/G4,00)
Capacitor, Electrolytic aluminum, 100 (if
734,4,5
40 " (Mfg. No. C4,37AR/G100)
Fig.
Ref.
23
23
23
23
23
23
Keithley
Part No.
C150-4,OOM
Cl50-100M
DlOl
D102
D103
D104.
FlOl
F102
JlOl
_--
RlOl
TlOl
Diode, Silicon, lN3253
Diode, Silicon, lN3253
Diode, Silicon, lN3253
Diode, Silicon, lN3253
Fuse,
l/8 amp, 8AG (Mfg. No. 361.125)
FUSE!, l/8 amp, 8AG (Mfg. NO. 361.125)
connector,
part of pc board
Connector, furnished mating 15 pin card-edge
Resistor, Composition, 2.2 kfl, lo%, 1 w
(Mfg. No. GB)
Transformer
02735 RF-20
02735 RF-20
02735
RF-20
02735 RF-20
75915
FU-5
75915 FU-5
---
80164,
01121
80164~
---
cs-175-4,
RZ-2.2K
TR-97
38
0167R
MODEL 300 OPERATIONAL AMPLIFIER REPLACEABLE PARTS
01121 Allen-Bradley Corp. 07716 International Resistance Co.
Milwaukee, Wis. Burlington, Iowa
01295 Texas Instruments, Inc.
Semi Conductor-Components Division
Dallas, Texas
02660 Amphenol-Borg Electronics Corp. North Adams, Mass.
Broadview, Chicago, Illinois
02735 Radio Corp. of America Erie, Pa.
Commercial Receiving Tube and
Semiconductor Division 734.4.5 Amperex Electronic Co. Division of
Somerville, N. J.
02985 Tepro Electric Corp.
Rochester, N. Y.
03612 Burndy Corp.
Lynwood, Calif.
04,713 Motorola, Inc.
Semiconductor Products Division 80294. Bourns Laboratories, Inc.
Phoenix, Arizona Riverside, Calif.
07263 Fairchild Camera and Instrument Corp. 93332 Sylvania Electric Products, Inc.
Semiconductor Division Semiconductor Products Division
Mountain View, Calif. Woburn, Mass.
13050 Potter co.
Wesson, Miss.
56289 Sprague Electric Co.
72982 Erie Technological Products, Inc.
North American Philips Co., Inc.
Hicksville, N. Y.
79727 Continental-Wirt Electronics Corp.
Philadelphia, Pa.
80164, Keithley Instruments, Inc.
Cleveland, Ohio
TABLE 8. Code List of Suggested i@nufacturers. (Based on Federal supply
facturers, Cataloging Handbook H&l.)
code
for Manu-
0167~
39
b-f-----
--Y
--1
r---
\I
--
1
KEITHLEY INSTRUMENTS.
INC
28775 AVRORA ROAD .
TELEX 98.5469 . CABLE: KEITHLEY
CLEVELAND. OH,0 4413s . ,216) 248-0400
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