We warrant each of our products to be free from defects in material
atid workmanship. ,Our obligation under this warranty iS’to repair
or replace any instrument or part thereof which, within a year after
shipment, proves defective upon examination. We will pay local
domestic surface freight costs.
To exercise this warranty, write or call your local Keithley ~representative, or contact Keithley headquarters in Cleveland, Ohto.
.
You will be given. prompt assistance and shipping instructions.
repairs and; calibrat,ion
Keithley lnstrbments~ maintains a compl&e repair~,and.calibration
service as well as a standards laboratory in Cleveland, Ohio. A,
service facility is also located in Los Angeles for c&r west coast
customers.
A Keithley service facility at our Munich, Germany office is
available for our customers throughout Europe. Service in the
United Kingdom can be handled at our office i,n Reading. Additionally, Keithley representatives in most countries maintain service
and calibration facilities..
To insure prompt repair or recalibration service, ,please contact
your local field representative or Keithley headquarters directly
before returning the instrument. Estimates for repairs, normal
recalibrations and calibrations traceable to the National Bureau of
1 Front pane1 Controls, ___--____-__________-------------------------2 Rear Panel Conrrols, ____-____-____-_________________________------3 Divider circuits *cross Picoamerer outpur. -----------------------4 Simplified Diagram for Ameter Circuit. ---------------------------5 Test Set-up for Model 410A Rise Time Checks an all ranges. --------6 Chassis, Top View. ________________________________________--------7 componenr Layour, p+1p,4, ____--___--_____________________________-8 Top cover *ssem~ly. __-_______--____________________________--------
RANGE: 3 x 10’13 ampere full scale to 10.3 ampere in
twenty Ix and 3x ranges. positive or negative currents.
ACCURACY: 12% of full scale on 10’” to XV ampere
ranges: *4%off”li scaleon 3 x 10+to3 x 10’~~ampere
ranges.
ZERO DRIFT: Less than
0.02% per “C on ice to l0.y ampere ranges; less than
1.5% per week plus 0.06% per “C on 3 x 1Q.13 ampere
range after a
l&minute
greater than 1 “OIL
OFFSET CURRENT: Less than lo-” ampere.
INPUT VOLTAGE DROP: Less than 1 millivolt for full.
scale meter deflection on any range when properly
zeroed.
EFFECTIVE fNPUT RESISTANCE: Less than 1 ohm on
lo’” ampere range,
on 3 x lo“3 ampere range.
RISETIME, MAXIMUM: Seconds, from 10% to 90%.
Range,
ampere
IO-”
IL? 1 I 1.0 2
IO-‘0 0.25 cl.4
IO- 3 0.1 0.1
1Q.a 0.1 0.1
10-T and above
MAXlMUM INPUTOVERLOAD:
Transiant:1QQQvoltsforupto3secondsusinga Keithley
(or other 10 mA limited) High Voltage Supply.
Continuous:6QQvoltson3 Y 10’llto Wampere ranges.
decreasing to 12 volts on the 1Q’2 ampere range.
RECORDEROUTPUT:
Output: *I volt or 1 milliampere for fullxale meter
deflection. Output polarity i* opposite input polarity.
Noise: Less than 1% of full scale peak.to-peak on 10’”
to 10’” ampere ranges. increasing to 5To peak-ta-
peak on 3 x llT~‘ampere range.
CONNECTORS: Input: Teflon.insulatod UHF type.
Output: Amphenol 8QPCZF.
POWER: 105.125
Hz, 5 watts.
DIMENSIONS, WEIGHT: 5%” high x 8%” wide x 10” deep;
net weight. 10 pounds.
ACCESSORIES SUPPLIED: Mating-input and output
Con”ector*.
0.5%
of full scale per week plus
warm-up with source voltage*
increasing to less than 3 x 109 ohms
With Yp to 100 pF
AC.0.I lnpYt
2.5
less tnan 0.001
or
210.250 volts (switch
Wl,h YP to 5000 pf
A6rOSL l”PY,
12
kS5 than 0.001
selected). 50.60
MODEL 410A
iv
1274
CN410A-4
Sheet I of I
0776
KEITHLEY INSTRUMENTS.
INSTRUCTION MANUAL
CHANGE NOTICE
MODEL 4lOA PICOAMMETER
INTRODUCTION: Since Keithley Instruments is continually improving pro-
duct performance and reliability, it is often necessary to make changes
to Instruction Manuals to reflect these improvements. Also, errors in
Instruction Manuals occasionally occur that require changes. Sometimes,
due to printing lead time and shipping requirements, we can’t get these
changes immediately into printed Manuals.
formation is supplied as a supplement to this Manual in order to provide
the user with the latest improvements and corrections in the shortest
possible time. Many users will transfer this change information directly
to a Manual to minimize user error. All changes or additions are indi-
cated in
CHANGES :
PAGE I9
Q103
Q104
+‘:;Replace QIOI, QIOZ or RI16 by ordering Plug-in board 23733.
italics.
PNP, Case R-110
PNP, Case R-110
F-I
F-I
The following new change in-
Sl7638 1”G-33
527638 T&33
I No C
7
7
SECTION 1.
GENERAL DESCRIPTION
l-1. GENERAL.
a. The Keithley Model 410A is a sensitive, complete-
ly solid-state picoammeter which measures currents over
20 ranges from 10-3 to 3 x 10-13 ampere full scale.
accuracy is b% of full scale on the lo-3 to 10-B am-
pere ranges and 14% of full scale on ctle 3 x 109 co
3 x 10-13 ampere ranges.
b. The Pic"ammeeer employs matched MOs FET transis-
tars in the input followed by a differenrial amplifier
stage, a transistor driver and a transistor O"epUC
stage. Negative feedback is used for stability and
aCC"rXy.
1-2. FEATURES.
a. A unique circuit provides complete overload pro-
tection for Model 410.~ without compromising the outstanding
features of the MOS FET input. The Picoammeter will withstand transient overloads up CO 1000
volts wirhout damage, and overload recovery is almost
instantaneous.
b. The time and temperature stability of the Model
410A Picoamneter is excellent. The Model 410.4 will
operate for
days without requiring rezeroing. Zera
drift with time is less than 0.5% of full scale per
week. Temperature drift is equally small - a change
of 10°C affects the reading less than 0.2% of full
scale on ehe 10‘3
to 10-12 ampere ranges.
c. Fast warm-up is an inherent characterisric of
the Picoammeter. It can be used almost immediately
on its most SensiCive range. For maximum seability,
however, about 10 minutes warm-up should be allowed.
d.
One
volt
or 1 milliampere at
full scale deflecfFon on all ranges is provided to drive chart recorders. The 1 milliampere recorder output will drive
the Keithley 370 Recorder directly. When potentiometric recorders are used, the output voltage ca" be
conveniently divided by a shunt resistor and adjusted
for full scale with the rear
panel Calibration
paten-
tiometer.
0172
1
GENERAL DESCRIPTION
MODEL 410A
TABLE 2. Model 410A Front Panel Conrrols (Figure 1).
Control
AMPERES Switch
METER Switch.
ZERO ADJ. Control
Pilot Light
ZERO CHECK Sutton
selects full-scale Current range instrument is to measure. 2-2
Turns inserument on; selects meter polarity.
ZemeS meter on any range. 2-2
Glows to indicate instrument is on.
Checks zero on any range.
CO”tlWl
INPlsI Receptacle connects input to source.
Olsi"PuT Receptacle
co""ectar.
connects output to monitoring device.
Funceional Description
Functional Description
1 MA - 1 ” Switch Selects output of instrument:
receptacle is a Teflon-insulated UHF
1 milliampere or 1 volt.
Par.
Z-2,2-4
___
_--
Par.
I
2-1,2-z
2-4
2-4
1 MA CAL Control
117-234 " Switch
Fuse
2
Adjusts output
sets instrument for 117 or 234 Volt ac power line. z-2,2-5
from 0.95 eo 1.05 mA.
3Acz Slow-Blow. 117 volt - ,125 A; 234 volt - ,062 A.
2-4
2-5
0172
MODEL 410A
GENERAL OESCRIPTTION
0172
FIGURE 2.
sear Panel Controls.
3
OPERATION
MODEL 41OA
SECTION 2. OPERATION
2-l. INPUT CONNECTIONS. “se the following precautions
when using the Picoammeter on the more sensitive ranges.
e. Attach the current source to the INPUT Kecepta-
cle and turn the METER Switch to rhe polarity of the
input signal, + or -. Increase sensieivity with the
AMPERES Switch until the greatest on scale deflection
is achieved.
a. The INPUT Receptacle of the Model 410~ is a Tef- 1. When the AMPERES Switch is see to 10, I, 0.1,
Ion-insulated UHF co”“ector. The ce”Ler rermina1 is etc. positions, use the upper meter scale. Full
the high impedance terminal, and the outer shield is scale current range is equal LO the AMPERES Switch
ca?,e ground.
b. Carefully shield rhe input connection and the
current source being measured, since power line frequen-
setting.
2.
When the AMPERES Switch is set to 3, 0.3, 0.03,
etc. positions, use the lower meter scale.
Full
ties are well within the pass band of the Picoammeter scale current range is equal to the AMPERES Swirch
on all ranges. unless the shielding is thorough, pick-
setting.
up may cause definite meter disturbances.
c. Use high resiseance, low-loss materials - such
as polyethylene, polystyrene or Teflon - for insulation. The insulation resistance af test leads and fix-
2-3. MEASUREMENT CONSIDERATIONS.
turee should be several orders of magnitude higher than
the So”rCe resistance. Excessive leakage will reduce
accuracy. Any coaxial cable used should be a low-noise
type which employs a
graphite coating between
the die-
lectric and the surrounding shield braid.
a. The Picoammeter employs the fast method of curren? measurement - the measuring resistor is between
the amplifier input and output in the feedback loop.
This method largely neutralizes the effecr of input
capacity and greatly increases the response speed.
d. Any change in the capacitance of the measuring
circuit to ground will cause disturbances in the read-
Also, the input voltage drop is reduced to a maximum
of One millivolt On any range.
ing, especially an the more sensitive ranges. Make the
measuring setup as rigid as possible, and tie down connecting cables to prevent their movement. If a continuous vibration is present, it may appear at the atput
as B sinusoidal signal and other precautions may be
necessary to isolate the instrument and the connecting
cable from the vibration.
b. Rise time varies with the current range and the
input capacity (see specifications, Table 1). The rise
time, though, is not affected with up ea 500 picofarads
across the input; however, it is better to place the
Picoammecer nearer the current scnrce than to the data
reqding instrument, Transmitting the input signal
through long cables - with greater than 500 picofarads
of capacitance - “ill increase response time and meter
noise, especially on ranges below lo-10 ampere.
2-2. OPERATING PROCEDURES.
a. Check the fuse and the 117-234 Line Switch for
the proper line voltage.
~,
b. Connect the power card to the power saurce.
c. Set the AMPERES Switch to 10 x 1O-4 ampere and
the METER Switch f~ (c). Within seconds the meter
needle should read zero, Zero the meter with the ZERO
ALU. Control. After a few moments increase the current
sensitivity by advancing the AMPERES Switch in decade
steps LO the .3 x
ing with
the ZERO A”J. Control. The instrument is
10-12
ampere range. continue zero-
now ready to use.
d. If long term measurements are ea be made, allow
the instrument to “arm up far at least 10 minutes.
4
c. The internal resistance of the unknown source
should not be less than the reciprocal af the current
range being used, otherwise the zero stability “ill be
affected.
The instrument will still be operable, how-
ever, but the sensitivity will be approximately
RF/R,
Equation 1.
where Rf is the feedback resistance in ohms;
and R, is the source resistance in ohms.
For example, if the eource to be measured has a resis-
tance of 105
back resistor “ill be lo6 ohms.
gain of the Picoammeter is 106110
ohms and the current is 10-6
This mean;h~~a:h~h~e,,
= lo.
then tbe feed-
stability of .X/week “ill be .5X x 10 = Z%lweek, nnd
the offset due to temperature “ill be .o2%xx1o x .2%/0c.
This is the reason that it is advantageous +a have the
source resistance at least equal Co the feedback resisear.
0172
MODEL 4lOA
OPERATION
Allowable Overloads on Ranges Abo”e LO-6 Ampere.
Range Voltage Overload current Overload
10-5 A
d A
10-3
10-2 A
d. Overload Protecfion. A unique circuit provides
complete overload protection for rhe Model 410A without
compromisi”~ the features of the MOS FET input. over-
load recovery is almost i”stn”taneous on the 10-10 ampere range and above. Howe”er, an the more sensitive
ranges, especially o” the 3 x lo-l3 ampere range, the
instrument may develop considerable offset which may
take anywhere from .9 few minutes co a few hours to dis-
appear.
1. on the
meter can withstand overloads of up to 1000 volts for
3 seconds and continuous overloads of up to 600 volts
wirhaue damage.
2. nor ranges above
tinuous overload is restricted due to the power dissipation of the feedback resistors (See Table 4).
&lx. continuous Man. continuous
A
104
TABLE 4.
300 "
120 "
30 v 10 *
12 v 40 In4
ampere range and below the ~icoam-
10-6
ampere, the maximum con-
ImA
4mA
PICURE 3. Divider Circuits Across Picoameter Output
for Driving 50 and IOO-millivolt Recorders. use 5%
resistors in the dividers. The value of resistor R
is one ohm for every 1 m!’ of output.
d.
l-Milliampere output. Connect l-milliampere
instruments to the 0”TP”T Receoeacle.
the high terminal. Set the 1 i.tA 1” Switch to 1 MA.
*he oueput is approximately 1 milliampere for fullscale meter deflection on any range. For exact out-
put, apply a know” full scale signal LO the Picoammeter
and adjust the 1 MA CAL Control until the recorder reads
full scale. Check the Recorder and meter zero and repeat adjustment if necessary.
not revere.= the output polarity which is always oppasite input polarity.
The METER Switch does
Pin no. 1 is
3. For maximum protection, use a Keithley Model
24OA Voltage Supply or some other 10 milliampere cur-
rent limited supply in combination with the ~icoam-
meter.
2-4. RECORDER OUTPUTS.
a. For recording with the Model 410A, use the Keithicy wade1 370 Recorder for ease, eco”omy,‘“ersatility and performance. The Model 370 is a pen recorder
with 10 chart speeds and 1% linearity. The Model 370’s
input cable has a connector which mates directly with
the OUTPUT Connector on the Picoammeter; this avoids
interface problems often encountered between a meas-
uring instrument and a recorder. The Pifoammeeer output, when set to the 1 MA Posifio”, will drive the
370; no preamplifier is needed. No special wiring is
required.
b. Other recorders, oscilloscopes and similar insfruments can be used wieh the Model 410A. The Picoammeter has two outputs, *I volt and *I milliampere,
to amplify signals for recorders, oscilloscopes and
similar instruments. These can be used on all ranges.
c. l-Volt OUtpUt,
recorder amplifiers to the OUTPUT Receptacle. pi” no.
1 is the high terminal and pin no. 2 is ground. Set
LilC ! \L\ I ‘*’ Svitcll t” 1 I’. The Picoammeter output
is now ii voLt for full scale meter deflection o” any
Noise is less than 1% of full scale peak-to-peak on
the 10-l to 10-11 ampere r*e~e~,,%iy;rm&;p ‘b~mT,,,R
peak-to-peak on the 3 v 10‘
Switch does nof reverse the oueput polarity. output
polarity is always opposite input polarity.
connect oscilloscopes and pen
e. For servo rebalance recorders, use a divider
across the Picoammeter Output Receptacle. See Figure
3. Set the OUTPUT Switch to 1 MA. “se the 1 MA CAL
Control to trim the output for full-scale recorder de-
flection. Operation is the same as for current outputs.
2-5.
234-VOLT OPERATION. The instrument is shipped
for use with a 117~volt power source unless otherwise
ordered.
SOUIICBS, use a screwdriver to change the slide switch
on the back panel to the 234.volt position. Change
the fuse from 0.125 ampere LO ,062 ampere. NO ocher
adjustment is necessary. To switch from 234 to 117volt operation, reverse the procedures.
To convert the Picoammeeer for 234~volt
0172
5
CIRCUIT DESCRIPTION
MODEL 41”A
SECTION 3.
3-l. GENERAL. The Keithley Model 410A is a linear dc
amplifier with a full scale sensitivity of 0.3, 1 or 3
““its. By using the front panel controls, shunt resistors are selected to make measurements over a toeal of
20 current ranges.
3-2. AMMETER OPERATION.
a. The amplifier has matched insulated-gate fieldeffect transiet”r8 followed by a differential transistor stage, a transistor amplifier and a transistor output stage. Figure 4 shows the simplified circuit for
the Picoamnefer.
1f it is assumed that the input voltage drop,
b.
is negligible, then all the input current, ii”,
‘,p,
ows through the measuring resistor, R,, and
= -iin Rs. Equation 2.
=o
But the output voltage, e”, is also equal to the input
voltage times the amplifier gain.
= -A ein. Equation 3.
e.
Therefore, from equation 2 and 3, we get
ein/iin = Rs/A
where ein/iin
Thus, the input voltage drop is kept at a small frac-
tion, l/A, of the output voltage, and the effective
input resistance is l/A of the measuring resistor.
is the effective input resistance.
Equation 4.
CIRCUIT DESCRIPTION
AMMETER CIRCUIT
3-3.
a. Two matched insulared-gare field-effect tran-
sistors, ~101 and Q102, are used for the amplifier
input.
21850B (see schematic) protect the gate of tran~ietor
QlOl, the active field-effect transistor, from “verloads. The gate of Q102 is returned to amplifier ground.
short from the input to the output and zeroes the instrument.
andC’Q104, drives an amplifier stage, transisror 9105,
which in turn drives the output emitter follower, tranSlSE”r QIOb.
trol, R120, varies the source voltage of transistor
QlOl with respect to the franeistor Q102. The ZERO ADJ
ConeroL, R124, varies the drain voltage of transistor
QlOl with respect to rransistor 4102.
current through transistors QlOl and Q102 by adjusting the source bias.
R118 plus R119, or R119 alone determines the full
scale sensitivity of the emplifier - either 3 volts
from 10 x 1O-4 through 3 x 10-8, .3 x 1O-8 .3 x lo-10
and 3 x lo-l2 or 1 volt on 10-8, 10 x loand 10 x lo-l2 ranges or .3 volt on .3x10range. Applying a full scale signal to the input causes e 1 milliampere current to flow through R117, Rllg
and R119. The meter is connected across the 3-volt
output. Resistors R131 and R132 set the meter current.
Resistors ~115 and R116 and circuit designation
NOTE
Refer to Schematic Diagram 22547E for circuit
designations.
b. Turning the ZERO CK. Button to LOCK places a
4 differential amplifier stage, transistors Q103
d. Two zero controls are used. The Coarse Zero Con-
e. The DC Bal Potentiometer, R121, sets the drain
f. The volrage drop across ~117 plus Rllg plus R119,
16
l* 1x10-10
ampere
=in o--J@0 %t
I
FIGURS 4.
6
0
simplified Diagram for Ammeter Circuit
0
g. The full scale current sensitivity is determined
by the range resistors RlOl through R114 in combina-
tion with resistors R117, R118 and R119. The current
measuring resistor is connected in the feedback loop.
This configuration increases the response speed by
minimizing the effects of input capacity. It ale” reduces the input voltage drop to less than 1 millivolt.
h. The 1 volt recorder output is derived from 1
milliampere flowing through resistor R136. In the 1
milliampere output mode an external load is substi-
tuted for R136. Potentiometer R135 varies ehe current
to the external load.
0172
MODEL 41OA
SERVICING
SECTION 4.
SER”ICISG SCl,EOCI,E. The value Of the high-megotlm
4-2.
resistors, 11111 through K114, should be checked approximately every six months for specified accuracy. EScept for rtlis the Yodel 4101, requires “0 periodic maintenance beyond the normal care required Of high-quality
electronic equipment.
PARTS REPLACEMENT.
4-3.
a. The Replaceable Parts LiSf in section 7 describes
the electrical campanenes of the Picoammecer. Replace
companenrs only as necessary.
ments which meet the specifications.
Ike only reliable replace-
Instrument “SC?
SERVICING
3. The procedures which follow give instructions
for repairing troubles which might occur in rhc Model
410A. “se the procedures outlined and use only specified replacement parts.
ommended for troubleshooting.
be readily located or repaired, contact Keifhley In-
Str”“entS, Inc.,
or its representative.
b. Table 6 contains the more common troubles which
might occur. If the repairs indicated in the cable
do not clear up the trouble, find the difficulty
Table 5 Lists equipment ret-
if the Lrouble cannot
Keiehley Model 163 Digital Voltmeter
1 0” to 1000”, 0.1% accuracy
Keithley Instruments Model 153 Microvolt-Ammeter; 10 vv
co 1000 v, 200 MR input resistance; ;fl% accuracy; float
$500 ” off ground.
Keithley Instruments Model 261 Picoampere Source; 10-l’
to 10-4 ampere.
Keithley Instruments Model 370 Recorder
Keirhley Instruments Model 515A Megohm Bridge
Keithley Insfruments Model 662 Guarded Differential
Voltmeter; 100 uv to 500 V, *O.Ol%.
Shielded resistors of different values, and shielded
5 pr, 50 PF, 500 pF and 5000 pF polystyrene capacitors.
Tektronix Model 561A oscilloscope
General calibration.
Rise rime check.
General circuit checking
Connecting cable for Models 410.A and 261.
Monitor drift.
Verify high megohm resistors in Range Switch.
Calibrate lacer zero.
Noise and rise time check.
0172
7
SERVICING
MODEL 410A
through a circuit-by-circuit check, such as given in
paragraph 4-5. Refer to circuit description in Section
3 to find the more critical companents and to determine
their *unction in the circuit. The complete circuit
schematic, ?2547E, is in Section 7.
4-5. PROCEDURES TO GUIDE TROUBLESHOOTING.
a. If the instrument will not operate, check ehe
power supplies. The typical voltage values, gi”e” on
the schematic, are referenced to chassis ground. Make
measurements with the Model 153 Microvolt Ammeter.
b. At times, the meter will not zero on any ran&e
with the METER Switch in the ZERO CK position. If
this occurs, adjust the front panel ZERO ADJ. Control
or, if necessary, the Coarse Zero Poten!ziomeeer, R120,
located on the PC Board. If this does not work, inspect all PC boards for a possible break in the tapes.
If these appear all right proceed with step c.
C. Amplifier.
1. To check the amplifier, disconnect rhe feedback loop by removing Ql06, 0102, Dl05 and R.130 from
rbe PC board. Check diodes Dl02 and Dl05
2. Connect a Model 153 between the bases of QlO3
and Q104. Adjust the Coarse Zero Potentiometer, Ri20,
and the front panel ZERO ADJ. Control for a null (it
may be difficult to reach a steady null; however, it
is sufficient to be able to swing through zero in a
smooth manner). If this is not possible, remO”e QlO3
and Q104 from the circuie and repeat the same process.
If null can now be reached, replace Q103 and Q104.
If it cannot be reached, QlOl and Ql02 are faulty.
3. Check the next stage, QIO5, by placing a Model
153 from the collector end of R129 to ground. Adjust the Model 410.4 Zero Controls for null. If this
cannot be accomplished, check DlOl for a possible
open by shorring it with a clip lead. If null can
now be reached, DlOl is open and should be replaced.
If null cannot be reached, replace Q105.
4. If null can now be attained at the collector
of QlO5, rbe trouble is in the output stage and Q106
should be replaced. If this does not cure the
trouble, carefully check all the diodes associaeed
with the output stage - Dl02, Dl03, 0104 and DlO5
Difficulty
Excessive zero offset
cannot zero on any range
Meter off scale on one of
range settings
One range out of specification
TABLE 6. Model 410.4 Troubleshooting.
Probable cause
Input transistors may be defective Check QlOl and 4102; replace if faulty.
Power supply voltage low Check power supply.
Excessive temperature fluctuations Check QlOl and Ql02; replace if faulty.
or defecrive input transistors
Refer to paragraph 4-5. Refer to paragraph 4-5.
Faulty range resistor Check resistor; replace if faulty.
Defective range resistor Check resistor: replace if faulty.
I
so1ueian
8
0172
MODEL 410.4 CALIBRATION
SECTION 5.
5-1. GENERAL.
a. The following procedures are recommended for calibrating the Model 410A. Use ,the equipment recommended
in Table 5.
if difficulty is encountered, coneact Keithley ~nstru-
merits, Inc., or its .representatives to arrange for
factory calibration.
0.
If the Model 41OA is not within specifications
after the calibration, fallow the troubleshooeing procedures or contact Keithley Instruments, Inc., or its
representatives.
5-Y. PRELIMINARY PROCEDURES
a. Make sure the 1 MA - 1 V and 117-234 V Switches
in the rear panel are see to 1 V and 117” respectively
set the front panel controls as fallows:
HMPERES Switch 10 x 10-4
METER
ZERO AOJ. Control Mid-range
ZERO CHECK Sutton Unlock.
b. see the DC B81 Potentiometer, R121, coarse zero
Pacentiometer, RlZC, and Meter Cal. PoLentiometer, R132,
near mid-range,
c. Zero the meter wifh the Mechanical Zero Coneral.
d.
Plw the Model 410~ into a 117 volt eource and
set the K&R Switch to + and check zero with the ZERO
CHECK Button.
1
should read an scale for either polarity (t or -).
Adjust the Coarse Zero Potentiometer for a zero indication on the meter.
2.
not zero the meter, check for a shorted beat sink
on the MOS FET transistors, QlOl and Q102. The two
halves of the heat sink must be insulated in order
for the Coarse Zero Potentiometer to function pro-
perly.
If proper facilities a;e no? available or
Switch POWER OFF
If the Model 410A is operative, then the meter
If the coarse.zero PatenLiometer, R120, can
CALIBRATION
5-3. POWER SUPPLY CHECK. (See Figure 6 for test
points for the Power Supplies.
a. Check the positive and then the negative 26 volt
supply by connecting the Model 163 between ground and
the pIus and minus 26 volt test points respectively
(Hg. b). The voltage should be plus and minus 26
volts *3 volts respectively. The ripple in each caee
should be less than 3 YOlt8 peak-to-peak.
b. Check the posieive and then the negative 15 volt
supplies by connecting the Model 163 between ground
and the plus and minus 15 volt fese points respectively
(Figure 6). The voltage for the plus and minus 15 vole
supplies should be plus and minus 15 volts *2.0 volts
respectively. The ripple in each case should be less
than 20 m” peak-to-peak.
c. Check the positive and then the negative 9 volt
supplies by connecting the Model 163 between ground
and the plus and minus 9 volt test paints respectively
(Figure
plus and minus 9 volts il.0 volt respectively. The
ripple in each case should be less than 3 mv peak-topeak.
the line voltage is changed from 105 volts ac to 125
volts ac.
volt supplies should be less than f0.2 volt.
meter for 234 volr. 50 Hz operation.
410.4 into a 220 volt ac, 50 Hz line and check the positive and negative 25 volt supplies per paragraph 5-3a
above. The seme readings as in subparagraph a above
should be obtained except that an additional 1 volt
tolerance should be allowed for each 10 volr difference
between 234 volts ac and the actual line voltage.
6).
the voltage for these supplies muse be
d. Monitor the plus and minus 15 volt supplies as
The voltage change of the plus and minus 15
e. Turn the Model 410.4 off and prepare the Picoam-
NOTE
The remaining calibration procedures should
all be performed with the Model 410A operating from 117 volts ac, 60 Hz.
Plug the Model
0172
9
MODEL 410h
5-4. MOS FET CURRENT ADJUST.
a.
set the Picoammeeer AMPERES Switch to 10 x 1W4.
the METER switch to + and check zero with the ZERO
CHECK Button.
b. set the front panel ZERO AD.,. Control to approximately mid-range and adjust the Coarse Zero Potentiometer, R120, for a zero indication on the meter.
C. Connect the Model 163 DVM across resistor R.123
and adjust the DC BAL Potentiometer, R121, for an indication of -5.4 “olrs +0.2 “olt.
NOTE
When making this measurement, be certain
that the WI., co,,,,,,on is above ground.
5-5. OFFSET CHECK.
a. See the Picoammeter AMPERES Switch to 10 x 10e4,
the METER Switch to + and check zero with the ZERO
CHECK Button.
Cap the INPUT Receptacle and connect the
Model 41OA to the Model 163 WM.
NOTE
When checking the offset make sure the Model
410A CoYer is on.
b. If necessary, adjuse the ZERO ADJ. Conerol for
zero voles at the outpnt.
Set the AMPERES Switch to .3 Y 10-12. Make sure
C.
that the output remains at zero “olts,
adjusting
the
front panel ZERO ADJ. Control if necessary.
d. Unlock the ZERO CHECK Button. Output voltage
should be less than 33 m” (lo-l4 ampere).
If the Meter
has been calibrated, the offset should be less than
two minor divisions on the lower meter scale.
5-6. METER AND LMA OUTPUT CALImATION.
a. see the AMPERES Switch to 1 x 10-6. Connect the
Model 261 Picoampere Source to the Model 41OA INPUT
~ecepeacle and connect the Model 163 D”M to the OUTPUT
ReCeptaCle.
Set the Model 410A METER Switch to + and apply
b.
10-e
ampere with the Model 261. If necessary, adjust
the ZERO ADJ. Control for exactly 1.000 “olt at the
output.
C, Adjust the Meter Cal Potentiometer, R132, for
full scale meter deflection.
d. Load the Model 41OA output with a 1.5 kilohm re-
sistor and see the 1 V - 1 MA Switch to 1 MA.
e. Adjust the rear panel 1 Ew CAL Control and note
that the output voltage can be adjusted at least 0.1
volt either side of 1.5 volts.
remove the 1.5 kilohm load and set the 1 V - 1
f.
MA Switch to 1 V.
g. Check zero with the ZERO CHECK Button and re-
zero the olitpue if necessary.
5-7. RANGE ACCURACY CHECK
a. Cmnect the Model 410.4 INPUT Receptacle to the
Model 261. Connect the O”TP”T Receptacle fo the Model
163
b. Check the full-scale accuracy of all positions
on the AMPERES Switch. Check both positi”e and negative inputs to ensure proper operation of both palarities at various current input levels. Check the accuracy of the 10 x 1O-4
through the 1 x 10-S ranges to
i2% of full scale af the output (1.0 volt *20 millivolts). Check the accuracy of the .3 x 10.8 rhrough
the .3 x lo-12 ranges to *4% of full scale at the outout (1.0 volt T40 milli”olts).
5-S. RISE TIME CHECK. To check the rise time of the
\lodel 410A requires three different test set-ups. The
first set-up is for checking rise times on the 10~10‘~
through 1 x 10-S ranges. The second set-up is for check.
ing the rise times on the 10 x 10-10 and 1 x 10-10
ranges. The third set-up is for checking the rise times
on the 10 x lo-l2 and 1 x lo-l2 ranges.
10 x 10-4 through 1 x 1O-8 w. Set the tell
a.
fixture up as illuserated in Figure 5.
1. Equipment used (Refer to Table 5): The Model
202A Function Generator,
six shielded resistors rang-
ing in value from 3 kilohms to 300 megohms (See Table
8), a UHF Tee connector, a 500 pF polystyrene shunt
capacitor, the Model 41OA and the Model 561A Oscilla-
scope.
The oscilloscope used mutt be dc coupled.
2. Procedures:
a) Apply a square wave from the Model 202A Func-
tion Generator across the selected series resistor,
through the W Tee to the Model 4lOA INPUT Receptacle. Observe the output of rhe Model 410A with
the Model 561A.
b) For each Model 410A range, use the Model 202A
frequency setting and the series resistor indicated
in Table 8.
TABLE 8.
Model 410A Rise Time Check for 10 x 10e4
Through 1 x 10-S Ranges. The Table gives the Model 41OA
AMPERE Switch settings, the Function Generator frequen-
cy settings, the series resistor used for each AMPERE
Switch setting, and the maximum allowable rise time.
Funcrio"
Model 410A
AMPERE Switch Series Frequency
setting Resistors
Ge”eratOX
(HZ)
Maximum
Rise Time
(milliseconds)
10 x 10-4 3 kfi 250 less than 1
1 x 10-4 30 k!l 250 less than 1
IO x
10-6
300 kn 250 less than I
1 x 10-6 3 MCI 250 less than I
IO x
1 x
10-8
10-8
30 Ml? 250 less than 1
300 MC? 2.5 130
10
0172
MODEL 410A
CALIBRATION
b. 10 Y 10 & 1 -10 x 10
-10
m. Set this test
fixture up as illuSerafed in Figure 5, except use a
5000 PF shunt capacitor end Substitute a shielded 50
1. Equipmenr Used: This test set-up uz.eS the Same
equipment of the previous set-up with the exception
of the 5000 pF and 50 pF palysytrene capacitors.
50
pF series capacitor in
this ret-up served a similar function as the series re~i~for~ in the previous
test set-up.
2. Proceduree:
a) Apply a triangular wave from the Model 202.4
r
across the capacitor, through the UHF Tee to the
yodel
410.4
410A output with the Model 561A.
INPUT receptacle. Monitor the Model
Use the proper
Model 202A frequency setting as indicated in Table 9.
b) Adjust the Model 202A amplitude control as
needed to obtain 2 volt?. peak-to-peak at the Model
41OA
output. Check the 10 - 90% rise rime to the
figures shown in Table 9.
TA8l.E 9. Model 410A Rise Time Check for 10 x 10el"
1 x lo-lo Ranges. The
Table gives the Model 410A AMPERE
Switch setrings, the Function Generator frequency settings, and the maximum allowable rise time.
Model 410A Function Generamr Maximum
AMPERE Switch Frequency
Settine.
(HZ)
2.5
1.0 400
(milliseconds)
Rise Time
100
The
and
c.
10 x lo-l2
and 1 x lo-l2 w.
Set this test
fixture up as in paragraph 5-8b above except use a 500
pF shunt capacitor and a 5 pF series capacitor berween
the Function venerator and the WE Tee.
1. Equipment Used: Except for the values of the
capacitors mentioned above,
this set-up USES the fame
equipment as in paragraph 5-8b.
2,. Procedures:
Set the Picaammeter AMPERES Switch to 10 x
“1
10.
2.
Model
Apply a 0.5 Hz triangular wave from the
202A
ecross the capacitor, through the UHF
Tee to the Model 410A INPUT Receptacle.
b) Adjust the Model 202A amplitude control as
needed to obtain 2 volts peak-to-peak at ehe Model
410A output. Check the 10 _ 90% rise time on the
Model
561A.
It should be less than one second.
c) Set the Picoammeeer AMPERK+ Switch to
1 x 10-12.
Apply a 0.05 Hz triangular uave from
the Model 202A to rhe Model 410A.
d) Adjust the Model 202A amplitude control to
obtain 2
voles peak-to-peak at the Model 41OA output. Adjust the slide on resistor RI14 to obtain
between 2 to 2.5 secondr 10 - 90% rise time.
e) Replace the
5000 pF shunt capacitor.
500
pF shunt cap~cimr with a
f) Apply a triangular signal from the Function
Generaear to the Model 4lOA as listed in Table 10.
Adjust the Model 202A amplitude control as needed
I
to obtain 2 voles peak-to-peak at the Model 410A
output. Check the 10 - 90% rise times to the figures in Table 10.
.
FIGURE 5. lest Set-up for
Model 410A Rise Time
Checks on all ranges.
and the UHF Tee and shunt capacieor are properly shielded.
0172
Make Sure rhe series reSiStor or capacitor,
11
CALIBRATION
MODEL 410A
TABLE 10. Model 410A Rise Time Check for 10 x 10-12
and 1 x 10-12 Ranges.
AMPERES Switch settings, the Function Generator frequen
cy settings, and the maximum allawable rise time.
~~
g) Cap the Model 410A INPUT Receptacle and check
the output noise on the 10 x lo-l2 and .3 x lo-l2
ranges. The noise muet be less than 10 millivolts
end 50 millivolts peak-to-peak respectively.
h) If the noise is high, readjust the 10~10~1~
and 1x10-” rise times prior to athee corrective
measures. High naise may be due to too fast rise
rimes.
5-9. NOISE CHECK.
a. Set the AMPERES Switch to 10 x 10m4, METER Switch
to c and check Picoammeter zero with the ZERO CHECK
Sutton. Connect the Model 410A OUTPUT Receptacle to
the Model 561A Oscilloscope and cap the Made1 &lo.& INPUT Receptacle. Set the oscilloscope to 5 mV/div dc
coup led.
b. Unlock the ZERO CHECK Button and check the o”tput
noise on the 10m4 through 10-l’ ampere ranges for less
than 10 millivolts peak-to-peak.
C, decrease the oscilloscope sensitivity to 10 or 20
peak-to-peak.
The Table gives the Model 410A
Check the output noise on the 3x10-1‘
ranges far less than 50 millivolts
5-10.
ohm resistor with the AMPERE Switch set to 1 x 10-6,
the METER Switch set to + or -, es necessary, and the
ZERO CHECK Buttcrr unlocked. Using the shunt increases
the sensitivity 100 times.
Set the Recorder eteenuat~r to 1 volt (10 millivolts
drift full scale) or 0.3 volts (3 millivolts full scale).
Control far near zero volte ~ucput. The ZERO ADJ Cantrol
is very sensitive with the sensitivity increased 100
times. Set the METER Switch to - if the drift is negstive.
drift 700 microvolts per 24 hours plus or minus 200
microvoles per ‘C change in temperature.
ginal or it may be slightly out of specification due
to e steep drift elape during the early pert of the
drift. 1f ehis ie so, if may be desired LO continue
the drift for e,, additional 24 hours and calculate e
weeks drift as fallaws:
1”
DRIFT vERIFICATION.
Shunt the Input of the Model 410.4 with a lo-kil-
a.
NOTE
While doing the drift run make sure the
Model 410A ccwer is on.
b. Connect the Model 370 Recorder to the Model 410.4.
C. Set the METER Switch to + and adjust the ZERO AoJ
d. After a lo-minute warm-up, the Model 410A may
e. In ecrne cases, the 24-hour drift may appear mar-
1. Multiply drift during second 24-hour period
times 6 and add the drift noted during the first 24-
hour period.
2. Total drift should be less than 5 m”.
12
0172
MODEL 41OA
CALIBRATION
0172
FIGURE 6.
I
Chassis, Top view.
13
CALIBRATION
MODEL 410A
14
FIGURE 7.
Component Layout, Pc184.
0172
MODEL 410A ;
ACCESSORIES
SECTION 6.
6-l. GENERAL. The following Keithley accessories 6-2. OPEPATlNG INSTRUCTIONS. A separate Instru~eion
can be used wifh the Model 410A to provide additional
convenience and versatility. operating information.
I
Model 6106 Electrometer Connection Kit
Description:
The Model 6106 contains a group of the most useful
leads and adparecs far low current measurements. All
components are housed in a rugged carrying case with
individual compartments.
ACCESSORIES
Manual is supplied with each accessory giving complete
Parts List:
Description
Cable, 30”, UHF to clips
Cable, 24”, UHF to UHF
Connector, UHF to UHF
Adaptor, UHF to BNC :, a-115
Adaptor, UHF to BNC 5 G-172
Adaptor Tee, UHF to UHF
Adaptor, Binding Post 7 190718
The two cables (Items 1 and 2) are coaxial shielded
leads useful for connections where low noise is essential. The 24” cable (Item 2) can be used to interconnect two instruments having UHF receptacles. The 30”
cable (Item 1) can be used to connect to the circuit
under test through the use of clip leads. A binding
post adapter gives easy access to the electrometer
“high” rerminal. Two UkB’ female couplers (Item 3)
permit cables to be connected togefher. The UHF “tee”
connector simplifies galvanometric current measurements
when using a current source and electrometer or picoameter. Adapters (items 4 and 5) are useful far conversion from LIHF to BNC terminations.
It=”
NO.
1
2
6
Keirhley
Part No.
1907x
18265C
B-5
cs-171
Model 261 Picoampere Source
Oeseription:
The Model 261 is an accurate picoampere current source
with 3 digit resolution. The output ranges are lo-l4
ampere to 1.1 x 10m4 ampere, positive or negative, in
eight decade ranges. Accuracy is rated from 1.25% to
21.6% exclusive of input drop considerations.
Application:
‘The Model 261 is a secondary standard for use in calibrating picoameters and electrometers. It can also be
used as an accurate current source for zero suppression
and for galvanometric measurements.
0172
15
ACCESSORIES
MODEL 41OA
Models 24OA, 244, 245, 246 Voltage Supplies
Description:
Keiehley voltage supplies are highly-stable, low-noise
power supplies for voltages up to 23100 volts dc.
Application:
Keithley voltage supplies are commonly used with pico-
ameters in the measurement of resistance, light levels
(photomultipliers), and radiation intensity (ion chambers).
These high voltage supplies have been designed to
operate with the Keithley line of electrameters,
picoameters and resisrivity accessories. A typical
application is shown using the Model 414s (or 414A)
and the Model 240A in a photomultiplier experiment.
Output Ranges:
Model No. Voltage
240A
244
245
246
0 to i12oov
-200 to -2200"
0 to ~2100"
0 to i31oov
Model 4104 Electronic
Trip
The Model 4104 is an electronic trip installed in the
p'coameter to provide automatic current control.
Combinations of high, low, + polarity, and latching
is available.
16
Model 4109 Polarizing Supply
The Model 4109 provides +300 volts at 1 mA for applications requiring a stable voltage source. The Model
4109 can be ordered installed in the picoameeer if
desired.
0172
MODEL 410A
ACCESSORIES
Model 4003A Rack Mounting Kit
Description:
The Model 4003A is a rack mounting kit with overall
dimensions, 5-l/4 inches high x 19 inches wide. TWO
top cover‘s are provided far use with either 10 inch or
13 inch deep instruments.
t
Application:
The Model 4003A converts the instrument from bench
mounting to rack mounting.
.
ing one instrument in one-half of a standard 19-inch
It is suitable for mount-
rack.
Parts List:
1eem
NO.
1
2
Description
Too Cover. 10"
Panel Adagter Plate
3 Angle support
4
5
Screw,#lO x 3/S"
Connecting Plate
6 Screw, #IO x l/Z"
7 Angle
8
Top Cover, 13"
oty. Per
Assembly
1 185548
1
1
4
1
4
1
1
Keithley
Part NO.
174520
17476A
___
19126A
___
146248
200158
Model 4004A Dual
Description:
The Model 4004A is B rack mounting kit with overall
dimensions,
5-l/4
inches high x 19 inches wide. Two
top covers are provided for use with either 10 inch
Or 13 inch deep instruments.
Application:
The
Model 4004~ converts the instrument
mounting to rack mounting.
It is suitable for mount-
from bench
ing two instruments in a standard 19-inch rack.
0172
Rack “ou”ei”g Kit
Parts List:
Item
-NO.
1
4
5
6
7 Angle
8 Top Cover, 13"
9 Zee Bracket
Description
Top Cover, 10"
Screw, 010 x l/2
Connecting Plate
Screw, #lo x 112
10 Plate (not shown)
Qey. Per
Assemblv
2
8
1
4
2
2
1
1
Keithley
par-c NO.
185548
---
19126A
---
146248
200158
19144.4
17454.4
17
REPLACEABLE PAR+S
SECTION 7. REPLACEABLE PARTS
7.1,
REPLACEABLE PARTS LIST. The Replaceable part's
!.ist describes the components of the mdel 410~. me
List: vi"es the circuit designation, the pare descrip-
tion, a suggeswd manufacturer, ehe manufacturer's part
number Brld the Keithley part Number. The last column
idicates the figure picturing the part. The name and
address of the manufacturers listed in "Mfg. Code" colLLnm are in Table 14,
7.:9,
HOW TO ORDER PflllTS
a. ?or parts orders, include the inserunent's model
TABLE 13. Abbreviations and symbols.
MODEL 410A
and serial number, the Keithley Pare Number, the cir-
cuit designation and a description of the pare. All
structural parts and those coded for Keithley manufacture (80164) must be ordered throu8h Keithley ~nscru-
rents. Inc., or its represencncives. In ordering a
part not listed in the replaceable Parts List, completely describe the part, its function and its locntion.
b. Order parts through your nearest Keithley repre
sentative or the Sales service Deonrfment. Keithle"
Instruments, 1°C.
A
CbVar
Ampere
cartan Variable
cem ceramic, disc
camp Composition
DCb
Deposited Carbon
EAl Electrolytic, Aluminum
F
Farad
(Refer to Schematic Diagram 225478 far Circuit Designations.)