ORTEC 439 User manual

Model 439
Digital Current Integrator
Operating Manual
Printed in U.S.A. ORTEC®Part No. 733240 0908
Manual Revision K

Advanced Measurement Technology, Inc.
a/k/a/ ORTEC®, a subsidiary of AMETEK®, Inc.
WARRANTY
ORTEC* warrants that theitems will be delivered free from defects in material or workmanship. ORTEC makes
nootherwarranties,expressorimplied,andspecificallyNOWARRANTYOFMERCHANTABILITYORFITNESS
FOR A PARTICULAR PURPOSE.
ORTEC’s exclusive liability is limited to repairing or replacing at ORTEC’s option, items found by ORTEC to be
defective in workmanship or materials within one year from the date of delivery. ORTEC’s liability on any claim
of any kind, including negligence, loss, or damages arising out of, connected with, or from the performance or
breach thereof, or from the manufacture, sale, delivery, resale, repair, or use of any item or services covered by
this agreement or purchase order, shall in no case exceed the price allocable to the item or service furnished or
any part thereof that gives rise to the claim. In the event ORTEC fails to manufacture or deliver items called for
in this agreement or purchase order, ORTEC’s exclusive liability and buyer’s exclusive remedy shall be release
of the buyer from the obligation to pay the purchase price. In no event shall ORTEC be liable for special or
consequential damages.
Quality Control
Before being approved for shipment, each ORTEC instrument must pass a stringent set of quality control tests
designed to expose anyflaws in materials or workmanship. Permanent records of these tests are maintained for
use in warranty repair and as a source of statistical information for design improvements.
Repair Service
If it becomes necessary to return this instrument for repair, it is essential that Customer Services be contacted
in advance of its return so that a Return Authorization Number can be assigned to the unit. Also, ORTEC must
beinformed, either in writing,bytelephone[[phone]]orbyfacsimiletransmission[[phone]],ofthe
nature of the fault of the instrument being returned and of the model, serial, and revision ("Rev" on rear panel)
numbers. Failure to do so may cause unnecessary delays in getting the unit repaired. The ORTEC standard
procedure requires that instruments returned for repair pass the same quality control tests that are used for
new-production instruments. Instruments that are returned should be packed so that they will withstand normal
transit handling and must be shipped PREPAID via Air Parcel Post or United Parcel Service to the designated
ORTEC repair center. The address label and the package should include the Return Authorization Number
assigned. Instruments being returned that are damaged in transit due to inadequate packing will be repaired at
the sender's expense, and it will be the sender's responsibility to make claim with the shipper. Instruments not
in warranty should follow the same procedure and ORTEC will provide a quotation.
Damage in Transit
Shipments should be examined immediately upon receipt for evidence of external or concealed damage. The
carrier making delivery should be notified immediately of any such damage, since the carrier is normally liable
fordamageinshipment.Packingmaterials,waybills,andothersuchdocumentationshouldbepreservedinorder
to establish claims. After such notification to the carrier, please notify ORTEC of the circumstances so that
assistance can be provided in making damage claims and in providing replacement equipment, if necessary.
Copyright © 2008, Advanced Measurement Technology, Inc. All rights reserved.
*ORTEC®is a registered trademark of Advanced Measurement Technology, Inc. All other trademarks used herein are
the property of their respective owners.

iii
CONTENTS
WARRANTY........................................................................... ii
SAFETY INSTRUCTIONS AND SYMBOLS ..................................................iv
SAFETY WARNINGS AND CLEANING INSTRUCTIONS ....................................... v
1. DESCRIPTION ...................................................................... 1
2. SPECIFICATIONS ................................................................... 1
2.1. PERFORMANCE ................................................................ 1
2.2. CONTROLS .................................................................... 1
2.3. INPUTS........................................................................ 1
2.4. OUTPUT....................................................................... 2
2.5. PHYSICALDATA ................................................................ 2
3. INSTALLATION...................................................................... 2
3.1. GENERAL...................................................................... 2
3.2. CONNECTIONTOPOWER........................................................ 2
3.3. INPUT CONNECTION FOR DC CURRENT ........................................... 2
3.4. INPUT CONNECTION FOR PULSED CURRENT ....................................... 2
3.5. CONNECTORDATA ............................................................. 3
4. OPERATING INSTRUCTIONS .......................................................... 4
4.1. TEST-OPERATESWITCH......................................................... 4
4.2. POLARITYSWITCH.............................................................. 4
4.3. BAL/TRIGSWITCH .............................................................. 4
4.4. CURRENT F.S. AND COULOMB/PULSE SWITCH ...................................... 4
4.5. MULTIPLIERSWITCH ............................................................ 4
4.6. INTERNALTESTCHECK ......................................................... 4
4.7. OFFSET CURRENT ADJ .......................................................... 5
4.8. USEOFDIGITIZEDOUTPUT ...................................................... 5
5. MAINTENANCE ..................................................................... 5
5.1. TESTINGPERFORMANCE ........................................................ 5
5.1.1. TestEquipment ............................................................ 5
5.1.2. Preliminary Procedures ...................................................... 5
5.2. CALIBRATION PROCEDURE ...................................................... 6
5.2.1. Digital.................................................................... 6
5.2.2. Analog ................................................................... 7
5.3. SUGGESTIONSFORTROUBLESHOOTING .......................................... 8
5.4. FACTORYREPAIR .............................................................. 8
5.5. TABULATEDTESTPOINTVOLTAGESONETCHEDBOARD ............................ 8

iv
SAFETY INSTRUCTIONS AND SYMBOLS
This manual contains up to three levels of safety instructions that must be observed in order to avoid personal
injury and/or damage to equipment or other property. These are:
DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction is
not observed.
WARNING Indicates a hazard that could result in bodily harm if the safety instruction is not observed.
CAUTION Indicates a hazard that could result in property damage if the safety instruction is not
observed.
Please read all safety instructions carefully and make sure you understand them fully before attempting to
use this product.
In addition, the following symbol may appear on the product:
ATTENTION – Refer to Manual
DANGER – High Voltage
Please read all safety instructions carefully and make sure you understand them fully before attempting to
use this product.

v
DANGER Opening the cover of this instrument is likely to expose dangerous voltages. Disconnect the
instrument from all voltage sources while it is being opened.
WARNING Using this instrument in a manner not specified by the manufacturer may impair the protection
provided by the instrument.
CAUTION To prevent moisture inside of the instrument during external cleaning, use only enough liquid
to dampen the cloth or applicator.
SAFETY WARNINGS AND CLEANING INSTRUCTIONS
Cleaning Instructions
To clean the instrument exterior:
! Unplug the instrument from the ac power supply.
! Remove loose dust on the outside of the instrument with a lint-free cloth.
! Remove remaining dirt with a lint-free cloth dampened in a general-purpose detergent and water solution.
Do not use abrasive cleaners.
! Allow the instrument to dry completely before reconnecting it to the power source.

vi

1
439 DIGITAL CURRENT INTEGRATOR
1. DESCRIPTION
The ORTEC 439 Digital Current Integrator* was
designedtoaccuratelymeasure thedirectcurrentor
the average value of pulse currents such as
accelerator beam currents. The ORTEC 439
digitizes the input current by producing an output
pulse for specific values of input charge. A front-
panel switch permits the selection of three different
amounts of charge (10-10, 10-8, or 10-6 Coulomb)
required to produce an output pulse. This gives the
user the option of more than one count rate for a
given input current. The instrument has a digitizing
rate from 0
! 10 kHz to provide wide dynamic range
on each setting and high-resolution readout without
meter interpolation. When combined with a preset
scaler such as the 431, this instrument forms a
digital charge integrator. When itis combined with a
digital ratemeter such as the 434, a digital
electrometer is obtained.
A front-panel meter is provided to read the input
current. Full-scale analog outputs of 1 mA, 100 mV
and10mVareprovidedonrear-panelbindingposts.
There are 15 ranges from 1 × 10-9 to 1 × 10-2 A for
obtaining full-scale readings for the front-panel
meter and the analog outputs.
BNC connectors are provided on the front and rear
panels for the application of a gate signal to inhibit
the digitized output. This gate may be used to
remotely control the 439 or it may be used to inhibit
the digitized output with the multichannel analyzer
dead-time pulse.
2. SPECIFICATIONS
2.1. PERFORMANCE
LEAKAGE IMPEDANCE FROM INPUT TO
GROUND >1 ×1010
Ω .
INPUT LEAKAGE CURRENT <1 × 10-12A.
TEMPERATURE STABILITY 0.05%/
E C, 0 to
50
E C.
DIGITIZED OUTPUT ACCURACY ±0.2% of
reading from 100 nA to 10mA dc; typical accuracy
±0.3% of reading at 50 nA. Count rate on 10-10
Coulomb/pulse range limited to 1kHz.
DIGITIZED REPRODUCIBILITY 0.01%.
ANALOG ACCURACY Front-panel meter, 2%;
rear-panel binding posts, 1.5%.
2.2. CONTROLS
INPUT CHARGEPER OUTPUT PULSE Selectable
byfront-panelswitch,10-10,10-8,10-6 Coulomb/pulse.
TEST CURRENT Selectable by front-panel switch;
produces a digital output of ~1 kHz on each
Coulomb/pulse setting.
2.3. INPUTS
SIGNAL INPUT Through SHV connectors on front
and rear panels.
! Impedance Virtually ground with maximum
excursion of <±5mV.
! Current Polarity Positive or negative.
! Current Range 1 × 10-9 to 1 × 10-2 A.
GATE INPUT Signal normally enabled in absence
of an input or when the dc value is nominally +6V;
BNC connectors on front and rear panels.
! To Enable Output +3 V or greater.
! To Inhibit Output +1.5 V or less (e.g., can be
shorted to ground by a relay).
! Maximum Input +25 V, -10 V.
Duty Cycle Limitation None, dc-coupled.
Input Impedance >1000
Ω ;drivingsourcemustbe
capable of sinking 1 mA of current from a positive
source.
*Based on a design by F.M. Glass, ORNL. See F.M. Glass et al.,
“A New Approach to Direct Current Integration,” IEEE Trans.
Nucl. Sci. NS-14 (1), 143-146 (February 1967).

2
2.4. OUTPUT
DIGITIZED Signal +5 V, 500 ns wide; 0 to 10 kHz;
BNC connectors on front and rear panels.
ANALOG
! Front-Panel Meter 0 ! 1and0 ! 3scalesserving
all multiplier ranges; there are 15 full-scale
ranges.
! Rear-Panel Binding Posts 0 to 1 mA full scale,
0 to 100 mV full scale, 0 to 10 mV full scale;
there are 15 full-scale ranges.
2.5. PHYSICAL DATA
POWER REQUIRED +24 V,45mA; +12V,95mA;
-24 V, 45 mA; -12 V, 110mA.
DIMENSIONS NIM-standard triple-width module
(4.05 in. Wide by 8.714 in. High) per TID-20893
(Rev.).
3. INSTALLATION
3.1. GENERAL
The 439, used in conjunction with the 4001A/4002A
Bin and Power Supply, is intended for rack
mounting; therefore any vacuum tube equipment
operated in the same rack must be sufficiently
cooled by circulating air to prevent any localized
heating of the all-transistorized circuitry used
throughout the 439. The temperature of equipment
mounted in racks can easily exceed the
recommended maximum temperature of 120
E F
(50
E C) unless precautions are taken.
3.2. CONNECTION TO POWER
The 439 contains no internal power supply but must
obtain necessary operating power from a Nuclear
Standard Bin and Power Supply, such as the
ORTEC 4001A/4002A. It is recommended that the
Bin and Power Supply be turned off when modules
are inserted or removed. The 400 Series is
designed so that it is notpossible tooverload theBin
and Power Supply with a full complement of
modules in the Bin; however, this may not be true
when the Bin contains modules of other than
ORTECdesign,andinsuchinstancesPowerSupply
voltages should be checked after the modules are
inserted. ORTEC 4001A/4002A has test points on
the Power Supply control panel to monitor the dc
voltages.
3.3. INPUT CONNECTION FOR DC
CURRENT
Input SHV connectors are provided on the front and
rear panels. To ensure maximum accuracy, the
impedance of the current source should be kept as
high as possible (>1010
Ω ), even though the 439
dynamic input impedance is very low. The input
varies less than 3 mV from ground during operation.
This small voltage variation should present no
leakage problems except in those cases where
water-cooledtargetcurrentismeasured.Thecurrent
source impedance (Rsin Fig. 1) required to make a
0.1% accuracy measurement can be calculated by
the formula
For example, to measure 1
µ A to an accuracy of
0.1%, a source impedance of at least 3 M
Ω is
required. If a 1%accuracywere acceptable, R could
be reduced to 300 k
Ω . The following table may be
helpful to determine the source impedance required
to measure the current in your system. Be careful to
avoid ground loops when installing the 439. If a
coaxial cable is used to connect the current source
to the input of the 439, it may be necessary to leave
the cable shield ungrounded at the current source.
Of course, it would be advantageous to locate the
439 as near as possible to the current source to
avoid long ground returns.
3.4. INPUT CONNECTION FOR PULSED
CURRENT
The beam current from manyaccelerators arrives in
the target area as a pulsed beam, whose rate varies
from the megahertz range to a few pulses per
second. Problems could be encountered when

3
Fig. 1. Source Impedance Requirements.
Fig. 2. Input Storage Network for 10
! 6Coulomb/Pulse
Range.
high peak currents occur or when the charge in a
beam current pulse exceeds one-tenth the amount
selected by the Coulomb/pulse range selected on
the 439. These problems can be overcome by
adding a low leakage capacitor to the input of the
439. This capacitor will act as a storage element for
the charge until the 439 can process it (see
Section 5.1 for a functional description of the 439).
If it becomes necessary to add a capacitor to the
input when the 10-6 Coulomb/pulse range is used,
then 30 to 50
Ω should be added in series with the
input of the 439 as shown in Fig. 2.
Whenever practical, the value of C should be large
enough so that the charge in each beam pulse does
not create a voltage of more than 10 mV on C. For
instance, if each beam pulse contained 10-9
Coulomb of charge, the 10-10 Coulomb/pulse range
could be used on the 439 if a capacitor of the
following size were added to the input:
Of course, this assumes that the average current
does not exceed the dynamic range of the 10-10
Coulomb/pulse range.
3.5. CONNECTOR DATA
INPUT SHV connectors are provided on the front
andrearpanelsforconnectiontothe439 input.SHV
connectors are used because of their low-leakage
characteristics. Care should be taken to keep the
439 input circuitry as clean as possible in order to
prevent leakage paths to ground. The Test-Operate
switch should be positioned to Standby before
making connections to or from the input. Even
though the input circuitry is protected against
overvoltage, transients drive the input amplifier into
saturation, producing a temporary imbalance in the
input amplifier due to the long time required for the
MOS-FET’s to recover from overload.
DIGITIZED OUTPUT The outputisdc-coupled and
isprovidedonboththe frontandrearpanelsthrough
BNC connectors. A standard logic pulse 5 V in
amplitude and 500
µ s wide is produced each time
the required amount of charge is received a the
input. The width of this pulse can be altered as
desiredbychangingthevalueofC15.Theamplitude
can be increased by increasing the value of R93.
GATE INPUT The gate input signal is connected to
the 439 by front- and rear-panel BNC connectors.
With no connection made to thegateinput,the input
voltage level is about +6 V and the gate will permit
digital pulses to appear at the Digitized Output
connector when an appropriate amount of charge is
received at the input. When the gate input is pulled
below +1.5 V, the digital output pulses are blocked
anddonot appearatthe DigitizedOutputconnector.
To pull the gate input below +1.5 V, the driving
circuit must be capable of absorbing 1 mA from the
gate input circuit. The gate circuit will permit normal
operation of the 439 when the gate input is at +3 V
or greater.

4
4. OPERATING INSTRUCTIONS
4.1. TEST-OPERATE SWITCH
The Test-Operate is a three-position switch which
controls the function of the instrument:
STANDBY This position grounds the input of the
439, preventing the application of transients to the
input amplifier and should therefore be selected
before applying power to the 439, making any
connections to or from the Inputs connectors, or
changingthePolarityorCurrentF.S.switches.This
position must be selected when adjusting the input
amplifier by use of the Bal and Trig potentiometers
(see Section 4.3).
OPERATE This is the position in which the
instrumentwillnormallybeused.Inthis positionthe
input amplifier is connected to the input connectors
(SHV’s) on the front and rear panels.
TEST In this position an internal test current is
provided to produce an output of approximately
1000 Hzon all Coulomb/pulse ranges. This current
is not meant to be used as a calibration but merely
as a reference test current once the unit has been
calibrated.
4.2. POLARITY SWITCH
The polarity switch should be set to the polarity of
the input current to be measured.
4.3. BAL/TRIG SWITCH
The Bal/Trig switch, in conjunction with the two
front-panelscrewdriveradjustmentpotentiometers,
the Bal/Trig Meter and the Test-Operate switch, is
used to balance and adjust the 439 input amplifier.
Uninterrupted power should be applied to the 439
for approximately 20 min before the instrument is
used. This is necessary because of the long-term
drift characteristics exhibited by MOS-FET’s. The
following adjustments should be made on the 439
before it is used.
1. Set Test-Operate switch to Standby.
2. Set Bal/Trig switch to Bal.
3. Adjust Bal potentiometer to zero the Bal/Trig
Meter.
4. Set Bal/Trig switch to Trig.
5. Adjust Trig potentiometer to zero the Bal/Trig
Meter.
6. Set Bal/Trig switch to Bal; recheck meter zero.
Note: The accuracy of the 439 is not affected as long
as the Bal and Trig adjustments are within ±4
divisions of zero.
The adjustment of the input amplifier should be
rechecked by placing the Test-Operate Switch to
Standby each time the power is applied to the
instrument and at convenient intervals.
4.4. CURRENT F.S. AND
COULOMB/PULSE SWITCH
The Current F.S. and Coulomb/pulse switch controls
the amount of charge that must be injected at the
input to obtain a digital output pulse (10-10,10-8,or 10-
6Coulomb). The Coulomb/pulse range is read from
the bottom side of the double-indicating knob on the
switch. The top index of this knob in conjunction with
the multiplier switch indicates the amount of current
required at the inputtoproduceafull-scaledeflection
on the ampere meter. Currents up to 1
µ A can be
measured on the 10-10 Coulomb/pulse range with
0.01% repeatability; however, the accuracy of the
measurement may be in error byas much as 1% for
currents ranging from 100 nA to 1
µ A. The 10-8
Coulomb/pulse range should be used for accurate
measurementsofcurrentsinthisrange.Inaccuracies
begin to appear on the 10-10 Coulomb/pulse range
when the digitized output rates exceeds 1000 Hz.
4.5. MULTIPLIER SWITCH
The position of the Multiplier Switch determines the
multiplier to be applied to the Current F.S. reading in
order to produce a full-scale deflection on the
Ampere Meter. The rear-panel analog outputs (0-
10 mV, 0-100 mV, 0-1 mA) have the same current
input requirements for full-range signals as the
Ampere Meter and are affected in a similar manner
by the Multiplier switch.
4.6. INTERNAL TEST CHECK
After power has been applied to the 439 for a few
minutes and the Bal and Trig trim potentiometers
have been adjusted properly, the test position on the
Test-Operate switch should produce a digitized
output rate of approximately 1000 Hzand a full-scale
reading on the Ampere Meter when 102is selected
on the Multiplier switch.

5
4.7. OFFSET CURRENT ADJ
A potentiometer is provided on the rear panel to
adjust the input offset current over a range of
approximately ±10 pA. See Section 5.1.2 of this
manual for the procedure to measure and adjust
the input leakage current of the 439. The 439 input
leakage current is adjusted to less than 1 pA at the
factory and should not require additional
adjustment.
4.8. USE OF DIGITIZED OUTPUT
In order to take full advantage of the accuracy and
versatilityofthe439,thedigitizedoutputpulsemust
be counted by a scaler. Depending on the
application, it may be desirable for this scaler to
have a preset time or scale capability, as does the
ORTEC 431. This would permit integration for a
preset time or until a preset quantity of charge is
obtained. If it is desirable to know at what rate an
event or process is occurring, then a scaler with an
internal time base such as the ORTEC 434 or 715
is needed.
Even though the 439 was designed primarily to
measure accelerator beam current, it performs
equally well for measuring current or charge from
any source. All that is required is a transducer
which will convert the variable to be measured to a
current or charge.
5. MAINTENANCE
5.1. TESTING PERFORMANCE
The following information on front-panel controls
and testing procedures is intended as an aid in the
installation and checkout of the 439.
5.1.1. Test Equipment
The following or equivalent test equipment is
needed:
! NIM Bin and Power Supply, ORTEC
4001A/4002A.
! Extender cable, ORTEC 401-C3.
! A current source with a known accuracy of
better than 0.1%.
Note: If a voltage and a resistor are used to form a
current source, the voltage source should have a
value greater than 5 V. The accuracy of the 439 is
1000 ppm, which is better than the temperature
and/or voltage coefficients of most high-value
resistors.
! Counter with an internal time base.
! Oscilloscope.
! Schematic and block diagram of 439.
5.1.2. Preliminary Procedures
1. Visually check the module for damage due to
shipment.
2. Connect ac power to the Nuclear Standard Bin
and Power Supply, ORTEC 4001A/4002A..
3. Plug module into Bin and check for proper
mechanical alignment.
4. Switch on ac power and check the dc Power
Supply voltage at the test points on the 401A
control panel.
5. Set the 439 Test-Operate switch to Standby.
NOTE: The Test-Operate switch should be set to
Standby at any time Bal and Trig adjustments are
made or the polarity or current range is changed.
6. After uninterrupted power has been applied to the
439 for approximately 20 min, set Bal/Trig switch
to Bal.
7. Adjust the Bal potentiometer to zero the Bal/Trig
Meter.
8. Set the Bal/Trig switch to Trig.
9. Adjust the Trig potentiometer to zero the Bal/Trig
Meter.
10. Set the Bal/Trig switch to Bal and recheck meter
zero.
Note: The accuracy of the 439 is not affected as long
as the Bal and Trig adjustments are within ±4
divisions of zero; however, an attempt should be
made to keep them adjusted to zero. During
operation the Bal/Trig Meter will not necessarily
indicate zero. No attempt should be made to adjust

6
the Bal or Trig until the Test-Operate switch is
placed to the Standby position. The adjustment of
the input amplifier should be rechecked at
convenientintervalsandeachtimepowerisapplied
to the instrument.
11. Set Coulomb/pulse switch to 10-10.
12. Set multiplier switch to 102.
13. Set Test-Operate switch to Test.
14. Monitor the Digitized Output with a scaler. The
digital rate should be approximately 1000 Hz,
andthefront-panelmetershouldreadfullscale
with the Multiplier switch on 102.
15. Using the precaution mentioned in the Note in
Step 5, check the 10-8 and 10-6 Coulomb/pulse
range on the Test position. A digital rate of
approximately 1000 Hz should be obtained.
16. The input leakage current of the 439 can be
checked by removing all connections from the
input connectors, selecting the 10-10
Coulomb/pulse range and setting the Test-
Operate switch to the Operate position. If the
Bal/Trig Meter moves to the right, Neg polarity
should be selected. The output count rate
should be less than 1 pulse per 100 s. If the
leakage current is greater than1 pulse per100
s, it should be adjusted to zero with the Offset
Current Adj potentiometer on the rear panel.
17. Check the calibration of the 439 by applying a
known current to the input connector and
measuring the digitized output rate.
Note: The 439 is calibrated at the factory on the
10-10, 10-8, and 10-6 Coulomb/pulse range for a
positive current and the 10-10 Coulomb/pulse range
for negative current. If a negative current is
measured on the 10-8 or 10-6 Coulomb/pulse range
as calibrated at the factory, an error as large as 1%
may be observed. These ranges can be calibrated
for negative current byadjustingR2 and R5. Check
Section 5.2 of this manual for calibration
procedures.
5.2. CALIBRATION PROCEDURE
5.2.1. Digital
The 10-10 Coulomb/pulse range is calibrated by
adjusting the width of the pulse created by the
pulse-shaping circuit. This pulse width is normally
about 44
µ s and is adjusted by R68 for positive and
negative calibration. Calibration of the 10-8 and 10-6
Coulomb/pulse is accomplished by adjusting R2 an
R5. Since achange in the width of the pulse from the
pulse-shaping circuit affects the calibration of all
ranges, the 10-10 Coulomb/pulse range must be
calibrated first. The polarity of the current to be
measured in the experiment should be selected
before calibrating the 10-8 and 10-6 Coulomb/pulse
ranges. When calibrating the 439 it is desirable to
apply a current to the input which will produce
approximately the following count rates:
Range (Coulomb/pulse) Count Rate (Hz)
10-10 1000
10-8 10000
10-6 10000
Note: If a current source made from a high-value
resistor and a voltage source is used, a minimum of
5V should be used across the resistor. Most high-
value resistors have extreme voltage and/or
temperature coefficients; so this should be taken into
consideration.
The following steps should now be taken:
1. Set the Test-Operate switch to Standby.
2. Set the Multiplier switch to 103.
3. Set the Bal/Trig switch to Bal.
4. Adjust Bal trim potentiometer to zero the Bal/Trig
Meter.
5. Set the Bal/Trig switch to Trig.
6. Adjust the Trig trim potentiometer to zero the
Bal/Trig Meter.
7. Connect the digitized output of the 439 to a scaler
that has an internal time base.
8. Set the Coulomb/pulse switch to 10-10.
9. Set the Polarity switch to the polarity of the test
current.
10. Connect a current source to the 439 input. (The
desired value of this current source is 100 nA;
this should produce a digitized output rate of
1000 Hz.)
11. Set Test-Operate switch to Operate.

7
12. Adjust trim potentiometer R68 to give the
desired digitized output rate. Access to all
calibrationadjustmentsisavailablethroughthe
top cover of the 439.
13. Set the Test-Operate switch to Standby.
14. Connect a test current source of opposite
polarity to the 439 input and check the
calibration of the 439 for the opposite polarity.
The 10-10 Coulomb/pulse range is now calibrated.
The 10-8 and the 10-6 Coulomb/pulse range should
be calibrated for the same polarity as the current to
be measured in the experiment.
15. Set the Test-Operate switch to Standby.
16. Set the Coulomb/pulse switch to 10-8.
17. Set the Polarity switch to polarity of input test
current.
18. Connect a test current (approximately 100
µ A)
to the 439 input.
19. Set the Test-Operate switch to Operate.
20. Adjust the 10-8 calibrate trim potentiometer to
obtain the desired digitized output.
21. Set the Test-Operate switch to Standby.
22. Set the Coulomb/pulse switch to 10-6.
23. Connect a 10-mA test current to the 439 input.
24. Set the Test-Operate switch to Operate.
25. Adjust the 10-6 calibrate trim potentiometer to
obtain the desired digitized output.
26. Set the Test-Operate switch to Standby.
The digitized output of the 439 is now calibrated.
.
5.2.2. Analog
1. Set the Test-Operate switch to Standby.
2. Adjust the Bal and Trig trim potentiometers in
steps 1 through 6 above.
3. Connect a digital voltmeter across the 100 mV
terminals on the rear panel.
4. Connect the digitized output to a scaler with an
internal time base.
5. If count rate is not zero, adjust the meter zero trim
potentiometeruntilthedigitalvoltmeterreadszero.
6. Connect a variable current source to the input. (A
variable voltage source of zero to 25V and a 2.5
k
Ω resistor in series with the 439 input may be
used.)
7. Set the Polarity switch to the same polarity as the
variable current source.
8. Set the Coulomb/pulse range switch to the proper
range.
9. Set the Test-Operate switch to Operate.
10. Set the Multiplier switch to 103.
11. Adjust the variable current source to obtain
10000 Hz digitized output rate.
12. Adjust the Multiplier calibrate potentiometer until
the voltmeter reads 100 mV.
13. Adjustthevariablecurrentsourceuntiladigitized
output rate of 3000 Hz is obtained.
14. Set the Multiplier switch to 300.
Digital voltmeter should read 100 mV with 1.5%
tolerance.
15. Adjust the variable current source until the
digitized output rate reads 1000 Hz.
16. Set the Multiplier switch to 102.
Digital voltmeter should read 100 mV with 1.5%
tolerance.
17. Adjust the variable current source until the
digitized output rate is 300Hz.
18. Set the Multiplier switch to 30.
Digital voltmeter should read 100 mV with 1.5%
tolerance.
19. Adjust the variable current source until the
digitized output rate is 100 Hz.
20. Set the Multiplier switch to 10.

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Digital voltmeter should read 100 mV with 1.5%
tolerance.
21. Adjust the variable current source until the
digitized output rate is 30 Hz.
22. Set the Multiplier switch to 3.
Digital voltmeter should read 100 mV ±1 mV.
23. Adjust the variable current source until the
digitized output rate is 10 Hz.
24. Set the Multiplier switch to 1.
Digital voltmeter should read 100 mV with 1.5%
tolerance.
The analog portion of the 439 is now calibrated.
5.3. SUGGESTIONS FOR
TROUBLESHOOTING
SettheTest-OperateswitchtotheStandbyposition
and recheck the Bal and Trig adjustment following
the procedure given in Section 4.3 of this Manual.
Iftheseadjustmentscannotbemadeas described,
the malfunctioning is in the input amplifier, A1, and
the instrument should be returned to the factory for
repair. If an attempt is made to repair the
instrumentlocally,Sections 5and 6.4andtheblock
diagram and schematic should be referred to.
After the Bal and Trig adjustments have been
made, the Polarity and Current Range switches
should be checked for proper settings. If pulsed
current is being measured, refer to Section 3.4 for
assistance.Iffurtherinformationisneeded,contact
the factory.
The testing instructions in Section 5.1 of this
manual along with the voltage table in Section 5.5
should provide assistance in locating the region of
trouble and repairing the malfunction. The guide
plate and shield cover can be completely removed
from the module to enable oscilloscope and
voltmeter observations with a minimal chance of
accidentally short-circuiting portions of the etched
board.
5.4. FACTORY REPAIR
This instrument can be returned to the ORTEC
factoryfor service andrepair atanominalcost. Our
standard procedure for repair ensures the same
qualitycontrol andcheckoutthatareusedforanew
instrument. Always contact the ORTEC Global
ServiceCenter,[phone],beforesendinginan
instrument for repair to obtain shipping instructions
andsothattherequiredReturnAuthorizationNumber
can be assigned to the unit. Write this number on the
address label and on the package to ensure prompt
attention when it reaches the ORTEC factory.
5.5. TABULATED TEST POINT VOLTAGES
ON ETCHED BOARD
The following voltages are intended to indicate the
typical dc voltages measured on the etched circuit
board. The voltages given here should not be
considered as absolute values, but should merely be
used as an aid in troubleshooting.
Notes:
1. All voltages were measured from ground with a
voltmeter having an input impedance of 10 M
Ω or
greater.
2. Voltages are dc values with no current applied to
the input.
3. SettheTest-OperateswitchtoStandby.Adjustthe
Bal and Trig trim potentiometers as stated in
Section 4.3.
4. Set the Polarity switch to Positive.
5. Set the Coulomb/pulse range to 10-10.
Q1b - 0.100 Q23e - 0.500
Q2b + 0.100 Q26e 0
Q3e -14.0 Q26c +16.5
Q12b - 8.9 Q27C 0
Q13b - 8.9 Q28c 0
Q14e 0 Q29e - 0.500
Q15e 0 Q31e + 0.600
Q16b 0 Q33e - 12.08
Q17b - 0.500 Q35e 0
Q19c +22 Q37b + 2.7
Q20c + 0.1 Q37e + 3.3
Q22e + 2.0 Q39e + 2
Q21c + 1.2 Q40e - 2
Q43e + 12

9
Pin Function Pin Function
1 +3 V 23 Reserved
2
! 3 V 24 Reserved
3 Spare bus 25 Reserved
4 Reserved bus 26 Spare
5 Coaxial 27 Spare
6 Coaxial *28 +24 V
7 Coaxial *29
! 24 V
8 200 V dc 30 Spare bus
9 Spare 31 Spare
*10 +6 V 32 Spare
*11
! 6 V *33 117 V ac (hot)
12 Reserved bus *34 Power return ground
13 Spare 35 Reset (Scaler)
14 Spare 36 Gate
15 Reserved 37 Reset (Auxiliary)
*16 +12 V 38 Coaxial
*17
! 12 V 39 Coaxial
18 Spare bus 40 Coaxial
19 Reserved bus *41 117 V ac (neutral)
20 Spare *42 High-quality ground
21 Spare G Ground guide pin
22 Reserved
Pins marked (*) are installed and wired in ORTEC’s 4001A and
4001C Modular System Bins.
Bin/Module Connector Pin Assignments
For Standard Nuclear Instrument Modules
per DOE/ER-0457T.

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