ORTEC 551 Service manual

Model 551
Timing Single-Channel Analyzer
Operating and Service Manual
Printed in U.S.A. ORTEC®Part No. 733450 1202
Manual Revision E

Advanced Measurement Technology, Inc.
a/k/a/ ORTEC®, a subsidiary of AMETEK®, Inc.
WARRANTY
ORTEC* warrants that the items will be delivered free from defects in material or workmanship. ORTEC makes
no other warranties, express or implied, and specifically NO WARRANTY OF MERCHANTABILITY OR
FITNESS 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 orpurchaseorder, ORTEC’s exclusiveliabilityandbuyer’s exclusive remedyshall berelease
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 any flaws 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 be
informed, either in writing, by telephone [[phone]] or by facsimile transmission [[phone]], of the
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 evidenceof external or concealeddamage. Thecarrier
making deliveryshouldbenotifiedimmediately ofanysuch damage, sincethecarrier is normallyliablefor damage
in shipment. Packing materials, waybills, and other such documentation should be preserved in order 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 © 2002, 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
1.1. PURPOSE ................................................................ 1
1.2. MODESOFOPERATION..................................................... 1
1.3. OUTPUTPULSETIMING..................................................... 2
1.4. LOWER LEVEL REFERENCE ................................................. 2
2. SPECIFICATIONS ................................................................ 2
2.1. PERFORMANCE ........................................................... 2
2.2. CONTROLS ............................................................... 3
2.3. INPUTS .................................................................. 3
2.4. OUTPUTS ................................................................ 3
2.5. RELATEDEQUIPMENT...................................................... 4
2.6. ELECTRICALANDMECHANICAL.............................................. 4
3. INSTALLATION .................................................................. 4
3.1. CONNECTIONTOPOWER................................................... 4
3.2. CONNECTION FROM LINEAR AMPLIFIER
........................................................................ 4
3.3. OUTPUTCONNECTIONS .................................................... 4
3.4. LOWER LEVEL REFERENCE INPUT ........................................... 5
4. OPERATING INSTRUCTIONS ....................................................... 5
5. CIRCUIT DESCRIPTION ........................................................... 7
5.1. GENERAL ................................................................ 7
5.2. INTEGRATED CIRCUITS ..................................................... 7
5.3. LOWER LEVEL BIAS ........................................................ 8
5.4. UPPER LEVEL BIAS ........................................................ 8
5.5. INPUT CIRCUIT ............................................................ 8
5.6. LOWER LEVEL DISCRIMINATOR .............................................. 8
5.7. UPPER LEVEL DISCRIMINATOR .............................................. 9
5.8. CONSTANT FRACTION CIRCUIT .............................................. 9
5.9. SCAGATE................................................................ 9
5.10. RESET CIRCUIT ......................................................... 10
5.11. DELAY CIRCUIT ......................................................... 10
5.12. DCPOWER ............................................................. 11
6. CALIBRATIONANDMAINTENANCE................................................. 11
6.1. GENERAL ............................................................... 11
6.2. CALIBRATION ............................................................ 11
6.3. FACTORY REPAIR ........................................................ 11
6.4. TABULATEDTESTPOINTVOLTAGES......................................... 11

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
ORTEC MODEL 551
TIMING SINGLE-CHANNEL ANALYZER
1. DESCRIPTION
1.1. PURPOSE
The ORTEC 551 Timing Single-Channel Analyzer
provides a versatile group of related signal
derivation functions. It can be used as either a
single-channel analyzer or as an integral
discriminator. The principal output, furnished as
both a NIM-standard fast negative signal and a
NIM-standard slow positive signal, can be used for
accurate timing information or canbestrobed by an
external input. In addition, separate NIM-standard
slow positive outputs are furnished separately for
each response by the lower level and upper level
discriminators in the module.
When the output signal is internally generated, its
timing relative to that of the input signal is derived
accurately, using a time recognition technique
called Constant Fraction Discrimination. This
technique provides unexcelled timing on either
unipolaror bipolarsignalswhichdisplaceslessthan
3 ns for an input amplitude variation as great as
100:1. This eliminates the degradation of time
resolution for varying input amplitudes that is
characteristic of leading-edge time recognition.
The 551 accepts either unipolar or bipolar input
pulseshavingeitherRCordelay-linepulse-shaping
waveforms.Itexaminestheamplitudeofeachinput
pulse and generates appropriate output pulses
separately for SCA, LLD, and ULD responses. For
internal strobe operation the SCA output isdelayed
from the time of recognition (at 50% of full
amplitude on the trailing edge of the input positive
waveform). The delay is adjusted on the front panel
between 100 ns and 11
: s so that the output time
can be normalized to its application.
The instrument is designed to meet the
recommended inter-changeability standards of
USAEC Report TID-20893 (Rev). An ORTEC
4001/4002 Series Bin and Power Supply provides
all the necessary power through the rear panel
power connector. Al I signal levels and impedances
are compatible with other ORTEC NIM modules.
The 551 has a front panel switch that selects the
integral mode of operation or either of two types of
differential single-channel analysis modes. For
Normal operation, each of the discriminator levels
is adjusted independently through the full dynamic
range of 0 to 10 V. For Window operation, the
range of the lower level control is 0 to 10 V and the
range of the upper level (or window) control is the
adjusted lower level plus 0 to 1 V.
1.2. MODES OF OPERATION
Integral Mode Operation In the integral mode, the
551 generates an output through the SCA
connector on the rear panel and through both the
Pos Out and NegOut connectors on the front panel
if the input pulse amplitude exceeds the adjusted
lower level threshold; the range is 0 to 10 V.
Normal Mode Operation In the normal mode, the
551 generates an output through the SCA
connector on the rear panel and through both the
Pos Out and Neg Out connectors on the front panel
if the input pulse amplitude exceeds the adjusted
lower level but does not exceed the adjusted upper
level threshold. In this mode, each threshold is
adjusted independently in the range of 0 to 10 V,
and the upper level must be set higher than the
lower level to permit the SCA outputs to be
generated.
WindowModeOperationInthewindowmode,the
551 generates an output through the SCA
connector on the rear panel and through both the
Pos Out and Neg Out connectors on the front panel
if the input pulse amplitude exceeds the adjusted
lower level threshold, but by an amount that is less
than the adjusted window width. The range of the
lower level control is0 to 10 V, and the range of the
upper level control is0to 1 V above the lower level.
This mode is especially adapted to high-resolution
spectroscopybecausetheverynarrowwindowsthat
are required can be obtained easily and
reproducibly.

2
1.3. OUTPUT PULSE TIMING
The SCA, Pos Out, and Neg Out pulses from the
551 are generated at a delay (with internal strobe)
following the precise constant-fraction time
recognition, which occurs at 50% of the peak
amplitude on the trailing edge of the input pulse.
The delay interval isadjustable throughtworanges,
selected by a front panel switch; the low range is
0.1 to 1.1
: s and the high range is 1.0 to 11 : s. The
front panel Delay control is a 10-turn precision
potentiometer that is marked in 1000 increments
that read the adjusted delay directly in the units.
When external strobe is used, the SCA, Pos Out,
and Neg Out pulses from the 551 are furnished
promptly at the strobe time. To be effective, the
strobe's leading edge must occur within about 5
: s
(or 50
: s) after the constant-fraction recognition.
The choicebetweenthe twoacceptance intervals is
made with the front panel switch that is marked for
adjustable delay intervals (.1—1.1 and 1—11).
For any mode of operation, a signal is furnished
through the LL Out connector on the rear panel
when the lower level discriminator is triggered on
the leading edge of the input signal. Also a signal is
furnished through the UL Out connector on the rear
panel when the upper level discriminator is
triggered on the leading edge of the input signal.
Each of these outputs is a NIM-standard positive
signal that can be used for any desired external
application.
1.4. LOWER LEVEL REFERENCE
A rear panel 2-positionlocking toggleswitchselects
either the front-panel Lower Level control or the
voltage signal applied throughtherear panel LLRef
connector as the reference level for the lower level
discriminator. This permits flexibility in operation,
where an external reference source can furnish the
lower level threshold from a stepped- or sliding-
voltage source to automatically sweep the SCA
response through a spectral range of 0 to 10 V.
The selected source for the Lower Level Reference
is effective for all three operating modes.
2. SPECIFICATIONS
2.1. PERFORMANCE
Dynamic Range 200: 1.
Pulse-Pair Resolving Time Output pulse width
plus Delay (as selected by the front panel Delay
controls), plus 100 ns for fast NIM output or plus
200 ns for positive NIM output. Minimum resolving
timefor negative output, 220ns;for positive output,
800 ns.
ThresholdTemperatureInstability
# 0.01%/°Cof
full scale, 0 to 50°C using a NIM class A power
supply (referenced to -12 V).
Discriminator Nonlinearity
# ±0.25% of full scale
(integral) for both discriminators.
Delay Temperature Instability
# 0.03%/°'C of full
scale, 0 to 50°C.
Delay Nonlinearity <±2% of delay range.
WindowWidthConstancy<0.1%variationof full-
scale window width over the linear 0-to 10-V range.
Minimum Input Threshold 50 mV for Lower
Level discriminator.
Time Shift vs Pulse Height (Walk)
WALK (ns)
Dynamic System System
Range A B
10:1 ±1.0 ±2.0
50:1 ±2.5 ±4.0
100:1 ±3.0 ±8.0
System A: Using an ORTEC 460 Amplifier, single
delay-line mode, integrate
# 0.1 : s with delay line 1
: s.
System B: Using an ORTEC 471 or 472 Amplifier,
unipolar output with 0.5
: s shaping time. Input from
ORTEC 419 Pulser.

3
2.2. CONTROLS
Lower Level Front panel 10-turn potentiometer
adjustable from 0 to 10 V; when the rear panel LL
Ref mode switch is set on lnt, determines the
threshold setting for the Lower Level discriminator.
When the LL Ref mode switch on the rear panel is
in the Ext position, this control is ineffective.
Window or Upper Level Front panel 10-turn
potentiometerdeterminesthewindowwidth(0to+1
V) in the Window mode or the Upper Level (0 to
+10 V) threshold in the Normal and Integral modes.
lnt/Nor/Win Front panel 3-position locking toggle
switch selects one of three operating modes.
Integral LL sets a single-discriminator threshold (0
to +10 V) and UL response is ignored for SCA
outputs.
Normal UL and LL are independently adjustable
levels (0 to +10 V); differential mode operation.
Window LL sets the baseline level (0 to +10 V) and
UL sets the window width (0 to +1 V); differential
mode operation.
Delay Range Front panel locking toggle switch
selects delay ranges of 0.1 to 1.1
: s or 1.0 to 11 : s
for internal strobe or automatic reset without SCA
output after 5 or 50
: s for external strobe.
Delay Front panel 10-turn potentiometer for
continuous adjustment of output delay over
selected range. In the external strobe mode the
delay control adjusts the automatic reset time from
- 5 : s to 50 : s.
Walk Adjust Front panel screwdriver adjustment
for precise setting of walk compensation.
LL Ref Mode Rear panel two-position locking
toggle switch selects either the front panel LL
potentiometer or the voltage signal applied to the
rear panel LL Ref Ext connector as the LL
discriminator reference threshold.
Strobe Rear panel 2-position locking toggle switch
selects either Internal or External source for the
SCA output signal strobe function.
2.3. INPUTS
Signal input Front panel dc-coupled BNC
connector accepts positive unipolar or bipolar
signal, 0 to +10 V linear range, ±12 V maximum;
width,
$ 100 ns; 100 S input impedance. Rear panel
ac-coupled BNC connector accepts positive
unipolar or bipolar signal, 0 to +10 V linear range,
±100 V maximum; width, 0.2 to 10
: s; 100 S input
impedance.
LL Ref Ext When the rear panel LL Ref mode
switch is on Ext, the rear panel LL Ref Ext BNC
connectoracceptstheLowerLevelbiasing(aninput
of 0 to -10 V on this connector corresponds to a
range of 0 to 10 V for the Lower Level discriminator
setting). Input protected to ±24 V.
Ext Strobe In When the rear panel Ext/int Strobe
locking toggle switch is in Ext, the rear panel Ext
Strobe In BNC connector accepts a positive NIM-
standard input, nominally +5 V, 500 ns wide, to
cause an output to occur from the SCA. The
external strobe should be given within 5
: s (or 50
: s as determined by the front panel Delay control)
of the linear input. At the end of this period, the 551
resets its internal logic without producing an output
signal if no strobe has been furnished.
2.4. OUTPUTS
SCA Pos Out Front panel and rear panel BNC
connectors provide positive NIM-standard output,
nominally +5 V; 500 ns wide;
# 10 S output
impedance.Forinternal strobe, output occursat the
mid-point of the linear input trailing edge plus the
output Delay asselected bythefrontpanel controls.
For external strobe, output occurs at strobe time.
SCANeg out Front panel BNC connector provides
fast NIM-standard output, nominally -16 mA (800
mV on 50
S load); width, # 20 ns; rise time, # 5 ns.
Output occurs at the mid-point of the linear input
trailing edge plus the output Delay as selected by
the front panel controls.
LL Out Rear panel BNC connector provides
positive NIM- standard output, nominally +5 V, 500
ns wide;
# 10 S output impedance. Output occurs
as leading edge of linear input crosses the LL
threshold.
UL Out Rear panel BNC connector provides NIM-
standard output, nominally +5 V, 500 ns wide;
# 10 S output impedance. Output occursasleading
edge of linear input crosses the UL threshold.

4
2.5. RELATED EQUIPMENT
The 551 is compatible with all ORTEC amplifiers
and other amplifiers having a 0- to 10-V positive,
linear output range.
2.6. ELECTRICAL AND MECHANICAL
Power Required
+24 V, 90 mA; + 12 V, 160 mA;
-24 V, 50 mA; -12 V, 110 mA.
Dimensions NIM-standard single-width module
(1.35 by 8.714 in.) per TID-20893 (Rev).
3. INSTALLATION
The 551 must be used in conjunction with an
ORTEC4001/4002SeriesBinandPowerSupply or
equivalent, which is intended for rack mounting.
Therefore if vacuum tube equipment or any other
source of heat is operating in the same rack, there
must be sufficient cooling air circulating to prevent
any localized heating of the transistorized and
integrated circuits used throughout the 551. The
temperature of equipment mounted in racks can
easily exceed the maximum unlessprecautionsare
taken; the 551 should not be subjected to
temperatures in excess of 120°F (50°C).
3.1. CONNECTION TO POWER
Turn off the Bin Power Supply when inserting or
removing modules. The ORTEC NIM modules are
designed so that it is not possible to overload a
properly operating power supply with a full
complement of modulesinthe bin. Since, however,
this may not be true when the bin contains modules
other than those of ORTEC design, power supply
voltages should be checked after the moduleshave
beeninserted.The4001/4002hastestpointsonthe
power supply control panel to monitor dc voltages.
When using the 551 outside the 4001/4002 Bin and
Power Supply, be sure that the power extension
cable that is used properly accounts for the power
supply grounding circuits that are provided
according to the recommended AEC standards
outlined in TID-20893 (Rev). Both high-quality and
power-return ground connections are provided to
ensure proper reference voltage feedback into the
power supply, and these must be preserved in
remote cable installations. Be careful also to avoid
ground loops when the module is operated outside
the bin.
3.2. CONNECTION FROM LINEAR
AMPLIFIER
Either of two inputs in the 551 can be used for the
analog signals that are furnished from a linear
amplifier. The BNC on the front panel accepts input
signals through a dc-coupled path; the rear panel
BNC accepts signals through an ac-coupled path.
The circuit through the DC Input on the front panel
is generally preferred. However, if there is any dc
baseline offset, if signal amplitudes exceed the ±12
V maximum limit of the dc circuit, or if the input
pulses decay slowly, the ac coupling that is
available through the rear panel AC Input BNC can
be used instead.
Either input circuit accepts positive unipolar pulses
or bipolar pulses(the positive lobewillbeanalyzed)
into an input impedance of
$ 1000 S . When long
cables (more than about 4 ft) are used to connect
the amplifier output to the 551 input, cable
termination may be necessary in order to prevent
reflections; match the cable impedance with a
terminator at the 551 input in such cases.
3.3. OUTPUT CONNECTIONS
The logic output pulses that are generated when
input pulses satisfy the amplitude and logic
requirements of the 551 are available through both
front andrear panel BNCconnectors.NIM-standard
fast negative signalsare available through the front
panel Neg Out BNC. NIM-standard slow positive
signals are available through both the front panel
Pos Out and the rear panel SCA Out connectors.