ORTEC 542 Service manual
Re
iR
OGfy
5
O
-5
ORTEC
®
Model
542
Linear
Gate
and
Stretcher
Operating
and
Service
Manual
733430
E
0600
r
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
W.JJIRANTY
OF
MERCHANTABILITY
OR
FTTNESS
FOR
A
P.\RTICULAR
PURPOSE.
ORTEC's
exclusive
liability
is
limited
to
repairing
or
replacing
at
ORTEC's
option.
itemsToiind
by'ORTEC
to
be
defective
^
workmanship
or
materials
within
one
year
from
the
date
of
deUvery.
ORTEC's
liability
on
any
claim
of
any
kind
including
negligence,
loss,
or
damages
arising
out
of,
connected
with,
or
fr
om
the
performance
or
breach
thereof,
or
fr
om
the
tnanufacnn-e'
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
claiia
In
the
event
ORTEC
fails
to
manufacture
or
deliver
items
caOed
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
desianed
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
instrummt
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
vvritina
by
telephone
[(865)
482-4411]
or
by
facsimile
transmission
((865)
483-2133],
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
exanmed
unmediately
upon
receipt
for^vidence
of
external
or
concealed
damage.
The
carrier
ma
kino
delivery
should
be
notified
unmediately
of
any
such
damage,
since
the carrier
is
normally
liable
for
damage
in
shipment.
Packin*'
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.
AH
ri
ahts
reserved.
ORTEC®
is
a
registered
trademark
of
Advanced
Measurement
Technology,
Inc.
AH
other
trademarks
used
herein
are
the
property
of
their
respective
owners.
Ill
CONTENTS
STANDARD
WARRANTY
ji
SAFETY
INSTRUCTIONS
AND
SYMBOLS
iv
SAFETY
WARNINGS
AND
CLEANING
INSTRUCTIONS
v
1.
DESCRIPTION
1
2.
SPECIFICATIONS
1
2.1.
PERFORMANCE
1
2.2.
CONTROLS
2
2.3.
INPUTS
2
2.4.
OUTPUTS
2
2.5.
ELECTRICAL
AND
MECHANICAL
3
3.
INSTALLATION
3
3.1.
CONNECTION
TO
POWER
3
3.2.
LINEAR
INPUT
CONNECTION
3
3.3.
LINEAR
OUTPUT
CONNECTIONS
3
3.4.
GATE
INPUT
4
3.5.
EXTERNAL
STROBE
INPUT
4
3.6.
CONNECTION
FOR
BUSY
OUTPUT
4
4.
OPERATION
4
4.1.
SELECTION
OF
INPUT
CIRCUIT
4
4.2.
DISCRIMINATOR
LEVEL
ADJUSTMENT
!
!!.
!!
5
4.3.
OUTPUT
DELAY
AND
STROBE
ACCEPTANCE
TIME
ADJUSTMENT
5
4.4.
OUTPUT
WIDTH
ADJUSTMENT
5
4.5.
OUTPUT
DC
ADJUSTMENT
"
'
5
4.6.
GATED
OPERATION
5
4.7.
STROBED
OPERATION
5
4.8.
OVERALL
LOGIC
6
5.
MAINTENANCE
6
5.1.
TESTING
PERFORMANCE
OF
PULSE
STRETCHER
6
5.2.
CALIBRATION
PROCEDURES
7
5.3.
SUGGESTIONS
FOR
TROUBLESHOOTING
8
5.4.
FACTORY
REPAIR
SERVICE
8
IV
SAFETY
INSTRUCTIONS
AND
SYMBOLS
This
manual
contains
up
to
three
levels
of
safety
instructions
that
must
be
observed
in
order
to
avoid
pers
onal
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
A
DANGER
-
High
Voltage
Please
read
all
safety
instructions
carefully
and
make
sure
you
understand
them
fully
before
attempting
to
use
this
product.
SAFETY
WARNINGS
AND
CLEANING
INSTRUCTIONS
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.
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.
CAUTION
To
prevent
moisture
inside
of
the
instrument
during
external
cleaning,
use
only
enough
liquid
to
dampen
the
cloth
or
applicator.
Allow
the
instrument
to
dry
completely
before
reconnecting
it
to
the
power
source.
VI
iiiCl
t>UTPUT
'Ik
BUSY
t
:
EXT
STIU)BE
.
'»
V
a'
.
.
.
rt4
\
s
WL3
ORTEC
MODEL
542
LINEAR
GATE
AND
STRETCHER
1.
DESCRIPTION
The
ORTEC
542
Linear
Gate
and
Stretcher
accepts
short
duration
input
pulses
and
provides
output
pulses
of
the
same
amplitude,
but
stretched
in
duration,
for
applications
which
have
minimum
pulse
width
requirements.
This
effectively
reduces
the
bandwidth
requirements
of
analog-to-digital
converters
in
multichannel
pulse
height
analyzers
and
improves
the
resulting
li
nearity.
The
linear
gate
included
in
the
542
permits
selective
control
of
the
acceptance
of
input
pulses,
and
is
also
used
to
prevent
positive-on-positive
pulse
pileup.
The
542
accepts
linear
signals,
when
the
input
gate
is
qualified,
from
any
linear
source.
The
input
signal
is
reshaped
as
required,
providing
a
suitable
waveform
to
a
circuit
which
measures
the
peak
amplitude.
Any
reshaping
of
the
input
pulse
must
retain
the
linear
parameter
of
the
i
nput
signal,
which
is
its
relative
peak
amplitude.
The
input
pulse
width
is
unimportant
as
long
as
the
peak
amplitude
duration
is
long
enough
to
permit
accurate
res
ponse
and
measurement.
The
input
gate,
which
can
be
controlled
from
an
external
source,
may
be
operated
in
either
a
coincidence
or
an
anticoincidence
mode.
The
Gate
Period
generator
is
triggered
on
the
leading
edge
of
a
gate
input
pulse
and
continues
for
an
effective
period
set
by
a
front
panel
adjustment.
The
Gate
Period
must
overlap
the
linear
input
pulse
peak
for
coincidence
mode
operation
or
must
overlap
the
discriminator
response
for
anticoincidence
mode.
An
Extemal
Strobe
Input
and
switch
on
the
rear
panel
provide
for
strobing
the
output
after
a
peak
detect
occurs.
W
hen
the
Strobe
switch
is
in
external
position,
an
output
w
ill
be
generated
in
time
coincidence
with
the
external
strobe
signal.
The
output
pulse
occurs
if
and
only
if
a
positive
logic
pulse
arrives
at
the
rear
panel
Strobe
Input
during
the
acceptance
time
as
set
by
the
Delay
adjustment
(10
times
the
setting)
on
the
front
panel.
An
i
nput
pulse
must
exceed
the
discriminator
level
to
initiate
a
response
in
the
542.
When
the
discriminator
fires,
it
initiates
the
stretching
action
unless
the
gate
control
is
in
the
extemal
coincidence
mode
and
a
gate
pulse
is
not
present.
The
input
gate
remains
open
only
until
the
peak
of
the
linear
pulse
has
been
detected,
and
then
is
again
closed
to
prevent
pil
eup.
A
delayed
output
pulse,
with
selectable
width,
is
generated
following
the
input
peak.
Both
the
delay
and
width
adjustments
are
front
panel
screwdriver
controls
on
the
542.
The
input
gate
cannot
be
opened
again
until
the
output
pulse
has
been
completed
and
the
linear
input
pulse
has
returned
to
baseline.
This
internal
logic
prevents
pulse
pileup,
therefore
enhancing
high
count
rate
performance.
The
542
can
be
used
in
any
system
to
assure
an
adequate
duration
of
the
peak
amplitude
where
a
pulse
width
might
otherarise
have
been
too
short
or
where
the
width
variations
would
produce
a
nonlinear
response
or
measurement.
It
may
be
used
at
any
point
in
the
linear
system
after
a
basic
linear
amplifier.
The
gate
and
strobe
functions
permit
logical
placement
directly
after
the
linear
amplifier.
2.
SPECIFICATIONS
2.1.
PERFORMANCE
NOISE
CONTRIBUTION
<20
pV
rms,
referred
to
input.
GATE
FEEDTHROUGH
amplitude
with
gate
closed.
GATE
PEDESTAL
calibrated.
<0.05%
of
signal
Essentially
zero,
factory-
STRETCHER
DROOP
mV/psA/
output.
Typically
less
than
0.1
PILEUP
REJECTION
After
the
input
pulse
has
reached
its
peak,
subsequent
inputs
are
rejected
until
both
the
output
pulse
has
terminated
and
the
input
has
recovered
to
the
baseline.
LINEAR
INPUT
AMPLITUDE
range;
±12
V
maximum.
+0.1
to
+
10V
linear
LINEAR
INPUT
RISETIME
100
ns
to
10
ps.
LINEAR
OUTPUT
WIDTH
0.5
TO
5
ps,
adjustable.
LINEAR
OUTPUT
DELAY
0.5
to
5
ps
after
peak
detect,
adjustable.
GAIN
Unity
(nominal).
INTEGRAL
NONLINEARITY
<0.2%
for
pulse
risetime
>100
ns
and
pulse
width
>400
ns.
TEMPERATURE
INSTABILITY
<0.01
%/°C,
0
to
50°C
for
V„
=
5
V.
Gain
shift
COUNTING
RATE
do-coupled
throughout
when
DC
Couple
input
is
selected.
The
centroid
of
a
pulser
spectrum
at
85%
of
full
scale
will
shift
<0.1%
when
modulated
by
5
x
lO"*
counts/s
of
random
signals
from
"^Cs
source-detector
combination
with
photopeak
at
70%
of
full
scale
(DC
Couple
mode
and
amplifier
shaping
time
r
=
1
ps).
When
dc
restorer
modes
are
used,
count
rate
is
dependent
on
shaping
amplifier
time
constants
and
pulse
undershoot.
2.2.
CONTROLS
The
following
controls
are
on
the
front
panel:
INPUT
3-position
slide
switch,
selects
input
circuit
desired:
BLR
High,
BLR
Low,
or
DC
Couple.
DISC
LEVEL
Screwdriver
potentiometer;
adjusts
sensitivity
level
for
input
discriminator;
range
+0.1
to
+1
V;
discriminator
remains
triggered
while
input
level
exceeds
adjusted
sensitivity.
OUTPUT
DELAY
Screwdriver
potentiometer;
adjusts
delay
period
from
peak
detect
to
start
of
output
pulse;
typical
range
0.5
to
5
ps.
Delay
r
anges
up
to
50
ps
available
on
special
request.
In
External
Strobe
mode,
adjusts
Acceptance
Time;
typical
range
5
to
50
ps.
OUTPUT
WIDTH
Screwdriver
potentiometer
adjusts
width
of
the
output
pulse;
typical
range
0.5
to
5
ps.
NORMAL/GATED
Locking-toggle
switch
selects
exclusion
(Normal)
or
inclusion
(Gated)
of
external
gating
function.
GATE
PERIOD
Screwdriver
potentiometer,
adjusts
duration
of
gating
control
from
leading
edge
of
Gate
Input
pulse;
range
0.5
to
5
ps;
includes
test
point
for
monitoring
adjusted
gate
period.
OUTPUT
DC
ADJ
Screwdriver
potentiometer,
permits
adjustment
of
output
dc
level
between
±1.5
V.
COINC/ANTICOINC
Locking-toggle
switch
selects
effective
mode
for
Gate
Input
function.
The
following
control
is
on
the
rear
panel:
EXT/INT
Locking-toggle
switch
selects
External
strot)e
operation.
External
Str
obe
Acceptance
Time
is
adjustable
from
5
to
50
ps
by
the
front
panel
Delay
potentiometer.
2.3.
INPUTS
LINEAR
INPUT
BNC
connector,
front
panel.
Polarity
Positive
unipolar,
or
bipolar
with
positive
portion
leading.
Amplitude
+0.1
to+10
V;
±12
V
maximum.
Risetime
100
ns
to
10
ps.
Impedance -lOOOQ.
GATE
INPUT
BNC
connector,
front
panel,
for
optional
external
control
of
switch-selectable
coincidence
or
anticoincidence
mode
triggering.
Standard
NIM
slow
logic
pulse,
triggers
selected
gate
function
at
+3
V
(100
ns
minimum
width),
protected
to
±25
V.
STROBE
INPUT
BNC
connector,
rear
panel,
for
optional
external
control
of
the
output
pulse
timing.
Standard
NIM
slow
positive
logic
pulse
tri
ggers
the
strobe
functions
at
+3
V
(100
ns
minimum
width),
protected
to
±25
V.
2.4.
OUTPUTS
OUTPUT
Front
panel
BNC
connector;
furnishes
linear
positive
output
pulses
through
Z
„
<
10;
risetime,
300
ns;
includes
test
point.
930
OUTPUT
Rear
panel
BNC
connector
furnishes
the
linear
positive
output
pulses
through
Z„=93Q.
Polarity
Positive.
Amplitude
+0.1
to
+10
V;
equal
to
peak
amplitude
of
the
linear
input
pulse.
Delay
Adjust
by
front
panel
control;
typical
range
0.5
to
5
ps
after
input
pulse
peak
detect.
Strobe
Acceptance
Time
range
5
to
50
ps.
width
Adjusted
by
front
panel
control;
r
ange
0.5
to
5
ps
typical.
impedance
<1Q
on
front
panel.
DC
Offset
Adjust
+1.5
V.
BUSY
OUTPUT
Rear
panel
BNC
connector
fumishes
+5
V
nominal
through
Z
<
10
Q
through
all
periods
when
input
pulses
c
annot
be
accepted;
may
be
used
to
control
external
equipment
or
for
monitoring
internally
created
deadtime.
Busy,
+5
V
nominal
-
linear
pulse
cannot
be
accepted.
Not
Busy,
0
V
nominal
-
linear
pulse
can
be
accepted.
2.5.
ELECTRICAL
AND
MECHANICAL
POWER
REQUIREMENTS
+24
V,
83
mA;
-24
V,
80
mA;
+12
V,
130
mA;
-12
V,
30
mA.
WEIGHT
Shipping
1.9
kg
(4
lb).
Net
0.9
kg
(2
lb).
DIMENSIONS
NIM-standard
single-width
module
(1.35
by
8.714
in.)
Per
TID-20893
(Rev).
3.
INSTALLATION
The
542
contains
no
internal
power
supply
but
is
designed
for
installation
in
a
standard
Bin
and
Power
Supply,
such
as
the
ORTEC
4001/4002
or
401/402
Series,
which
are
intended
for
rack
mounting.
If
vacuum
t
ube
equipment
or
other
heat-
producing
equipment
is
operated
in
the
same
rack,
there
must
be
adequate
circulation
of
cooling
air
to
prevent
any
localized
heating
of
the
542
transistorized
circuits.
The
temperature
of
equipment
mounted
in
racks
can
easily
exceed
the
recommended
maximum
unless
precautions
are
observed.
The
ORTEC
542
should
not
be
subjected
to
temperatures
in
excess
of
50
°C
(122°F).
3.1.
CONNECTION
TO
POWER
Always
tum
off
power
for
the
Bin
and
Power
Supply
before
inserting
or
removing
any
modules.
ORTEC
NIM
instruments
are
designed
so
that
it
is
not
possible
to
overload
the
Power
Supply
with
a
full
complement
of
modules
in
the
Bin.
Since,
however,
this
may
not
be
true
when
the
Bin
contains
m
odules
other
than
those
of
ORTEC
design,
check
the
Power
Supply
for
any
overload
c
onditions
by
testing
the
dc
power
levels
after
all
modules
are
inserted.
The
ORTEC
542
may
be
operated
outside
the
Bin
and
Power
Supply,
using
a
power
extension
cable.
Be
sure
that
the
cable
used
accounts
properly
for
the
grounding
circuits
recommended
in
AEC
standards
of
TID-20893
(Rev).
Both
clean
and
dirty
ground
connections
are
included
to
ensure
proper
reference
voltage
feedback
into
the
Power
Supply
and
must
be
preserved
by
the
remote
cable.
Be
careful
to
avoid
ground
loops
when
the
module
is
operated
outside
the
Bin.
3.2.
LINEAR
INPUT
CONNECTION
Linear
input
pulses
can
be
furnished
from
any
ORTEC
NIM
linear
module.
These
include
amplifiers,
delay
circuits,
biased
amplifiers,
gates,
and
other
pulse-handling
equipment.
It
is
recommended
that
the
542
be
used
ahead
of
a
biased
amplifier
when
both
modules
are
used
in
a
system.
The
effective
input
range
will
be
from
the
adjusted
discriminator
level
(+0.1
to
1
V)
up
through
+10
V.
When
the
linear
i
nput
signals
are
furnished
through
a
cable
more
than
4-ft
long
(approximately),
the
input
should
be
terminated
with
the
characteristic
impedance
of
the
cable.
This
can
usually
be
avoided
by
the
use
of
shorter
cable
lengths.
3.3.
LINEAR
OUTPUT
CONNECTIONS
The
shaped
linear
output
pulses
can
be
furnished
into
any
ORTEC
NIM
linear
module
or
directly
into
the
ADC
input
of
a
multichannel
analyzer.
It
is
important
to
preserve
the
pulse
shape
and
linear
amplitude
relationship
of
the
output,
as
it
appears
at
the
inputs
of
subsequent
instrument
m
odules.
Either
of
two
standard
output
impedances
may
be
selected
according
to
the
type
and
length
of
interconnecting
cable
and
the
input
impedance
of
the
instrument
to
which
it
is
connected.
The
output
is
available
through
a
front
panel
connector,
with
an
output
impedance
of
less
than
1
Q.
,
or
through
a
rear
panel
connector,
with
Zo=
93
Q.
For
most
applications
the
1Q
front
panel
Output
connector
can
be
used,
with
a
short
cable
length,
to
transfer
the
output
signal
into
the
(normally)
high
input
impedance
of
the
next
module.
When
the
output
signals
must
be
furnished
through
the
cable
lengths
greater
than
approximately
4
ft,
proper
resistive
termination
of
the
cable
is
r
equired
in
order
to
preserve
the
linear
output
pulses
and
prevent
oscillations.
Either
of
two
convenient
methods
can
be
selected
for
the
542
outputs,
when
termination
is
required.
One
method
uses
a
series-
type
termination,
using
the
rear
panel
93
Q
Output
connector
and
an
appropriate
I
ength
of
93
Q
coaxial
cable
to
transfer
the
signal
into
the
next
module
or
instrument.
The
total
amplitude
of
each
output
pulse
will
be
divided
between
the
93
Q
output
impedance
of
the
542
and
the
input
impedance
of
the
next
module,
so
a
high
i
nput
impedance
is
desirable.
An
alternate
method
uses
shunt
termination
at
the
remote
end
of
the
cable.
For
this,
use
the
front
panel
1Q
Output
connector
and
whatever
type
of
coaxial
cable
is
desired.
Then
use
a
BNC
Tee
at
the
input
to
the
next
module
to
accept
both
the
cable
and
a
BNC
Terminator,
selected
to
match
the
characteristic
impedance
of
the
cable
when
connected
in
parallel
with
the
instrument's
input
impedance.
For
your
convenience,
ORTEC
stocks
BNC
Tee
connectors
and
both
50
to
100
Q
BNC
Terminators.
3.4.
GATE
INPUT
When
Gate
Input
signals
are
required,
they
w
ill
be
furnished
through
the
BNC
connector
on
the
front
panel
of
the
542.
When
selected,
a
gate
i
nput
pulse
will
trigger
the
542
Linear
Input
gate
for
an
adjusted
Gate
Period.
The
function
may
be
selected
as
either
Coinc
or
Anticoinc
by
a
front
panel
locking-toggle
switch.
Gate
Input
pulses
are
valid
when
they
exceed
+3
V
for
a
period
of
at
least
100
ns.
A
standard
NIM
slow
logic
pulse
may
be
used.
The
Gate
Input
circuit
is
protected
to
±25
V;
so
a
wide
variety
of
alternate
sources
can
also
be
used
to
initiate
this
control.
W
hen
operating
in
the
Coinc
mode,
the
Gate
Period
must
be
tri
ggered
before
the
peak
of
the
li
near
input
pulse
and
must
be
continued
until
after
the
peak.
When
operating
in
the
Anticoinc
mode,
the
Gate
Period
must
be
tri
ggered
prior
to
a
discriminator
response
to
the
linear
input
and
must
be
continued
until
the
discriminator
has
been
reset.
No
Gate
Input
is
required
if
the
front
panel
Normal/Gated
switch
is
set
at
Normal.
Likewise,
if
the
front
panel
switches
are
set
at
Gated
and
Anticoinc,
a
Gate
Input
pulse
is
not
required
except
when
a
linear
input
signal
is
to
be
rejected.
When
these
switches
are
set
for
Gated
and
Coinc,
respectively,
a
linear
input
pulse
w
ill
be
accepted
only
If
it
is
accompanied
by
a
time
coincident
Gate
Input
pulse.
3.5.
EXTERNAL
STROBE
INPUT
The
External
Strobe
Input
is
a
rear
panel
BNC
connector.
When
the
rear
panel
Strobe
switch
is
set
for
Ext,
an
output
will
be
generated
only
if
a
standard
NIM
slow
positive
logic
pulse
arrives
at
the
connector
during
the
Strobe
Acceptance
Time,
as
set
by
the
front
panel
Delay
potentiometer.
The
Strobe
Acceptance
Time
is
approximately
10
times
the
Delay
setting
at
a
given
potentiometer
setting.
Therefore
the
Strobe
Acceptance
Time
may
be
set
within
a
typical
range
of
5
to
50
ps.
3.6.
CONNECTION
FOR
BUSY
OUTPUT
The
duration
of
each
busy
output
signal
is
from
the
time
that
an
input
pulse
peak
is
detected
until
the
resulting
output
pulse
has
been
furnished
and
the
input
discriminator
has
been
reset.
This
identifies
each
period
during
which
a
new
input
pulse
cannot
be
accepted
in
the
542.
This
output
can
be
integrated
externally
to
indicate
relative
deadtime.
4.
OPERATION
4.1.
SELECTION
OF
INPUT
CIRCUIT
Any
of
three
circuit
connections
can
be
selected
with
the
slide
switch
at
the
top
of
the
front
panel:
DC
Couple,
BLR
(Base
Line
Restorer)
Low,
or
BLR
High.
The
proper
selection
w
ill
depend
on
the
type
of
output
circuit
in
the
module
from
which
the
linear
input
pulses
are
furnished
to
the
542
and
on
the
relative
counting
rate.
The
DC
Couple
switch
position
provides
an
optimum
signal
transfer
circuit
with
1000
Q
input
impedance
if
the
pulses
are
furnished
from
an
amplifier
with
a
dc-coupled
output
and
properly
adjusted
zero
baseline.
If
the
source
does
not
include
baseline
restoration,
use
a
capacitive
coupling
into
the
542
and
select
either
Low
or
High
BLR
at
the
542.
For
an
ac-coupled
signal
input,
select
one
of
the
baseline
restorer
input
circuits
in
the
542.
There
is
no
precise
method
of
input
circuit
selection
because
of
the
various
shaping
time
constants
which
may
be
affecting
the
pulse
shape
furnished
to
the
542.
For
1-ps
pulses
the
division
is
approximately
15,000
counts/s.
If
bipolar
pulses
are
applied
to
the
input,
the
DC
Couple
or
BLR
Low
configurations
must
be
selected.
The
most
practical
method
of
selecting
between
High
and
Low
is
observation
of
the
output
on
an
oscilloscope
and
using
the
setting
that
provides
the
better
results.
4.2.
DISCRIMINATOR
LEVEL
ADJUSTMENT
The
Disc
Level
adjustment
is
for
the
purpose
of
preventing
response
to
all
noise
pulses.
This
threshold
voltage
should
be
adjusted
high
enough
in
its
+0.1
to
1
V
range
to
ensure
discrimination
against
the
maximum
noise
amplit
ude
that
may
exist
at
the
input
to
the
542
in
the
system.
The
logic
in
the
542
prevents
response
to
a
new
input
pulse
until
the
Disc
Level
has
been
recrossed
and
the
output
pulse
has
been
completed.
Too
high
a
setting
of
the
Disc
Level
can
permit
a
small
amount
of
pileup
to
occur
if
the
input
pulse
has
a
very
long
time
constant
decay.
Although
this
interference
is
possible,
it
is
unlikely
in
most
applications.
Still
an
unnecessarily
high
adjustment
is
not
recomm
ended.
4.3.
OUTPUT
DELAY
AND
STROBE
ACCEPTANCE
TIME
ADJUSTMENT
The
adjustment
of
the
Output
Delay
permits
a
control
for
normalizing
timing
in
the
system
in
which
the
542
is
included.
The
delay
period
is
measured
from
the
time
that
the
internal
stretch
amplifier
senses
a
peak
amplitude
in
the
accepted
linear
input
pulse
and
is
typically
adjustable
through
the
range
of
0.5
to
5
ps.
At
the
end
of
the
delay
period
the
Output
Gate
is
opened
and
an
output
pulse
is
furnished
to
the
next
instrument
in
the
system.
For
Strobed
operation,
the
Delay
adjustment
becomes
a
Strobe
Acceptance
Time
adjustment,
providing
a
period
of
from
5
to
50
ps
after
linear
input
peak,
during
which
the
strobe
signal
will
cause
an
output
to
be
generated.
4.4.
OUTPUT
WIDTH
ADJUSTMENT
The
stretch
circuit
provides
an
output
pulse
of
a
fixed
and
known
width.
The
range
of
the
control
is
typically
0.5
to
5
ps,
and
its
proper
setting
w
ill
be
determined
by
the
input
requirements
of
subs
equent
instruments
in
the
system.
Each
output
pulse
will
have
the
adjusted
width,
regardless
of
the
width
of
li
near
pulses
furnished
to
the
542
input.
4.5.
OUTPUT
DC
ADJUSTMENT
In
normal
usage
the
quiescent
level
for
the
output,
through
both
the
front
and
rear
panel
connectors,
should
be
at
ground
potential.
Use
the
test
point
for
the
front
panel
Output,
and
adjust
the
screwdriver
control
as
necessary
to
set
the
level
at
ground
potential
when
there
are
no
output
signals.
When
the
dc
input
is
used
on
some
analyzers
it
is
necessary
that
the
signal
source
have
a
quiescent
dc
level
other
than
zero.
When
the
542
is
used
in
such
applications
adjust
the
output
dc
level
as
required.
4.6.
GATED
OPERATION
No
Gate
Input
pulse
is
required
if
the
front
panel
slide
switch
is
set
at
Normal.
Likewise,
if
the
slide
switch
is
set
at
Gated
and
the
mode
selector
on
the
front
panel
is
set
for
Anticoinc,
linear
input
pulses
will
be
accepted
when
there
is
no
signal
through
the
Gate
Input
connector.
Whenever
a
signal
is
furnished
through
the
Gate
Input
with
Gated
Anticoinc
effective,
all
linear
input
signals
are
inhibited
throughout
the
Gate
Period.
To
be
effective,
the
Gate
Period
must
be
adjusted
to
overlap
the
period
of
discriminator
response
to
any
pulse
that
is
to
be
inhibited
by
the
Anticoinc
signal;
if
the
linear
input
triggers
the
discriminator
before
the
Gate
Input
or
if
the
Gate
Period
terminates
prior
to
discriminator
recovery,
there
will
be
an
output,
but
the
amplitude
will
probably
not
duplicate
the
peak
input
amplitude.
When
the
542
is
set
for
gated
coincidence
operation,
a
linear
input
signal
is
accepted
for
stretching
if
and
only
if
there
is
a
time-coincident
Gate
Input.
The
Gate
Input
signal
must
occur
before
the
peak
amplit
ude
of
the
linear
input
pulse,
and
the
Gate
Period
must
be
long
enough
to
continue
the
control
beyond
the
internal
detection
of
the
peak
amplitude.
Refer
to
Section
5.2
for
linear
gate
pedestal
adjustment
procedures.
4.7.
STROBED
OPERATION
When
the
542
is
to
be
used
in
Externally
Strobed
mode,
the
rear
panel
INT/EXT
locking-t
oggle
switch
is
placed
in
EXT
position.
The
strobing
device
is
connected
via
the
External
Strobe
BNC
connector
on
the
rear
panel.
In
Externally
Strobed
Mode,
an
output
will
be
generated
only
if
a
standard
NIM
slow
positive
logic
pulse
arrives
at
the
External
Strobe
connector
within
the
Strobe
Acceptance
Time
(range
5-50
ps)
as
set
by
the
front
panel
potentiometer
labeled
Output
Delay.
4.8.
OVERALL
LOGIC
When
the
amplitude
of
an
input
pulse
exceeds
the
discriminator
threshold,
the
discriminator
may
be
fired
or
it
may
still
be
set
because
of
not
having
recovered
from
a
previous
input
pulse.
The
linear
input
pulse
will
not
be
accepted
unless
the
discriminator
has
recovered
prior
to
the
new
pulse;
it
will
also
be
rejected
if
(1)
an
output
pulse
has
not
been
completed
for
a
previously
accepted
i
nput;
(2)
the
operating
mode
is
gated
coincidence
and
no
Gate
Input
has
been
furnished;
(3)
the
operating
mode
is
gated
anticoinci
dence,
a
Gate
Input
signal
has
been
furnished,
and
the
Gate
Period
is
in
effect;
or
(4)
in
the
External
Strobe
mode
and
no
strobe
signal
is
present
during
the
Strobe
Acceptance
Time.
When
the
discriminator
recovers,
it
will
permit
the
i
nput
to
be
gated
on
unless
(1)
the
output
pulse
has
not
been
completed
or
(2)
External
Gate
Input
logic
has
closed
the
li
near
input
circuit.
When
the
output
pulse
has
been
completed,
the
linear
input
is
qualified
unless
(1)
the
discriminator
is
not
reset
or
(2)
External
Gate
Input
logic
has
closed
the
linear
input
circuit.
When
the
discriminator
is
triggered
prior
to
a
Coincidence
Gate
Input
but
the
linear
input
is
otherwise
qualified,
the
linear
input
signal
is
not
applied
to
the
stretch
circuit
until
the
Gate
Input
signal
is
furnished.
Under
these
conditions,
the
linear
input
signal
is
applied
to
the
stretch
circuit
at
the
Gate
Input
time;
an
output
signal
w
ill
result,
which
has
an
amplitude
equal
to
(1)
the
peak
input
amplitude
or
(2)
the
input
amplitude
at
the
end
of
the
adjusted
Gate
Period
(whichever
occurs
first).
Thus,
it
is
important
that
the
gate
be
triggered
during
the
risetime
of
the
linear
input
pulse
and
that
it
remain
effective
until
after
the
peak
amplitude
has
been
sensed.
5.
MAINTENANCE
5.1.
TESTING
PERFORMANCE
OF
PULSE
STRETCHER
The
following
paragraphs
are
intended
as
an
aid
in
the
installation
and
checkout
of
the
542.
These
instructions
present
information
on
waveforms
at
test
points
and
output
connectors.
Test
Equipment
The
following,
or
equivalent,
test
equipment
is
needed.
ORTEC
419
Pulse
Generator
50-MHZ
Bandwidth
Oscilloscope
100Q
BNC
Terminators
Digital
Voltmeter
ORTEC
Pulse
Shaping
Amplifier
Preliminary
Procedures
Visually
check
the
module
for
possible
damage
due
to
shipment
and
then
perform
the
following
steps:
1.
Connect
ac
power
to
NIM
standard
Bin
and
Power
Supply,
ORTEC
4001/4002
or
401/402.
2.
Plug
module
into
Bin
and
check
for
proper
mechanical
alignment.
3.
Switch
ac
power
on
and
check
the
dc
Power
Supply
voltages
at
the
test
points
on
the
Bin
Power
Supply
control
panel.
Pulse
Stretcher
The
following
procedure
will
check
the
performance
of
the
Pulse
Stretcher:
■1.
Feed
the
output
of
the
419
Pulse
Generator
into
the
input
of
the
Amplifier.
2.
Set
the
Amplifier
controls
for
a
gain
of
approximately
200
with
equal
integration
and
differentiation
time
constants.
3.
Set
the
542
Input
switch
to
DC
Couple,
the
Gate
switch
to
Normal,
and
the
Strobe
switch
to
Int.
4.
Adjust
the
419
Pulse
G
enerator
for
a
100-mV
pulse
from
the
unipolar
output
of
the
Amplifier.
5.
Feed
the
100-mV
unipolar
output
of
the
Amplifier
into
the
input
of
the
542.
Load
the
542
output
with
a
100
Q
terminator.
6.
Adjust
the
discriminator
time
potentiometer
on
the
front
panel
until
triggering
of
the
stretcher
circuit
just
occurs,
as
evidenced
by
an
output
pulse
from
the
542.
7.
Increase
the
input
signal
to
the
542
(by
adjusting
the
419
Pulse
Generator)
to
500
mV.
8.
The
output
of
the
542
should
have
a
peak
amplitude
of
500
±
25
mV
(see
"Linear
Gate
Pedestal
Adjustment"
Procedure
in
Section
6.2
if
these
limits
are
exceeded);
the
top
of
the
pulse
should
exhibit
a
smooth
slope
of
less
than
0.5
mV/ps.
9.
Increase
the
input
signal
to
the
542
to
10
V;
the
output
should
be
essentially
10
V.
10.
The
time
at
which
the
output
occurs
should
be
adjustable
from
approximately
0.5
to
5
ps
after
peak
detect.
The
duration
of
the
output
waveform
should
be
adjustable
over
the
range
of
approximately
0.5
to
5
ps.
11.
Select
the
Gated
and
Coinc
positions
on
the
front
panel
switches.
The
542
output
should
disappear.
12.
Select
the
Anticoinc
position
and
the
542
output
should
reappear.
(A
more
complete
check
of
the
542
Gate
can
be
made
if
a
logic
pulse
in
time
coincidence
with
the
li
near
input
pulse
is
available.)
13.
Increase
the
input
to
the
542
to
the
saturation
level
of
the
amplifier,
approximately
12
V;
the
output
of
the
542
should
be
greater
than
10.5
V.
14.
Connect
the
amplifier
output
to
the
542
Gate
Input
and
monitor
the
Gate
Period
pulse
with
an
oscilloscope.
The
Gate
Period
should
be
adjustable
from
approximately
0.5
to
5
ps.
Pulse
Pileup
Test
A
dual
or
variable
high-
frequency
pulser
is
needed
to
check
the
operation
of
the
542
pileup
circuit.
1.
Connect
a
dual
or
variable
high-frequency
pulser
to
the
542
input.
2.
Monitor
the
542
input
and
output
simultaneously
with
an
osc
illoscope.
3.
Adjust
the
output
delay
and
width
controls
to
full
clockwise
positions.
4.
Gradually
decrease
the
time
interval
between
the
input
pulses.
5.
The
second
pulse
should
be
blocked
by
the
542
when
the
time
interval
betw
een
the
peaks
of
two
consecutive
pulses
is
short
enough
to
cause
pileup
greater
than
the
discriminator
threshold.
5.2.
CALIBRATION
PROCEDURES
Linear
Gate
Pedestal
Adjustment
The
input
and
output
gates
are
shunt-type
gates
which
clamp
the
signal
line
to
ground.
If
the
signal
line
is
not
at
ground
potential
in
the
quiescent
condition,
then
a
pedestal
is
introduced
by
the
gating
action.
This
can
be
avoided
by
adjusting
the
output
of
the
Buffer
Amplifier
(TP1)
to
zero
volts
and
then
adjusting
the
output
of
the
Stretch
Amplifier
(TP2)
to
zero
volts.
Use
the
following
procedure
when
making
this
adjustment:
1.
Set
the
input
gate
switch
to
Normal
and
the
strobe
switch
to
Int.
2.
Set
the
Input
switch
to
the
m
ode
desire.
If
the
DC
Couple
position
is
used,
ensure
that
the
dc
level
of
the
amplifier
driving
the
542
is
set
to
zero
volts.
3.
Monitor
TP1
with
a
digital
voltmeter
and
adjust
R7,
on
the
front
of
the
printed
circuit
board,
to
obtain
zero
volts
at
TP1.
4.
When
the
Input
switch
is
moved
to
either
of
the
other
two
positions,
the
voltage
at
TP1
should
remain
at
0
V
±
20
mV.
5.
Monitor
TP2
with
the
voltmeter
and
adjust
RIB
to
obtain
zero
volts
at
TP2.
The
542
is
now
adjusted
for
a
zero
pedestal.
These
adjustments
must
be
made
regardless
of
whether
or
not
the
linear
gating
function
of
the
542
is
being
used.
CAUTION:
If
the
Input
switch
is
set
to
DC
Couple
and
the
output
dc
level
of
the
Amplifier
driving
the
542
is
not
set
at
zero
volts,
the
542
w
ill
appear
to
have
a
pedestal
since
the
542
gate
circuit
w
ill
be
gating
a
dc
voltage.
Discriminator
Adjustment
The
542
Disc
Level
should
be
set
well
above
the
system
noise
because
each
pulse
that
exceeds
the
discriminator
level
will
be
stretched,
whether
it
be
noise
or
a
legitimate
signal.
If
the
Disc
Level
is
set
far
below
the
system's
noise,
the
542
pileup
rejection
circuit
may
completely
block
the
input
and
prevent
any
outputs
from
occurring.
Normally
a
discriminator
level
of
100
mV
is
adequate.
A
precise
discriminator
setting
can
be
made
by
the
following
procedure:
1.
Apply
a
0.5-ps
shaped;
signal
to
the
542
input
with
amplitude
equal
to
the
desired
Disc
Level
setting.
2.
Monitor
the
M2
input
and
output
signals
with
an
oscilloscope.
3.
Adjust
the
542
discriminator
control
(front
panel)
until
the
number
of
output
pulses
is
approximately
equal
to
one-half
the
number
of
input
pulses.
The
discriminator
is
now
properly
adjusted.
5.3.
SUGGESTIONS
FOR
TROUBLESHOOTING
In
situations
where
the
542
is
suspected
of
malfunction,
it
is
essential
to
verify
such
malfunction
in
terms
of
simple
pulse
generator
impulses
at
the
input.
In
consideration
of
this,
the
542
must
be
disconnected
from
its
position
in
any
system
and
routine
diagnostic
analysis
be
performed
with
a
test
pulse
generator
and
oscilloscope.
It
is
important
that
testing
not
be
performed
with
a
source
and
detector
until
the
amplifier-pulse
stretcher
system
performs
satisfactorily
with
the
test
pulse
detector.
The
testing
instructions
in
Section
5.1
of
this
■».manual
should
provide
assistance
in
locating
the
region
of
trouble
and
repairing
the
malfunction.
The
two
side
plates
can
be
completely
removed
from
the
module
to
enable
osc
illoscope
and
voltmeter
observations
with
a
minimal
chance
of
accidentally
short-circuiting
portions
of
the
etched
board.
If
the
problem
involves
an
inability
to
get
an
output
pulse,
there
are
several
solutions:
1.
3.
4.
If
Input
switch
is
in
the
DC
Couple
position,
switch
to
low
or
high
positions.
If
output
appears,
a
dc
level
is
probably
being
applied
to
the
542
input
and
locking
up
the
pulse
pileup
circuit.
Adjust
the
output
dc
level
of
the
amplifier
during
the
542
to
zero
volts.
Adjust
the
Disc
Level
fully
clockwise.
If
an
output
occurs,
the
discriminator
was
probably
set
below
the
system
noise
level,
locking
up
the
pileup
circuit.
If
operating
in
the
Gated
mode,
switch
to
the
Normal
mode.
If
an
output
occurs,
the
gating
logic
is
probably
not
in
time
coincidence
with
the
linear
pulse.
If
operated
in
Gated
or
Normal
mode,
check
that
Strobe
switch
is
in
Int
position.
5.4.
FACTORY
REPAIR
SERVICE
The
542
may
be
returned
to
ORTEC
for
repair
service
at
nominal
cost.
Our
standard
procedure
requires
that
each
repaired
instrument
receive
the
same
extensive
quality
control
tests
that
a
new
instmment
receives.
Contact
our
Customer
Service
Department,
865/482-4411,
for
shipping
instructions
before
returning
the
instrument.
The
unit
will
be
assigned
a
Return
Authorization
Number
which
must
accompany
the
returned
instrument.
Bin/Module
Connector
Pin
Assignments
For
Standard
Nuclear
Instrument
Modules
per
DOE/ER-0457T.
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
do
30
Spare
bus
9
Spare
31
Spare
*10
+6V
32
Spare
*11
-6V
*33
117
Vac
(hot)
12
Reserved
bus
*34
Power
return
ground
13
Spare
35
Reset
(Sealer)
14
Spare
36
Gate
15
Reserved
37
Reset
(Auxiliary)
*16
+12V
38
Coaxial
*17
-12V
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.
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