ORTEC 407 User manual
PRECISION
INSTRUMENTATION
FOR
RESEARCH
Oak
Ridge
Technical
Enterprises
Corporation
OAK
RIDGE,
TENNESSEE
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INSTRUCTION
MANUAL
MODEL
407
CROSSOVER
PICKOFF
STANDARD
WARRANTY
FOR
ORTEC
ELECTRONIC
INSTRUMENTS
DAMAGE
IN
TRANSIT
Shipments
should
be
examined
immediately
upon
receipt
for
evidence
of
external
or
con
cealed
damage.
The
carrier
making
delivery
should
be
notified
immediately
of
any
such
damage,
since
the
carrier
is
normally
liable
for
damage
in
shipment.
Packing
materials,
waybills,
and
other
such
documentation
should
be
preserved
in
order
to
establish
claims.
After
such
notification
to
the
carrier,
notify
ORTEC
of
the
circumstances
so
that
we
may
assist
in
damage
claims
and
in
providing
replacement
equipment
when
necessary.
WARRANTY
ORTEC
warrants
its
electronic
products
to
be
free
from
defects
in
workmanship
and
materials,
other
than
vacuum
tubes
and
semiconductors,
for
a
period
of
twelve
months
from
date
of
ship
ment,
provided
that
the
equipment
has
been
used
in
a
proper
manner
and
not
subjected
to
abuse.
Repairs
or
replacement,
at
ORTEC
option,
will
be
made
without
charge
at
the
ORTEC
factory.
Shipping
expense
will
be
to
the
account
of
the
customer
except
in
cases
of
defects
discovered
upon
initial
operation.
Warranties
of
vacuum
tubes
and
semiconductors,
as
made
by
their
manufacturers,
will
be
extended
to
our
customers
only
to
the
extent
of
the
manufacturers'
liability
to
ORTEC.
Specially
selected
vacuum
tubes
or
semiconductors
cannot
be
warranted.
ORTEC
reserves
the
right
to
modify
the
design
of
its
products
without
incurring
responsibility
for
modification
of
previously
manufactured
units.
Since
installation
conditions
are
beyond
our
control,
ORTEC
does
not
assume
any
risks
or
liabilities
associated
with
the
methods
of
installation,
or
installation
results.
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
ORTEC
instruments
not
in
warranty
may
be
returned
to
the
factory
for
repairs
or
checkout
at
modest
expense
to
the
customer.
Standard
procedure
requires
that
returned
instruments
pass
the
same
quality
control
tests
as
those
used
for
new
production
instruments.
Please
contact
the
factory
for
instructions
before
shipping
equipment.
INSTRUCTION
MANUAL
MODEL
407
CROSSOVER
PICKOFF
Serial
No.
Purchaser
_
Date
Issued
OAK
RIDGE
TECHNICAL
ENTERPRISES
CORPORATION
p.
O.
BOX
C
OAK
RIDGE,
TENNESSEE
Telephone
(615)
483-8451
TWX
810-572-1078
I
Oak
Ridge
Technical
Enterprises
Corporation
1966
CONTENTS
1.
DESCRIPTION
1.1
General
Description
1.2
Description
of
Basic
Function
2.
SPECIFICATIONS
2.1
General
Specifications
2.2
Crossover
Pickoff
Specifications
3.
INSTALLATION
3.1
General
Installation
Considerations
3.2
Connection
to
Power—Nuclear
Standard
Bin
ORTEC
Model
401/402
3.3
Connection
to
Linear
Amplifier
3.4
Installations
With
Inputs
Other
Than
Conventional
Linear
Amplifiers
4.
OPERATING
INSTRUCTIONS
4.1
Front
Panel
Controls
—
Description
and
Familiarization
4.2
Initial
Testing
and
Observation
of
Pulse
Waveforms
4.3
Connector
Data
4.4
Typical
Operating
Considerations
5.
CIRCUIT
DESCRIPTION,
CROSSOVER
PICKOFF
(Etched
Board
407-0201)
6.
MAINTENANCE
6.1
Testing
Performance
of
Crossover
Pickoff
6.2
Crossover
Pickoff
Threshold
Adjustment
6.3
Troubleshooting
6.4
Tabulated
Test
Point
Voltages
on
Etched
Board
7.
PARTS
LIST
8.
BLOCK
DIAGRAMS
AND
SCHEMATICS
407-0201-B
Model
407
Block
Diagram
407-0201-S
Model
407
Crossover
Pickoff
Schematic
407-0301-S
Model
407
Chassis
Wiring
Schematic
ORTEC
-i
'
MODEL
407
CROSSOVER
mCKOFF
0
ns
200
ns
OUTPUT
DELAY
0-250
ns
INPUT
OUTPUT
'
MODEL
407
CROSSOVER
PICKOFF
■
1-1
MODEL
407
CROSSOVER
PICKOFF
1.
DESCRIPTION
1.1
General
The
Model
407
Crossover
Pickoff
is
designed
to
be
used
with
amplifiers,
such
OS
the
ORTEC
Model
410
Multimode
Amplifier,
that
provide
a
bipolar
output
pulse,
either
RC
or
delay
line
shaped.
The
Model
407,
when
used
with
the
Model
410
Amplifier,
makes
possible
crossover
pickoff
timing
measurements
from
nuclear
radiation
detectors,
featuring
a
minimum
of
time
slewing
as
a
function
of
input
pulse
amplitude.
The
Model
407
also
incorporates
a
variable
delay
time
on
the
output
pulse
to
enable
the
crossover
pickoff
output
to
be
placed
in
time
coincidence
with
other
signals.
1.2
Description
of
Basic
Function
The
bipolar
output
pulse
from
the
amplifier
is
fed
into
the
Model
407
Cross
over
Pickoff
circuit
where
a
fast
timing
signal
is
generated
when
the
bipolar
signal
crosses
from
a
positive
to
a
negative
value,
i.e.,
when
the
bipolar
signal
"crosses
over"
the
zero
voltage
baseline.
The
trigger
point
where
the
timing
signal
is
initiated
is
variable
over
narrow
limits
to
allow
the
optimum
timing
when
used
with
different
amplifier
and
pulse
shapes.
The
trigger
point
is
normally
set
to
trigger
on
the
point
on
the
output
pulse
from
the
amplifier
that
has
minimum
time
slewing
as
a
function
of
amplitude,
sometimes
called
"walk."
The
output
signal
from
the
Model
407
can
be
delayed
from
0
to
450
nano
seconds
by
operation
of
a
front
panel
switch
and
10-turn
control.
This
variable
delay
greatly
facilitates
setting
up
the
timing
conditions
for
coincidence
cir
cuits,
and
also
allows
the
taking
of
chance
coincidence
spectra
by
simply
operating
the
OUTPUT
DELAY
switch.
2-1
2.
SPECIFICATIONS
2.1
General
Specifications
The
Model
407
is
housed
in
a
Nuclear
Stondord
Module;
it
is
one
standard
module
wide,
and
weighs
2.1
pounds.
It
contains
no
internal
power
supply
and
therefore
must
obtain
the
necessary
operating
power
from
a
Nuclear
Standard
Bin
and
Power
Supply
such
as
the
ORTEC
Model
401/402.
All
sig
nals
in
and
out
of
the
module
are
on
front
panel
BNC
connectors,
and
the
input
power
is
via
the
standard
connector
on
the
rear
panel.
2.2
Crossover
Pickoff
Input
Bipolar,
with
positive
portion
leading;
0.2
to
10
volts
rated
range,
20
volts
maximum
Input
Impedance
1000
ohms
Crossover
Pickoff
Threshold
The
Crossover
Pickoff
has
an
integral
discriminator
which
is
typically
set
at
240
mV.
The
range
of
the
dis
criminator
is
approximately
100
mV
to
300
mV,
adjustable
via
an
internal
trimpot.
Count
Rate
Capabilities
The
Crossover
Pickoff
maximum
count
is
normally
limited
by
the
pulse
shaping
time
constants
of
the
pre
ceding
linear
amplifier.
Pulse
Pair
Resolution
Pulse
pair
resolution
is
760
nsec,
as
normally
supplied.
For
operation
with
pulse
pair
resolution
as
low
as
approximately
300
nsec,
refer
to
section
5
of
this
manual.
Walk
of
Crossover
Pickoff
The
walk
of
the
logic
output
pulse
from
the
Crossover
Pickoff,
with
respect
to
the
input
pulse
to
the
main
amplifier,
is
less
than
4
nsec
for
a
10:1
change
in
output
voltage
(0.8V
to
B.pV)
when
used
with
a
Model
410
main
amplifier
in
either
Delay
Line
or
0.1-/u-sec
RC
pulse
shaping
modes.
Output
Pulse
The
output
pulse
is
a
positive
pulse
of
4V
minimum
amplitude
and
full
width
at
half
maximum
(fwhm)
of
500
nsec.
Output
Impedance Impedance
of
driving
source
is
less
than
10
ohms.
2-2
Minimum
Delay
of
Crossover
Pickoff
Output
The
minimum
delay
from
the
actual
crossover
of
a
bipolar
input
signal
is
approximately
100
nsec.
Crossover
Pickoff
Output
Pulse
Delay...Two
front
panel
controls
are
available
that
provide
additional
internal
de
lay
of
the
Crossover
Pickoff
output
pulse.
Zero-
or
200-nsec
delay
is
provided
by
a
toggle
switch,
and
0-
to
250-nsec
delay
is
selectable
with
a
10-turn
control.
Output
Pulse
Temperature
Coefficient
The
time
shift
of
the
output
pulse
is
less
than
0.5
nsec
per
°C.
Operating
Temperature
Range
0
to
50°C
Power
Requirements
+24V,
21
mA
+12V,
58
mA
-24V,
60
mA
Mechanical
One
module
wide,
and
designed
to
meet
recommended
interchange-
ability
standards
outlined
in
AEC
Report
TID-20893,
it
is
1.35
inches
wide,
8.75
inches
high,
and
9.75
inches
long.
3-1
INSTALLATION
3.1
General
Installation
Considerations
The
Model
407,
used
in
conjunction
with
a
Model
401
/402
Bin
and
Power
Sup
ply,
is
intended
for
rock
mounting,
and
therefore
it
is
necessary
to
ensure
that
vacuum
tube
equipment
operating
in
the
same
rack
with
the
Model
407
have
sufficient
cooling
air
circulating
to
prevent
any
localized
heating
of
the
all-
transistor
circuitry
used
throughout
the
Model
407.
The
temperature
of
equip
ment
mounted
in
racks
can
easily
exceed
the
recommended
maximum
unless
precautions
are
taken;
the
Model
407
should
not
be
subjected
to
temperatures
in
excess
of
120°F
(50°C).
3.2
Connection
to
Power
—Nuclear
Standard
Bin,
ORTEC
Model
401/402
The
Model
407
contains
no
internal
power
supply
and
therefore
must
obtain
power
from
a
Nuclear
Standard
Bin
and
Power
Supply
such
as
the
ORTEC
Model
401/402.
It
is
recommended
that
the
bin
power
supply
be
turned
off
when
inserting
or
removing
modules.
The
ORTEC
400
Series
is
designed
so
that
is
not
possible
to
overload
the
bin
power
supply
with
a
full
complement
of
modules
in
the
Bin.
However,
this
may
not
be
true
when
the
Bin
contains
modules
other
than
those
of
ORTEC
design.
In
such
instances,
the
power
sup
ply
voltages
should
be
checked
after
the
insertion
of
modules.
The
ORTEC
Model
401/402
has
test
points
on
the
power
supply
control
panel
to
monitor
the
dc
voltages.
3.3
Connection
to
Linear
Amplifier
The
input
to
the
Model
407
is
on
the
front
panel
INPUT
BNC
connector
and
is
compatible
with
all
linear
amplifiers
capable
of
producing
bipolar
output
signals
(positive
excursion
leading)
into
a
1000-ohm
load.
The
input
oper
ating
range
is
from
threshold,
typically
200
millivolts
to
10
volts.
The
input
is
ac
coupled
but
may
be
dc
connected
if
necessary,
as
the
input
operates
at
0
volts
dc.
3.4
Installations
With
Inputs
Other
Than
Conventional
Linear
Amplifiers
The
Crossover
Pickoff
circuit
of
the
Model
407
does
not
require
the
exact
bi
polar
waveform
found
in
nuclear
physics
pulse
amplifiers.
Any
positive
leading
bipolar
waveshape
will
activate
the
Crossover
Pickoff
circuit
and
generate
a
timing
output
when
the
input
signal
crosses
from
a
positive
to
a
negative
volt
age.
The
Crossover
Pickoff
circuit
is
not
dc
coupled
throughout,
and
therefore
the
input
bipolar
signal
must
be
fast
compared
to
the
RC
time
constants
of
the
crossover
circuitry.
The
shortest
time
constant
of
consequence
is
approxi
mately
680
microseconds,
and
the
requirements
of
the
input
signal
can
be
judged
from
this.
4-1
4.
OPERATING
INSTRUCTIONS
4.1
Front
Panel
Controls
OUTPUT
DELAY
When
the
bipolar
signal
passes
from
a
positive
to
a
negative
value,
the
Cross
over
Pickoff
circuit
generates
a
logical
signal
to
be
used
for
timing
or
counting
applications.
The
OUTPUT
DELAY
control
and
switch
allow
Crossover
Pickoff
output
signal
to
be
delayed
in
time
from
a
reference
time
Tq
over
a
range
of
0
to
450
nsec.
The
OUTPUT
DELAY
control
is
continuously
variable
from
0
to
250
nanoseconds
with
a
10-turn
dial,
and
the
OUTPUT
DELAY
toggle
switch
allows
selection
of
either
0-
or
200-nanosecond
fixed
delay.
4.2
Initial
Testing
and
Observation
of
Pulse
Waveforms
See
Section
6.1
of
this
manual
for
information
concerning
testing
performance.
4.3
Connector
Data
PGl
-
INPUT
(BNC)
Input
impedance
is
1000
ohms,
ac
coupled.
Maximum
input
voltage
is
20
volts.
To
minimize
reflections
when
driving
into
the
Mo.del
407
input
from
a
low
im
pedance
voltage
source
such
as
the
output
of
the
Model
410,
the
input
should
be
terminated
in
the
characteristic
impedance
of
the
connecting
coaxial
cable.
PG2-OUTPUT
(BNC)
Output
driving
source
is
less
than
10
ohms,
ac
coupled.
OUTPUT
Test
Point
There
is
an
oscilloscope
test
point
for
monitoring
a
signal
on
the
OUTPUT
BNC;
this
test
point
has
a
470-ohm
series
resistor
connecting
it
to
the
OUTPUT
BNC.
Power
Connector
The
Nuclear
Standard
Module
power
connector
is
an
AMP
202515-3.
4.4
Typical
Operating
Conditions
The
realization
of
both
optimum
timing
and
optimum
energy
resolution
is
mutually
exclusive
when
using
the
crossover
pickoff
method
of
timing;
how
ever,
a
satisfactory
compromise
of
timing
and
resolution
is
usually
not
difficult
to
attain.
Optimum
timing
is
realized
with
wide
bandwidth
capabilities
in
the
linear
amplifier,
resulting
in
fast
rise
and
fall
times.
Optimum
energy
reso
lution
is
realized
with
narrow
bandwidth
so
that
the
bandpass
of
the
noise
spectrum
can
be
selectively
chosen
at
a
particular
location
in
the
frequency
spectrum.
The
method
of
compromise
is
illustrated
with
reference
to
the
Model
410
Multi-
mode
Amplifier
when
used
in
conjunction
with
the
Model
407
Crossover
Pick-
off.
To
optimize
timing,
the
Model
410
would
be
operated:
(1)
with
a
minimum
of
integration
and
double
delay
line
differentiation,
or
(2)
in
the
double
RC
shaping
mode
with
the
integration
and
differentiation
time
constants
set
on
0.1
microsecond.
The
optimization
of
timing
would
be
at
the
expense
of
energy
resolution.
If
it
is
desired
to
optimize
the
energy
resolution,
the
Model
410
4-2
would
be
operated:
(1)
with
on
integration
time
constant
of
1
or
2
micro
seconds
and
double
delay
line
differentiation,
or
(2)
in
the
double
RC
shaping
mode
with
the
integration
and
differentiation
time
constants
set
on
1
or
2
microseconds.
In
the
latter
case,
it
is
observed
that
the
rate
of
change
of
volt
age
when
the
linear
amplifier
output
crosses
through
zero
is
very
much
less
than
in
the
former
case.
With
the
lower
rate
of
change,
the
noise
modulation
of
the
linear
amplifier
output
signal
causes
a
time
jitter
of
the
timing
output
signal;
whereas
in
the
former
case,
the
rate
of
change
is
quite
high
and
the
jitter
in
the
timing
output
due
to
linear
amplifier
noise
modulation
is
quite
small.
5-1
5.
CIRCUIT
DESCRIPTION,
CROSSOVER
PICKOFF
(Etched
Board
407-0201)
5.1
The
input
to
the
Crossover
Pickoff
circuit
is
through
the
emitter
follower,
Ql.
The
output
of
Ql
is
then
fed
through
the
1-volt
limiter
consisting
of
resistors
R3,
R4,
and
R5
diodes
D1
and
D2.
RIO
is
the
load
resistor
for
the
limiting
net
work.
Refer
to
block
diagrams
407-0201-B1
and
407-0201-SI.
The
output
of
the
1-volt
limiter
is
fed
into
the
ac-coupled
Schmitt
trigger
circuit,
Q2
and
Q3.
The
Schmitt
trigger
circuit
is
characterized
by
a
fixed
hysteresis
of
approxi
mately
150
millivolts,
and
Q3
is
ON
in
the
quiescent
state.
The
Schmitt
trigger
circuit
is
characterized
by
a
fixed
hysteresis
of
approximately
150
millivolts,
and
03
is
ON
in
the
quiescent
state.
The
Schmitt
trigger
circuit
has
an
adjust
able
threshold
which
is
controlled
by
potentiometer
R8,
the
5K
trimpot.
The
procedure
for
adjusting
R8
for
minimum
walk
of
the
Crossover
Pickoff
is
to
adjust
the
threshold
(point
A
in
Figure
5.1)
so
that
due
to
the
hysteresis,
the
trigger
circuit
is
reset
at
point
B
(Fig.
5.1).
Notice
that
the
time
from
t^
to
t
is
essentially
independent
of
the
amplitude
of
the
input
signal;
therefore,
the
walk
is
minimized.
The
output
of
the
Schmitt
trigger
circuit
is
sharply
differ
entiated
by
the
inductance,
LI,
and
inverted
by
04.
05
and
06
constitute
a
long-tail
trigger
pair,
with
06
ON
in
the
quiescent
state,
which
is
triggered
with
the
differentiated
positive
portion
of
the
output
of
04.
The
trigger
circuit,
05
and
06,
is
triggered
in
actual
time
at
t^,
i.e.,
the
approximate
time
when
the
bipolar
amplifier
signal
crosses
from
plus
to
minus
in
voltage
polarity
(point
B,
Fig.
5.1).
The
output
of
the
trigger
pair,
05
and
06,
is
a
square
voltage
pulse
on
the
collector
of
06
lasting
approximately
600
nanoseconds.
This
voltage
pulse
is
fed
to
the
input
of
the
ac-coupled
Schmitt
trigger
circuit,
08
and
09.
In
the
quiescent
state
09
is
ON.
The
period
of
time
that
08
and
09
remain
in
the
SET
condition
is
determined
by
the
quiescent
voltage
at
the
emitter
of
07,
a
dc
emitter
follower.
When
the
voltage
pulse
from
the
06
collector
is
fed
to
the
08
base,
diode
D5
is
bock-biased.
With
the
diode
back-
Trigger
Threshold
for
Minimum
Walk
Reference
Level
Hysteresis
Reset
Point
for
Minimum
Walk
Figure
5-1.
Typical
Bipolar
Double
RC
Shaped
Input
Pulse
5-2
biased,
the
voltage
at
the
base
of
Q8
is
determined
by
the
original
quiescent
voltage
of
the
emitter
of
Q7
and
by
the
time
constant
of
C8
and
R28.
The
discharge
time
constant
of
C8
and
R28
is
very
long
compared
to
the
time
duration
t,
to
t2,
and
therefore,
the
delay
from
t,
to
t2
(as
shown
in
Block
Dia
gram
407-0201-Bl)
is
essentially
linear.
The
SET
time
of
Q8
and
Q9
is
deter
mined
by
the
period
t,
to
t2,
i.e.,
the
duration
that
the
voltage
at
the
base
of
Q8
is
greater
than
the
base
potential
of
Q9.
5.2
For
any
particular
setting
of
the
OUTPUT
DELAY
control
(R1
on
drawing
407-
0301-S)
a
0-
or
200-nanosecond
increase
in
time
duration
from
t
to
t
can
be
accomplished
by
raising
the
amplitude
of
the
output
voltage
pulse
from
the
trigger
circuit,
Q5
and
Q6.
The
increase
in
amplitude
in
the
output
voltage
at
the
Q6
collector
is
accomplished
by
back-biasing
Q14,
a
normally
saturated
switch,
which
is
shunting
R21.
5.3
The
output
of
Q9
is
sharply
differentiated
by
the
inductance,
L3,
and
fed
into
the
inverter,
QIO.
The
positive
portion
of
the
output
signal
at
the
collector
of
Q10
switches
the
trigger
pair,
Q11
and
Q12,
at
time
tj.
Q11
and
Q12
consti
tute
the
output
trigger
pair,
which
feeds
the
output
pulse
to
Q13,
an
emitter
follower.
The
width
of
the
output
pulse
is
controlled
by
capacitor
C14
and
re
sistor
R40,
and
is
nominally
500
nanoseconds.
6-1
6.
MAINTENANCE
6.1
Testing
Performance
of
Crossover
Pickoff
6.1.1
Introduction
The
following
paragraphs
are
intended
as
an
aid
in
the
installation
and
checkout
of
the
Model
407.
These
instructions
present
information
on
front
panel
controls,
waveforms
at
test
points
and
output
con
nectors.
6.1.2
Test
Equipment
The
following,
or
equivalent,
test
equipment
is
needed:
(1)
ORTEC
Model
419
Pulse
Generator
(2)
Tektronix
Model
580
Series
Oscilloscope
(3)
100-ohm
BNC
terminators
(4)
Vacuum
tube
voltmeter
(5)
ORTEC
Model
410
Multimode
Amplifier
(6)
Schematic
and
block
diagrams
for
Model
407
Crossover
Pickoff
6.1.3
Preliminary
Procedures
(1)
Visually
check
module
for
possible
damage
due
to
shipment.
(2)
Connect
ac
power
to
Nuclear
Standard
Bin,
e.g.,
ORTEC
Model
401/402.
(3)
Plug
module
into
Bin
and
check
for
proper
mechanical
alignment.
(4)
Switch
on
ac
power
and
check
the
dc
power
supply
voltages
at
the
test
points
on
the
401
Power
Supply
control
panel.
6.1.4
Crossover
Pickoff
The
discriminator
level
has
been
set
at
the
factor
for
minimum
walk,
and
steps
1
through
10
can
be
omitted
in
original
installations.
(1)
Set
the
OUTPUT
DELAY
control
to
000,
and
the
OUTPUT
DELAY
toggle
switch
to
0
ns.
(2)
To
check
the
setting
of
the
trimpot
which
controls
the
Crossover
Pickoff
threshold
level,
trigger
the
oscilloscope
externally
from
the
DIRECT
OUTPUT
of
the
pulse
generator.
It
is
imperative
in
this
test
that
the
signal
triggering
the
oscilloscope
does
not
change,
as
this
will
change
the
time
at
which
the
oscilloscope
is
triggered
and
thereby
change
the
time
reference.
(3)
Set
the
INTEGRATION,
1st
and
2nd
DIFFERENTIATION
(outer
and
inner
concentric
controls)
on
0.1,
D.L.,
and
D.L.,
respectively.
(4)
Connect
the
bipolar
output
of
the
Model
410
to
the
input
of
the
Model
407.
An
assumption
is
made
at
this
step
that
the
zero
crossing
point
of
the
amplifier
does
not
shift
as
a
function
of
amplitude.
6-2
(5)
Adjust
the
input
pulse
and/or
the
other
gain
controls
so
thot
the
Model
410
bipolar
output
is
1.4
volts.
(6)
Observe
the
baseline
crossover
output
pulse
at
the
OUTPUT
test
point
on
the
Model
407
front
panel.
This
should
be
a
positive
pulse
approximately
5.7
volts
in
amplitude,
having
a
width
greater
than
0.5-microsecond.
Loading
the
Crossover
Pickoff
OUTPUT
with
a
100-ohm
terminator
should
cause
this
output
voltage
to
drop
to
no
less
than
4.0
volts.
(7)
Decrease
the
output
of
the
Model
410
to
28!
millivolts.
(8)
Observe
the
Model
407
output
pulse
at
the
front
panel
OUTPUT
test
point.
(9)
If
no
pulse
is
seen,
adjust
the
trimpot
at
the
rear
of
the
Crossover
Pickoff
etched
board
until
an
output
signal
from
the
Model
407
occurs.
(10)
Increase
the
amplitude
of
the
Model
410
bipolar
output
to
400
millivolts;
this
should
give
a
continuous
output
from
the
Crossover
Pickoff
circuit.
(11)
Increase
the
amplitude
of
the
bipolar
output
to
8
volts.
(12)
Observe
the
Model
407
output
signal
with
the
oscilloscope
sweep
speed
at
20
nanoseconds
per
centimeter
or
faster.
(13)
Attenuate
the
Model
407
input
signal
to
PGl
(INPUT
BNC)
con
nector)
by
a
factor
of
10
from
the
pulse
generator.
Care
must
be
taken
at
this
step
to
ensure
that
the
signal
magnitude
going
to
the
oscilloscope
trigger
does
not
change.
As
a
factor
of
10
attenua
tion
is
inserted
between
the
pulse
generator
and
PGl,
the
Cross
over
Pickoff
output
signal
should
not
shift
more
than
4
nano
seconds.
There
will
be
time
jitter
due
to
amplifier
noise,
but
the
centroid
should
not
shift
more
than
4
nanoseconds.
If
the
Crossover
Pickoff
output
signal
does
shift
more
than
4
nano
seconds,
it
will
be
necessary
to
adjust
the
trimpot
to
move
the
location
of
the
crossover
pulse
back
in
the
direction
of
the
ref
erence
location
(the
reference
location
being
taken
at
the
8.0-volt
bipolar
signal
output
level).
If
adjustment
of
the
trimpot
is
nec
essary,
it
will
be
necessary
to
"rock
in"
the
trimpot
for
all
positions
of
the
INTEGRATION
and
the
1st
and
2nd
DIFFERENTIATION
con
trols
on
the
Model
410.
Once
the
trimpot
is
correctly
set,
the
cross
over
walk
should
not
exceed
4
nanoseconds
for
a
10:1
bipolar
output
amplitude
change,
and
should
not
exceed
6
nanoseconds
for
a
20:1
bipolar
amplitude
change
when
in
the
Delay
Line
and
0.1-microsecond
double
RC
shaping
modes.
(14)
Observe
the
double
delay
line
output
at
the
front
panel
test
point
on
the
Model
410.
(15)
Adjust
the
input
amplitude
and/or
the
Linear
Amplifier
GAIN
controls
for
a
Model
410
output
pulse
of
4
volts.
6-3
(16)
Accurately
note
the
zero
crossing
time
of
the
bipolar
waveform.
(17)
Observe
the
Model
407
output
pulse
on
the
front
panel.
(18)
With
the
OUTPUT
DELAY
control
set
at
000,
and
the
OUTPUT
DELAY
toggle
switch
at
0
ns,
the
Model
407
output
pulse
should
cross
the
1-volt
level
at
100
±
15
nanoseconds
after
the
zero
crossing
time
previously
noted.
When
the
OUTPUT
DELAY
control
is
at
1000,
an
additional
delay
of
250
±
20
nanoseconds
should
be
measured.
The
OUTPUT
DELAY
control
should
be
approximately
linear
over
its
complete
range.
(19)
Switching
the
OUTPUT
DELAY
toggle
switch
to
200
ns
should
add
200
±
20
nanoseconds
additional
delay
to
the
Model
407
output
pulse.
6.2
Crossover
Pickoff
Threshold
Adjustment
The
trigger
threshold
of
the
Crossover
Pickoff
is
adjustable
with
the
trimpot,
R8,
which
is
mounted
on
etched
board
407-0201.
The
threshold
is
set
at
the
optimum
value
for
minimum
walk
of
the
Crossover
Pickoff
output
timing
sig
nal,
approximately
240
millivolts.
The
threshold
can
be
varied
by
adjustment
of
the
trimpot
over
the
approximate
range
of
100
to
290
millivolts.
The
procedure
for
setting
the
threshold
for
minimum
walk
is
found
in
Section
6.1
of
this
manual.
Refer
also
to
Section
5
and
see
drawings
407-0201-B1
and
407-0201-SI.
6.3
Suggestions
for
Troubleshooting
In
situations
where
the
Model
407
is
suspected
of
malfunction,
it
is
essential
to
verify
such
malfunction
in
terms
of
simple
pulse
generator
impulses
at
the
input
and
output.
In
consideration
of
this,
the
Model
407
must
be
disconnected
from
its
position
in
any
system,
and
routine
diagnostic
analysis
performed
with
a
test
pulse
generator
and
oscilloscope.
It
is
imperative
that
testing
not
be
performed
with
a
source
and
detector
until
the
amplifier-crossover
pickoff
system
performs
satisfactorily
with
the
test
pulse
generator.
The
testing
instructions
listed
in
Section
6.1
of
this
manual
and
the
circuit
descriptions
in
Section
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.
The
Model
407
utilizes
the
modular
etched
board
concept
in
that
all
the
active
circuitry
in
the
module
can
be
removed
from
a
plug-in
socket.This
has
the
ad
vantage
of
servicing
the
unit
by
substitution
of
the
affected
etched
board,
either
from
spares
kept
on
hand
or
obtained
from
the
factory.
6-4
The
Model
407,
or
the
etched
circuit
board,
may
be
returned
to
ORTEC
for
repair
service
at
nominal
cost.
The
standardized
procedure
requires
that
each
repaired
instrument
receive
the
same
extensive
quality
control
tests
that
a
new
instrument
receives.
6.4
Tabulated
Test
Point
Voltages
on
Etched
Boards
The
following
voltages
are
intended
to
indicate
the
typical
dc
voltages
mea
sured
on
the
etched
circuit
board.
In
some
cases
the
circuit
will
perform
satis
factorily
even
though,
due
to
component
variations,
there
may
be
some
volt
ages
that
measure
outside
the
given
limits.
Therefore,
the
voltages
given
here
should
not
be
taken
as
absolute
values,
but
rather
are
intended
to
serve
as
an
aid
in
troubleshooting.
Table
6.1
Typical
DC
Voltages
Notes:
1.
All
voltages
v^ere
measured
from
ground
with
vtvm
having
input
impedances
of
10
megohms
or
greater.
2.
Voltages
are
dc
values
with
no
input
pulses.
3.
Set
OUTPUT
DELAY
control
to
000
divisions
and
OUTPUT
DELAY
switch
to
0
ns.
location
1
2
3
4
5
6
7
8
9
Transistor
No.
and
Element
Q2e
Q3c
Q6c
QBb
Q8e
Q8c
Q12c Q13c
Q14b
Voltage
Upper
-0.6
4.4
1.6
-1.3
-0.5
4.4
3.2
-0.9
2.9
Limits
Lower
-0.8
4.9
2.9
-1.8 -0.8
4.9
3.8
-1.4
3.6
BIN/MODULE
CONNECTOR
PIN
ASSIGNMENTS
FOR
AEC
STANDARD
NUCLEAR
INSTRUMENT
MODULES
PER
TID-20893
Pin
Function
Pin
Function
1
+3
volts
23
Reserved
2
—3
volts
24
Reserved
3
Spore
Bus
25
Reserved
4
Reserved
Bus
26
0—30
volts
oc
5
Cooxiol
27
0—30
volts
ac
6
Cooxiol
*28
+24
volts
7
Coaxial
*29
—24
volts
8
200
volts
dc
30
Spare
Bus
9
200
volts
dc
31
Carry
No.
2
10
+6
volts
32
Spore
1
1
—6
volts
33
1
1
5
volts
oc
12
Reserved
Bus
*34
Clean
Ground
13
Carry
No.
1
35
Reset
14
Spare
*36
Gate
15
Reserved
37
Spore
*16
+
1
2
volts
38
Coaxial
*17
—12
volts
39
Coaxial
18
Spare
Bus
40
Coaxial
19
Reserved
Bus
41
115
volts
oc
20
Spare
*42
Dirty
Ground
21
Spare
G
Ground
Guide
Pin
22
Reserved
*These
pins
are
installed
and
wired
in
parallel
in
the
ORTEC
Model
401
Modular
System
Bin.
The
transistor
types
installed
in
your
instrument
may
differ
from
those
shown
in
the
schematic
diagram.
In
such
cases,
necessary
replace
ments
can
be
made
with
either
the
type
shown
in
the
diagram
or
the
type
actually
used
in
the
instrument.
Table of contents
