Operating Instructions; Installation; Triggering - Tektronix DD 501 Instruction Manual

Section
1— DD
501
OPERATING INSTRUCTIONS
INTRODUCTION
The
DD
501 Digital
Delay
is
an events counting
plug-in unit
designed
for
use
in
a
TM
500-Series
Power Module
mainframe. Separate external trigger signals are
connected
to
the
EVENTS
and
START INPUT
connectors which
allows up
to
99999 events
to
be counted.
The
plug-in unit
counts a predetermined
number
of events,
from
0
to
99999,
which
are
selected
by
the front-panel
thumb-wheel
switches.
The
last
event
counted
generates a trigger pulse to the
DLY'D TRIG
OUT
connector on
the front panel.
Installation
The
DD
501
is
calibrated
and
ready for
use
when
received.
It
is
designed
to
operate
in
any compartment
of a
TM
500-Series
Power Module
only.
To
install,
align the
upper and lower
rails
of
the
DD
501 with the
Power
Module
tracks
and
fully
insert
it.
The
front will
be
flush
with the
front of
the
Power Module
when
the
DD
501
is
fully inserted.
To remove
the
DD
501, pull
on
the
latch
at
the
bottom
of
the
front
panel
and
the
DD
501
will
unlatch.
Continue
pulling
on
the latch to slide
the
DD
501 out
of
the
Power
Module.
See
Fig. 1-1.
Signal
Connection
The
DD
501
utilizes
dc coupling
into
the
EVENTS
and
START
trigger
INPUT
connectors.
In
general,
probes
offer
the
most
convenient
means
of
connecting
signals
to
the
DD
501 trigger inputs.
Tektronix probes are shielded
to
prevent pickup
of electrostatic interference.
A
10X
attenuation probe
offers
a high input
impedance and
allows the
circuit
under
test to
perform
very close to
normal
operating conditions. Also, a
10X probe
attenuates
the input signal 10 times.
Tektronix probes are designed
to
monitor
the signal
source
with
minimum
circuit loading.
The
use
of
a probe
will,
however,
limit
the
maximum
trigger
frequency
range.
To
obtain
maximum
trigger
bandwidth
when
using
probes, select a
probe capable
of
compensating
the input
capacitance. Observe thegrounding considerations given
in
the probe manual.
The
probe-to-connector adapters
and
the bayonet-ground
tip
provide the best frequency
response.
In
high-frequency
applications,
which
require
max-
imum
overall
bandwidth, use a coaxial cable terminated
at
the output
end
in
the characteristic
impedance
of the
source.
To
maintain the high-frequency
characteristics of
the appiied
signal,
use
high-quality,
low-loss
cable.
Resistive coaxial attenuators
can be used
to
minimize
reflection
if
the applied signal
has
suitable amplitude.
High-level,
low-frequency
signals
can be connected
directly to
the external
trigger inputs with short, unshield-
ed
leads.
When
this
method
is
used, establish a
common
ground between
the
DD
501
and
the associated equip-
ment.
The
common
ground
provided
by
the
line
cords
is
usually inadequate.
If
interference
is
excessive
with
unshielded
leads,
use a coaxial cable or probe.
The
front-panel
output
signal
from
the
DLY'D TRIG
OUT
connector should be connected
to other
equipment
with
50
ohm
coaxial cable.
The
cable should determinated
in
50
ohms
to maintain the risetime
and
falltime
characteristics of the signal.
Triggering
The
input signal
may
have
a
wide
variety of
shapes and
amplitudes,
many
of
which
are unsuitable as delay-
initiating triggers.
For
this
reason, these signals are
first
RELEASE
LATCH
:
1818^0
Fig. 1-1.
Release
latch.
REV
B
AUG
1979 1-1