Counted Burst - Tektronix DD 501 Instruction Manual

Operating Instructions—
DD
501
applied
to a trigger
circuit
where
they are converted
to
pulses
of
uniform amplitude and shape. This makes
it
possible to
start
the delay with a pulse
that
has
a
constant
size,
eliminating variations
of
the delay
circuit
operation
caused by changing
input
signals.
The
trigger
controls
provide
a
means
to select
the
START
and
EVENT
pulses
at
any
voltage
level
on
either slope
of the
waveform.
The
trigger
SLOPE
and
LEVEL
controls determine
the
slope
and
voltage of the input signal
where
the
trigger
circuit
responds. Generally, the best point on
a
waveform
for triggering
is
where
the slope
is
steep,
and
therefore
usually free of noise.
Assuming
a
sine-wave
input
waveform,
the steepest
slope occurs
at
the zero-crossing
point. This
is
the
point selected for triggering with the
LEVEL
control
is
set to 0 (center).
A
more
positive
or
negative point
on
the
waveform
is
selected as the
LEVEL
control
is
rotated clockwise
or
counterclockwise
respec-
tively
from
0 (toward
+
or
-
symbols on
panel).
Before
setting
the
trigger level,
the desired slope
should be
selected. Adjust the
START
LEVEL
control to
the desired
start
trigger point.
Then
adjust the
EVENTS
LEVEL
control to trigger the
events pulse either
simultaneously or
after
the
start
trigger pulse.
The
relationship
between
start
and events
triggering
is
monitored
at
the
START
and
EVENTS TRIG VIEW
con-
nectors.
Either
LEVEL
control
can be
preset
to
a fixed voltage
level
by adjusting the front-panel
PRESET
adjustment.
Rotate
either
LEVEL
control
fully
clockwise
(into
the
detent),
and
set
the
PRESET
screwdriver adjustment
to
the desired triggering voltage
level.
Counted
Burst
This
application permits preselecting the
number
of
output pulses from the
PG
508.
The
event
is
initiated
by an
externally applied signal or pulse, 5 ns
or longer.
The
time
duration
of this
signal or pulse has
no
effect
on
the output
from
the
PG
508.
To
use
this feature, place the
DD
501
in
the delay
interval
mode
of
operation by moving
the wire
strap as
shown
in Fig.
1-2 or
changing
connections, depending on
the
DD
501 available.
Connect
the
PG
508 and
the
DD
501
as
shown
in Fig. 1-3.
Use
ten inch or shorter cables
for
interconnecting the
two
units to
reduce
delays.
Make
certain
the
PG
508
TRIG/GATE
IN input
impedance
is
set for
50
fi.
Set the controls
of
the
PG
508
for the desired output waveform
with the
PG
508
in
FREE
RUN. Do
not use
the
SQ
WAVE
mode.
Place the
PG
508
in
the
+
SLOPE,
SYNC GATE
mode
and
set
the
TRIG/GATE
LEVEL
control
at
the 2 o'clock
position. Select
EVENTS +
SLOPE, START
-f
SLOPE
and
place the
EVENTS
and
START
LEVEL
controls
at
the 2 o'clock
position
on
the
DD
501.
The
three
TRIG'D
lights
on the
DD
501
and
the
TRIG'D/GATED
light
on
the
PG
508
will
be
off until
the
DD
501 istriggered.
Upon
receipt ofatrigger,
all
lights
will
illuminate.
If
not,
check
the setup and
slightly adjust the
LEVEL
controls as necessary.
Set the
EVENTS DELAY COUNT
on
the
DD
501
for
one
less
than the desired
number
of
counts up
to
PG
508
repetition rates of
about 20 MHz. See below
for further
information.
If
necessary,
asingletriggermay beobtained
by
rotating the
DD
501
START
LEVEL
control throughthe
0 position, with
no
external trigger applied.
A
single trigger
may
also
be obtained by
using the
TEKTRONIX
manual
(One
Shot) Trigger Generator, Tektronix
Part
Number
016-0597-00.
All
other
DD
501
and
PG
508
operating
controls function normally.
"S'
2
^
I
WE
ifl
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i
aQaEHui
00HQS0B.
Connect
pins
1
and
3 for
delay
interval out for
counted
burst.
Pins
1
and
2 provide normal delayed
trigger out.
2044-29
Fig. 1-2.
Location
of trigger
jumpers
in
DD
501
for selecting trigger or delay
interval output.
1-2
REV
B
AUG
1979