Tektronix DD 501 User manual

Tektronix, Inc.
P.O. Box 500
Beaverton, Oregon
070-1818-01
Product Group 75
IbktfDnix-
COMMITTED TO EXCELLENCE
PLEASE CHECK FOR CHANGE INFORMATION
AT THE REAR OF THIS MANUAL.
INSTRUCTION MANUAL
97077 Serial Number
First Printing SEP 1974
Revised APR 1982

|Gopynght ©1974, t975 Tektironix, Inc/7VII rights reserv^d/^'
iContents of this publcatfon may not be reproduced in
Iany forrh withoutthe written permission of Tektronix, Inc.
Products of Tektronix, inc. and its Subsidiaries are
;• covered by arid f^eign patenta and/or pendBng.-,
5patents. ''''*
'TEKTRONIX, TEK, SCo|&MOBlLE,:ind- ^are^
regtstf^, trademarks cl itektronix, Jnc. •TELECluiPr
registered trademark of Tektronix 'U.K.
,i4rolted. ;
.
Printed in U.S.A. Specification and price change
privileges are reserved.

DD 501
TABLE OF CONTENTS
Page
SECTION 1OPERATING INSTRUCTIONS
Installation 1-1
Signal Connection 1-1
Triggering 1-1
Counted Burst 1-2
FRONT-PANEL CONTROLS, CONNECTORS,
AND INDICATORS 1-4
SECTION 2SPECIFICATION
SECTION 3THEORY OF OPERATION
BLOCK DIAGRAM DESCRIPTION 3-1
CIRCUIT OPERATION
TRIGGER CIRCUIT 13-2
COUNTER CIRCUIT (SN B020530-up) 23-2
COUNTER CIRCUIT (SN B020529 and below) 23-5
POWER SUPPLY &TRIGGER INDICATOR 33-7
SECTION 4MAINTENANCE
FUSE REPLACEMENT 4-1
TABLE 4-2. Rear Connector Pin Assignments 4-1
REPACKAGING FOR SHIPMENT 4-2
SECTION 5PERFORMANCE CHECK/CALIBRATION
PRELIMINARY INFORMATION 5-1
Test Equipment Required 5-1
INDEX TO PERFORMANCE CHECK/CALIBRATION 5-3
START AND EVENTS INPUT 5-4
START AND EVENTS TRIGGERING 5-6
SECTION 6ELECTRICAL PARTS LIST
OPTIONS
SECTION 7DIAGRAMS
SECTION 8MECHANICAL PARTS LIST
CHANGE INFORMATION
REV CAUG 1979

Section 1—DD 501
OPERATING INSTRUCTIONS
INTRODUCTION
The DD 501 Digital Delay is an events counting plug-in unit designed for use in aTM 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 apredetermined number of events, from 0to 99999, which are
selected by the front-panel thumb-wheel switches. The last event counted generates atrigger 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. A10X
attenuation probe offers ahigh input impedance and
allows the circuit under test to perform very close to
normal operating conditions. Also, a10X probe attenuates
the input signal 10 times.
Tektronix probes are designed to monitor the signal
source with minimum circuit loading. The use of aprobe
will, however, limit the maximum trigger frequency range.
To obtain maximum trigger bandwidth when using
probes, select aprobe 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 acoaxial 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 acommon
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 acoaxial 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 awide 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 BAUG 1979 1-1

Operating Instructions—DD 501
applied to atrigger circuit where they are converted to
pulses of uniform amplitude and shape. This makes it
possible to start the delay with apulse that has aconstant
size, eliminating variations of the delay circuit operation
caused by changing input signals. The trigger controls
provide ameans 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 awaveform
for triggering is where the slope is steep, and therefore
usually free of noise. Assuming asine-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). Amore 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 afixed 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, 5ns 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 2o’clock position. Select EVENTS +
SLOPE, START -f SLOPE and place the EVENTS and
START LEVEL controls at the 2o’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
0position, with no external trigger applied. Asingle 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
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Connect pins 1and 3for delay interval out for counted burst. Pins 1and 2provide 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 BAUG 1979

Operating Instructions—DD 501
Fig. 1-3. PG 508-DD 501 Interconnections for counted burst operation.
Due to propagation delays in the PG 508, DD 501 and
the interconnecting cables, one or more pulses in addition
to the desired number are generated when the PG 508
repetition rates are set between 20 MHz and 50 MHz.
These extra pulses are consistent for any given frequency
irrespective of the desired EVENTS DELAY COUNT
setting. To determine the number of extra pulses for a
given PG 508 period, set the PG 508 and the DD 501
controls as previously described. Now adjust the PG 508
TRIG/GATE LEVEL or the DD 501 EVENTS LEVEL forthe
same number of extra pulses at DD 501 EVENTS DELAY
COUNT setting of zero and nine.
Fig. 1-4. Typical propagation delays using PG 508 with DD 501 in counted burst mode at 50 MHz repetition rate.
REV BAUG 1979 1-3

Operating Instructions—DD 501
FRONT-PANEL CONTROLS,
CONNECTORS, AND INDICATORS
NOTE
See Fig. 1-3 for location and brief description of
front-panel controls, connectors, and indicators.
EVENTS DELAY COUNT Switch
The EVENTS DELAY COUNT switch is a5decade,
digital readout switch that increases or decreases the
count at which adelayed pulse will occur. This switch
selects the number of events to be counted. The delay
count is displayed on the front-panel switch readout. The
DLY’D TRIG OUT signal is delayed 1count more than the
EVENTS DELAY COUNT switch setting: that is, aswitch
setting of 00000 will count 1event pulse, or aswitch setting
of 99999 will count 100,000 event pulses to produce a
DLY’D TRIG OUT pulse.
INPUT Connectors
Individual front-panel connectors are provided for
connecting the external trigger signals to the EVENTS and
START trigger preamplifiers.
EVENTS and START SLOPE Switches
Determine the amplitude point on the trigger signal at
which the circuit triggers. In the fully clockwise detent
position, the circuit triggers at the amplitude point on the
trigger signal selected by the PRESET screwdriver adjust-
ment.
LEVEL IN/OUT Connectors
Individual front-panel pin jacks are provided to monitor
the EVENTS and START dc level at which the triggering
occurs.
EVENTS TRIC’D Indicator
Provides avisible indication that the Events circuit has
received atrigger, and that an adequate trigger signal is
applied.
START TRIC’D Indicator
Provides avisible indication that the Start gate circuit
has received atrigger, and is open, ready for the events
count to begin.
RESET Pushbutton
Afront-panel RESET button Is provided to clear the
EVENTS counter and reset the START circuit. The next
START pulse will restart the EVENTS count at 00001 .The
RESET pushbutton allows the operator to reset the
counter and start circuit when in longterm count cycles or
when afalse trigger occurs.
1-4 REV BAUG 1979

Operating Instructions—DD 501
POWER. Pilot Light indicates power
applied.
TRIG'D. Indicates EVENTS circuit has
received atrigger.
SLOPE, Selects EVENTS trigger
polarity.
LEVEL. Selects the amplitude point
where the EVENTS circuit triggers.
PRESET. Allows trigger point to be
preset (LEVEL clockwise in detent).
LEVEL IN/OUT. Provides an output to
monitor the dc level at which the
EVENTS trigger occurs.
INPUT. Provides ameans of connecting
the external trigger signal to the
EVENTS trigger preamplifier.
TRIG'D. Indicates adelayed trigger
output has occured.
DLY'D TRIG OUT. Provides an output
of the delayed trigger pulses.
[
[
[
[
[
[
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EVENTS DELAY COUNT. Selects
number of events to be counted.
RESET. Restarts count cycle.
TRIG'D. Indicates START gate
triggering.
SLOPE. Selects START trigger polarity.
LEVEL. Selects the amplitude point
where the START circuit triggers.
PRESET. Allows trigger point to be
preset (LEVEL clockwise in detent).
LEVEL IN/OUT. Provides an output to
monitor the dc level at which the START
trigger occurs.
INPUT. Provides ameans of connecting
the external trigger signal to the START
trigger preamplifier.
TRIG VIEW. Allows viewing of shaped
trigger pulses to START latch circuit.
TRIG VIEW. Allows viewing of shaped
trigger pulses to EVENTS counting
circuit.
1S18-7A
Fig. 1-5. DD 501 front panel controls and connectors.
@AUG 1979 1-5

Operating Instructions—DD 501
TRIG VIEW Connectors
Individual front-panel probe-tip connectors are
provided for monitoring the EVENTS and the START
trigger pulse waveforms. The TRIG VIEW output signals
are arepresentation of the input trigger signals repetition
rates. The TRIG VIEWoutput pulse width is determined by
the input waveshape and the triggering voltage level. For
example, the sinewave EVENTS INPUT signal, triggered
at the amplitude point shown in Fig. 1-6, produces an
output trigger width of 5microseconds. Consequently,
varying the trigger amplitude point on the input waveform
will vary the output pulse width proportionally.
DYL’D TRIG OUT Connector
Provides ameans of applying the shaped delayed
trigger pulsesto associated equipment. Output signals are
generated as positive-going rectangular pulses coinci-
dent with the end of the delay interval. The DLY'D TRIG
OUT pulse width will be identical to the Schmitt-trigger
pulse width, which can be monitored at the front-panel
TRIG VIEW connector.
The display shown in Fig. 1-7 illustrates the relationship
between the EVENTS INPUT signal, TRIG VIEW pulse,
and the DLY’D TRIG OUT pulse, with the EVENTS DELAY
COUNT switch set at 00002.
DELAYED TRIG’D Light
Provides avisible indication when adelayed trigger
output has occurred.
Fig. 1-6 Delayed output pulse width vs. events input-signal Fig. 1-7. Time and pulse-width relationships between input and
trigger voltage level. output signals.
1-6 @AUG 1979