Tektronix 7D14 User manual

INSTRUCTION
MANUAL
Serial Number ____ _
7D14
DIGITAl.
COUNTER
Tektronix, Inc. P. O. Box 500 • Beaverton, Oregon 97005 • Phone [phone] • Cables: Tektronix
070-1097-00 371

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WARRANTY
All Tektronix instruments are warranted against
defective materials
and workmanship for one year.
Any questions with respect to the warranty,
mentioned above, should be taken up with your
Tektronix Field Engineer or representative.
All requests
for repairs and replacement parts
should be directed to the Tektronix Field Office or
representative in your area. This procedure will assure
you
the fastest possible service. Please include the
instrument Type (or Part Number) and Serial or
Model Number with all requests for parts or service.
Specifications and price change privileges reserved.
Copyright @ 1971 by Tektronix, Inc., Beaverton,
Oregon. Printed in the United States of America. All
rights reserved. Contents of this publication may not
be reproduced in any form without permission of the
copyright owner.
U.S.A. and foreign Tektronix products covered
by U.S. and foreign patents and/or patents pending.

®
I t
TABLE OF CONTENTS
SECTION 1
SECTION 2
SECTION 3
SECTION 4
SECTION 5
SECTION 6
SECTION 7
SECTION 8
SPECIFICATION
Introduction
Electrical Characteristics
Environmental Characteristics
Physical Characteristics
OPERATING INSTRUCTIONS
Installation
Display
Controls and Connectors
First-Time Opennion
General Operating Information
Measurement Modes
Operating Modes
CIRCUIT DESCRIPTION
Introduction
Block Diagram Description
Detailed Circuit Description
MAINTENANCE
Introduction
Preventive Maintenance
Troubleshooting
Replacement Parts
Component Replacement
CALIBRATION
Recalibration Interval
Test Equipment Required
Part I -
Performance Check
Part II - Adjustment
ELECTRICAL PARTS LIST
Abbreviations and Symbols
Parts Ordering Information
DIAGRAMS AND CIRCUIT BOARD ILLUSTRATIONS
Symbols and Reference Designators
Voltage and Waveform Conditions
MECHANICAL PARTS LIST
Mechanical Parts List
Information
Index of Mechanical Parts Illustrations
Mechanical Parts List
Accessories
CHANGE INFORMATION
Page
1-1
1-1
1-5
1-5
2-1
2-1
2-1
2-4
2-5
2-8
2-10
3-1
3-1
3-3
4-1
4-1
4-1
4-4
4-4
5-1
5-1
5-4
5-12
Abbreviations and symbols used in this manual are based on or taken directly from lEE E
Standard 260 "Standard Symbols for Units", MIL-STD-12B and other standards of the
electronics industry. Change information, if any, is located at the rear of this manual.
7D14

7014
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®

7D14
SECTION 1
SPECIFICA TION
Change information, if any, affecting this section will be found at the rear of this manual.
Introduction
The 7D14 Digital Counter plug-in unit is designed for use
with Tektronix 7000-series Oscilloscopes equipped with
readout system. The 7D 14 uses the readout system to
display an eight-digit readout on the CRT of the associated
oscilloscope.
The 7D14 will measure frequency from 0 to
525 megahertz, frequency ratio from 0 to lOs: 1 and
totalize (count number of events) from 0 to 10
8.
The 7D14
features counting capability to 525 megahertz without
prescaling, input impedance of 50 ohms or 1 megohm,
blanking of all zeros to the left of the most significant digit,
trigger
pickoff from vertical amplifier unit (which allows
simultaneous signal viewing and counting, and a trigger
indicator analog CRT display to view the "shaped" input
signal.
The following electrical characteristics are valid for
instruments calibrated at an ambient temperature between
+20°C and +30°C after a 20 minute warmup period. The
7D14 should be calibrated every 1000 hours, or every six
months if used infrequently.
TABLE 1-1
ELECTRICAL
Characteristic
Performance Requirement
Supplemental Information
CHANNEL A (Count Channel)
INPUT SENS
P-P VOLTS
Switch Setting
50n
lMn
Frequency Range
DC Coupled
DC to
525 mega-
DC to 525 mega-
hertz hertz
AC Coupled
200
kilohertz
to
5 hertz to
525
525
megahertz megahertz
Sensitivity
100
millivolts
100 millivolts
peak-to-peak peak-to-peak
Input
Resistance As indicated
by
INPUT SENS Switch
within
10%. VSWR
in 50-ohm position
~1.5:1
Capacitance
Not applicable
20 picofarads
within 20% when INPUT
SENS is set to 1 Mn input impedance.
® 1-'

Specification-7D 14
TABLE 1-1 (cont.)
Characteristic Performance Requ
irement
Supplemental Information
Maximum Input Voltage 10 volts RMS
200 volts (DC +
Peak AC)
to
5
megahertz.
50
volts (DC + Peak
AC) to 525 mega-
hertz
TRIG SOURCE
Sensitivity 1.5 divisions
of
vertical deflection
minimum
Frequency Range Depends upon
amplifier plug-in
unit TRIG SOURCE is AC coupled.
and oscilloscope being used.
BW-5 MHz Limits upper bandwidth (-3 dB point)
to 5 megahertz within 1 megahertz.
Trigger
PRESET Triggers on the positive slope
at 0 volt
level.
VAR LEVEL SLOPE control selects positive
or
nega-
tive slope triggering.
Range
INPUT SENS Switch Setting
100 mV +0.5 volt to -0.5 volt
1 V +5 volts to -5 volts
10 V +50 volts to -50 volts
MEASUREMENT INTERVAL
Internal Time Base
Crystal Oscillator
Frequency 5 megahertz
Accuracy
O°C to +50°C
Within 0.5 part per million
Long Term Drift 1 part or less in 107 per month
1-2 ®

Specification-7D 14
TABLE 1-1 (cont.)
Characteristic Performance
Requirement
Supplemental Information
Internal Gate
Range 1 millisecond
through 10 seconds Selectable in decade steps
Resolution
Up to 0.1
hertz
Accuracy
Within ±~± Time Base Accuracy
ota
Count
CH B
Frequency Range 10 hertz
to 2 megahertz AC Coupled
Only
Sensitivity
At least 0.8 volt peak-to-peak Sine wave
or pulse with 30%-70% duty
cycle
Input
R 10
kilohms within 20%
C
30 picofarads within 30%
-~-
Max Input Voltage
50 volts
(DC + Peak AC) to 2 mega-
hertz
EXT GATE
Input Requirements
Compatible with TTL Logic.
Turn On Level Logic "1" at least +2 Volts
Turn Off Level Logic
"0" +500 millivolts or less
Risetime
500 nanoseconds (Maximum)
Falltime
500 nanoseconds (Maximum)
Minimum Off Time
500 nanoseconds
Minimum On Time 200 nanoseconds
Propagation Delay
+ Transition
40 nanoseconds within 20
nano-
seconds
-
Transition
40 na no seconds
within
20
nano-
seconds
Input
Resistance 8.2
kilohms within 20%
Capacitance 35 picofarads
within 20%
® 1-3

Specification-7D 14
Characteristic
EXT GATE (cont)
Max
Input Voltage
DISPLAY TIME
Range
Detent Position
RESET
Input Requirements
Amplitude
Duration
Input
Resistance
Capacitance
Max I
nput Voltage
MONITOR
INT 1 MHz
Signal
Amplitude
Open Circuit
Source Impedance
1 ms-l0s
Signal
Amplitude
Open Circuit
1-4
TABLE 1-1 (cont.)
Performance Requirement
±15 volts (DC + Peak AC) to 10 mega·
hertz
At least 2 volts positive-going pulse.
Compatible with TTL Logic,
Logic "0" +500 millivolts or less
Logic" 1" at least +2 volts
At least 500 nanoseconds
±20 volts (DC + Peak AC) to 10 mega-
hertz
OUTPUT SIGNALS
Positive-going pulse from internal
crystal
oscillator
5 volts within 10%
Time marker pulses from internal gate.
TTL Logic compatible.
5 volts within 10%
Supplemental
Information
Continuously variable from
or less to at least 5 seconds
00 (infinite)
8.2 kilohms within 10%
30 picofarads
Logic "0" 1 kilohms
Logic "1" 2.2 kilohms
0.1 seconds
®

Characteristic
1 ms -10 s (cont)
Polarity
Source Impedance
TABLE 1-1 (cont.)
Performance Requirement
Positive-going
Specification-7D 14
Supplemental Information
Logic "0" "" 1 kilohm
Logic "1" ""5.7 kilohms
Trigger Indicator CRT analog display of trigger output
------------------------------~---
Display
Amplitude
0.2 div within 25%
Position Range
Usable
Frequency Range
Signal Delay
TABLE 1-2
ENVIRONMENTAL CHARACTERISTICS
Refer to the Specification for the associated oscillo·
scope.
®
Size
Weight
Positionable over 8 div by internal
control
System Dependent
""5 nanoseconds
TABLE 1-3
PHYSICAL
Fits all 7000-series plug-in compartments.
2 Pounds 6 Ounces (1075 grams)
'-5

NOTES

7D14
SECTION 2
OPERA TING INSTRUCTIONS
Change information, if any, affecting this section will be found at the rear of this manual.
General
The 7D14 Digital Counter plug-in unit operates with the
readout system of Tektronix 7000-series Oscilloscopes to
measure frequency or frequency ratio, and to totalize
(count number of events)_ To effectively use the 7D14, the
operation and capabilities of the instrument should be
known. This section describes the function and operation
of the controls and connectors, and gives first-time and
general
operating information.
Installation
The 7D14 is designed to operate in any plug-in compart-
ment of Tektronix 7000-series oscilloscopes. However,
certain modes of operation require the 7D14 to be installed
in a specific
compartment. The unit must be operated in a
Horizontal compartment to count a signal which is being
displayed
on the CRT (see Counting a Displayed Signal).
Operation in a Vertical compartment is necessary to view
the 7D14 Trigger Indicator Display on the CRT (see Trigger
Indicator Display).
To install the 7D 14 into a plug-in compartment, push
the unit in until it is seated flush against the front panel of
the oscilloscope. To remove, pull the release latch to dis-
engage the 7D14. Continue to pull the release latch to
remove the unit from the oscilloscope.
Display
The digital readout display for the 7D 14 is presented on
the CRT of the oscilloscope in which the unit is operated,
along
with information encoded by the other plug-in units.
This display is written by the CRT beam on a time-shared
basis
with the analog waveform displays.
The digital display for the 7D14 will appear on the CRT
in a location corresponding to the plug-in compartment
used. The measurement data portion of the display will be
in
the top division of the CRT graticule area and the
measurement
units (MHz or kHz), when displayed, will
appear in the bottom division.
It is not necessary to select the 7D14 with the oscillo-
scope Vertical or Horizontal Mode switches to view the
®
digital display. However, in order to view the 7D14 Trigger
Ind icator Display, selection with the Vertical Mode switch
is required.
The readout display of the measurement data consists of
four to eight digits depending on the measurement being
made.
All zeros to the left of the most significant digit are
blanked
out.
The measurement units and decimal position in the d is-
play are determined by the MEASUREMENT INTERVAL
pushbutton selected. When the measurement range in use is
exceeded, the display is preceded by a "greater than"
symbol (».
CONTROLS AND CONNECTORS
The major controls and connectors for operation of the
7D14 are located on the front panel of the instrument.
These are shown in Fig. 2-1. Two auxiliary functions are
provided by controls located inside the instrument. A de-
scription of the function and/or operation of the controls
and connectors follows.
Measurement Interval Controls
MEASUREMENT
INTERVAL
1 ms -10 s (one
millisecond through
10 seconds)
MANUAL GATE
GATE Indicator
Seven self-cancelling pushbutton
switches that select internal, exter-
nal,
or manual gate.
Selects one
of five measurement
intervals
from the internal time-
base gates. A time-marker output
with a period equal to the selected
interval
is provided at the MONI-
TOR connector.
ON: Initiates gate interval (start
count), and holds the gate open
for totalizing.
OFF: Terminates gate interval (stop
cou
nt), and starts display ti me.
Also selects external gating
signal
from the EXT GATE con-
nector.
Lights during the active gating
interval.
2-1
"--------- ------------

Operating Instructions-7D14
2-2
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Fig. 2·1. 7014 front ·panel co ntrol s and connectors.
®

EXT GATE/MONI-
TOR Connector
BSM connector for external gate in-
put or time marker output as
selected by M EASU R EMENT
INTERVAL pushbuttons.
Display Time Controls
DISPLAY TIME Variable control to set the length of
time the reading will be displayed
after the count is made and before
the next measurement is taken. D is-
play time can be varied from 0.1
second to five seconds. 00 (infinite)
position (fully clockwise) provides
continuous display until reset by an
external signal or by pressing the
RESET pushbutton.
RESET
Pushbutton: Manually resets the
counter to zero.
Pin-jack connector: Provides input
for external signal to reset the
cou nter to zero.
Reference Frequency/Channel B Controls
REF FREQ/CH B Pushbuttons that select the func-
tion of the EXT IN/MONITOR
connector.
INT 1 MHz
(Internal 1 mega-
hertz)
EXTIN
(external input)
Trigger Controls
LEVEL/SLOPE
®
Selects 1 MHz signal from internal
crystal
oscillator at MONITOR con-
nector.
Selects external input to Channel B
for an external timing standard, or
for signal input for ratio measure-
ments.
Selects the amplitude point and
slope on trigger signal where
counter is triggered (V AR push-
button pressed). When the indicator
line on the outer ring is to the left
of center, the counter is triggered
on the positive-going slope of the
input signal as shown by the
positive-going edge symbol. To the
right of center, the counter is trig-
gered on the negative-going slope of
the input signal as shown by the
negative-going edge symbol.
PRESET
VAR
INPUT SENS/P-P
VOLTS
50n
lMn
TRIG SOURCE
BW (bandwidth)
COUPLING
Operating Instructions-7D14
Pushbutton that selects a fixed trig-
ger
point at the zero-volt level on
the positive-going slope (LEVEL/
SLOPE control inoperative).
Pushbutton to allow manual selec-
tion of trigger level and slope with
the LEVEL/SLOPE control.
Rotary switch that selects internal
or external signal input to trigger
counter and selects sensitivity.
I nput signal provided from CH A
INPUT connector at 50-ohm input
impedance.
V: Minimum signal amplitude
must be one volt or greater.
100 mV: Minimum signal ampli-
tude must be 100 mV or greater.
I nput signal provided from CH A
I NPUT connector at one-megohm
input impedance.
100 mV: Minimum signal ampli-
tude must be 100 mV or greater.
V: Minimum signal amplitude
must be one volt or greater.
10 V: Minimum signal amplitude
must be 10 volts or greater.
I nput signal provided from the ind i-
cator oscilloscope trigger pickoff
circu itry. (Th is mode of operation
enables simultaneous counting and
CRT display of a signal. For more
information, see Counting a D is-
played SignaL)
Pushbutton switches that select the
bandwidth of the trigger input cir-
cuits (affects signals
from internal
TRIG SOURCE and CH A INPUT
connector) .
500 MHz: Selects full bandwidth
capability.
5 MHz: Limits upper bandwidth to
about 5 megahertz (-3 dB
point).
Pushbutton switches that select the
method of coupling the signal from
the CH A I NPUT connector to the
trigger circuits (does not affect sig-
nals from internal TRIG SOURCE).
2-3

DperatiT\9lnstructions-7D14
Fie. 2·2. M.nu, 1 Gill Sto rage switch , nd DispilY Pos adjustment.
CH A INPUT
IBNC connector)
Internal Controls
See Fig . 2-2
Man Gate Storage
Slide switch
Display Pos
AC: Selects capacitive coupling to
block DC signal components.
This switch position
is used for
most signal measurements.
DC: Selects direct coupling to pass
all components of the signal
from DC to the upper limit of
the unit. This switch position is
used mainly for DC and low·
frequency signals.
I
nput connector for external
signals.
Se lects manual gate storage mode
(use with MANUAL
or EXT GATE).
OFF (forward): Readout display
follows the counter.
ON (rear): Readout display is up ·
dated at the end of each gate
interval.
Variable control to 5et the Trigger
Indicator Display vertical position.
FIRST· TIME OPERATION
General
When shipped from the factory, the 7014 has been cali-
brated to meet the specifications listed in Section 1 and is
ready to be used with a readout-equipped Tektronix
7000 -series Oscilloscope.
2·4
The following First-Time Operation procedure demon·
strates the basic operation of the 7014 controls. It is
recommended that this procedure be followed completely
for familiarization with the instrument.
NOTE
The First-Time Operation procedure along with Table
2-' can be used to provide a confidence check of the
instrument's operation.
These steps should be per-
formed each rime the lD14 is placed in a different
oscilloscope. andbefore each use.
Preliminary Instructions
1. In stall the 7014 in any available plug· in compan -
ment of a 7000 ·series oscilloscope (referred to in this proce·
dure as the Indicator Oscilloscope).
2. Connect the osci ll oscope to a power source which
meets
the frequency and voltage requirements of the Indi-
cator Oscilloscope power supply.
3. Turn the oscilloscope power on and allow about
twenty minutes warmup time.
4. During the warmup period, set
the controls as
follows:
INDICATOR OSCILLOSCOPE
Intensity
Readout Counterclockwise
Off
Any controls not mentioned can be set as desired.
MEASUREMENT
INTERVAL
DISPLAY TIME
REF FREO/CH B
TRIGGER
7014
INPUT SENS/P-P VOLTS
BW
COUPLING
Dig ital Display Check
10 ,
Midrange
INT I MHz
PRESET
I MU/ I V
5 MHz
AC
5. Advance the Readout control until a readout display
is observed. Adjust the oscilloscope Focus and Astigmatism
controls for a well-defined display.
6. Connect the 1 MHz signal from the EXT IN /
MONITOR connector to the
CH A INPUT connector with a
BSM male to BNC female adapter and a 50-ohm BNC cabl e.
®
-
-
-

7. The readout display should read 1000.0000 kHz ±1
count (999.9999 to 1000.0001 kHz).
8. Check that the GATE indicator light is on during the
time the 7D14 is counting (10 seconds).
9.
Sequentially press the MEASUREMENT INTERVAL
1 s through 1 ms pushbuttons and check that the display
corresponds to the read ings given in Table 2·1.
TABLE 2-1
OPERATING CHECK DISPLAY
MEASUREMENT READOUT LIMITS
INTERVAL MINIMUM
MAXIMUM
10 s
999.9999 1000.0001
1 s 999.999
1000.001
100 ms 0.99999 1.00001
10 ms
0.9999 1.0001
1 ms
0.999
1.001
10.
Disconnect the cable and the adapter.
UNITS
kHz
kHz
MHz
MHz
MHz
GENERAL OPERATING INFORMATION
Signal Connection
In general, probes offer the most convenient means of
connecting signals to the 7D14 CH A INPUT. Tektronix
probes are shielded to prevent pickup of electrostatic inter·
ference. A lOX attenuation probe offers a high input
impedance and allows the circuit under test to perform very
close
to normal operating conditions. Also, a lOX probe
attenuates
the input signal ten times.
Tektronix probes are designed to monitor the signal
source with minimum circuit loading. The use of a probe
will, however, limit the maximum bandwidth capability of
the 7D14. To obtain maximum bandwidth when using
probes,
use a probe capable of compensating 20 pF; use one
of the 1 MS1 input impedance positions of the INPUT
SENS/P·P VOLTS switch; and observe the grounding con-
siderations given in the probe manuals. The probe-to-
connector adapters and the bayonet-ground tip provide the
best frequency response.
In high-frequency applications requiring maximum over-
all
bandwidth, use a coaxial cable for the signal connection
and a 50 S1 input impedance position of the INPUT
SENS/P·P VOLTS switch. To maintain the high-frequency
characteristics
of the applied signal, use high-quality, low-
loss cable. Resistive
attenuators can be used to minimize
reflections if the applied signal has suitable amplitude.
®
Operating Instructions-7D14
A signal can also be routed to the 7D 14 through an
amplifier unit in a vertical plug-in compartment via the
internal trigger pickoff circuitry of the indicator Oscillo-
scope. This method of signal connection minimizes circuit
loading for measurements requiring simultaneous counting
and CRT display (see Counting a Displayed Signal).
General Control Settings
Introduction. The following discussion provides control
setup information for general measurement applications.
Further information can be found under Controls and Con-
nectors or in the discussion for a specific measurement
mode (e.g., Frequency Measurements).
Trigger
Controls. Signals to be counted may have a wide
variety of shapes and amplitudes, many of which are unsuit-
able
to drive the counting circuits. For this reason, the
signals are first applied to signal conditioning circuits; then
to the trigger circuit, where they are converted to rectangu-
lar pulses of uniform amplitude.
Signals often have characteristics which would prevent
triggering
or resu It in an erratic count. These signals must
be
conditioned before they are applied to the trigger input.
The INPUT SENS, COUPLING, and BW switches provide
means of conditioning the trigger signal. Obtaining a steady,
reliable reading is dependent upon the proper setting of
these controls and proper adjustment of the LEVEL!
SLOPE control.
The INPUT SENS/P-P VOLTS switch selects either inter-
nal
routing of the signal from the Indicator Oscilloscope
trigger circuitry or connection through the CH A INPUT
connector. Operation in the TRIG SOURCE position
requires that the 7D14 be installed in a horizontal plug-in
compartment. The oscilloscope Trigger Source switch for
that horizontal channel then provides further selection of
the signal source. (For more information on this mode of
operation, see Counting a Displayed Signal.)
For signals connected to the CH A I NPUT connector, set
the INPUT SENS/P-P VOLTS switch to select the desired
input impedance. An input impedance of 50 S1 should be
used when coupling into a 50-ohm system for high-
frequency measurements. The 1 MS1 settings provide a
higher
input impedance for minimizing loading on the
signal source.
Select a pop VOLTS setting appropriate to the amplitude
of the signal being measured. The pop VOLTS figure on the
front panel indicates the minimum signal amplitude which
will produce a count. The best pop VOLTS setting is one
that is much larger than the largest noise signal anticipated,
2-5

Operating I nstructions-7D 14
but where the signal is sufficiently larger than the P-P
VOLTS setting to ensure a steady count. Generally, begin
with the largest P-P VOLTS setting. Then decrease the
switch setting if necessary to obtain a steady count.
The COUPLING switch determines the coupling be-
tween the CH A I NPUT connector and the trigger circuit.
Generally, use AC coupling to block the DC component of
a signal. Otherwise, the DC component might cause the
signal level to be beyond the range of the LEVEL/SLOPE
control. DC coupling can be used for low-frequency signals,
or for pulses with known DC levels. See Table 1-1 in the
Specification section for the frequency range and amplitude
limits for each coupling method. The COUPLI NG switch
does not affect signals selected via the TRIG SOURCE posi-
tion of the INPUT SENS switch.
The BW switch provides a means of filtering out high-
frequency noise pulses wh ich may cause erratic readings.
Generally, use the 5 MHz setting unless the signal to be
counted is above this frequency. The BW switch affects
signals connected through both the internal T RIG SOURCE
and the CH A INPUT connector.
The trigger circuit has a hysteresis (basic sensitivity) of
approx imately 100 mill ivolts. A typical signal waveform at
the inpu t to the trigger is shown in Fig. 2-3A. The
hysteresis of the trigger is represented by the shaded area.
Each
time the signal level (including DC level) rises above
the upper hysteresis limit e2, and falls below the lower
hysteresis limit e1, the trigger circuit produces a rectangular
waveform as shown in Fig. 2-3B. This rectangular waveform
is the signal actually counted by the counting circuits.
Generally, the best point on a waveform for triggering
the counter is where the slope is steep, and therefore
usually free of noise Assuming a sine-wave signal wave-
form, the steepest slope occurs at the zero-crossing point.
(A)
(8)
Fig. 2-3. (A) Signal input to trigger; shaded area represents trigger
hysteresis with PRESET button depressed. (8) Trigger output.
2-6
This is the point on the positive-going slope selected for
triggering when the PRESET pushbutton is pressed, and is
the condition represented in Fig. 2-3A and B.
Noise pu Ises or other signal components may be pre-
sented which are of sufficient amplitude to produce un-
wanted trigger pulses. A typical condition is represented in
Fig. 2-4A. The resulting trigger pulses shown in Fig. 2-4B
will cause an erratic or incorrect count.
Pressing the VAR pushbutton enables the LEVEL/
SLOPE control to be used to move the hysteresis above or
below the O-volt level. The condition represented in Fig.
2-4A
and B can be corrected by using the LEVEL/SLOPE
control to move the hysteresis to a level above or below the
L
Fig. 2-4. (A) Input signal with noise in PRESET hysteresis level; and
(8) resultant trigger output.
(A)
(8)
I
I
_-----'nL- ___ --'
Fig. 2-5. (A) Signal input to trigger; shaded area represents hysteresis
set above noise pulses. (8) Resultant Trigger output.
®

(A)
(6)
u
Fig. 2-6. (A) Signal input to trigger; shaded area represents hysteresis
set above noise pulses; (6) Trigger output with LEVEL/SLOPE con-
trol set in negative-slope region_
noise. Fig. 2-5A shows the signal with the hysteresis moved
above the noise
with the corrected trigger output shown in
B. Fig. 2-6A and B shows the same waveforms as in Fig_
2-5, only with the LEVEL/SLOPE control set in the nega-
tive slope region. Note that the trigger pulse shown in Fig.
2-6B goes positive
when the signal input goes negative.
Measurement
Interval Controls_ The MEASUREMENT
INTERVAL switch selects the time interval (also called gate
time) during which the 7014 counts.- The source of the
pulses which control the time interval determines the
measurement mode.
The internal gate circuits derive gate times from a one
megahertz reference
frequency signal to make frequency
measurements. The gate times thus derived are selected by
the 1 ms, 10 ms, 100 ms, 1 s, and lOs pushbuttons_ The
measurement interval selected determines the measurement
range and
resolution. These pushbuttons also automatically
select the measurement units and decimal position in the
display_ Table 2-2 gives the frequency range and resolution
for each time interval, and shows the display decimal posi-
tion and measurement units.
Generally, use the shorter measurement intervals for
hi gh- frequency, low-resolution measurements and the
longer intervals for measurements requring high resolution_
Totalizing, or counting a number of events, is accom-
pi ished by counting during a time selected by the
MANUAL GATE ON/OFF pushbuttons_ The gate time is
started by pressing the MANUAL GATE ON pushbutton,
and stopped by pressing the OFF button. The manual mode
is generally used to count a number of events for a rela-
tively long, indefinite time_ The 7014 can be set to display
®
Operating Instructions-7D14
the total count at the end of the gate time or to display
each count as it is made. Also, the 7014 can add the counts
made
during successive gate times_ (For further informa-
tion, see Totalize under Measurement Modes.)
An external gating signal can be used to control the gate
time or measurement interval. The gating signal is con-
nected to the EXT GATE connector and is selected by
pressing the MANUAL GATE OFF pushbutton. See the
Specification section for external gate signal requirements_
REF FREQ/CH B controls_ The INT 1 MHz pushbutton
selects the internal crystal oscillator for use as a reference
signal
for frequency measurements_ The one megahertz
signal
is available at the front-panel EXT I N/MON ITOR
connector when the I NT 1 MHz button is pressed in.
When greater accuracy is required
than is provided by
the internal crystal oscillator, a one megahertz external
timing standard can be connected to the EXT I N/
MONITOR connector. Pressing the EXT IN pushbutton
selects the signal connected to the EXT IN connector.
The EXT IN connector and pushbutton are also used for
making ratio measurements. The 7014 will compare the
frequency of the signal connected to the EXT IN connector
to the frequency of the Channel A signal. (For further
information, see Ratio Measurements under Measurement
Modes.)
Display Time Controls_ The 0 ISPLA Y TI ME control is
used to set the length of time a measurement is displayed
before the next measurement is started. The display time
can be varied from at least 0.1 second to five seconds or
longer.
The 00 (infinite) detent position of the DISPLAY TIME
control sets the 7014 to display the last measurement
indefinitely, or until reset by the RESET pushbutton or an
external signal.
The display time circu it is locked to the 1 ms through 10
s
MEASUREMENT INTERVAL pushbuttons so that the
total display time is the sum of the DISPLAY TIME control
setting and the measurement interval selected.
When used
with manual gate operation, the DISPLAY
TIME control determines when to totalize the counts made
during separate gate intervals (for further information, see
Totalize under Measurement Modes).
2-7

Operating Instructions-7D14
MEASUREMENT MODES
Introduction
The 7D14 has three primary measurement modes: fre-
quency, ratio, and totalize (number of events). The
following discussion gives general information about each
mode and
instructions on making the measurements.
Frequency Measurements
The 7D14 provides direct measurement of the average
frequency
of signals up to 525 MHz. The input to the
counting circuits is selected by the INPUT SENS/P-P
VOLTS control from either the signal connected to the CH
A I
NPUT connector or the internal trigger pickoff signal
from the Indicator Oscilloscope trigger circuits. (TRIG
SOURCE; see Counting a Displayed Signal).
The 7D14 counts the input pulses over an interval
selected by the MEASUREMENT INTERVAL 1 ms
through 10 s pushbuttons. The measurement interval
selected determines the measurement range and resolution.
These pushbuttons also automatically select the measure-
ment units and decimal point position in the display. Table
2-2 gives the frequency range and resolution for each time
interval and shows the display decimal point position and
measurement units.
Generally, use the shorter measurement intervals for
high-frequency, low-resolution measurements and the
longer intervals for measurements requiring high resolution.
Greater Accuracy. For greater accuracy and/or stability
when measuring frequency, an external 1 MHz crystal signal
can be substituted for the internal time-base oscillator. The
external signal must have greater accuracy than the internal
oscillator (see Specification section) and have a minimum
amplitude of 0.8 volt peak-to-peak.
TABLE 2-2
MEASUREMENT INTERVAL DATA
MEASUREMENT MAXIMUM
INTERVAL UNITS RESOLUTION FREQUENCY
1 ms
MHz 1 kHz
525.000 MHz
10 ms MHz 100 Hz
525.0000 MHz
100 ms MHz 10 Hz
525.00000 MHz
1 s kHz 1 Hz 99999.999 kHzl
10 s kHz 0.1 Hz 9999.9999 kHzl
Ilf the maximum frequency is exceeded, a "greater than" symbol
(» will precede the readout display.
2-8
Connect the external signal to the REF FREO/CH B
EXT IN connector and press the EXT IN pushbutton. The
function of the MEASUREMENT INTERVAL 1 ms -10 s
pushbuttons is the same as when using the internal time-
base oscillator.
Ratio Measurements
Ratio measurements compare the frequencies of two
signals. Normally, the higher frequency signal is applied to
Channel A (via CH A INPUT connector or internal TRIG
SOURCE) and the lower frequency signal is applied to
Channel B (via EXT IN connector with the REF FREO/CH
B EXT IN pushbutton pressed). The MEASUREMENT
INTERVAL 1 ms through 10s pushbuttons select the
counting time as derived from the signal applied to Channel
B. The 7D14 then counts the pu Ises derived from the
Channel A signal during a time interval established by the
Channel B signal.
The display ratio measurement is equal to:
Frequency Channel A X 106 X MEASUREMENT
Frequency Channel B INTERVAL
whose denominator is known to be 1. Thus, a ratio of
30.000: 1 will be displayed as 30.000. The decimal point in
a
ratio measurement display is correctly positioned only
when using the 1 ms, 10 ms, or 100 ms MEASUREMENT
INTERVAL pushbuttons. Readings obtained when the 1 s
or 10 s buttons are pressed must be multiplied by 10-3 to
correct the decimal position.
Ratio measurements are dimensionless (i.e., no measure-
ment units); however, the MHz or kHz legend will remain
displayed.
Totalize (Count Number of Events)
Introduction. The 7D14 will count the number of
pulses applied to Channel A (via the CH A INPUT connec-
tor or TRIG SOURCE) up to 99,999,999 pulses at a rate
not to exceed 525 megahertz. The pulses will be counted
during a time interval (gate time) determined either by the
MANUAL GATE ON/OFF pushbuttons or by a gating
signal connected to the EXT GATE input connector. Over·
ranging (count exceeding 99,999,999) is indicated by a
"greater than" symbol (» preceding the digital readout.
Display Storage Modes. Two modes of displaying the
count can be selected when using MANUAL or EXT GATE
operation. These modes are selected by the Man Gate Stor-
age switch.
With the Man Gate Storage switch ON, the total cou nt
is displayed at the end of the gate or count interval.
®

This is the mode normally used for EXT GATE applications
when counting a number of events within short, repetitious
gate times. The advantage of using the storage ON mode is
that no display flicker is observed during the count cycle.
The last measurement taken remains displayed until the
next measurement has been completed and is ready to be
displayed. This is the same mode used when making fre-
quency measurements with the gate time determined by the
1 ms through 10 s pushbuttons.
In the storage OFF mode, each count is displayed as it
occurs;
thus, the display always indicates the total count at
that time. This mode is normally used with MANUAL
GATE
operation when counting a number of events over a
relatively long, indefinite time. A typical application would
be counting items passing a transducer or an assembly line.
Display
Time. In the usual application (MANUAL
GATE
operation only), in which pulses are counted over
one interval only, the DISPLAY TIME control functions in
its usual
manner; i.e., the display will be reset to zero after
the display time has elapsed. However, if it is desired to add
one interval to the next (totalize the count), the DISPLAY
TIME
control should be set to <Xl. The same effect will be
obtained whenever another gate interval is initiated before
the display time has elapsed.
I
n EXT GATE applications, where the gate times are
repetitious, the external gating signal is locked to the dis-
play timer circuitry. Thus, after one measurement has been
taken, another gate interval will not be initiated until the
completion of either the display time or the gate "off"
time, whichever is longer. In this way; one interval is not
added to another.
Using the MANUAL GATE. To make a count measure-
ment using the MANUAL GATE ON/OFF pushbuttons,
proceed as follows:
1. Set the internal MAN GATE STORAGE switch for
the desired mode. (The OFF position is usually used for
long gate intervals.)
2. Install the 7D14 in any available plug-in compart-
ment of the Tektronix 7000-series oscilloscope.
3. Turn the oscilloscope power on. Allow about 20
minutes warmup.
4. Advance the oscilloscope Readout control to obtain a
usable readout display.
5. Connect the input signal to the CH A INPUT
connector.
®
Operating Instructions-7D14
6. Set the INPUT SENS/P-P VOLTS, COUPLING, BW,
and TRIGGER LEVEL/SLOPE controls as necessary to
obtain a steady count.
7. Set the DISPLAY TIME control to <Xl (fully clock-
wise).
8. Depress the MANUAL GATE ON pushbutton and
the counter will start counting. If necessary, press the
RESET pushbutton so that the count will start from zero.
9. To terminate the count, depress the OFF button.
Using the External Gate. To make a count measurement
using an external gating signal, proceed as follows:
1. Set the internal Man Gate Storage switch for the de-
sired
mode. (The ON position is usually used for short gate
intervals.)
2. Install the 7D 14 in any available plug-in compartment
of a Tektronix 7000-series oscilloscope.
3. Turn the oscilloscope power on. Allow about 20 min-
utes warmup.
4. Advance the oscilloscope Readout control to obtain a
usable readout display.
5. Connect the input signal to the CH A INPUT
connector.
6. Connect the external gating signal to the EXT GATE
input connector through the BSM to BNC male adapter
(suppl ied accessory). The external gating signal must meet
the input requirements as given in Section 1 of this manual.
7. Set the 7D14 TRIGGER controls as necessary to
obtain a steady count.
The external gate function can be used in conjunction
with a delayed sweep to count the quantity of pulses within
a burst. The 7D 14 external gate input is driven by the
delayed-sweep gate output to count the number of pulses
within the delayed-sweep time (intensified zone). To use
this
function, proceed as follows:
1. Set the internal Man Gate Storage switch for the de-
sired
mode. (The ON position is usually used for short gate
intervals.)
2-9