Tektronix 067-1011-00 User manual

Tektronix,
Inc.
P.O.
Box
500
Beaverton,
Oregon
97077
070-3679-00
Product Group 20
1'!ktron00
COMMITTED
TO
EXCELLENCE
PLEASE CHECK
FOR
CHANGE INFORMATION
AT
THE
REAR
OF
THIS MANUAL.
067
-1
011
-00
DIGITAL
SWEEP GENERATOR
INSTRUCTION
MANUAL
Serial
Number
______
_
First Printing JAN 1982

Copyright © 1982 Tektronix, Inc.
All
rights reserved.
Contents of this publication may not
be
reproduced
in
any
form without the written permission of Tektronix,
Inc.
Products of Tektronix,
Inc.
and
its subsidiaries
are
covered
by U.S.
and
foreign patents and/or pending patents.
~
TEKTRONIX, TEK, SCOPE-MOBILE,
and
~
are
registered trademarks of Tektronix,
Inc.
TELEQUIPMENT
is a registered trademark of Tektronix U.K. Limited.
Printed
in
U.S.A. Specification
and
price change privileges
are reserved.
I
i
I ,
I

067-1011-00
DSG
TABLE
OF
CONTENTS
Page
OPERATOR'S
SAFETY
SUMMARY
.................................
iv
SERVICE
SAFETY
SUMMARY
••••••••••••••••••••••••••••••••••••
v
Section
1
SPECIFICATION
PRODUCT
DESCRIPTION
........................
PERFORMANCE
CONDITIONS
•••••••••••••••••••••
CHARACTERISTlCS
............................
Seotion
2
OPERATING
INSTRUCTIONS
Installation
and Removal
Instructions
Functions
of
Controls,
Connectors,
......
and
Indicators
•••••••••••••••••••••••••••••
APPLICATIONS
.................................
Jumper
Options
•••••••••••••••••••••••••••••
Frequency Response
Testing
•••••••••••••••••
Digitally
Locking
the
DSG
to
the
1900
Digital
TRS
•••••••••••••••••••••••••••
Genlocking
the
1900
to
the
DSG
Blackburst
••
Blanking
for
Composite
Sweep
•••••••••••••••
Picture
Monitor
Testing
••••••••••••••••••••
Sinewave
Horizontal
Reset
••••••••••••••••••
Markers
••••••••••••••••••••••••••••••••••••
OPERATING
CONSIDERATIONS
.....................
Harmonics
of
Digital
Sweep
•••••••••••••••••
ECL
Data
Transmission
••••••••••••••••••••••
NBS
Traceability
•••••••••••••••••••••••••••
i
1-1
1-3
1-3
2-1
2-2
2-3
2-3
2-4
2-4
2-4
2-4
2-6
2-6
2-9
2-9
2-9
2-9
2-11

Section
3
Section
4
067-1011-00
DSG
TABLE
OF
CONTENTS
(cont)
THEORY
OF
OPERATION
General
Circuit
....................................
Overview
•••••••••••••••••••••••••••
PART
1:
THE
SWEEP
GENERATOR
••••••••••••••••••
Internal
Lock
..............................
External
Lock
••••••••••••••••••••••••••••••
Timing
•••••••••••••••••••••••••••••••••••••
Black
Burst
Generator
••••••••••••••••••••••
Sweep
Control
••••••••••••••••••••••••••••••
Manual Frequency
Control
•••••••••••••••••••
Cosine
Generator
•••••••••••••••••••••••••••
Output
•••••••••••••••••••••••••••••••••••••
Reset Off
Operation
••••••••••••••••••••••••
PART
2:
THE
SWITCHING
POWER
SUPPLY
••••••••••
General
••••••••••••••••••••••••••••••••••••
+5V
Supply
•••••••••••••••••••••••••••••••••
-5.2V Supply
•••@•••••••••••••••••••••••••••
CALIBRATION
Introduction
...............................
General
Instructions
•••••••••••••••••••••••
Preliminary
Procedure
••••••••••••••••••••••
PERFORMANCE
AND
FUNCTIONAL
CHECK
PROCEDURE
3-1
3-1
3-1
3-1
3-3
3-5
3-9
3-9
3-10
3-10
3-10
3-10
3-11
3-11
3-11
3-13
4-1
4-1
4-3
4-3
ADJUSTMENT
PROCEDURE
•••••••••••••••••••••••••
4-11
ii

067-1011-00
DSG
TABLE
OF
CONTENTS
(cont)
Section
5
MAINTENANCE
Preventive
Cleaning
Maintenance
••••••••
~
••••••••••••
.................................
Lubrtcation
••••••••••••••••••••••••••••••
Adjustment
•••••••••••••••••••••••••••••••
TROUBLESHOOTING
AIDS
•••••••••••••••••••••••••
Theory
of
Op.eration
••••••••••••••••••••••••
Diagrams
•••••••••••••••••••••••••••••••••••
Circuit
Board
Illustrations
••••••••••••••••
Component and Wiring
Color
Codes
•••••••••••
Testing
Equipment
••••••••••••••••••••••••••
TROUBLESHOOTING
TECHNIQUES
•••••••••••••••••••
Control
Setting
••••••••••••••••••••••••••••
Fuses
••••••••••••••••••••••••••••••••••••••
Static-Sensitive
Components
••••••••••••••••
Test
Equipment
•••••••••••••••••••••••••••••
Circuit
Isolation
••••••••••••••••••••••••••
Voltages
and Waveforms
•••••••••••••••••••••
Component Checking
•••••••••••••••••••••••••
Transistors
and
Integrated
Circuits
(IC)
••••
Resistors
••••••••••••••••••••••••••••••••••
Crystal
Oven
•••••••••••••••••••••••••••••••
5-1
5-1
5
....
1
5-2
5
....
2
5-2
5-2
5
...
2
5-2
5--2
5-3
5-3
5-3
5-3
5-5
5-5
5-5
5-5
5-6
5-6
5-6
PARTS
ORDERING
AND
REPLACING
•••••••••••••••••
5-8
Ordering
•••••••••••••••••••••••••••••••••••
5-8
Section
6
OPTIONS
Section
7
REPLACEABLE
ELECTRICAL
PARTS
Section
8
DIAGRAMS
AND
CIRCUIT
BOARD
ILLUSTRATIONS
Section
9
REPLACEABLE
MECHANICAL
PARTS
iii

067-1011-00 DSG
OPERATORS SAFETY SUMMARY
The general safety information in this part of thesummary
is
for both operating and servicing personnel. Specific
warnings and cautions will be found
throughout the
manual where
they apply, but may not appear in this
summary.
Terms In This Manual
CAUTION statements identifyconditions or practicesthat
couldresultindamage
to theequipment or otherproperty.
WARNING statements identify conditions
or practices
that could result in personal
injury or loss of life.
Terms As Marked on Equipment
CAUTION indicates a personal injury hazard not im-
mediately accessible as one reads the marking, or a
hazard
to property including the equipment itself.
DANGER indicates a personal
injury hazard immediately
accessible
as one reads the marking.
Symbols In This Manual
This symbol indicates where applicable
cautionary
or other information is to be
found.
Symbols As Marked on Equipment
~ DANGER - High voltage.
@ Protective ground (earth) terminal.
,& ATIENTION -refer to manual.
Power Source
This product la Intended to operate from a power source
that will not apply more than 250 volts rms between
the
supply conductors or between either supply conductor
and ground. A protectivegroundconnection bywayof the
grounding conductor In the power cord Is essential for
safe operation.
iv
Grounding the Product
This product is grounded through thegrounding conduc-
tor of the power cord. To avoid electrical shock, plug the
power cord
into a properly wired receptacle before
connecting
to the product input or output terminals. A
protective ground connection
by way of the grounding
conductor in the power cord is essential for safe opera-
tion.
Danger Arising From Loss of Ground
Upon loss of the protective-ground connection, all
accessible conductive
p~rts (including knobs and con-
trols that may appear
to be insulating) can render an
electric shock.
Use the Proper Power Cord
Use only the powercord and connector specified for your
product.
Use
only a power cord that is in good condition.
For detailed information on power cords and connectors,
Jee Fig. 4-1.
Refer cord and connector changes
to qualified service
personnel.
Use the Proper Fuse
To avoid fire hazard, use only the fuse of correct type,
voltage rating and current rating
as specified in the parts
list for your product.
Refer fuse replacement
to qualified service personnel.
Do Not Operate In Explosive Atmospheres
To avoid explosion, do not operate this product in an
explosive atmosphere unless it has been specifically
certified
for such operation. ·
Do Not Remove Covers or Panels
To avoid personal injury, do not remove the product
covers
or panels. Do not operate the product without the
covers and panels properly installed.

067-1011-00
DSG
SERVICE SAFETY SUM ARY
FOR
QUALIFIED
SERVICE PERSONNEL
ONLY
Refer also to the preceding Operators Safety Summary.
Do Not Service Alone
Do not perform internal service or adjustment of this
product unless another person capable of rendering first
aid
and
resuscitation is present.
Use Care When Servicing With Power On
Dangerous voltages exist
at
several points inthis product.
To avoid
perso.nal
injury, do not touch exposed connec-
tions and components while power is
on.
v
Disconnect power before removing protective panels,
soldering, or replacing components.
Power Source
This product is intended
to
operate from a power source
that will not apply more than
250
volts rms between the
supply conductors or between either supply conductor
and ground. A protectivegroundconnection byway ofthe
grounding conductor in the power cord is essential for
safe operation.

067-1011-00
DSG
1-1.
Digital
Sweep
Generator.
vi

067-1011-00 DSG
SECTION 1
SPECIFICATION
Product Description
The 067-1011-00 Digital Sweep Generator (DSG) is designed to
support the Performance Check and Adjustment procedures of the
Tektronix 1900 Digital Test Signal Generator. The Digital Sweep
Generator provides a 10-bit digital data signal to drive the 1900
digital-to-analog converter (DAC) or any other video DAC
compatible with the proposed ·sMPTE standard ("Digital Video
Format
for a Parallel Interface (System M/NTSC), July, 1979)
digital video interface, generating a swept-frequency sinewave
test signal. The Digital Sweep Generator permits the division of
an A/D - D/A pair to make frequency domain measurements on the
D/A alone. Future digital processing equipment will require
separation of A/D and D/A frequency response characteristics as
part of the calibration and performance check procedures. When
used in conjunction with a 1900 and an 015-0408-00 Peak-to-Peak
Detecto~, the Digital Sweep· Generator provides an NBS-traceable
analog frequency response standard, and is part of an effort to
provide NBS-traceable performance verification of Tektronix
television generators, waveform monitors, and other television
equipment (See Fig. 2-11).
The Digital Sweep Generator provides 10-bit, 14.31818 MHz (Mega
samples
per second) word data derived from a cosine lookup table
stored in three PROMs. To generate digital data representing a
55.9 kHz sinewave, all 256 words stored in the PROMs are used.
Digital d~ta representing higher frequencies is generated by
decreasing the number of words per sinewave. The DIGITAL DATA
OUTPUT of the 067-1011-00 provides digital data to sweep a DAC
from 55.93 kHz to 7.159 MHz in each field by increments of 55.93
kHz every two lines of active video. A front-panel
switched-variable control also permits an operator to manually
vary the digital data used to generate a CW signal. Because the
DIGITAL DATA OUTPUT supplies non-composite digital data, the
Digital Sweep Generator provides a BLANKING output which may be
used to enable sync and burst insertion by the 1900. It also
provides a BLACK BURST OUTPUT to which the 1900 may be genlocked.
The Digital Sweep Generator may be locked to the 1900 through the
DIGITAL CLOCK INPUT connector which uses the TRS and Clock
signals from the 1900 DIGITAL OUTPUT. A separate MARKER output
provides identification of nominal 1-MHz intervals during the
sweep, and also provides nominal 3.58 MHz and 4.43 MHz markers.
1-1

067-1011-00 DSG
The 067-1011-00 Digital Sweep Generator consists of two small
circuit boards and one large board in a single-wide TM500 package
(shown in Fig. 1-1). The front panel includes a green LED power
indicator, two 25-pin D-type Digital Data connectors, three bnc
connectors for blanking, markers, and blackburst output, and one
switched-variable frequency control. Digital interfaces of the
Digital Sweep Generator conform to the signal levels, clock rate,
and pinout of the proposed SMPTE Standard.
1-2

067-1011-00
DSG
Performance
Conditions
The
following
electrical
characteristics
are
valid
only
if
the
Digital
Sweep
Generator
is
calibrated
at
an ambient
temperature
of
25
degrees
+-5
degrees
C and
is
operated
at
a normal ambient
temperature
between
O
and
50
degrees
c.
Allow a 20-minute
warm
up
period
before
performing
verification
tests.
Characteristics
DIGITAL
DATA
OUTPUT
Frequency Range
Format
Sample Clock
Frequency
Voltage·
Levels
Driver
Impedance
Dynamic Range
Table
1-1
ELECTRICAL
CHARACTERISTICS
Performance
Requirement
55.93kHz
to
7.159MHz
in
55.93kHz
increments
10-bit
data
words
14.31318MHz (4 x
fsc),
+/-
100Hz
Digital
Word
240
(Blanking)
to
Digital
Word
800
(
100
IRE)
1-3
Supplemental
Information
Field
Sweep
or
CW
digital
.data
SMPTE
Standard
(Proposed
July,
1979)
parallel
10-bit
signal.
10K
balanced
ECL
10K
balanced
ECL

Characteristics
DIGITAL
CLOCK
INPUT
Format
Voltage
Levels
Input
Impedance
BLANKING
Polarity
Vertical
Blanking
Horizontal
Blanking
067-1011-00
DSG
Table
1-1
(cont.)
ELECTRICAL
CHARACTERISTICS
Performance
Requirement
Jumper
selectable
Line
261,Field
2
Through
Line
21
,Field
1
And
Line
262,Field
1
Through
Line
20,Field
2
10.8
microseconds
1-4
Supplemental
Information
SMPTE
Standard
(Proposed,
July
1979)TRS &Clock
10K
balanced
ECL
100
ohm,+/-5%
TTL-compatible
levels
Factory
set
for
high
during
bl
an
king.
23
Lines
Total
22
Lines
Total
Digitally
derive
d
from
the
sample
clock
frequency.

Characteristics
MARKER
BLACKBURST
OUTPUT
Mainframe
Interface
067-1011-00
DSG
Table 1=1
(cont.)
ELECTRICAL
CHARACTERISTICS
Performance
Requirement
1
v@
1.006747
MHz
1 v @
2.013494
MHz
1 v @
3.020241
MHz
0.5
v
@
3.579545
MHz
1 v @4.026988
MHz
0.5
v
@
4.418501
MHz
1 v
@
4.977805
MHz
1 v @5.984552
MHz
-,
1-5
Supplemental
Information
Marker
Frequencies
are
multiples
of
55.93 kHz.
Amplitude
within
10%.
A
utility
signal
for
genlock
only.
Not
shaped
for
use
as
a
test
signal.
Sync 286mV,nominal.
Burst
286mV,nominal.
TM500
or
TM5000.
Uses any
single-wide
location.
Keyed
be-
tween 6-7 and 23-24
as
a
signal-source
family
plugin.

Characteristics
Temperature
Operating
Storage
Altitude
Operating
Storage
Characteristics
Finish
Length
Width
Height
Net Weight
067-1011-00
DSG
Table
1-2
ENVIRONMENTAL
CHARACTERISTICS
Supplemental
Information
0
degrees
C
to
+50
degrees
C
-40
degrees
C
to
+65
degrees
C
To
4,572
m
(15,000
feet)
To
15,240 m
(50,000
feet)
Table
1-3
PHYSICAL
CHARACTERISTICS
Information
Anodized aluminum
side-panel
and
chassis.
29.2
cm
(11.5
in.)
6.6
cm
(2.6
in.)
12.7
cm
(5.0
in.)
0.82
kg
(1.8
lbs)
Net
Shipping
Weight
1.5
kg
(3.3
lbs)
1-6

067-1011-00
DSG
SECTION
2
OPERATING
INSTRUCTIONS
This
section
describes
installation,
operating
controls,
connectors
and
indicators.
Following
those
discussions
are
example
applications,
explanations,
and jumper
options.
Installation
and Removal
Instructions
The
Digital
Sweep
Generator
(DSG)
is
calibrated
and
ready
to
use
when
received.
It
operates
in
any
of
the
Tektronix
TM500
or
TM5000
Series
Power Modules
referred
to
hereafter
as
"TM500".
Refer
to
the
power
module
instruction
manual
for
line-voltage
requirements
and power
module
operation.
~J
Turn
the
power module
off
before
inserting
or
removing
the
DSG,
otherwise
arcing
may
occur
at
the
rear
interface
connectors.
Arcing
reduces
the
useful
life
of
the
connectors
and damage
may
be done
to
the
plug-in
circuitry.
Check
for
plastic
barriers
on
the
interconnecting
jacks
of
the
power
module
in
the
selected
compartments.
If
the
barriers
do
not
match
the
cutouts
~n
the
DSG
circuit
board
edge
connector,
they
may
indicate
special
rear
interface
connections
for
another
type
of
instrument.
Do
not
insert
the
plug-in
until
this
has
been
verified
by
qualified
service
personnel.
The
TM500
power module
MUST
have a
barrier
installed
between
pins
6
and 7
at
the
standard
barrier
location
to
ensure
proper
connector
alignment.
The
TM500
Power Module
may
also
have
an
optional
barrier
between
pins
23 and
24.
A
barrier
in
any
other
location
will
preclude
insertion
of
the
DSG,
because
that
barrier
would
indicate
that
the
compartment
has
been
reserved
for
other
plug-ins.
When
the
units
are
properly
matched,
align
the
DSG
with
the
upper
and
lower
guides
or
the
selected
compartments.
Insert
the
DSG
into
the
compartment and
press
firmly
to
seat
the
circuit
board
in
the
interconnecting
jack.
The
DSG
POWER
indicator
should
be
illuminated
when
the
TM500
Power Module power
switch
is
turned
on.
2-1

067-1011-00 DSG
To remove the DSG, turn off the TM500 Power Module and pull the
release latch, located on the lower left corner of the DSG, until the
connector disconnects from the power module. The DSG will now slide
out of the power module.
Funotions ot Controls, Connectors, and Indioators
POWER
DIGITAL CLOCK INPUT
CLOCK INT/EXT
DIGITAL DATA OUTPUT
SINEWAVE H RESET
FREQUENCY MANUAL/SWEEP
A green LED indicating voltage present
in the power supply.
Accepts proposed SMPTE standard TRS
and Clock information via a 25-pin
D-type subminiature connector to lock
the Digital Sweep Generator to an
outside source.
Button switch to cause the Digital
Sweep Generator to INTernally
produce the 14.31818 MHz clock signal
when not using the DIGITAL CLOCK
INPUT. Setting the button switch
to EXTernal allows an outside clock
source to drive the Digital Sweep
Generator through the DIGITAL CLOCK
INPUT.
Provides 10-bit 14.31818 MHz words
via a 25-pin D-type subminiature
connector to drive a SMPTE-compatible
video DAC.
Button switch-to phase-lock each
line of digital sweep information
to horizontal sync.
Switched variable control to manually
control the frequency of the sinewave
represented by the DIGITAL DATA OUTPUT
word information when the control is
pulled out. Normal sweep information
is generated when control is pushed in.
2-2

067-1011-00 DSG
Functions of Controls, Connectors, and Inicators (Cont.)
BLANKING
MARKER
BLACKBURST OUTPUT
Jumper Options
TTL-logic levels via a BNC connector
to indicate to an outside source the
time for composite video blanking.
In the case of the Tektronix 1900,
this information may be.used for
sync and burst insertion.
1V markers via a BNC conector at
1-MHz intervals, and 0.5V markers
at nominal 3.58 MHz and 4.43 MHz
points for references when using
the sweep mode.
Composite
black burst output via a
BNC connector to allow an outside
source to genlock to the Digital
Sweep Generator. This signal
conforms to the RS170A EIA Video
Standard in format only. It is
intended to be used as a utility
synchronizing signal, not as a
precision standard.
APPLICATIONS
J857 inverts BLANKING when jumpered pin 2 to pin 3. J447
disables the nominal 1 MHz markers when jumpered pin 2 to pin 3.
J445 disables the nominal 3.58 and 4.43 MHz markers when jumpered
pin 2 to pin 3. Removing J533 will halve the resolution of the
MANUAL FREQUENCY control.
All of these jumpers can be found on the Main Sweep board (A1)
with the help of the parts location illustration in the foldouts
section of the manual.
2-3

067-1011-00 DSG
Frequency Response Testing
The Digital Sweep Generator is intended primarily for checking
the frequency response of digital television equipment. An
example is shown in Fig. 2-1, where the 1900 DAC frequency
response is being checked. When used with a high quality DAC,
the Digital Sweep Generator can also serve as an analog sweep
signal source as shown in Fig. 2-2. Many frequency response
measurements can be made even more accurately using a differential
detection technique. Using the differential technique, errors in
the frequency response of the test signal generator cancel out,
leaving only device-under-test errors displayed, as explained in
the manual for the 015-0408-00 Peak-to-Peak Detector.
Digitally Looking the DSG to the 1900 D.igital TRS
Fig. 2-1 shows a typical application of the Digital Sweep
Generator. The external clock is being provided by the 1900
Digital Output. The Digital Sweep Generator provides digital
data for the 1900 Digital Input. To use the External Clock from
the 1900 to drive the DSG, the 1900 must be configured in the
following factory-set manner: The Digital Data Source Control
jumper P206 must be in the "Remote TTL" position (pins 1-2).
The Clock Source jumpers P532, P534, and P536 must be in the
"Internal Clock" positions {pins 2-3).
Genlooking the 1900 to the DSG Blackhurst
Another way to lock the 1900 and the Digital Sweep Generator
together is to use the internal oscillator of the Digital Sweep
Generator, and genlock the 1900 to the DSG. Connect the
BLACKBURST OUT of the Digital Sweep Generator to the Program In
on the back of the 1900. The cable between the 1900 Digital Out
and the Digital Sweep Generator DIGITAL CLOCK INPUT is no longer
needed.
Blanking for Composite Sweep
It is possible to generate a composite video sweep using sync and
burst from the 1900. A cable from the BLANKING OUT on the
Digital Sweep Generator is connected to pins 16 (hot) and 7 (Gnd)
2-4

Tektronix i 900
Digital Generator
Tektronix 175-3671-00
Interconnecting
Cables
067-1011-00 DSG
Detector
Head
015-0413-00
Peak-to-Peak
Detector Amp
015-0408-00
"COMP
SYNC OUT" from 1900 to the 7B53A MAIN TRIG IN.
"MARKER OUT" from Digital Sweep Generator to 7A26 INPUT.
Oscilloscope
Test
System
D Tektronix
7603
i
7A13 7A26 7853A
3679-02
2-1. Calibrating the 1900 frequency response.
Tektronix 1900
Digital Generator
Tektronix 175-3671-00
Interconnecting
Cables
Device Under Test Detector
Head
015-0413-00
Peak-to-Peak
Detector Amp
015-0408-00
"COMP
SYNC OUT" from 1900 to the 7B53A MAIN TRIG IN.
"MARKER OUT" from Digital Sweep Generator to 7A26 INPUT.
Oscilloscope
Test
System
D Tektronix
7603
i
7A13 7A26 7B53A
3679-03
2-2. Checking frequency response of device under test.
2-5

067-1011-00
DSG
of
the
Remote
Control
input
on
the
1900.
This
allows
the
Digital
Sweep
Generator
to
switch
the
1900
to
the
external
digital
input
mode
during
sweep
time.
During
blanking,
as
defined
by
the
Digital
Sweep
Generator's
non-sweep
time,
the
1900
is
switched
back
to
the
internally-generated
information
for
sync,
burst,
and
VITS.
Picture
Monitor
Testing
With a
Tektronix
1900
in
the
signal
path
between
the
DSG
and a
picture
monitor,
resolution
of
the
picture
monitor
may
be checked
(see
Figs.
2-3
and
2-4).
The
MARKER
output
of
the
Digital
Sweep
Generator
can
be added
into
the
picture
via
the
A-B
mode.
Do
not
terminate
the
MARKER
output
in
this
case.
Sinewave
Horizontal
Reset
Provision
is
made
on
the
Digital
Sweep
Generator
to
lock
the
sinewave
outputs
to
horizontal
or
to
allow
free-running
sinewave
output.
Both
are
useful
depending
on
the
application.
For
use
with
a
picture
monitor
in
evaluation
of
resolution,
the
output
should
be
locked
to
horizontal.
Locking
to
horizontal
creates
a
phase
discontinuity
on
the
output
sinewaves,
however,
since
the
sinewave
frequency
is
not
an
integer
multiple
of
the
horizontal
frequency
(Figs.
2-5
and
2-6).
Fig.
2-5
shows
how
the
sinewave
looks
on a
scope,
in
the
SINEWAVE
H
RESET
mode.
The
sine-
wave
gets
abruptly
reset
in
phase
at
the
trailing
edge
of
blanking,
where
the
frequency
will
also
be
changing.
Fig.
2-6 shows
the
same
part
of
the
sweep
signal
with
SINEWAVE
H
RESET
disabled,
leaving
a change
in
frequency
being
the
only
change
at
that
point.
SINEWAVE
H
RESET
on
causes
additional
spectral
components
as
shown
in
Figs.
2-7
and
2-8.
When
using
the
sweep
generator
with
a
detector,
a
cleaner
output
display
is
obtained
with
H
RESET
off
(out)
as
shown
in
Figs.
2-9
and
2-10.
It
should
be
noted
that
when
using
a
detector
with
the
Digital
Sweep
Generator
and a
DAC,
anything
other
than
pure
sweep
information
(SINEWAVE
H
RESET,
Blanking,
Markers,
VITS,
etc.)
will
cause
noise
and/or
distortion
in
the
resultant
detector
output.
2-6