Anritsu 68137B Operation Manual

SERIES
681XXB

SYNTHESIZED SWEEP GENERATOR

OPERATION MANUAL

Serial Number 512001 and above

490 JARVIS DRIVE
MORGAN HILL, CA 95037-2809

P/N: 10370-10298

PRINTED: AUGUST 1995

COPYRIGHT 1995 WILTRON CO.

REVISION: B

WARRANTY

The WILTRON product(s) listed on the title page is (are) warranted against defects in materials
and workmanship for one year from the date of shipment, except for YIG-tuned oscillators and all
WILTRON manufactured microwave components, which are warranted for two years.

WILTRON’s obligation covers repairing or replacing products which prove to be defective during
the warranty period. Buyers shall prepay transportation charges for equipment returned to WIL­TRON for warranty repairs. Obligation is limited to the original purchaser. WILTRON is not liable
for consequential damages.

LIMITATION OF WARRANTY

The foregoing warranty does not apply to WILTRON connectors that have failed due to normal
wear. Also, the warranty does not apply to defects resulting from improper or inadequate mainte­nance by the Buyer, unauth or ized modification or misuse, or oper ation outside of the environmen tal
specification s of the produc t. No other warran ty i s expressed or implied, an d the remedies pr ovided
herein are the Buyer’s sole and exclusive remedies.

NOTICE

WILTRON Company has prepared this manual for use by WILTRON Company personnel and
customer s as a guide for the proper installation, operation, and maintenan ce of WIL TRON Compan y
equipmen t and comp utor pr ogr ams. Th e draw ings, specifications, an d information co ntain ed he rein
are the property of WILTRON Company, and any unauthorized u se or disclosur e of these draw ing s,
specifications, and information is prohibited; they shall not be reproduced, copied, or used in whole
or in part as the basis for manufacture or sale of the equipment or software programs without the
prior writtten c onsent of WILTRON Company.

MANUAL CHANGES

MANUAL :

Title: Series 681XXB Synthesized Sweep Generator Operation Manual
Part Number: 10370-10298
Rev. Ltr/Date: B / Augus t 1995

CHANGE PACKET

Part Number: 10900-00165

INSTRUCTIONS

1. Make the manual changes listed below. The changes are listed in numerical order by page number.
Effectivity is all sweep generator serial numbers.

2. The replacement pages provided are for technical changes to the manual. The black bar or bars in the
replacement page margins shows the area in which the changes were made.

CHANGE 1, November 1995

Safety Symbols

1.

Add enclosed pages Safety-1 and Safety-2 after the Declaration of Conformity page,
Changed: November 1995.

2.

Page 1-4

Replace with enclosed pages 1-3 and 1-4, Changed: November 1995.

3.

Pages 2-3 thru 2-6

Replace with enclosed pages 2-3 thru 2-6, Changed: November 1995.

4.

Page 3-13

Replace with enclosed pages 3-13 and 3-14, Changed: November 1995.

5.

Pages 3-3 4 th ru3-3 6

Replace with enclosed pages 3-33 thru 3-36, Changed: November 1995.

6.

Page 3-41

Repalce with enclosed pages 3-41 and 3-42, Changed: November 1995.

7.

Page 3-71

Replace with enclosed pages 3-71 and 3-72, Changed: November 1995.

8.

Page 4-17

Replace with enclosed page 4-17/4-18, Changed: November 1995.

9.

Pages 6-3 thru 6-7

Replace with enclosed pages 6-3 thru 6-8, Changed: November 1995.

10.

Pages 6-13 thru 6-15

Replace with enclosed pages 6-13 thru 6-15/6-16, Changed: November 1995.

681XXB OM C-1

11. Page A-2

Replace with enclosed pages A-1 and A-2, Changed: November 1995.

12.

Pages B-2 thru B-5

Replace with enclosed pages B-1 thru B-6, Changed: November 1995.

PCOs: 22121, 22151, and 22191

C-2 681XXB OM

Declaration of Conformity

Application of Council Directive: EMC- 89/336/EEC

Manufacturer: Wiltron Company

490 Jarvis Drive
Morgan Hill, CA 95037
USA

Products: Synthesized CW / Sweep / Signal Generators

Models: 680XXB, 681XXB, 682XXB, 683XXB

Standards: EN 55011: 1991, Group 1, Class A

EN 50082-1: 1992
IEC 801-2, 1991, Level 3
IEC 801-3, 1984, Level 2
IEC 801-4, 1988, Level 2

Signature Date

John Pink
Managing Direct or
Wiltron Measurements LTD.
Wiltron House
Rutherford Close
Stevenage
Herts, SG1 2EF
UNITED KINGDOM

Safety Symbols

To prevent the risk of person al inju ry or loss related to equipmen t malfun ctio n, WILTRON Compan y uses
the following symbols to indicate safety -related information. For your own safety, please read the informa­tion caref ully BEFORE operating the equipment.

WARNING WARNING indicates a hazard . It calls attention to a procedure that

could result in personal injury or loss of life if not performed properly.
Do not proceed beyon d a WARNING no tice until the in dic ated con di­tions are fully under stoo d and met.

CAUTION CAUTION indica tes a hazard. It calls attention to a procedu re which,

if not performed proper ly, could result in damage to or destruction of a
component of the instru men t. Do not procee d beyo nd a CAUTION
note until the indicated condition s are fu lly und er stood and met.

The instrumen t is marked with this symbol to indicate that it is neces­sary for the user to refer to the instru ction s in the operation manual.

Indicates ground.

Indicates heavy weight equipment.

681XXB OM Safety-1

For Safety

WARNING

When supply ing power to this equipment, always use a
three-wir e power cable conn ec te d to a three-w ir e pow er line
outlet. If power is supplied without grounding the equip­ment in this manner, there is a risk of receiving a severe or
fatal electric shock.

WARNING

Before changing the fuse, always remove the powe r cor d
from the power outle t. There is the risk of receiv in g a fatal
electric sho ck if the fuse is replac ed with the power cord con­nected.

Always use a new fuse of the type and rating specified by
the fuse markings on the rear pan el of the instr ume nt.

WARNING

There are no operator servic eable c ompon ents inside. Refer
servicing of the instrume nt to qualified serv ice technic ian s.

To prevent the risk of electric al shoc k or damage to precision
components, do not remove the equipment covers.

WARNING

Use two or more people to lift and move this equipment, or
use an equipment cart. There is a risk of back injury, if this
equipment is lifted by one person.

Safety-2 681XXB OM

TABLE OF CONTENTS

Chapter 1 — General Informati on

Chapter 1 provides general information about the WILTRON Series 681XXB Synthesized Sweep
Generator. It includes a general description of the sweep generator and information on its identifi­cation number, related manuals, options, and performance specifications. A listing of recommended
test equipment is also provided. Chapter contents are detailed immediately following the tab.

Chapter 2 — Installation

Chapter 2 provides installation instructions for the Series 681XXB Synthesized Sweep Generator.
It includes information on initial inspection, preparation for use, storage, and reshipment, and
GPIB setup and interconnections. Chapter contents are detailed immediately following the tab.

Chapter 3 — Local (Fron t Panel) Operation

Chapter 3 provides information and instructions for operating the Series 681XXB Synthesized
Sweep Generator using the front panel controls. It includes illustrations of the front panel, data dis­play area, and data entry area; an annotated diagram of the menu display format; and instructions
for performing sweep generator operations. Chapter contents are detailed immediately following
the tab.

Chapter 4 — Local Operation—Me nu Maps

Chapter 4 provides menu maps that support the local (front panel) operating instructions found in
Chapter 3. It includes menu maps for all of the frequency, power level, and modulation modes of op­eration plus system configuration. Chapter contents are detailed immediately following the tab.

Chapter 5 — Operati on Veri fication

Chapter 5 provides three operation verification tests that can be used to verify Series 681XXB Syn­thesized Sweep Generator operation. Setup instructions and step-by-step procedures are included
for each test. Test results can be compared with the specified limits shown on the test record forms
that are provided for each 681XXB model configuration. Chapter contents are detailed immediately
following the tab.

Chapter 6 — Operator Ma intenance

Chapter 6 provides the information necessary for operator maintenance of the sweep generator.
Operator maintenance is limited to basic troubleshooting and repairs that can be made without re­moving the instrument covers. Chapter contents are detailed immediately following the tab.

Chapter 7 — Use With Other Instrumen ts

Chapter 7 provides information and instructions for using the Series 681XXB Synthesized Sweep
Generator with other WILTRON instruments. Chapter contents are detailed immediately following
the tab.

681XXB OM i

Table of Contents (Continued)

Appendix A — Rear Panel Connectors

Appendix A provides descriptions of the rear panel connectors on a typical Series 681XXB Synthe­sized Sweep Generator. It includes pinout diagrams and descriptions for the AUX I/O and IEEE­488 GPIB connectors.

Appendix B — Performanc e Specifications

Appendix B lists the performance specifications for the Series 681XXB Synthesized Sweep
Generator.

Supplements

This tab provides a repository for application notes and other material used to supplement manual
chapters.

Index

Provides a subject index.

ii 681XXB OM

Chapter 1
General Information

Table of Contents

1-1 SCOPE OF MANUAL . . . . . . . . . . . . . . . . 1-3

1-2 INTRODUCTION . . . . . . . . . . . . . . . . . . 1-3

1-3 DESCRIPTION . . . . . . . . . . . . . . . . . . . . 1-3

1-4 IDENTIFICATION NUMBER . . . . . . . . . . . . 1-6

1-5 RELATED MANUALS . . . . . . . . . . . . . . . . 1-6

GPIB Programming Manual 1-6
SCPI Programming Manual 1-6
Mainten ance Manual 1-6

1-6 OPTIONS . . . . . . . . . . . . . . . . . . . . . . . 1-7

1-7 PERFORMANCE SPECIFICATIONS . . . . . . . 1-8

1-8 RECOMMENDED TEST EQUIPMENT . . . . . . 1-8

Figure 1-1. Series 681XX B Synthes ize d Sw ee p Gen erator

Chapter 1
General Information

1-1

1-2

1-3

SCOPE OF MANUAL

INTRODUCTION

DESCRIPTIO N

This manual prov ides gener al inf orm ation, installation, and operatin g
information for the WILTRON Series 681XXB Syn the sized Sweep Gen-
erator. (Thr oug ho ut this manu al, the terms 681XX B and sweep ge ner-
ator will be used inter ch an geably to refer to the ins trumen t.) M anu a l
organization is shown in the table of contents.

This chapter co ntains general information about the series 681XXB
sweep generator s. It inclu de s a general desc rip tion of the ins trumen t
and information on its identific ation numbe r, related man uals, options,
and perfor manc e specific ation s. A listing of reco mmen ded test equ ip­ment is also provided.

The Series 681XXB Synthesized Sweep Generators are microprocessor­based, synthesized sign al sou r ce s wi th high resolu tion phase-lock capa­bility. The y gener a te both broad (full r ange) and nar r ow band swe eps
and discrete CW frequ en cies acr os s the frequen cy range of 10 MHz to
65 GHz. All function s of the swe ep gen era tor are fu lly contr ollable lo­cally from the front pan el or remotely (except fo r power on/stand by) via
the IEEE-488 General Pur pose In terf ace Bus (GPIB).

The series presently consists of 15 models coverin g a variety of fre­quency and pow er rang es. Table 1-1, on page 1-4, lists models, fre­quency ran ges, and max imum lev eled outpu t.

681XXB OM 1-3

GENERAL 681XXB
INFORMATION MODELS

Table 1-1. Series 681X XB M odels (1 of 2)

681XXB

Model

68137B 2.0 – 20.0 GHz +13.0 dBm +11.0 dBm
68145B 0.5 – 20.0 GHz +13.0 dBm +11.0 dBm
68147B 0.01 – 20.0 GHz +13.0 dBm +11.0 dBm

68153B

68155B

68159B

68163B

68165B

68169B

68175B

68177B

68185B

68187B

68195B

Frequenc y

(GHz)

2.0 – 20.0 GHz

20.0 – 26.5 GHz

0.5 – 2.2 G H z

2.2 – 20.0 GHz

20.0 – 26.5 GHz

0.01 – 2.0 GHz

2.0 – 20.0 GHz

20.0 – 26.5 GHz

2.0 – 20.0 GHz

20.0 – 40.0 GHz

0.5 – 2.2 G H z

2.2 – 20.0 GHz

20.0 – 40.0 GHz

0.01 – 2.0 GHz

2.0 – 20.0 GHz

20.0 – 40.0 GHz

0.5 – 2.2 G H z

2.2 – 20.0 GHz

20.0 – 40.0 GHz

40.0 – 50.0 GHz

0.01 – 2.0 GHz

2.0 – 20.0 GHz

20.0 – 40.0 GHz

40.0 – 50.0 GHz

0.5 – 2.2 G H z

2.2 – 20.0 GHz

20.0 – 40.0 GHz

40.0 – 50.0 GHz

50.0 – 60.0 GHz

0.01 – 2.0 GHz

2.0 – 20.0 GHz

20.0 – 40.0 GHz

40.0 – 50.0 GHz

50.0 – 60.0 GHz

0.5 – 2.2 G H z

2.2 – 20.0 GHz

20.0 – 40.0 GHz

40.0 – 50.0 GHz

50.0 — 6 5.0 GHz

Output Power

+9.0 dBm
+6.0 dBm

+13.0 dBm

+9.0 dBm
+6.0 dBm

+13.0 dBm

+9.0 dBm
+6.0 dBm

+9.0 dBm
+6.0 dBm

+13.0 dBm

+9.0 dBm
+6.0 dBm

+13.0 dBm

+9.0 dBm
+6.0 dBm

+11.0 dBm
+10.0 dBm

+2.5 dBm
+2.5 dBm

+12.0 dBm
+10.0 dBm

+2.5 dBm
+2.5 dBm

+11.0 dBm
+10.0 dBm

+2.5 dBm
+2.0 dBm
+2.0 dBm

+12.0 dBm
+10.0 dBm

+2.5 dBm
+2.0 dBm
+2.0 dBm

+11.0 dBm
+10.0 dBm

+2.5 dBm

0.0 dBm
–2.0 dBm

Output Pow er

w/Step Att enuato r

+7.0 dBm
+3.5 dBm

+11.0 dBm

+7.0 dBm
+3.5 dBm

+11.0 dBm

+7.0 dBm
+3.5 dBm

+7.0 dBm
+3.0 dBm

+11.0 dBm

+7.0 dBm
+3.0 dBm

+11.0 dBm

+7.0 dBm
+3.0 dBm

+10.0 dBm

+8.5 dBm

0.0 dBm
–1.0 dBm

+10.0 dBm

+8.5 dBm

0.0 dBm
–1.0 dBm

+10.0 dBm

+8.5 dBm

0.0 dBm
–1.5 dBm
–2.0 dBm

+10.0 dBm

+8.5 dBm

0.0 dBm
–1.5 dBm
–2.0 dBm

Not Available

1-4 681XXB OM

Changed: November 1995

GENERAL 681XXB
INFORMATION MODELS

T abl e 1-1. Series 681XXB Models (2 of 2)

681XXB

Model

68197B

68137B 2.0 – 20.0 GHz +17.0 dBm +15.0 dBm
68145B

68147B

68153B

68155B

68159B

68163B

68165B

68169B

68175B 0.5 – 50.0 GHz Standard Standar d
68177B 0.01 – 50.0 GHz Standard Standard
68185B 0.5 – 60.0 GHz Standard Standar d
68187B 0.01 – 60.0 GHz Standard Standard
68195B 0.5 – 65.0 GHz Standard Not Available
68197B 0.01 – 65.0 GHz Standard Not Available

Frequency

(GHz)

0.01 – 2. 0 G Hz

2.0 – 20. 0 G Hz

20.0 – 40.0 GHz

40.0 – 50.0 GHz

50.0 — 65 .0 GHz

With O p ti on 1 5A (H ig h P o we r) Insta lle d

0.5 – 2.2 GHz

2.2 – 20. 0 G Hz

0.01 – 2. 0 G Hz

2.0 – 20. 0 G Hz

2.0 – 20. 0 G Hz

20.0 – 26.5 GHz

0.5 – 2.2 GHz

2.2 – 20. 0 G Hz

20.0 – 26.5 GHz

0.01 – 2. 0 G Hz

2.0 – 20. 0 G Hz

20.0 – 26.5 GHz

2.0 – 20. 0 G Hz

20.0 – 40.0 GHz

0.5 – 2.2 GHz

2.2 – 20. 0 G Hz

20.0 – 40.0 GHz

0.01 – 2. 0 G Hz

2.0 – 20. 0 G Hz

20.0 – 40.0 GHz

Output Pow er

+12.0 dBm
+10.0 dBm

+2.5 dBm

0.0 dBm
–2.0 dBm

+13.0 dBm
+17.0 dBm

+13.0 dBm
+17.0 dBm

+13.0 dBm
+10.0 dBm

+13.0 dBm
+13.0 dBm
+10.0 dBm

+13.0 dBm
+13.0 dBm
+10.0 dBm

+13.0 dBm

+6.0 dBm

+13.0 dBm
+13.0 dBm

+6.0 dBm

+13.0 dBm
+13.0 dBm

+6.0 dBm

Output Power

w/Step Attenuator

Not Available

+11.0 dBm
+15.0 dBm

+11.0 dBm
+15.0 dBm

+11.0 dBm

+7.5 dBm

+11.0 dBm
+11.0 dBm

+7.5 dBm

+11.0 dBm
+11.0 dBm

+7.5 dBm

+11.0 dBm

+3.0 dBm

+11.0 dBm
+11.0 dBm

+3.0 dBm

+11.0 dBm
+11.0 dBm

+3.0 dBm

681XXB OM 1-5

GENERAL IDENTIFICATION
INFORMATION NUMBER

1-4

1-5

IDENTIFICATION NUMBER

RELATED MANUALS

All WILTRON instr ume nts are a ssign ed a uniqu e six-dig it ID numbe r,
such as “301001”. The ID number is imprinted on a decal that is af­fixed to the rear pane l of the unit. Sp ec ial-or der instr ume nt conf igu ra ­tions also have an additional special serial number tag attached to the
rear panel of the unit.

When ordering parts or corresponding with WI LTRON Customer Serv-
ice, please use the corre ct se rial n umbe r with reference to the specific
instrumen t’s model number (i.e., Model 68147B Synth esized Swee p
Generator, Serial No. 301001).

This is one of a four manual set that consists of an Operation Manual,
a GPIB Programming Manu al, a SCPI Progr amming Man ual, an d a
Mainten ance Manual.

GPIB
Progr am min g
Manual

This manual prov ides info rmation for remote oper a­tion of the sweep generator with 681XXB Product
Specific comman ds sent from an extern al controller
via the IEEE 488 General Purpose Inter fac e Bus
(GPIB). It contain s a gene ral desc ription of the GPI B
and bus data transfer and contr ol func tion s, a com­plete listing and description of all 681XX B GPIB
Product Sp ecific comman ds, an d several pr og ram­ming examples. The WILTRON part number for the
GPIB Programming Manual is 10370-10260.

SCPI
Progr amming
Manual

Mainten an ce
Manual

This manual prov ides info rmation for remote oper a­tion of the sweep generator with Standar d Com­mands for Programmable Instrumen t s (SCPI)
commands sent from an ex ternal co ntr oller via the
IEEE 488 General Purpose In te rface Bus (GPI B). I t
contains a general desc rip tion of the GPIB an d bus
data transfer and control functions, a complete li st­ing and description of each command in the 681XXB
SCPI command set, and examples of command us­age. The WILTRON part number for the SCPI Pro-
gramming Manual is 10370-10274.

The Maintenanc e Manual su pplie s service infor ma­tion for all models in the 681XXB series. The service
information inc lu des func tion al cir c uit desc rip tions,
block diagrams, performance verif ication tests, cal i­bration procedu re s, troublesh ootin g data, and assem­bly and component re mov al/r eplac eme nt pr oc edu res.
The WILTRON part number for the Maintenance
Manual is 10370-10262.

1-6 681XXB OM

GENERAL
INFORMATION OPTIONS

1-6

OPTIONS

The following options are available.

Option 1, Rack Mounting. Rac k mount kit con tain ing a set of
track slides (90° tilt capability), mounting ear s, and front pane l
handles for mounting the instrument in a standard 19-inch equi p­ment rack.

Optio n 2A, 110 dB Step Atte nuator . Adds a 10 dB per step
attenuator with a 110 dB range for models having a high- end fre ­quency of ≤26.5 GHz. Output pow er is selected directly in dBm on
the front panel (or via GPIB). Rated RF output power i s reduc ed.

Option 2 B, 110 dB S tep Att enu a to r . Adds a 10 dB per step
attenuator with a 110 dB range for models having a high- end fre ­quency of ≤40 GHz. Output power is selected directly in dBm on
the front panel (or via GPIB). Rated RF output power i s reduc ed.

Option 2 C, 90 d B S tep Att enuator. Adds a 10 dB per step
attenuator with a 90 dB range for models hav in g a high -en d fr e­quency of ≤50 GHz. Output power is selected directly in dBm on
the front panel (or via GPIB). Rated RF output power i s reduc ed.

Optio n 2D, 90 dB Step Atte nuator. Adds a 10 dB per step
attenuator with a 90 dB range for models hav in g a high -en d fr e­quency of ≤60 GHz. Output power is selected directly in dBm on
the front panel (or via GPIB). Rated RF output power i s reduc ed.

Option 9, Rear Panel RF Output. Moves the RF output connec­tor to the rear panel.

Option 11, 0.1 Hz Frequency Resolut ion. Provides frequency
resolution of 0.1 Hz.

Optio n 1 4, WI LTRON 360 B VNA Co mp a ti bi l it y. Modifies rack
mounting hardware to mate unit in a WILTRON 360B VNA con-
sole.

Option 15A , H igh Powe r Ou tpu t . Ad ds h igh -p ow er RF c omp o­nents to the instrument providing increased RF output power in
the 2–26.5 GHz frequency ran ge. Option 15A is standard in mod­els having a high-end frequency that is >40 GHz.

Option 16, High-Stability Time Base. Adds an ovenized,
10 MHz crystal oscillator with <5 x 10

Option 17A, No Front Panel. Deletes the front pan el for use in
remote control applic a tions wher e a front pan el di splay or key­board control are not needed.

Option 19, SCPI Programmability . Adds G PI B comman d mn e­monics complying with Stan dard Commands for Programmable
Instruments (SCPI), Version 1993. 0. SCPI programmin g complies
with IEEE 488.2-1987.

–10

/day frequency stability.

681XXB OM 1-7

GENERAL RECOMMENDED
INFORMATION TEST EQUIPMENT

1-7

1-8

PERFORMANCE
SPECIFICATIONS

RECOMMENDED TEST
EQUIPMENT

Series 681XXB Synthe size d Sweep Generator performance specific a­tions are prov ided in Appen dix B.

Table 1-2 lists the recommended test equipment for performing the Se­ries 681XXB Synthe sized Sweep Generator oper ation verific a tion tests
in Chapter 5.

T abl e 1-2. Recommended Te st Equi pmen t

Instrument Critical Specification Recommended Manufacturer/Model

Range:

Frequency
Counter,
with
Cable Kit
and
External Mixer

Power Meter,
with
Power
Sensor

Oscilloscope

0.01 to 65 GHz

Input Z: 50
Resolution:
Other:

Input

Range:

(1µW to 100 mW)

Bandwidth:
Ver tic al Se ns itiv ity:

division

Horiz Sensitivity:

division

Ω

1 Hz

External Time Base

–30 to +20 dBm

DC to 150 MHz

50 ns/

2 mV/

EIP Microwave, Inc. Models 538B,
548B, or 578B,
with
Cable Kit: Option 590
and
External Mixer:
Option 91 (26.5 to 40 GHz)
Option 92 (40 to 60 GHz)
Option 93 (60 to 90 GHz)

Hewlett-Packard Model 437B,
with
Power Sensor:
HP 8487A (0.01 to 50 GHz)

Tektronix, Inc. Model TAS485

Adapter K (male) to 2.4 mm (female)

Adapts the Pow er Sensor,
HP 8487A, to the 681XXB
RF OUTPUT connector
(≤40 GHz models)

Hewlett-Packard
Part Number: HP 11904D

1-8 681XXB OM

Chapter 2
Installation

Table of Contents

2-1 INTRODUCTION . . . . . . . . . . . . . . . . . . 2-3

2-2 INITIAL INSPECTION . . . . . . . . . . . . . . . 2-3

2-3 PREPARATION FOR USE . . . . . . . . . . . . . 2-4

Power Requirements . . . . . . . . . . . . . . . . 2-4

Line Voltage Selection . . . . . . . . . . . . . . . 2-4

Power Connection . . . . . . . . . . . . . . . . . . 2-4

Standby Operation . . . . . . . . . . . . . . . . . 2-5

Warmup Time . . . . . . . . . . . . . . . . . . . . 2-6

Operating Environment . . . . . . . . . . . . . . 2-6

2-4 GPIB SETUP AND INTERCONNECTION . . . . . 2-7

Interface Connector . . . . . . . . . . . . . . . . . 2-7

Cable Length Restrictions . . . . . . . . . . . . . 2-7

GPIB Interconnection . . . . . . . . . . . . . . . 2-7

Setting the GPIB Address . . . . . . . . . . . . . 2-7

Selecting the Line Terminator . . . . . . . . . . . 2-9

Selecting the Interface Language . . . . . . . . . 2-9

2-5 PREP ARATION FOR STORAG E/SHIPMENT . . . 2-10

Preparation for Storage . . . . . . . . . . . . . . . 2-10

Preparation for Shipment . . . . . . . . . . . . . 2-10

Chapter 2
Installation

2-1

2-2

INTRODUCTION

INITIAL INSPECTION

This chapter prov ides installation instruction s for the Series 681XX B
Synthesized Sweep G en era tor. It includes inf or m ation on initial inspec ­tion, preparation for use, storage, and reshipment, and General Pur­pose Interface Bus (GPIB) setup and interconnections.

WARNING

Use two or more people to lift and move this equipment, or
use an equipment cart. There is a risk of back injury, if this
equipment is lifted by one person.

Inspect the shippin g contain er for damage . If the shippin g contain er or
cushioning material is damaged, retain until the contents of the ship­ment have been checked against the pack ing list and the sweep gener­ator has been checked for mechanical and electrical operation.

If the shipment is incomplete or if the sweep gen er ator is damaged me­chanically or electr ic ally, notify your local sales represent ative or WIL-
TRON Customer Service. If either the shippin g contain er is damaged
or the cushionin g material shows sig ns of stress, no tify the car rie r as
well as WILTRON. Keep the shipping materials for the carr ier’s insp ec -
tion.

681XXB OM 2-3
Changed: November 1995

PREPARATION

INSTALLATION FOR USE

2-3

PREPARATION FOR USE

Prepara tion for use c onsists of checking that the rear panel line volt­age selector swi tch is set for the cor re ct line voltage and c onne ctin g the
sweep generator to the power so urc e. The followin g parag r aph s provide
these procedu r es along with information about pow er requ ir emen ts,
warmup times, and the ope ratin g envir on men t.

Power
Requiremen ts

Before applying power, verify that the unit i s set to match
the available line voltage and tha t the installed fuse is of the
correct type and rating.

Line Voltage
Selection

The sweep generator accepts 90 to 132 Vac and 180
to 264 V ac , 48 to 400 Hz, single-ph ase p ower. Pow er
consumption is 400 VA maximum.

CAUTION

The line voltage selector switc h on the rear pan el
can be set for either 110 Vac or 220 Vac operation
(Figure 2-1). Wh en the switc h is set to 1 10 Vac, the
681XXB accepts 90 to 132 Vac line voltage. When
the switch is set to 220 Vac, the 681XXB accepts 180
to 264 V ac line voltage. If the selector setting is incor­rect for the line voltage available, change it to the
correct setting.

Whenever the selector setting is changed, the line
fuse must be changed to the correct value for the
line voltage selected. Lin e fuse values for the line
voltages are printed on the rear pan el ne xt to the
fuse holder.

WARNING

When supply ing power to this equipmen t, always use a
three-wir e pow er cable con ne cted to a three-w ir e power line
outlet. If power is supplied without grounding the equipment
in this manner, there is a risk of receivin g a severe or fa tal
electric shock.

Power
Connection

Connecting the 681XXB to line pow er automatically
places it in operation (front panel OPERATE LED
on). To connect it to the power source, plug the fe­male end of the power cable into the input line volt­age receptacle on the re ar pan el (Fig ure 2-1). Then
plug the male end of the power cord into a three­wire power line outlet.

2-4 681XXB OM

Changed: November 1995

PREPARATION

Figure 2-1. Sweep Generator Re ar Panel showing Power Connecti on

INSTALLATION FOR USE

Line
Fuse

Line Voltage
Selector Switch

GPIB

Connector

OPERATE

LINE

STANDBY

LEVEL

CONTROL

MODULATION

SYSTEM

Line
Key

Standby Op­eration

Whenever the swee p gener ator is not being used it
should be left connec ted to the power sour c e and
placed in standby. This keeps the internal timebase
frequency refer en c e at operatin g temperatu r e.

On the front panel, press

LINE to switch the
681XXB from OPERATE (green LED on) to
STANDBY (orange LED on).

NOTE

During standby operation, the fan runs
continuously.

681XXB OM 2-5
Changed: November 1995

PREPARATION

INSTALLATION FOR USE

W armup
Time

Operating
Environment

Before installing the 680XXB in its operating envir on men t,
ensure that all airflo w passage s at the sides an d rear of the
instrumen t are clear. This is of particular importan c e when­ever the unit is being rack-mo unted.

From a cold start (ac power application ), the sweep
generator requ ire s approx imately 120 hours (5 days)
of warm up to achieve 2 x 10
racy and stability.

If the Option 16 time base is installed, the 681XXB
requires approx imately 72 hours (3 days) of w arm
up to achieve 5 x 10
stability.

When placing the 681XXB in ope ration from stand­by, allow 30 minutes warmup to assure stable opera­tion.

The 681XXB can be oper ated with in the follow in g en­vironmental limits.

Temperature. 0°C to 50°C (-32°F to 122°F).
Humidity. 5 to 95% relative at 40°C.
Altitude. up to 4600 meters (approximately

15,000 feet).
Cooling. Internal cooling is provided by forced
airflow from the fan mounted on the rear panel.

CAUTION

–10

–8

/day frequ en cy ac cu -

/day frequency accuracy and

Keep the cooling fan filter clean so that the ven tilation holes
are not obstru cted . A blocked fan filter can cause th e in stru ­ment to overheat and shut down.

2-6 681XXB OM

Changed: November 1995

GPIB SETUP AND

INSTALLATION INTERCONNECTION

2-4

GPIB SETUP AND
INTERCONNECT ION

The 681XXB provides automated microwave signal generation via the
GPIB. The follow in g par ag rap hs pr ovide inf or m ation abou t inter fac e
connection s, cable requ ire men ts, setting the GPIB oper atin g param e­ters, and selecting the external interface language.

Interface
Connector

Cable Length
Restrictions

Interfac e betwee n the sweep g en er ator an d other de­vices on the GPIB is via a 24-wire interf ace cable.
This cable uses connector shells hav in g two conn ec­tor faces. These double- fac ed co nnec tor s allow for
the parallel connection of two or more cables to a sin­gle device. Figure 2-1 show s the loca tion of the rear
panel GPIB conn ec tor.

The GPIB can accommod a te up to 15 instruments at
any one time. To ach iev e design per for man c e on the
bus, proper timin g and vo ltage lev el re la tionsh ip s
must be maintained. If either the cable leng th be­tween separate instrume nts or the cumulativ e cable
length between all instruments is too long, the data
and control lines cannot be driven properly and the
system may fail to perform. Cable length restric tion s
are as follows:

No more than 15 ins trumen t s may be in stalled
on the bus.
Total cumulative cable len gth in meters may
not exceed two times the number of bus instru­ments or 20 meters—whichev er is less.

NOTE

For low EMI applications, the GPIB cable
should be a fully shielded type , with well­grounded metal-shell connectors

GPIB In ter­connection

Setting the
GPIB
Address

The only intercon n ection requ ir ed for GPI B oper a­tion is between the sweep gen era tor an d the contr ol­ler. This interconnection is via a standard GPIB
cable. The WILTRON Part number for suc h a cable
is 2000-1, -2, or -4 (1, 2, or 4 meters in length).

The default GPIB add ress i s 5. If a different GPI B
address is desired, it can be set from the front panel
using the Config ur e GPIB Me nu .

To change the GPIB address, first press the front
panel main menu key labele d
tem Menu (shown on the following page) is dis­played.

SYSTE M . The Sys-

681XXB OM 2-7

GPIB SETUP AND

INSTALLATION INTERCONNECTION

Now press the menu soft-key Co nf ig . The System
Configuration Menu (below) is displayed.

To go to the Configure GPIB men u from this menu,
press the menu soft-key
Menu (below) is displayed.

Press the menu soft-key
the current GPI B addre ss of the sweep ge ne rator.
Enter a new addr ess u sing th e c ursor control key or
the data entry keypad and the termin ator key

The new GPIB address will now appear on the di s­play. The entr y must be betwee n 1 and 30 to be rec­ognized as a valid GPIB address.

GPIB . Th e Confi gu r e GPIB

GPIB Address to change

Hz

ns

ADRS

2-8 681XXB OM

GPIB SETUP AND

INSTALLATION INTERCONNECTION

Selecting
the Li n e
Terminator

Selecting the
Interface
Language

Data is delimited on the GPIB by either the carriag e
return (CR) ASCII char ac ter or both the car riag e r e­turn and line fe ed (CR/ LF) A SCII c har ac ter s. Wh ic h
character is used depen ds upon the requirements of
the system controller. Most modern controlle rs can
use either CR or CR/LF, while many older control­lers require one or the other. Consult the controller’s
manual for its particu lar requir emen t s.

From the Configu re GPIB Men u display, you can se­lect which GPIB termin ator to use by pressin g the
menu soft-key
gles the GPIB terminator between CR and CR/LF.
The current selec tion appears on the display.

Series 681XXB Synthesized Swe ep Ge ne rator s can
be remotely operated via the GPIB usin g one of two
external interf ace lang uages— N ative or SCPI (Op­tion 19). The Native interfac e lang uag e uses a set of
681XXB GPIB Produc t Specific comman ds to contro l
the instrument; the SCPI inter fac e lan guag e uses a
set of the Standard Commands for Programmable In­struments comman ds to control the u nit.

The Configure G PIB Menu has an additional men u
display. For ins tru men ts with Option 19, selection of
which exter n al inter fac e lang u ag e is to be used is
made from this additional menu. From the Con fig ­ure GPIB Menu display, you can access the addi­tional menu by pressing
figure GPIB Men u (below) is displayed.

Line Term . This menu soft-key tog-

More . The additional Con-

Press

Native SCPI to select the external in terf ace
language to be used. This menu soft-key togg les the
language selec tion betw een Native and SCPI. The
current selection appears on the display.

681XXB OM 2-9

PREPARATION FOR

INSTALLATION STORAGE/SHIPMENT

2-5

PREPARATION FOR
STORAGE/SHIPMENT

The following paragraphs give instructions for preparing the 681XXB
for storage or shipment.

Preparation
for Storage

Preparation
for Shipment

Preparing the sweep generator for storage consists
of cleaning the unit, packing the insid e with mois­ture-absorbing desiccant crystals, and storing the
unit in a temperature environ men t that is main­tained between –40°C and +75°C (–40°F to +176°F ).

To provide maximum protection against damage in
transit, the sweep generator shou ld be re pac kag ed
in the original shipping container. If this container is
no longer available and the unit is being retu rned to
WILTRON for repair , adv ise WIL T RO N Customer
Service; they will send a new shippin g con tainer free
of charge. In the event neither of these two options
is possible, instruction s for pac kaging and shipment
are given below.

Use a Suitable Con tain er.

Obtain a corrugated cardboar d carton with a 275­pound test strength. This carton should have inside
dimensions of no less than six inche s large r than the
unit dimensions to allow for cushioning.

Protect the Instrument.

Surround the un i t wi th poly ethylene sheeting to pro ­tect the finish.

Cushion the Inst rume nt .

Cushion the instrument on all sides by tightly pack­ing dunnag e or ure than e foam betwe en the carton
and the unit. Provide at least three inches of dun­nage on all sides.

Seal the Cont aine r.

Seal the carton by using eithe r shippin g tape or an
industrial stapler.

Address the Container.

If the instrument i s being retu rned to WILTRO N for
service, mark the address o f the appropr iate WIL-
TRON service center (Table 2-1) and your return ad­dress on the carton in one or more prominent
locations.

2-10 681XXB OM

UNITED STATES

WILTRON COMPANY
490 Jarvis Drive
Morgan Hill, CA 95037-2809
Telephone: [phone]
Telex: 285227 WILTRON MH
FAX: [phone]

ANRITSU WILTRON SALES
COMPANY
685 Jarvis Drive
Morgan Hill, CA 95037-2809
Telephone: [phone]
FAX: [phone]

ANRITSU WILTRON SALES
COMPANY
10 Kingsbridge Road
Fairfield, NJ 07004
Telephone: [phone]
FAX: [phone]

AUSTRALIA

WILTRON PTY. LTD.
Level 2, 410 Church Street
North Parramatta
NSW 2151 Australia
Telephone: [phone]
Fax: [phone]

BRAZIL

ANRITSU WILTRON ELEC­TRONICA LTDA.
Praia de Botafogo, 440-SL 2401-Bo­tafogo
2225-Rio de Janeiro-RJ-Brasil
Telephone: [phone]
Fax: [phone]

CANADA

ANRITSU WILTRON INSTRU­MENTS LTD.
215 Stafford Road, Unit 102
Nepean, Ontario K2H 9C1
Telephone: [phone]
FAX: [phone]

CHINA

WILTRON BEIJING SERVICE
CENTER
416W Beijing Fortune Building
5 Dong San Huan Bei Lu
Chao Yang Qu, Beijing 100004,
China
Telephone: [phone]
FAX: [phone]

FRANCE

ANRITSU WILTRON S.A
9 Avenue du Quebec
Zone de Courtaboeuf
91951 Les Ulis Cedex
Telephone: [phone]
FAX: [phone]

GERMANY

ANRITSU WILTRON GmbH
Rudolf Diesel Strabe 17
8031 Gilching
Telephone: [phone]
FAX: [phone]

INDIA

MEERA AGENCIES (P) LTD.
A-23 Hauz Khas
New Delhi 110 016
Telephone: [phone]
FAX: [phone]

ISRAEL

TECH-CENT, LTD
Haarad St. No. 7, Ramat Haahayal
Tel-Aviv 69701
Telephone: [phone]
FAX: [phone]

ITALY

ANRITSU WILTRON Sp.A
Roma Office
Via E. Vittorini, 129
00144 Roma EUR
Telephone: [phone]
FAX: [phone]

JAPAN

ANRITSU CORPORATION
1800 Onna Atsugi-shi
Kanagawa-Prf. 243 Japan
Telephone: [phone]
FAX: [phone]

KOREA

WILTRON CORPORATION
#2103 Korea World Trade Center
159-1 Samsung-Dong
Kangnam-ku, Seoul
Telephone: [phone]
FAX: [phone]

SINGAPORE

ANRITSU WILTRON (SINGA­PORE) PTE LTD
3 Shenton Way #24-03
Shenton House
Singapore 0106
Telephone: [phone]
FAX: [phone]

SWEDEN

ANRITSU WILTRON AB
Box 247
S-127 25 Skarholmen
Telephone: [phone]
FAX: [phone]

TAIWAN

WILTRON CO., LTD.
8F, No. 96, Section 3
Chien Kuo N. Road
T aipei, Taiwan, R.O.C.
Telephone: [phone]
FAX: [phone]

UNITED KINGDOM

ANRITSU WILTRON LTD.
200 Capability Green
Luton, Bedfordshire
LU1 3LU, England
Telephone: [phone]
FAX: [phone]

Table 2-1. WILTRON Service Centers

WILTRON

INSTALLATION SERVICE CENTERS

681XXB OM 2-11/2-12

Chapter 3
Local (Front Panel) Operation

Table of Contents

3-1 INTRODUCTION . . . . . . . . . . . . . . . . . . 3-5

3-2 FRONT PANEL LAYOUT . . . . . . . . . . . . . . 3-6

Line Key . . . . . . . . . . . . . . . . . . . . . . . 3-6

Data

Display Area . . . . . . . . . . . . . . . . . . . . . 3-6

Data

Entry Area . . . . . . . . . . . . . . . . . . . . . . 3-7

RF Output

Control Key . . . . . . . . . . . . . . . . . . . . . 3-7

Connectors . . . . . . . . . . . . . . . . . . . . . . 3-7

3-3 DATA DISPLAY AREA . . . . . . . . . . . . . . . . 3-8

Menu
Display

Format . . . . . . . . . . . . . . . . . . . . . . . . 3-9

Menu Keys . . . . . . . . . . . . . . . . . . . . . 3-10

3-4 DATA ENTRY AREA . . . . . . . . . . . . . . . . . 3-12

3-5 INSTRUMENT START-UP . . . . . . . . . . . . . 3-12

Powering Up the 681XXB . . . . . . . . . . . . . 3-12

Start-Up

Display . . . . . . . . . . . . . . . . . . . . . . . . 3-12

Standby

Operation . . . . . . . . . . . . . . . . . . . . . . 3-12

Self-Testing the 681XXB . . . . . . . . . . . . . . 3-13

Resetting to Default Parameters . . . . . . . . . . 3-13

3-6 ENTERING DATA . . . . . . . . . . . . . . . . . . 3-16

Opening the Parameter . . . . . . . . . . . . . . . 3-16

Editing the Current Value . . . . . . . . . . . . . 3-17

Entering a New Value . . . . . . . . . . . . . . . 3-18

3-7 CW FREQUENCY OPERATION . . . . . . . . . . 3-19

Selecting CW Mode . . . . . . . . . . . . . . . . . 3-19

Selecting
a CW

Frequency . . . . . . . . . . . . . . . . . . . . . . 3-19

Selecting a Power Level . . . . . . . . . . . . . . 3-21

CW Ramp . . . . . . . . . . . . . . . . . . . . . . 3-22

3-8 SWEEP FREQUENCY OPERATION . . . . . . . . 3-23

Selecting Analog Sweep Mode . . . . . . . . . . . 3-23

Setting the Analog Sweep Time . . . . . . . . . . 3-24

Selecting a Sweep

Trigger . . . . . . . . . . . . . . . . . . . . . . . . 3-25

Selecting Step Sweep Mode . . . . . . . . . . . . . 3-26

Setting Step Size and Dwell Time . . . . . . . . . 3-27

Selecting Manual Sweep Mode . . . . . . . . . . . 3-28

Selecting a Sweep Range . . . . . . . . . . . . . . 3-29

Selecting a Power Level . . . . . . . . . . . . . . 3-31

Frequency Markers . . . . . . . . . . . . . . . . . 3-32

Selecting

Alternate Sweep Mode . . . . . . . . . . . . . . . 3-34

3-9 FIXED POWER LEVEL OPERATION . . . . . . . 3-37

Selecting Fixed Power Level Mode . . . . . . . . . 3-37

Selecting a Power Level . . . . . . . . . . . . . . 3-37

Level Offset . . . . . . . . . . . . . . . . . . . . . 3-40

3-10 POWER LEVEL SWEEP OPERATION . . . . . . . 3 -41

Selecting CW Power Sweep Mode . . . . . . . . . 3-41

Setting CW Power Sweep Step Size

and Dwell Time . . . . . . . . . . . . . . . . . . 3-42

Selecting a CW Power Sweep

Trigger . . . . . . . . . . . . . . . . . . . . . . . . 3-43

Selecting a Power Level Sweep Range . . . . . . . 3-44

Selecting a Sweep Frequency / Step Power Mode . 3-46

Setting Power Level Step Size . . . . . . . . . . . 3-47

3-11 LEVELING OPERATIONS . . . . . . . . . . . . . 3-48

Selecting a Leveling Mode . . . . . . . . . . . . . 3-48

Attenuator Decoupling . . . . . . . . . . . . . . . 3-52

ALC Power Slope . . . . . . . . . . . . . . . . . . 3-53

User Cal (User Level Flatness

Correction) . . . . . . . . . . . . . . . . . . . . . . 3-55

3-12 SIGNAL MODULATION . . . . . . . . . . . . . . 3-61

Amplitude Modulation Operating Modes . . . . . 3-61

Providing Amplitude Modulation . . . . . . . . . 3-61

Frequency Modulation Operating Modes . . . . . 3-62

Providing Frequency Modulation . . . . . . . . . 3-63

Square Wave Modulation Operating Modes . . . . 3 -65

Providing Square Wave Modulation . . . . . . . . 3-65

3-13 SYSTEM CONFIGURATION . . . . . . . . . . . . 3-68

Configuring the Front Panel . . . . . . . . . . . . 3-69

Configuring the Rear Panel . . . . . . . . . . . . 3-70

Configuring the RF . . . . . . . . . . . . . . . . . 3-71

Configuring the GPIB . . . . . . . . . . . . . . . . 3-72

Setting

Increment Sizes . . . . . . . . . . . . . . . . . . . 3-74

3-14 SAVING/ RECALLING INSTRUMENT SETUPS . 3-75

Saving

Setups . . . . . . . . . . . . . . . . . . . . . . . . 3-75

Recalling Setups . . . . . . . . . . . . . . . . . . 3-75

Erasing Stored

Setups . . . . . . . . . . . . . . . . . . . . . . . . 3-76

3-15 SECURE OPERATION . . . . . . . . . . . . . . . 3-77

Chapter 3
Local (Front Panel) Operation

3-1

INTRODUCTION

This chapter pr ov ides in formation and instructio ns on op er a ting the
Series 681XXB Synthe size d Sweep Generator using the front panel
controls. It contains the follo win g:

Illustrations and diagr ams of the fro nt pan el, data di splay ar ea,
and data entry area that identify and describe all fron t panel con­trols, inputs, and outputs.

An annotated diag r am of th e menu display format show ing
where the current fre que ncy, power , and modulation info rmation
is displayed.

Instructions for performing sweep generator operations; namely,
frequency and frequency sweep, power level and power sweep,
signal modulation, savin g and recallin g instrumen t setups, and
system configuration.

681XXB OM 3-5

LOCAL (FRONT FRONT PANEL
PANEL) OPERATION LAYOUT

3-2

SYNTHESIZED

SWEEP

GENERATOR

OPERATE

LINE

STANDBY

FRONT PANEL LAYOUT

Data Display Data Entry

CW/SWEEP

SELECT

FREQUENCY

CONTROL

LEVEL/ALC

SELECT

LEVEL

CONTROL

MODULATION

SYSTEM

The 681XXB front panel is divided into two main areas—the data dis­play area and the data entry area. The follow ing par agr aph s p rovid e a
brief description of the front panel contr ols, inpu ts, outpu ts, and data
display and da ta entry are a s as shown in Figure 3-1. De tailed descr ip­tions of the data display and data entry areas are containe d in para­graphs 3-3 and 3-4.

RF Output

Control

Key

CLEAR
ENTRY

7

0

MODULATION

AM IN

FM IN

EXTERNAL
ALC IN

IN

BACK

SPACE

231

GHz

Sec
dBm

98

MHz

ms

dB

654

kHz

µ

s

STEPS

Hz

ns

ADRS

OUTPUT

OFF

ON

RF OUTPUT

Ω

50

CAUTION

RF OUTPUT

MAY EXCEED 100mW

Line

Key

Menu

Keys

Figure 3-1. Front Panel, 681X X B Synthes ize d Sw ee p Gen erator

Line Key The line key provides for turning the sweep gener-

ator on and off. STANDBY (off) is indic ated by an or­ange LED; OPERATE (on) by a green LED.

Data
Display Area

The data display area consists of the data display
and the surrounding menu keys.

Data Display

The data display provides information about the cur­rent status of the 681XXB in a menu display for­mat. This information inclu des the ope ratin g mode
of the instrument, the valu e of the active fr equ en cy
and power lev el parame ters, and the modulation
status.

Menu Keys

Menu keys provide for selecting the ope ratin g mode,
parameters, and configuration of the sweep gener­ator.

Modulation

Connectors

External

ALC

Connector

RF Output
Connector

3-6 681XXB OM

LOCAL (FRONT FRONT PANEL
PANEL) OPERATION LAYOUT

Data
Entry Are a

RF Output
Control Key

Connectors The front panel has both input and output connec-

The data entry area consists of data entry keys and
controls th a t provide for (1) changing valu es for
each 681XXB par ameter, and (2) terminatin g the
value entry and assigning the appropriate units
(GHz, MHz, dBm, etc. ).

The RF output control ke y prov ides for tur ning the
RF output power on and off . OUT PUT OF F is indi­cated by a red LED; OUTPUT ON by a yellow LED.

tors.

Modulation Connectors

The modulation connectors provide for applying ex­ternal AM, FM, or Squar e Wav e modu lation to the
RF output signal.

Externa l ALC Co nnecto r

The extern al ALC c onn ec tor p ro vid es for leveling
the RF output signal externally using either a
detector or a power meter.

RF Output Co n nect or

The RF outpu t con nector provides RF outpu t from a
50Ω source.

NOTE

To prevent power losses du e to an imped­ance mismatch, the mating connector and
cable should also be rated at 50 Ω.

681XXB OM 3-7

LOCAL (FRONT DATA DISPLAY
PANEL) OPERATION AREA

3-3

Main Menu

Keys

DAT A DISPLAY AREA

Main Menu
Key Cursor

CW/SWEEP

SELECT

FREQUENCY

CONTROL

Frequency

Mode

Title Bar

The data display area consists of the data display and the surroundin g
menu keys. The data display is a dot matrix liquid crystal display
(LCD) that provides 16 lines of 40 characters each. Information is pre­sented on the LCD in the form of menu displays. The menu key s
either selec t the main me nu to be display ed, select a sub-menu of the
current men u display, or control a function on the current menu dis­play.

Figure 3-2 shows the for m at of the menu display an d id entif ies the di s­play elements. It also shows the placemen t o f the menu keys in re la­tion to the display. The paragr aph s that follow provide descr iption s of
the menu display element s and the menu ke ys.

Frequency

Parameters

Area

Level Mode

Title Bar

Level

Parameters

Area

Menu

Labels

Side Keys

Menu

Soft-Keys

LEVEL/ALC

SELECT

LEVEL

CONTROL

MODULATION

SYSTEM

Modulation

Status Areas

Figure 3-2. Front Panel Data Displ ay Are a

Modulation

Title Bars

Menu

Soft-Keys

Menu Labels

Bottom Keys

3-8 681XXB OM

LOCAL (FRONT DATA DISPLAY
PANEL) OPERATION AREA

Menu
Display
Format

The menu display is divided into specific areas that
show the frequ en cy, power level, and modulation in­formation for the cur ren t sweep g ener a tor setup.
Menu labels for the curren t menu ’s soft-keys appear
along the bottom and right side of the display.

Title B ar s

A shade d title bar identifies eac h parameter area.
Mode information is displayed in reverse video on
the title bars.

Frequen cy Mo de T i tl e Bar —The current fre­quency mode ( C W, Analog Sweep, Step Sw eep ,
or Manual Sweep) appe ars on the left side of
the bar . In an analog or step sweep mode, the
type of sweep trigger (Auto, Exter n , or Single)
appears on the right side.
Level Mode Title Ba r —The current power
level mode (Level or Level Sweep) appears on
the left side of the bar. In a level sweep mode,
the type of sweep trigger (Au to , Extern al, or
Single) appears on the right side of the bar.
Modulation Title Bars—Each type of signal
modulation (AM, FM, Square Wave) has a
separate title bar on the display.

Parameter A reas

The parameter are as show the frequency, power
level, and modulation infor m ation for the cur ren t
681XXB setup.

Frequen cy Para meters Area —The curren t
CW frequency in GHz, or the start and stop fre­quencies of the curr en t frequ en c y sweep r ang e
in GHz are displayed in this area.
Power Level Pa rameter s Area —The cur­rent power leve l in dBm, or the start an d stop
levels of the curre nt pow er level sw eep rang e
in dBm are displayed in this area.
Modulation Status Areas—These areas dis­play ON or OFF to indicate the status of signal
modulation for the current setup.

Menu Labels

Each of the menu soft-keys, located below an d to
the right of the display, has a corresponding me nu
label area on the display. These labels identify the
function of the soft-keys for the current menu dis­play. In most cases, when a menu soft-key is
pressed, its menu label changes appear anc e to visu­ally show the On/Off cond i tion.

681XXB OM 3-9

LOCAL (FRONT DATA DISPLAY
PANEL) OPERATION AREA

Window Display

A window display that overlays a portion of the cur­rent menu display is used to (1) show the parameter
being edited; (2) di splay selection lists of preset fre­quencies, pow er lev els, mark er s, etc. ; (3) show the
modul ation and sys tem con fig u ration choic es and
current se lec tio ns; or (4) show self-test err or mes­sages. A typical window di splay is show n on the left.

Menu Keys As show n in Figure 3-2, there are two types of menu

keys that surrou nd the data display— main men u
keys and menu soft-keys. The main menu keys are
positioned to the left of the data display. The menu
soft-keys are located a t the bottom and to the right
of the data display.

Main Menu Keys

Each of the main menu keys, show n on the left, se­lects a main (top-level) men u display. These menus
let you select the operatin g mode, operatin g para me-

CW/SWEEP

SELECT

FREQUENCY

CONTROL

LEVEL/ALC

SELECT

LEVEL

CONTROL

MODULATION

SYSTEM

ters, and con fig uration of the in str umen t. A brief
functional description of each main menu follows.

CW/SWEEP SELECT—This menu lets you
select between C W, Analog, Step, and M anual
Sweep frequency modes.
FREQUENCY CONTROL—In CW frequency
mode, this menu lets you select the CW fre­quency paramete r (F0-F9 or M0-M 9) to use. In
the Analog, Step, or Manu al Sw eep f re que ncy
mode, this menu lets you select the sweep
range parameter s (Full, F1-F2, F3-F 4, F5-dF,
or F6-dF) to use. In Analog or Step Sweep f re ­quency mode, the menu also lets you select up
to 20 independent, pre-se ttable frequ en cy
markers.
LEVEL/ALC SELECT—This menu lets you
select power leve l and ALC modes (Lev el,
Level Sweep, Level Of fset, ALC on or off , inter ­nal or external ALC, ALC/ attenuator decou­pling, ALC slope, and user lev el flatn ess correc ­tion).
LEVEL CONTROL—In Level mode, this
menu lets you select the level par ameter (L0­L9) to use for a CW frequency or a frequency
sweep. In the Level Sweep mode, this menu
lets you select the power sweep range parame­ters to use.

3-10 681XXB OM

LOCAL (FRONT DATA DISPLAY
PANEL) OPERATION AREA

MODULATION—This menu provides you
with access to sub-menus that let you select
the type of signal modulation (AM , FM, or
Square W ave) and control the option settings
for each type.
SYSTEM—Th is me nu pr ov ides y ou with ac­cess to sub-menus that let you (1) reset the in­strument to factory-selec ted def ault valu es; (2)
configu r e the fr on t panel, rear pan el, RF, and
GPIB; (3) set incremen tal sizes for editing fre­quency, power level, and time parameters; (4)
save or recall instrument setups; (5) disable
front panel data display; and (6) perfor m in­strument self-test.

Main Menu Key Cursor

With the exception of the
main menu key is pressed, the main menu that is
displayed contain s a cursor position ed adjac ent to
the pressed key (Fig ure 3-2). The cursor i s displayed
on all sub-menus of the curre nt men u until a differ ­ent main menu key is pressed .

SYSTE M key, when any

CW/SWEEP

SELECT

FREQUENCY

CONTROL

LEVEL/ALC

SELECT

CONTROL

MODULATION

SYSTEM

When the

SYSTEM key is pressed, the System

menu is displayed. The System menu and its sub­menus do not contain a main menu key cursor.

Menu Soft-Keys

As shown on the left, five menu soft-keys are lo­cated below the data display and five menu soft­keys are located to the right of the data display. In

LEVEL

general, the menu soft-keys located below the data
display select a sub-me nu of the curren t main (top­level) menu display; the menu soft-keys located to
the right of the data display either contr ol a func ­tion on the current men u display or select an addi­tional sub-menu. Menu labels that identify the
current fu nc tion of each soft-key are shown on the
menu display adjacent to the soft-keys.

681XXB OM 3-11

LOCAL (FRONT DATA ENTRY
PANEL) OPERATION AREA

3-4

DATA ENT RY AREA

Cursor

Control

Key

The value of a selected 681XX B par ameter can be chan g ed usin g the
rotary data knob and/or keys of the data entry ar ea. Eac h element of
the data entry area is identified in Figur e 3-3 and desc ribe d in the fol­lowing paragraphs.

87

5

2

Back

Space

Key

BACK

SPACE

9

6

3

Terminator

Keys

GHz

Sec

dBm

MHz

ms

dB

kHz

µ

s

STEPS

Hz

ns

ADRS

Clear

Entry

Key

CLEAR
ENTRY

4

1

0

Rotary

Data

Knob

Figure 3-3. Front Panel Data Entry Are a

Keypad

Cursor Control Key

In general, this diamon d-sh aped ke y con trols the
movemen t of the cursor on the di splay. When a pa­rameter is opened for edi ting, a cur sor appe ars un­der the open parame ter. Each time the < or > pad is
pressed , the cursor moves left or right by one digi t.
The ∧ or ∨ pad can then be used to in c r ease or de­crease the value of the parame ter. The unit size of
the increase or decrease that oc cur s each time the ∧
or ∨ pad is pressed is determined by the cursor posi­tion.

In addition, when edi ting fre que ncy, power level,
and time parameters, the incremental size can be
set to a specific value using a system config uration
sub-menu. Onc e set and activated, each time the ∧
or ∨ pad is pressed, the parameter’s value increases
or decreases by the set amount.

3-12 681XXB OM

LOCAL (FRONT DATA ENTRY
PANEL) OPERATION AREA

Rota r y Data Kno b

The rotary data knob can be used to change the
value of a parameter that is open for editing . The
cursor is moved under the open par ameter using
the < and > pads of the cursor control key. Then, by
slowly turning the knob clockwise or counter-clock­wise the value of the parameter is incre ased or de­creased by the unit size. The unit size is determine d
by the cursor placement. Turning the knob rapidly
changes the valu e of the parameter in larger steps.

When editing frequ enc y, power level, and time pa­rameters, the incremental size can be set to a spe­cific value usin g a system configu ration sub-men u .
Once set and activated, eac h time the knob is
turned clock wise or coun ter - clo ckw i se, the param­eter’s value increases or decreases by the set
amount.

KEYPAD

The numeric keypad provides for entering fre­quency, power level, time, and number-of - steps pa­rameters and GPIB address values. The “–” key
functions as a “change sign” key du ring any key pad
entry.

CLEAR ENT R Y Key

When a parameter is open for editing, the CLEAR
ENTRY key is used to clear the par ameter entry.

BACK SPAC E Key

The BACK SPACE key is used to correct keypad
data entry erro rs by deleting the last number, “–”,
or decimal point enter ed.

Terminator Keys

The termina tor keys are used to termin ate key pad
data entries and chan ge the paramete r value s in
memory. If the enter ed value is outside the allow­able range of the open parameter, an error message
will be displaye d alo ng with an audible “beep”. The
terminator keys are as follows:

GHz / Sec / dBm
MHz / ms / d B
kHz / µs / STEPS
Hz / ns / ADRS

681XXB OM 3-13

LOCAL (FRONT INSTRUMENT
PANEL) OPERATION START-UP

3-5

INSTRUMENT START-UP

Now that you have familiarized yourse lf with the layout of the sweep
generator’s front panel c on trols and data display, you are ready to be­gin operating the instrumen t. Begin by powering it up.

Powerin g Up
the 681XXB

Connect th e 681XXB to an ac pow er sou rc e by fol­lowing the procedure in the Installation chapter.
This automatically places the instr umen t in oper a­tion (front panel OPERATE LED on).

Start-Up
Display

During pow er up, the start-u p di splay (belo w) ap­pears on the data display. It provide s you with the
revision level of the installed firmware and informs
you that instrument is loading programs. The start­up display remains displaye d until the sweep gener ­ator has loaded all programs.

OPERATE

LINE

STANDBY

LEVEL

CONTROL

MODULATION

SYSTEM

Line
Key

Standby
Operation

Upon completion of pow er up , the 681XXB retur n s
to the exact config u ration it was in when last
turned off.

Wheneve r the sweep gen er a tor is not being used, it
should be left connected to the power source and
placed in standby. Standby operation provides
power to keep the inter nal time base at operatin g
temperature. This assures specified frequency accu­racy and stability when the 681XXB is place in op­eration.

NOTE

During standby operation, the fan runs
continuously.

Press

LINE to swi tch the 681XX B fr om OPERA TE

(green LED on) to STANDBY (orange LED on).

NOTE

When switching to operate from standby,
allow at least a 30-minute warmup before
beginning sweep generator operations.

3-12 681XXB OM

LOCAL (FRONT INSTRUMENT
PANEL) OPERATION START-UP

Self-Testing
the 681XXB

During self-test with RF OUT PUT set to ON, the output
power level is set to 0 dBm. Always disc on n ect sensitive
equipment from the unit before performing self-test.

The 681XXB firmware includes internal diagnostics
that self-test the instrumen t. The se self-test diag ­nostics perform a brief go/no -go test of most of the
PCBs and other internal assemblies. If the sweep
generator fails self-test, an error message is dis­played on the data display. Error messages and de­scriptions ar e listed in the Operator Maintenan ce
chapter of this manual.

CAUTION

You can perform a self-test of the sweep generator
at any time during normal operation. To perfo rm a
self-test from any menu, press
when the System Menu (below ) is displayed, press

Selftest .

SYSTEM . Then,

Resetting to
Default Pa ­rameters

You can reset the 681XXB to the factor y -selec ted de­fault parameter values at any time during normal
operation . The defau lt parameter s are shown in Ta­ble 3-1 on the followin g page.

NOTE

Resetting the instru men t clears the setup
presently in place. If these par ameter val­ues are needed for future testing, save
them as a stored setup before resetting
the sweep generator. (For information on
saving/recalling instrument setups, refer
to paragraph 3-14.)

To reset the sweep generator, press
When the System Menu (above) is displayed, press

Reset .

SYSTEM .

681XXB OM 3-13
Changed: November 1995

LOCAL (FRONT RESET (DEFAULT)
PANEL) OPERATION PARAMETERS

Table 3-1. Reset (Default) Param e nter s (1 of 2)

681XXB
MODEL

NUMBER

68137B 3.5 2.0 20.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 20.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68145B 3.5 2.2 20.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 20.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68147B 3.5 2.0 20.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 20.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68153B 3.5 2.0 26.5 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 26.5 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68155B 3.5 2.2 26.5 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 26.5 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68159B 3.5 2.0 26.5 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 26.5 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68163B 3.5 2.0 40.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 40.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68165B 3.5 2.2 40.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 40.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68169B 3.5 2.0 40.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 40.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68175B 3.5 2.2 50.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 50.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68177B 3.5 2.0 50.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 50.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68185B 3.5 2.2 60.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 60.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68187B 3.5 2.0 60.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 60.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0
68195B 3.5 2.2 65.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 65.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0

F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 M0 M1 M2 M3 M4 M5 M6 M7 M8 M9

FREQUENCY PARAMETERS (GHz)

∆F

68197B 3.5 2.0 65.0 2.0 5.0 8.0 1 1.0 14.0 17.0 20.0 3.5 2.0 65.0 2.0 5.0 8.0 11.0 14.0 17.0 20.0 1.0

681XXB
MODEL

NUMBER

68137B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68145B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68147B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68153B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68155B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68159B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68163B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68165B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68169B +1.0 0. 0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0

L0 L1 L2 L3 L4 L5 L6 L7 L8 L9

POWER LEVEL PARAMETERS (dBm)

3-14 681XXB OM

LOCAL (FRONT RESET (DEFAULT)
PANEL) OPERATION PARAMETERS

Table 3-1. Reset (Defau lt) Pa ra me nter s ( 2 of 2)

681XXB

MODEL

NUMBER

68175B +1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68177B +1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68185B +1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68187B +1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68195B +1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0
68197B +1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 –6.0 –7.0 –8.0

681XXB

MODEL

NUMBER

L0 L1 L2 L3 L4 L5 L6 L7 L8 L9

SWEEP

TIME

DWELL TIME

POWER LEVEL PARAMETERS (dBm)

STEP SWEEP LEVEL SWEEP

NUMBER OF

STEPS

DWELL TIME

NUMBER OF

STEPS

LEVEL

OFFSET

68137B 50 ms 50 ms 50 50 ms 50 0.0 dB
68145B 50 ms 50 ms 50 50 ms 50 0.0 dB
68147B 50 ms 50 ms 50 50 ms 50 0.0 dB
68153B 50 ms 50 ms 50 50 ms 50 0.0 dB
68155B 50 ms 50 ms 50 50 ms 50 0.0 dB
68159B 50 ms 50 ms 50 50 ms 50 0.0 dB
68163B 50 ms 50 ms 50 50 ms 50 0.0 dB
68165B 50 ms 50 ms 50 50 ms 50 0.0 dB
68169B 50 ms 50 ms 50 50 ms 50 0.0 dB
68175B 50 ms 50 ms 50 50 ms 50 0.0 dB
68177B 50 ms 50 ms 50 50 ms 50 0.0 dB
68185B 50 ms 50 ms 50 50 ms 50 0.0 dB
68187B 50 ms 50 ms 50 50 ms 50 0.0 dB
68195B 50 ms 50 ms 50 50 ms 50 0.0 dB
68197B 50 ms 50 ms 50 50 ms 50 0.0 dB

681XXB OM 3-15

LOCAL (FRONT ENTERING
PANEL) OPERATION DATA

3-6

ENTERING DA TA

Before pr oceedin g to the various modes of sweep generator oper ation ,
you need to kno w how to enter data from th e front panel. Entering
data refers to chan gin g a paramete r’s value by editing its curren t
value or entering a new value to replace the cur re nt valu e. The follow ­ing instructions describe how to (1) open a parameter, (2) edit its cur­rent value, and (3) en ter a new valu e.

A typical 681XX B men u display (below) is used throu ghou t the data
entry instruc tions. At this menu di splay, you can edit both the CW fre­quency and the outpu t power level parame ters.

If you wish to follow along on your synthesizer, you can obtain this
same menu display by resetting your instrumen t (pre ss
then press

Reset ).

SYSTEM ,

Opening the
Parame ter

In order for the value of a parame te r to be changed ,
the parameter mus t first be opened.

To open the frequenc y parameter from the abov e
menu, press
changes to show that the menu soft-key
has been pressed and that the frequency parameter
has been open ed . An open parameter i s indic ated by
placing it in a window with a movable cur sor under
its digits.

Only one parameter can be open at a time. If you
press

Edit L1, then the frequency parameter will

close and the power leve l parameter will ope n.

Edit F1 . The menu display now

Edit F1

3-16 681XXB OM

LOCAL (FRONT ENTERING
PANEL) OPERATION DATA

Cursor

Control

Key

Rotary

Data

Knob

Editing the
Current
Value

To change the curr ent valu e of a parameter by edit­ing, you can use either the cursor control key or the
rotary data knob.

Using the Cursor Control Key

Using the < and > pads of the cursor control key,
move the cur sor und er the digit wh er e you wan t to
begin editing. Then increase or decre a se the value
of the parameter using the ∧ or ∨ pad of the cursor
control key. The unit size of the increase or decrease
that occurs eac h time the ∧ or ∨ pad is pressed is de­termined by the cursor position .

Using the Rotary Data Knob

You can also increase or decrease the value of the pa­rameter using the rotar y data kn ob. Once you have
positioned the cursor under the digit where you
want to begin editing, slowly turn the knob cloc k ­wise or counter-c loc k wise to inc rease or dec rease
the value of the parameter by the uni t size. Turning
the knob rapidly changes the v alue of the parame­ter in larger steps.

Using a Set Incr emen t

When editing frequ enc y, power level, and time pa­rameters, you can incre ase or decr ease the par am e­ter’s value by a set amount each time the ∧ or ∨ pad
is pressed or the rotary data knob is turned clo ck­wise or counter-c loc k wise. For instruc tions on set­ting the increment size, refe r to the System
Configuration section of this chapter.

Now , try changing the current value of the CW fre­quency displayed on your synthesizer from 2.0 GHz
to 6.395 GHz. Use both the cursor co ntr ol key’s ∧
and ∨ pads and the rotary data kno b to make the
value chang es. Wh en you are fin ishe d, you r menu
display should look like the example below.

681XXB OM 3-17

LOCAL (FRONT ENTERING
PANEL) OPERATION DATA

To close the open parameter when you are finishe d
editing , pre ss
tion.

Edit F1 or make another menu selec-

Clear
Entry

Key

CLEAR
ENTRY

4

1

0

Back

Space

87

5

2

Keypad

Key

BACK

SPACE

9

6

3

Terminator

Keys

GHz

Sec
dBm

MHz

ms

dB

kHz

m

s

STEPS

Hz

ns

ADRS

Enterin g a
New Value

To change the curr ent valu e of a parameter by enter­ing a new value for the parameter, use the data en­try keypad and termin a tion keys.

As soon as you pr e s s one of th e ke ys on the data en­try keypad, the cur rent par ameter display clears for
entry of a new value . Enter the new value for the pa ­rameter, then press the appropr iate termin ator key
to store it in memory. If the entered value is outside
the allowable rang e of the open par ameter, the en­try is not accepted and the previous value for the pa­rameter is displayed.

NOTE

A frequency entry may be terminated in
GHz, MHz, kHz, or Hz; howev er, it is al­ways displayed on the data display in
GHz. A time entry may be terminated in
Sec, ms, µs, or ns; however it is always
displayed on the data display in Sec.

If you make an error durin g data entry, either (1)
press

BACK SPACE to delete the entry on e char ac­ter at a time starting from the last character en­tered, or (2) delete the entire entry by pressing
CLEAR ENTR Y . Then, reenter the corr ect value .

Now , try entering a new value for the CW frequency
displayed on you r synth esizer using the data entry
keypad and termin ation keys.

To close the open parameter when you are finishe d
entering data, press

Edit F1 or make another

menu selection.

3-18 681XXB OM

LOCAL (FRONT CW FREQUENCY
PANEL) OPERATION OPERATION

3-7

Refer to Chapter 7, paragraph 7-2
for Master-Slave mode operating
instructions.

CW FREQUENCY
OPERATION

NOTE

One of the sweep generator’ s major functions is to produce discrete
CW frequencies across the frequency range of the instrument. The fol­lowing parag r aph s describe ho w to place the 681XXB in the CW fre­quency mode, select a CW freque nc y and pow er level f or outpu t, and
activate the CW ramp. Use the CW Frequ ency Mode men u map (Cha p­ter 4, Figure 4-2) to follow the menu sequ ence s.

Selecting
CW Mode

To place the 681XXB in the CW frequen cy mode,
press the main menu key

CW/SW EEP

SELECT

At the resulting menu display, press
Menu (below) is displayed.

CW . The CW

Selecting
a CW
Frequency

NOTE

When the sweep generator is rese t, it
automatically come s up o per ating in the
CW frequency mode.

There are seve ral w ays to select a CW frequ en cy for
output. You can (1) edit the cu r r en t frequency, (2) en ­ter a new freque ncy, or (3) select one of the 20 pre­set frequency parameter s.

Editing the Current Frequency

Press

Edit F1 to open the frequenc y parameter,
then edit the current CW frequency using the cur­sor control key or the rotary data knob. To close the
open frequency parameter, press
another menu selection.

Entering a New Frequency

Press

Edit F1 to open the frequenc y parameter,
then enter the n ew CW frequ en c y usin g the key p ad
and appropriate ter minator key. T o close the open
frequency parameter, press
other menu selec tion.

Edit F1 or make

Edit F1 or make an-

681XXB OM 3-19

LOCAL (FRONT CW FREQUENCY
PANEL) OPERATION OPERATION

Selecting a Preset Frequency

To select one of the preset frequen cie s for outp ut,
press the main menu key

FREQUENCY

CONTROL

The CW Frequen cy Contro l menu (below ) is dis­played. This menu lets you (1) select preset frequ en ­cies F0, F1, F2, M1, or M2 for output, (2) go to the
frequenc y list menu, or (3) go to the tagged frequ en­cies menu.

Frequen cy Li st– To go to the Frequenc y List menu
(below), press
tag,edit, or output a frequ en cy from the li st.

Use the cursor contr ol key to select a frequ en cy
from the frequency list. The selected frequency is
highligh ted in rever se vide o and display ed in full be­low the frequenc y list.

Press

Tag to mark a selected frequency (place an F
in front of it). If the frequen c y is alread y tagged ,
pressing
selected frequen cies lets you qu ick ly swi tch betwee n
them using the scan key s of the Tagged Frequ enc ie s
menu.

Freqs List . This menu lets you

Tag will untag it (remov e the F ). Tag g ing

Press

Edit to edit the selected frequency or enter a
new frequ en cy.

3-20 681XXB OM

LOCAL (FRONT CW FREQUENCY
PANEL) OPERATION OPERATION

Press Output Freq to output the selected frequency.
This frequ en cy i s outpu t until yo u selec t another fre­quency from the list and press
the frequency list, the output frequency selection is
marked by a black square or, if tagged, an F h igh­lighted in rever se video.

Output Freq . On

Selecting a
Power Lev el

When you are finished, press
turn to the CW Frequency Contr ol men u display.

Scannin g Tagged Frequencies–To go to the
Tagged Frequencies me nu (below ) from the CW Fre­quency Control menu, press

This menu lets you select the tagged frequ enc ies for
output using the

Return to the CW Frequ en cy Con trol men u by press­ing Previous Menu .

While in the CW frequency mode, you can edit the
current CW frequency output power level or enter a
new output power level.

Scan Up and Scan Dn keys.

Previous Menu to re-

Tag Freq Menu .

Editing the Current Power Level

Press

Edit L1 to open the power lev el parame ter,
then edit the current power level using the cursor
control key or rotary data kno b. To close the open
power level par ameter, press
other menu selec tion.

Entering a New Power Level

Press

Edit L1 to open the power lev el parame ter,
then enter the n ew power lev el usin g the keyp ad
and appropriate ter minator key. T o close the open
power level par ameter, press
other menu selec tion.

Edit L1 or make an-

Edit L1 or make an-

681XXB OM 3-21

LOCAL (FRONT CW FREQUENCY
PANEL) OPERATION OPERATION

NOTE

You can al so selec t any of the pr eset
power levels or a power level sweep for a
CW frequency. For instructions, refer to
the Fixed Power Level Operation and
Power Level Sweep Operation section s o f
this chapter.

CW Ramp When active, the sweep generator’ s CW ramp pro-

vides a repetitive 0V to 10V ramp output to the rear
panel HORIZ OUT BNC connec to r an d AUX I/O con-
nector. The CW ramp is used to drive a scalar ana­lyzer display.

To go to the CW Ramp menu (below) from the CW
menu, press

CW Ramp Menu .

This menu lets you set the ramp speed and turn the
CW ramp on/off.

To set ramp speed, press
time parameter opens for editin g. Edit the curre nt
sweep time using the cur sor con trol ke y or rotary
data knob or enter a new sweep time using the key
pad and approp riate ter mination key. The sweep
time entered must be in the range of 30 ms to
99 sec. To close the open sweep time parameter
when you are done, press
other menu selec tion.

Press

CW Ramp to turn the CW ramp on. While
the CW ramp is on, the message
pears on the right side of frequ enc y title bar on all
CW menus.

Press

Previous Menu to return to the CW menu.

Sweep Time . The sw eep

Sweep Time or make an-

CW Ramp ap-

3-22 681XXB OM

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

3-8

In 681X5B models performing ana­log sweeps between 0.5 and

2.2 GHz, the sweep is phase-lock
corrected as follows. For sweep
widths of >25 MHz, phase-lock cor­rection occurs at both the start and
stop frequencies and at each band­switch point. For sweep widths of
≤25 MHz, o nly th e center f reque ncy
of the sweep is phase-lock corrected.

SWEEP F REQUENCY
OPERATION

NOTE

The sweep gen er a tor can g ener a te broad (fu ll ran g e) an d nar r ow band
sweeps acro ss the frequ en c y rang e of the ins trumen t. Th e 681XX B ha s
three sweep fre que ncy modes—an alog swee p, step sweep , and manu a l
sweep. The following paragraphs describe how to select each sweep fre­quenc y mode, a sw eep ran ge, an ou tpu t pow er lev el, a sweep trigg er,
and frequen c y mar k ers. U se the An alog Sweep , Step Swee p, an d Ma n ­ual Sweep Freque ncy Mode menu maps (Chapter 4, Figur es 4-3, 4-4,
and 4-5) to follow the menu sequen ces.

Selecting
Analog
Sweep Mode

In analog sweep fr equ enc y mode, the sweep ge ner­ator’s output frequency is swept between selected
start and stop frequenc ies. When the sweep width is
>100 MHz, the sweep is phase-lock corr ec ted at
both the start and stop freque ncies and at each
band-switc h point. Wh en the sweep width is
≤100 MHz, only the cen ter frequency of the sweep is
phase-loc k correc ted.

To place the 681XXB in analog sweep frequen cy
mode, press the main menu key

CW/SW EEP

SELECT

At the resulting menu display, press
Analog Swee p Men u (below ) i s then displayed.

Analog . The

This menu lets you perform the following:

Select a sweep range (ed it the sweep s tart and
stop frequency parameters).
Go to the sweep ramp menu (set the sweep
time and select a sweep trigger).
Select an output power level for the sweep .
Go to the alternate sweep menu.

681XXB OM 3-23

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Setting the
Analog
Sweep Time

The duration of the analog sweep can be set for any
time in the range of 30 ms to 99 sec. The sweep time
parameter is set from the sweep ramp menu.

To go to the Analog Sweep Ramp men u (below ) from
the Analog Swe ep men u , pre ss

This menu lets you set the sweep time and go to the
trigger men u.

To open the sweep time paramete r for editin g, pre ss
Sweep Time . Edit the cur rent swee p time usin g
the cursor control key or the rotary data knob or en ­ter a new sweep time using the key pad and appro­priate termination key. To close the open sweep time
parameter onc e you have set the desired time, pre ss

Sweep Time or make an othe r menu selection .

Sweep Ramp .

To go to the Analog Swee p Trigger menu from this
menu, press
scribed on the next page .

Press

Previous Menu to return to the Analog
Sweep menu.

Trigger Menu . Sweep trigger is de-

3-24 681XXB OM

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Selecting a
Sweep
Trigger

The 681XXB pr ov ides sweep triggering for analog
frequency sweep, step frequency sweep, and CW
power sweep. The sweep generator has three modes
of sweep triggerin g , each selectable f rom the trig ge r
menu. The following is a description of each mode.

Auto (Auto matic)–The sweep continually
sweeps from its start frequency or power level
to its stop frequency or power level with opti­mal retrace time.
External–Th e swee p rec u r s when trig ger ed by
an external TTL-c ompatible clo ck pulse to the
rear panel AUX I/ O connector.
Single–A single sweep starts when the trigger
key is pressed. If a sweep is in progress when
the key is pressed, it aborts and resets.

To go to the Analog Swee p Trig ger me nu (be low )
from the Analog Sweep Ramp men u, press
Trigger Menu .

To select a sweep trigger mode , pres s its menu soft­key. A message showing the sweep trigger mod e se­lected appear s on the right side of frequ en cy title
bar. When you are finished, press
to return to the Analog Sw eep Ramp menu.

If you selec t the sin gle sweep trigger mo de, the
menu display adds the menu sof t-key
ing

Trig starts a single sweep. If a single sweep is
in progress, pressing
abort and reset.

Trig causes the sweep to

Previous Men u

Trig . Press-

681XXB OM 3-25

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Selecting
Step Sweep
Mode

In step sweep frequency mode, the output frequency
changes in discrete, syn th esized step s between se­lected start and stop frequen cie s. Step sweeps can
be from a high frequency to a low frequency and
vice versa. The step size or number of steps between
the start and stop frequenc ies and the dwell time­per-step are contr ollable from a step sweep menu .

To place the 681XXB in step sweep fre que ncy mo de,
press the main menu key

CW/SW EEP

SELECT

At the resulting menu display, press
Step Sweep Menu (below) is then displayed .

Step . The

This menu lets you perform the following:

Select a sweep range (ed it the sweep s tart and
stop frequency parameters).
Go to the sweep ramp menu (set the dwell
time-per-step, the step size or number of steps,
and select a sweep trigger).
Select an output power level for the sweep .
Go to the alternate sweep menu.

3-26 681XXB OM

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Setting Step
Size and
Dwell T ime

There are two ways to set the size of each step of
the step sweep—set the step size or set the number
of steps. The step size range is 1 kHz to the full fre­quency range of the sweep generator (0.1 Hz to full
frequency range with Option 11); the number of
steps range is 1 to 10,000. The dwell time-per-step
of the step sweep c an be set for any time in the
range of 1 ms to 99 sec. The step size and dwell
time-per-step parameters are set from the step
sweep ramp menu.

To go to the Step Sweep Ramp menu (below) fro m
the Step Sweep men u, pr e ss

This menu lets you set the dwell time, the step size,
the number of steps, and go to the trigger men u.

Sweep Ramp .

RANGE

This error message is displayed
when (1) the step size value entered
is greater than the sweep range or
(2) the number of steps entered re­sults in a step size of less than 1 kHz
(0.1 Hz with Option 11). Entering a
valid step size will clear the error.

Press

Dwell Time to open the dwell time-per-step

parameter.
Press

Step Size to open the step size parameter.
Num of Steps to open the number of step s

Press
parameter.

Open the parameter you wi sh to change, then edit
the current value using the cur sor contr ol key or the
rotary data knob or enter a new valu e using the key
pad and approp riate ter mination key. When you
have finished setting the ope n parameter, close it by
pressing its menu soft-key or make another menu
selection.

To go to the Step Sweep Trigger menu from thi s
menu, press
you select a sweep trigger (previou sly described on
page 3-25).

Press

Previous Menu to return to the Step Sweep

menu.

Trigger Menu . The trigger menu lets

681XXB OM 3-27

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Selecting
Manual
Sweep Mode

In manual sweep fr equ en cy mode, the outp ut fre­quency can be manually tuned in phase-lo cked
steps between the selected start and stop frequ en­cies using the rotary data knob. As the knob is
turned, the current output frequency is displayed on
the data display as Fm. The step size or number of
steps between the start and stop frequenc ies are
controllable from th e manual swee p menu .

To place the 681XXB in manu al sweep frequ en c y
mode, press the main menu key

CW/SW EEP

SELECT

At the resulting menu display, press
Manual Sweep menu (below) is then displayed.

Manual . The

This menu lets you perform the following:

Select a sweep range (edi t the start and stop
frequency par ameters).
Set the step size or number of steps (pre­viously described on page 3-27).

3-28 681XXB OM

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

RANGE

This error message is displayed
when (1) the an alog swe ep s tart fre­quency entered is greater than the
stop frequency, or (2) the dF value
entered results in a sweep outside
the range of the 681XXB. Entering
valid values will clear the error.

Selecting a
Sweep Range

Selecting a sweep range involves choosing a start
and a stop frequenc y for the frequ en c y sweep. The
sweep range selection process is identical for all
sweep frequency modes (analog, step, and manual).
There are seve ral w ays you can selec t a swee p
rang e, in clu d in g :

Editing the current start and stop frequency
parameter values.
Enterin g new start and stop frequ en cy par ame­ter values.
Selecting one of the preset sweep ran ge pa ­rameters (F1-F 2, F3-F4, F5-dF, or F6-dF).

Editing the Current Start / Stop Frequencies

To edit the current sweep r ang e s tart by open in g
either the start or stop freque ncy parame ter (in the
display above,
rameter;
ter).

Edit the open frequ ency parameter using th e cu r sor
control key or the rotar y data knob. Wh en you are
finished, close the open parameter by pressing its
menu edit soft-key or by mak ing another menu se­lection.

Entering Ne w Star t / Stop Freq uen cies

To enter a new sweep ran g e start by open in g either
the start or stop frequenc y parameter (press
or

Edit F2 ).

Edit F1 open s th e start fr equ en c y pa-

Edit F2 open s th e stop frequency parame-

Edit F1

Enter a new frequen c y using the keyp ad and appr o­priate terminator key. When you are finished, close
the open parameter by pressing its menu edit soft­key or by making ano ther menu selection.

681XXB OM 3-29

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Selecting a Preset Sweep Range

There are four preset sweep ran ge parame ters, se­lectable in the analog swee p, s tep sweep, and man­ual sweep freque ncy modes. Th e followin g is a
description of each preset sw eep range .

F1-F2–provides a frequency sweep between
the start frequency, F1, and the stop frequency,
F2.
F3-F4–provides a frequency sweep between
the start frequency, F3, and the stop frequency,
F4.
F5-dF–pr ov ides a symmetric al frequ en cy
sweep about the center frequ en cy, F5. The
sweep width is determined by the dF fre­quency parameter.
F6-dF–pr ov ides a symmetric al frequ en cy
sweep about the center frequ en cy, F6. The
sweep width is determined by the dF fre­quency parameter.

To select one of the preset sweep rang es from an y
sweep frequency mode menu, press the main menu
key

FREQUENCY

CONTROL

The Sweep Frequ en cy Contro l menu (below ) is dis­played.

This menu lets you perform the following:

Select a full range sweep (Fmin–Fmax ) or one
of the preset sweep ranges for the sweep fr e­quency mode.
Select the frequenc y parameter s for each pre­set sweep rang e.
Select an output power level for the sweep .
Go to the marker list menu.

3-30 681XXB OM

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Setting a Pres et Sweep Rang e –At the men u, se­lect the swe ep ran g e ( F1-F 2 , F3- F4, F5-dF, or
F6-dF) that you wish to set. The menu then display s
the current frequ en cy par ameter s for the selected
sweep range. Now, use the menu edit soft-ke ys to
open the frequency parameters for editin g.

Edit the current frequency parameters or enter new
frequenc y parame ter value s for the sweep ran ge. To
close the open frequ en c y parameter when you are
finished, press its menu edit soft-ke y or make an­other menu selec tion.

You can set all the preset sweep ranges in this man­ner.

Selecting a
Power Lev el

While at the Sweep Frequency Control menu, you
can edit the curre nt ou tp ut pow er leve l or ente r a
new output power level for the frequency sweep.

Editing the Current Power Level

Press

Edit L1 to open the power lev el parame ter,
then edit the current power level using the cursor
control key or rotary data kno b. To close the open
power level par ameter, press
other menu selec tion.

Entering a New Power Level

Press

Edit L1 to open the power lev el parame ter,
then enter the n ew power lev el usin g the keyp ad
and appropriate ter minator key. T o close the open
power level par ameter, press
other menu selec tion.

You can al so selec t any of the pr eset
power levels fo r a frequency sweep or a
power level step for analog and step
sweeps. For instruc tion s, re fer to the
Fixed Power Lev el Op eration and Power
Level Sweep Op er a tio n sectio ns of thi s
chapter.

Edit L1 or make an-

Edit L1 or make an-

NOTE

681XXB OM 3-31

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Frequency
Markers

The sweep gen era tor prov ides up to 20 indepen den t,
pre-settable markers, F0-F9 and M0-M9, that can
be used in the analog and s tep sweep frequen c y
modes for precise frequency identification. Marker
frequenc y accu rac y is the same as sweep freque ncy
accurac y. The markers are visible on a CRT display.

The 681XXB gener ates two types of mark ers.

V ideo Marker–produces a pulse on a CRT dis­play at each marker frequency. The video
marker is either a +5V or a –5V pulse at the
rear panel. The polar ity of the video mark er
pulse is selectable from a system config uration
menu.
Intensity Marker–produces an intensified
dot on a CRT display at each marker fre­quency. Intensity mar ker s are only available
in the analog sweep frequency mode and are
obtained from a momentary dwell during the
sweep at each marker frequency.

To output markers dur in g a sweep you must first se­lect (tag) the marker frequencies from the Marker
List menu, then turn on the marker output.

To go to the Marker List menu from an analog or
step sweep frequen cy men u, pre ss

FREQUENCY

CONTROL

The Sweep Frequ en cy Contro l menu (below ) is dis­played.

To go to the Marker List menu from this menu,
press

Marker List . The Marker List menu, shown
on the next page, is displayed. This menu lets you
tag or edit marker list frequencies and turn the
mark ers on/off.

3-32 681XXB OM

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Use the cursor contr ol key to select a frequ en cy pa­rameter from the marker list. The selec ted fre ­quency par ameter is highlighted in reverse v ideo
and displayed in full below the marker list.

Editing a Mark er Li st Freq uen cy

If you want to chang e a selected mar ker li st fre­quency parameter’s value, press
frequency parameter, then edit the current fre­quency or enter a new frequency.

Edit to open the

Tagging a Marker List Frequency

Only frequenc ies on the marke r list that have been
tagged can be outpu t as marker s durin g a sweep .
Press

Tag to tag a selected frequency parameter
(place an m in front of it). If a frequency parameter
is already tagged, pressing
move the m).

Activating Markers

The soft-keys
toggle the marker s on an d off.

V ideo Marker s–To output the tagged mar ke r fre­quencies as video mark er s durin g an analog or step
sweep, pres s
displayed on the CRT for all tagged mark er frequen ­cies that are within the sweep fre que ncy rang e.

Intensity Markers–(only available in analog
sweep frequency mode) T o ou tput th e tagged marker

frequenc ies as intensity marke rs du rin g an analo g
sweep, pres s
will be displayed on the CRT for all tagge d mark er
frequenc ies that are within the analog swe ep fre­quency ra nge.

Video Markers and Intensity Markers

Video Markers . Video markers will be

Intensity Markers . Intensity markers

Tag will untag it (re-

Press

Previous Menu to return to the Sweep Fre­quency Control menu.

681XXB OM 3-33

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Selecting
Alternate
Sweep Mode

In alternate sweep fr equ ency mode, the swee p gen­erator’s output frequency sweeps alternately be­tween any two sweep rang es in analo g sweep or any
two sweep ranges in step sweep. The proc ess of se­lecting and activ ating the alternate swe ep i s identi­cal for both analog and step sweep frequ en cy modes.

To select the alternate sweep mode for analog
sweeps, start with the Analog Sweep M en u display;
to select the alternate sweep mode for step sweeps,
start with the Step Sweep Men u display (below).

To go to the Alternate Sweep menu (belo w) from the
Step Sweep menu, press

Alt Swp Menu .

This menu lets you perform the following:

Turn the alternate sweep mode on/o ff.
Go to the alternate range men u to select a
sweep range for the alternate sweep.
Go to the alternate level menu to select a
power level for the alternate sweep.

Activat ing the A lt erna te Sweep

The Alternate Sw eep me nu soft-k ey
gles the alternate sweep mode on and off .

Press

Alt Sweep to turn on the al ternate swee p
mode. Notice th at the Alter nate Sw eep men u (on
the following page) chang es to show tha t the alter­nate sweep is now active.

Alt Sweep tog-

3-34 681XXB OM

Changed: November 1995

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

Now, press Previous Menu to return to the Step
Sweep Menu display (or the Analog Sweep Men u
display if oper atin g in analog sweep frequ enc y
mode).

Notice the changes to the Step Sweep Me nu display
(below). These chan g es indic ate that the altern ate
sweep frequency mode is active.

Now, press
nate Sweep menu.

Selecting an A lt ern ate S weep Ran g e

To go to the Alternate Rang e menu (below ) from th e
Alternate Sweep menu, press

Select the alternate sweep ran ge (Full, F1-F2, F3-F4,
F5-dF, or F6-dF). The menu then displays the cu r-
rent freque ncy parame te rs for the selec ted sweep
range. If you wish to chan ge a frequ en cy par ameter,
use the menu edit soft-key to open the parameter,
then edit it.

Alt Swp Men u to r etu rn to th e Alter-

Alt Range .

681XXB OM 3-35
Changed: November 1995

LOCAL (FRONT SWEEP FREQUENCY
PANEL) OPERATION OPERATION

When you are done selec tin g the altern ate swee p
range, press
nate Sweep menu.

Selecting a n A ltern ate Swee p Po wer Lev el

To go to the Alternate Level men u (be low ) from th e
Alternate Sweep menu, press

Select the power level for the alternate sweep ran ge
(L0, L1, L2, L3, or L4). The menu then displays the
current lev el parame ter for the selected power level.
If you wish to change the level, use the menu edit
soft-key to open the parameter, then edit it.

Previous Menu to retu rn to the Alter-

Alt Level .

A men u edit soft-ke y is also provided to let you
change the power level of the main sweep.

CAUTION

Performin g altern a te sweeps usin g power lev els that cr os s
step attenuator switch points can cause excessive wear on
the switches and reduce the life expectancy of the step at­tenuator.

When you are done selecting the power level for the
alternate sweep ran ge and editin g the powe r level
of the main sweep, press
to the Alternate Sw eep men u.

Previous Men u to return

3-36 681XXB OM

Changed: November 1995

LOCAL (FRONT FIXED POWER
PANEL) OPERATION LEVEL OPERATION

3-9

FIXED POW ER LEVEL OPERATION

The sweep gen era tor prov ides lev eled ou tpu t power over a maximum
range of up to 28 dB (up to 131 dB with Option 2) for CW and sweep
frequency operations. Units with Option 15A provide leveled output
power over a maximu m range of up to 22 dB (up to 125 dB with Op­tion 2). The follow in g par ag r aphs describe how to place the 681X X B in
fixed (no n-sw ep t) powe r lev el mode, select a powe r lev el for outpu t,
and activate lev el offset. Use the Fix ed (Non -Sw ept) Pow er Level
Mode menu map (Chapte r 4, Figure 4-6) to follow the menu sequen c es.

Selecting
Fixed Power
Level Mode

To place the 681XXB in a fixed power level mode
from a CW or sweep (analog , step, or manual) fre ­quency menu , press the main men u key

LEVEL/ALC

SELECT

At the resulting menu display, press
Level Menu (below) is displayed.

Level . The

This menu lets you perform the following:

Edit the power level par ameter.
Edit the level off se t parameter.
Turn level offset on/off.

Selecting a
Power Lev el

There are seve ral w ays to select a power lev el for
output. You can (1) edit the cu r r en t po we r lev el, (2)
enter a new pow er level, or (3) selec t one of the 10
preset power lev el parameters.

Editing the Current Power Level

Press

Edit L1 to open the power lev el parame ter,
then edit the current power level using the cursor
control key or the rotar y data knob. To close the
open power level parameter, press
another menu selection.

Entering a New Power Level

Press

Edit L1 to open the power lev el parame ter,
then enter the n ew power lev el usin g the keyp ad

Edit L1 or make

681XXB OM 3-37

LOCAL (FRONT FIXED POWER
PANEL) OPERATION LEVEL OPERATION

and appropriate ter minator key. T o close the open
power level par ameter, press
other menu selec tion.

Selecting a Preset Power Level

To select one of the preset power leve l s for output,
press the main menu key

LEVEL

CONTROL

The Level Control menu (below) is displayed.

Edit L1 or make an-

This menu lets you perform the following:

Select preset power levels L0, L1, L2, L3, or L4
for output.
Go to the Level List menu.
Go to the T ag ged Lev els menu.

Level List– To go to the Level List menu (below),
press

Level List .

This menu lets you select a powe r level fr om the li st
to tag, edit, or output.

Use the cursor contr ol key to select a power lev el
from the level list. The selected power lev el is high­lighted in rever se video and display ed in full below
the level list.

3-38 681XXB OM

LOCAL (FRONT FIXED POWER
PANEL) OPERATION LEVEL OPERATION

Press Ta g to mark a selected power level (place an
L in front of it). If a power leve l is alread y tagged ,

pressing
selected power levels le ts you quick ly switch be ­tween them using the scan keys of the Tagged Lev­els menu.

Press
a new power level.

Press
This power level is output until you select another
level from the list and press
level list, the outpu t power level selection is marked
by a black square or, if tagged, an L high lighted in
reverse video.

Tag will untag it (remov e the L ). Tag g ing

Edit to edit the selected power level or enter

Output Level to output the selected level.

Output Level . On the

When you are finished , press
turn to the Level Control men u display.

Scanning Tagged Levels–To go to the T ag g ed Lev ­els menu (show n belo w) from the Level Control
menu, press

This menu lets you select the tagg ed powe r level s
for output using the

Return to the Level Con tro l menu di splay by press­ing

Previous Men u .

Tag Lvl Menu .

Scan Up and Scan Dn keys.

Previous Men u to re-

681XXB OM 3-39

LOCAL (FRONT FIXED POWER
PANEL) OPERATION LEVEL OPERATION

Level Offset Level offset lets you compensate for a device on the

sweep generator’s outp ut that alters the RF outpu t
power level at the poin t of interest. For example,
the power level at the test device may be less or
more than the displayed powe r level bec ause of the
loss through an external transmission line or the
gain of an amplifier located between the 681XX B
RF output and the test device. Using the level offset
function, you can apply a con stant to the displayed
power level that co mpen sa tes for this loss or gain.
The displayed powe r level will the n reflec t the ac­tual power level at the test device.

To enter an offset value and apply it to the dis­played pow er level, go to the Level Me nu. Then
press

Edit Offset . As shown in th e fo llowing menu,

this opens the offset par ameter for editing.

OFFSET

When Offset is selected ON, this
status message is displayed on all
menu displays to remind the oper a­tor that a con s tant ( offset) h as been
applied to the displayed power level.

Edit the current offset value using the cursor con­trol key or rotary data knob or enter a new offset
value using the keypad an d appr opr iate termin ator
key. To close the open offset par ameter when you
are done, press
selection.

Press

Offset to apply the offset to the displayed
power level. In this example, a+2.00 dB offset is
applied to L1. L1 then displays a power level of
+2.00 dBm.

Edit Offset or make another menu

3-40 681XXB OM

LOCAL (FRONT POWER LEVEL

CAUTION

PANEL) OPERATION SWEEP OPERATION

3-10

POWER LEVEL
SWEEP OPERATION

The sweep gener a tor provides lev eled ou tpu t power swee ps at CW fre­quencies and in conjun ction with frequency sweeps (analog and step).
Power level swe eps c an be from a high level to a low leve l or vice
versa. The followin g parag raph s prov ide desc ription s an d oper ating in­structions for the CW power sweep mode and the sweep frequency/
step power modes. Use the CW Power Sweep Mode and Sweep Fre ­quency/Step Pow er Mode menu maps (Chapter 4, Fig ures 4-7 and 4-8)
to follow the menu sequenc es.

Performing power level sweeps that cross step attenuator
switch points can cause excessive wear on the switches and
reduce the life expec tanc y of the step attenuator.

Selecting
CW Power
Sweep Mode

In the CW power sweep mode, output power steps
between any two powe r levels at a single CW fre­quency. Menus provided let you set or selec t the
sweep range, the step size, the dw ell time-per-step,
and the sweep trig g er.

To place the 681XXB in a CW power sweep mode
from a CW frequency menu, press the main menu
key

LEVEL/ALC

SELECT

At the resulting menu display, press
CW Level Sweep Menu (below) is displayed.

This menu lets you perform the following:

Select a power level sweep ran ge (edit the
sweep start and stop power level parameters).
Go to the sweep ramp menu (set the dwell
time-per-step, the step size or number of steps,
and select a sweep trigger).

Lvl Swp . The

681XXB OM 3-41
Changed: November 1995

LOCAL (FRONT POWER LEVEL
PANEL) OPERATION SWEEP OPERATION

Setting CW
Power Sw ee p
Step Size
and Dwell
Time

There are two ways to set the size of each step of
the CW power sweep— set the step size or set the
number of steps. The step size range is 0.01 dB to
the full power range of the synth esizer ; the number
of steps range is 1 to 10,000. The dwell time-per­step of the CW power sweep can be set for any time
in the range of 1 ms to 99 sec. The step size and
dwell time-per- step are set from the CW level sweep
ramp menu.

To go to the CW Level Sweep Ramp menu from the
CW Level Sweep men u , pr es s

This menu lets you set the dwell time, the step size,
the number of steps, and go to the trigger men u.

Sweep Ramp .

RANGE

This error message is displayed
when (1) the step size value entered
is greater than the level sweep
range or (2) the number of steps
entered result s in a step size of less
than 0.01 dB. Entering a valid step
size will clear the error.

Press

Dwell Time to open the dwell time-per-step
parameter.

Press

Step Size to open the step size parameter.

Num of Steps to open the number of step s

Press
parameter.

Open the parameter you wi sh to change, then edit
the current value using the cur sor contr ol key or ro­tary data knob or enter a new value usin g the key
pad and approp riate ter mination key. When you
have finished setting the ope n parameter, close it by
pressing its menu soft-key or by making another
menu selection.

To go to the CW Level Sweep Trigger menu from
this menu, press
lets you select a CW power sweep trigg er.

Press

Previous Menu to return to the CW Level
Sweep menu.

Trigger Menu . The trigger menu

3-42 681XXB OM

LOCAL (FRONT POWER LEVEL
PANEL) OPERATION SWEEP OPERATION

Selecting a
CW Power
Sweep
Trigger

There are three modes of triggering provided for the
CW power sweep— automatic , exter nal, and sing le.
The sweep trigg er is selec table from the CW Level
Sweep T r ig ger menu . The followin g is a description
of each trigger mode.

Auto (Auto matic)–The CW power sweep con­tinually sweeps from its start power level to
its stop power level with optimal retrace time.
External–Th e CW pow er sweep rec urs wh en
triggered by an extern al TTL-compatible c loc k
pulse to the rear panel AUX I/O connect or.
Singl e –A single CW power sweep starts when
the trigger key is pr es sed. If a sweep is in pro­gress when the key i s pressed, it aborts an d r e­sets.

To go to the CW Level Sweep Trigger menu from the
CW Level Sweep Ramp men u, press

Trigger Menu .

To select a CW power sweep trigg er mode, press its
menu soft-key. A message showing the CW pow er
sweep trigger mode selec ted appear s on the right
side of the level mode title bar .

If you selec t the sin gle sweep trigger mo de, the
menu display ch ang es, add ing the men u soft-k ey la­beled

Tr ig . Pressing Trig starts a single CW
power sweep. If a single CW pow er sweep is in pro­gress, pres sing
reset.

Press

Previous Menu to return to the CW Level

Sweep Ramp menu.

Trig causes the sweep to abort and

681XXB OM 3-43

LOCAL (FRONT POWER LEVEL
PANEL) OPERATION SWEEP OPERATION

Selecting a
Power Lev el
Sweep Range

Selecting a power level sweep r ange c onsists of
choosing a start and stop level for the pow er level
sweep. The power level sweep range selection proc­ess is identical for all power level swe ep modes—
CW power sweep, analog sweep frequency/step
power, and step sweep fr equ enc y /step pow er. You
can select a power lev el swee p ran ge as follows:

Edit the curren t star t and stop power level pa­rameter values.
Enter new start and stop power level parame­ter values.
Select one of the preset power level swee p
range parameters ( L1-L2, L3-L4, L5-L6, L7-L8,
or L9-L0).

Editing the Cur re nt Star t / Sto p Po wer Lev el s

To edit the current powe r level swee p rang e, start
by openin g either the start or stop powe r lev el pa­rameter (in the d i splay abov e,
start power level paramete r;
stop power level parameter) .

Edit the open powe r level par ameter using the cur­sor control key or the rotar y data kn ob. When yo u
are finished, close the open par ameter by pressin g
its menu edit soft-key or by mak ing another menu
selection.

Entering New Start / Stop Power Levels

To enter a new power level sw eep range start by
openin g either the start or stop power level parame ­ters (press

Enter a new powe r level usin g the keypad an d ap­propriate terminator key. When you are finished,
close the open parameter by pressing its menu edit
soft-key or by making an othe r menu selection .

Edit L1 or Edit L2 ).

Edit L1 open s th e

Edit L2 opens the

3-44 681XXB OM

LOCAL (FRONT POWER LEVEL
PANEL) OPERATION SWEEP OPERATION

Selecti ng a Preset Powe r Lev el Swee p Ran ge

There are five preset power level sweep range pa­rameters selectable in the pow er level swe ep modes.
These preset power level sweep r ang e par ameter s
are L1-L2, L3-L4, L5-L6, L7-L8, a nd L9-L0.

To select one of the preset power leve l sweep r ang es
from a Level Sweep menu, press the main menu key

LEVEL

CONTROL

The Level Sweep Con tro l menu (below ) is displayed.

In addition to letting you select one of the pre set
sweep ranges for the power level sweep, this menu
lets you set the start and stop power level parame­ters for each preset sweep range.

Setting a Pres et Power Level Sweep Range–At
the Level Sweep Contr ol menu, select the power
level sweep range (L1-L2, L3-L4, L5-L6, L7-L8, or
L9-L0) that you wish to set. The menu then displays
the current power level parame te rs for the selec ted
power level sweep range. Now, use the menu ed it
soft-keys to open the power lev el par ameter s for ed­iting.

Edit the current power level parameter values or en­ter new power lev el p arameter values for the power
level sweep rang e. To close the open power leve l pa­rameter when you are finish ed, pre ss its menu edit
soft-key or make another menu selection.

You can set all the preset power leve l sweep rang e s
in this manner.

681XXB OM 3-45

LOCAL (FRONT POWER LEVEL
PANEL) OPERATION SWEEP OPERATION

Selecting a
Sweep Fre­quency / Step
Power Mo de

In analog sweep fr equ en cy/ s tep power mode or step
sweep frequen c y/step pow er mode, a power leve l
step occurs after each frequen cy sweep. The powe r
level remains constant for the length of time re­quired to complete each frequen cy sweep. Menus
provided let you control the power level sweep
range and step size.

To select an analog swee p fre que ncy /step pow er
mode, start with an analo g sweep men u display; to
select a step sweep frequency /step pow er mode,
start with a step sweep menu display. Then press
the main menu key

LEVEL/ALC

SELECT

At the resulting menu display, press
Level Sweep Menu is displayed.

Lvl Swp . The

This menu lets you perform the following:

Select a power level sweep ran ge (edit the
sweep start and stop power level parameters).
Go to the sweep ramp menu (set the step size
or number of steps).

3-46 681XXB OM

LOCAL (FRONT POWER LEVEL
PANEL) OPERATION SWEEP OPERATION

RANGE

This error message is displayed
when (1) the step size value entered
is greater than the level sweep
range or (2) the number of steps
entered result s in a step size of less
than 0.01 dB. Entering a valid step
size will clear the error.

Setting
Power Lev el
Step Size

There are two ways to set the step size of the power
level step that occur s after each frequency sweep –
set the step size or set the number of steps. The
step size range is 0.01 dB to the full power range of
the synthesizer; the number of steps range is 1 to
10,000. The power level step size is set from the
level sweep ramp menu.

To go to the Level Sweep Ramp menu from the
Level Sweep menu, press

This menu lets you set the step size and the number
of steps.

Press

Step Size to open the step size parameter.
Num of Steps to open the number of step s

Press
parameter.

Open the parameter you wi sh to change, then edit
the current value using the cur sor contr ol key or ro­tary data knob or enter a new value usin g the key­pad and approp riate ter mination key. When you
have finished setting the ope n parameter, close it by
pressing its menu soft-key or by making another
menu selection.

Sweep Ramp .

Press

Previous Menu to return to the Level Sweep

menu.

681XXB OM 3-47

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

3-11

LEVELING
OPERATIONS

The 681XXB generates leveled output power over a maximum range
of up to 28 dB (up to 131 dB with Option 2). Instruments with Option
15A provide leveled outpu t power ov er a maximum ran g e of up to
22 dB (up to 125 dB with Option 2). An automatic lev el co ntr ol (ALC)
system contro ls the amplitude an d pow er level of the RF output. The
operator can selec t the ALC mode of oper ation —in ter nal, exter nal ( de­tector or power meter), or fixed gain (ALC off). In addition, the
681XXB provides (1) an ALC pow er slope fu nction that provides c om­pensation for high frequ enc y system or cable losses, (2) a decouple
function tha t allows decoup ling of the step attenuator (if equipped)
from the ALC system, and (3) a user level (flatne ss cor re ction ) calibr a ­tion function that pr ovides for calibrating out path variation s wi th fre­quency in a test setup.

The following paragraphs provide descriptions and operating instruc­tions for the power leveling modes and functions. Use the Leveling
Modes menu map (Chapter 4, Fig ure 4-9) to follow the menu se­quences.

Selecting a
Leveling
Mode

The ALC system is a feedback c ontrol sy s tem, in
which the output powe r is measured a t a detector
and compared w i th the expec ted pow er lev el. If the
output and desir ed pow er levels do not equal, the
ALC adjusts the power outp ut until they do. The
feedback signal can be pr ov ided by either the inter­nal detector or an exter nal detec tor or power meter.
Alternatively, the output power can be set to a fixed
level without usin g the normal feed back (ALC off).
The ALC mode menu lets you make the selection of
a leveling mode.

To go to the ALC Mode menu, first pr es s the main
menu key

LEVEL/ALC

SELECT

At the Level/ALC Select Menu display, press
ALC Mode . The ALC Mode M en u (below ) is dis­played.

3-48 681XXB OM

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

The ALC Mode men u lets you per form the follow in g :

Go to the leveling men u (selec t the ALC mo de
of operation).
Go to the attenuation menu (dec ou ple the at­tenuator, if equipped, from the ALC system
and set the power level and attenuation).
Select either the front pane l or rear panel ex ­ternal ALC input.

Interna l Lev el in g

This is the normal (default) lev elin g mode. Outpu t
power is sensed by the internal detector in the
681XXB. The detector outpu t signal is fed back to
the ALC circuitry to adjust the outpu t pow er lev el.
Internal ALC i s selected f rom the le ve ling menu .

To go to the Leveling M enu from th e ALC M ode
menu, press
(below) is displayed.

Leveling Men u . The Leveling Menu

To select inter nal AL C, press
Pressing one of the other leve ling men u soft-key s

External Detector , Power Meter , or Fixed Gai n
will turn off internal leveling.

Press

Previous Menu to return to the ALC M ode

menu.

Externa l Lev el in g

In external lev elin g, the outpu t pow er fr om the
681XXB is detected by an extern al detector or
power meter. The signal fro m the detec tor or pow er
meter is returned to the AL C c ircu itry. The ALC ad­justs the output power to keep the power lev el co n­stant at the point of detection. The exter nal AL C
source input is selected from the leveling menu.

Internal .

681XXB OM 3-49

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

Before goin g to the Levelin g Men u from the AL C
Mode menu, selec t wh ethe r the exter n al ALC sign a l
is to be connected to the front- or rear - pan el EXT
ALC IN connector.

At the ALC Mode menu , pr es s
lect front panel input, or
rear panel input.

Now, press
Menu.

Next, select the type of external sensor you are us­ing to detect the outp ut pow er.

To select the extern al ALC inpu t from an external
detector, press

To select the extern al ALC inpu t from a power me­ter, press

After you have made the external AL C inp ut c onn ec­tion and selected the sensor type, press AL C L o op .
The ALC Loop Me nu (be low ) is displayed.

Leveling Men u to go to the Leveling

External Detector .

Power Meter .

Ext ALC Fro nt to se-

Ext ALC Rear to select

While monitor in g the powe r level a t the extern al de­tection point, first press
cursor control ke y or rotar y data knob to adjus t the
external ALC sig n al to ob tain the set power level.

To return to the Leveling Me nu, press
then press

Leveling Menu .

Ext ALC Adj , then use the

ALC Mode

3-50 681XXB OM

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

At the Leveling menu, pressing either Internal or
Fixed Gain will turn off external leveling.

Previous Menu to return to the ALC M ode

Press
menu.

Fixed Gai n

In the fixed gain mod e, the ALC is disabled. The RF
Level DAC and step attenuator (if ins talled) are
used to control the re l ative pow er lev el. Pow er is
not detected at any point, an d the ab solute pow er
level is uncalibrated. Fix ed gain mode is selected
from the leveling menu.

Press

Leveling Menu to go to the Levelin g menu.

To select fixed gain mode, press
To return to normal A L C oper ation , pre ss

Previous Menu to return to the ALC M ode

Press
menu.

Fixed Gain .

Internal .

681XXB OM 3-51

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

Attenuator
Decoupling

In 681XXBs equipped with option 2 step attenu­ators, the ALC and attenuator work in co njunction
to provide leveled output powe r down to –120 dBm.
In the normal (coup led) lev elin g mode, whe n the de­sired power lev el is set, the correct combin ation of
ALC level and attenua tor setting is determined by
the instrument fir mwar e. In some application s,
such as receiver sensitivity testing, it is desireable
to control the ALC level and attenuator setting sepa­rately by decoupling the step attenuator from the
ALC. The ALC mode menu lets you select attenu­ator decoupling.

At the ALC Mode menu , pr es s
tenuator Menu (below) is displayed.

Atten Men u . Th e At -

NOTE

The set power level may not be
maintained when switching be­tween attenu ator cou plin g mod es.

This menu lets you decou ple the step attenu a tor
from the ALC, set the power leve l, and set the a t­tenuation in 10 dB steps.

Press

Decouple to decou ple the s tep attenua tor

from the ALC.
Press

Edit L1 to open the power lev el parame ter
for editing . Edit the curr ent level usin g the cur sor
control key o r rotary data knob or enter a new value
using the key pad and appropr iate te rmin ation key.
When you have finished setting the power level,
press

Edit L1 to close the open parameter.

To change the attenuation setting, press
or

Decr Attn . Pressin g these soft-key s chang es the

attenuation in 10 dB steps.
Press

Previous Menu to return to the ALC M ode
menu.

Incr Atten

3-52 681XXB OM

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

ALC Power
Slope

Power Level

The ALC power slope function lets you compensate
for system, cable, and waveguide variations due to
changes in frequency, by linearly increasing or de­creasing power ou tput a s the frequenc y increa ses.
As shown in the following illustration , the power
slope function provide s you with the ability to set
both the power slope and the piv ot poin t. Th e AL C
loop menu lets you activ ate the ALC p ower slope
function.

Power
Slope

Power Slope
Pivot Point

Power at DUT
With Compensation

Power at DUT
Without Compensation

Frequency

To go to the ALC Loop Menu from th e Le vel/ALC
Control Menu display, press

ALC Loop . Th e AL C

Loop Menu (below) is displaye d.

This menu lets you turn the powe r slope on or off
and edit the slope value and piv ot point fr equ en cy.

681XXB OM 3-53

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

Press Slope On/Off to activate the ALC power
slope function.

Press

Edit Piv ot to open the pivot point frequency
parameter for editing. Edit the current frequency us-

SLOPE

When Power Slope is selected ON,
this status message is displayed on
all menu displays to remin d the op­erator that a power slope cor rec tion
has been applied to th e ALC.

ing the cursor control key or rotary data knob or en­ter a new value using the keypad and appropriate
termination key. When you have finish ed settin g
the open parameter, close it by pressin g
again or by mak ing ano ther menu selection.

Press

Edit Slope to open the slope parameter for
editing. Edit the curren t slope valu e using the cur­sor control key or rotar y data knob or enter a new
value using the key pad and the STEPS termination
key. Whe n you have finish ed setting the open pa­rameter, close it by pressing
making anothe r men u selection .

Edit Slope again or by

Edit Pi vo t

While monitor in g the powe r level a t the device-un­der-te st (DUT), adjus t the powe r slope and pivo t
point to level the power at the DUT.

3-54 681XXB OM

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

GPIB

User Cal
(User Level
Flatness
Correction)

681XXB SWEEP GENERATOR

The User Cal (user level flatn es s correction ) fu nc­tion lets you calibrate out path variation s w ith fre­quency that are cau sed by exter nal switc h ing ,
amplifiers, co up ler s, and cables in the test setup.
This is done by means of an ente red p ower - offset ta­ble from a GPIB power meter or calculated data.
When user level flatne ss corr ection is activated, the
set power level is deliver ed at the point in the test
setup where the calibra tion was performe d. Thi s
“flattening” of the test point power level is accom­plished by summin g a power- offset wo rd (from the
power- offset table) with the sweep gener ator’s nor­mal power lev el DAC wo rd at each fr equ ency point.

Up to five user level flatness corr ectio n power-offset
tables from 2 to 801 frequency points/table can be
created and stored in 681XX B memory for recall.
The GPIB power meters supported are the Anr i tsu
Model ML4803A and the Hewlett-Packard Models
437B, 438A, and 70100A.

RF
OUTPUT

INPUT

SWITCH MATRIX,

AMPLIFIERS,

COUPLERS, ETC.

FLATNESS
CORRECTED
OUTPUT

DEVICE
UNDER

TEST

Figure 3-4. Setup for Creating a Pow er -Offs et Table (Use r Level Fla tnes s Corre ctio n)

POWER

SENSOR

GPIB

POWER

METER

681XXB OM 3-55

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

Equipment Setup

To create a power -off se t table for user level flatn ess
correction , connec t the equ ipmen t (show n in Figur e
3-4) as follows:

Step 1 Using a GPIB cable, conne ct the Pow er

Meter to the 681XXB.

Step 2 Calibrate the Power Meter with the

Power Sensor.

Step 3 Connect the Powe r Senso r to the point in

the test setup where the corrected power
level is desired.

Power Meter Model and G PI B A ddr ess

In order for the 681XXB to contro l the pow er meter,
the GPIB addres s and power meter model must be
selected from the Configure GPIB menu.

Press

SYSTEM to go to the System Menu display.

At the System Menu display, press
System Configuration Menu (below) is displayed.

Next, press
low) is displayed.

GPIB . The Config ure GPIB men u (be-

Config . The

3-56 681XXB OM

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

At the Configure GPIB menu , pres s More to go to
an additional Configure GPIB menu (below).

Press

Pwr Mtr Address to change the address of
the power mete r on the GPIB (the pow er meter’s de­fault address is 13). Enter the new addre ss, be­tween 1 and 30, usin g the cu rso r con trol ke y or the
data entry key pad and the terminator key

Hz

ns

ADRS

The new GPIB address will appear on the display.

Pwr Mtr Select to select the power meter

Press
model being used. (Su ppor ted pow er meter s are the
Anritsu ML4803A and Hewlett-Packard 437B,
438A, and 70100A.)

Press

Previous Menu to return to the main Config­ure GPIB menu display.

At the Configure GPIB menu , pres s
to return to the System Config u ration men u display.

Creating a Power-Offset Table

The 681XXB mus t be in CW frequency mode an d
fixed (no n-sw ep t) powe r lev el mode in orde r to cre­ate a power-offset table for user level flatne ss correc­tion.

Place the sweep generator in CW frequency mode
by pressing the main menu key

CW/SW EEP

SELECT

At the resulting menu display, press
681XXB is now in CW frequenc y mode.

Previous Menu

CW . The

681XXB OM 3-57

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

Place the sweep generator in a fixed power level
mode by pressing the main menu key

LEVEL/ALC

SELECT

At the resulting menu display, press
681XXB is now in fixed (non-sw ept) pow er level
mode.

At the Level Menu, press
Cal menu (below) is displayed.

This menu lets you perform the following:

Create a power- offset table.
Select a measurement frequ enc y range (edit
the start and stop frequency parame ters).
Select the number of points at which cor re c­tion information is to be taken.
Apply a power-offset table to the test setup.

User Cal . The User Level

Level . The

First, press the menu soft-ke y to select the power­offset table (User 1, User 2, User 3, User 4, or User

5) that you wish to create.
Next, set the measurement fr equ ency ran g e by

pressing
(Flo) or stop (Fhi) frequency parameter for editing.
Edit the current frequency using the cursor control
key or rotary data k no b or en te r a new value using
the keypad and appropr iate te rmin ation key. When
you have finishe d setting the open parameter, close
it by pressing its menu edit soft-key ag ain or by
making anothe r men u selection .

Then, select the numbe r of frequ en cy points at
which corre ction inf orm ation is to be taken by press­ing
rameter for editing . Edit the curr ent nu mber - of­points using the cursor con trol ke y or rotary data
knob or enter a new value using the keyp ad and the

Edit Start or Edit Stop to open the star t

Edit Points to open the number-of-points pa-

3-58 681XXB OM

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

STEPS termination key. (The number of points
range is 2 to 801.) When you have finishe d setting
the open number -of -poin ts par ameter, close it by
pressing
menu selection.

Edit Po in t s again or by making another

USER 1...5

When a power-offset table is se­lected ON, this status message is
displayed on all menu displays to
remind the oper ator that user lev el
flatness correction has been applied
to the ALC.

Now, press
power level cor re ction inf orm ation at each fre ­quency point. Durin g this process the men u dis­plays the status: Ca librating along with the current
measurement frequency point.

Once the power-offset table has been created, it is
stored in non-volatile memory. The power-offset ta­ble is now ready to be applied to the test setup. Dis­connect the Power Sensor and Power Meter from
the te st setup.

Applying User Level Flatness Correction

Whenever use r level flatness corr ection is applied to
the test setup by activating the power- offset table,
the set power level is deliv ered at the poin t whe re
the calibration was per for med.

To activate the selected pow er-offset table and apply
user level flatness cor rec tion to the test setup, pre ss
On/Off . The User Level Cal menu will display the
status: On.

To turn off the selected pow er-offset table and re­move user lev el flatness correction fr om th e te st
setup, press
menu will display the status: Off.

Start Cal to begin automa tically taking

NOTE

To terminate the measureme nt pr oce ss at
any time before completion, press

On/Off again . The User Lev el C al

Abort .

Entering a Power-Offset Table via GPIB

User level flatness correction can be applied to the
test setup using a power-offset table created from
calcula ted data and enter ed via the GPIB. Refe r to
the 681XXB Programmin g Manual (P /N 10370-

10260) for information and instructions on creating
a power-of fset table and enter in g it via the GPIB.

681XXB OM 3-59

LOCAL (FRONT LEVELING
PANEL) OPERATION OPERATIONS

Erasing th e Power -O f fset Tables from Memo ry

The power-o ffset tables are stored in non -volatile
memory. A master reset is required to erase the con­tents of the tables and reprogram them with default
data.

To perform a master reset, procee d as follows:

NOTE

The master reset function over­writes all information stored in the
non-volatile memory with default
values. This includes the nine
stored front panel setups.

Step 1 With the 681XXB in standby, press and

hold the RF OUTPUT ON/OFF ke y.

Step 2 Press the LINE OP ERATE/STANDBY ke y

to turn the instrument on.

Step 3 When the first menu is displayed (afte r

the start-up display), release the RF OUT-
PUT ON/OFF key.

The contents of non- vo latile memory have now been
erased and reprogrammed with default data.

3-60 681XXB OM

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

3-12

SIGNAL MODUL ATI ON

The sweep gener ator prov ides AM, FM, and square wave modulation
of the output signal. All modu lation modes—AM , FM, an d squar e
wave—can be activ e simultane ou sly. The following paragrap hs prov ide
description s and ope ratin g ins tructio ns for each modulation mode.
Use the Amplitude Modulation Mod e, Freque ncy Modu lation Mode,
and Square Wave Modulation Mo de men u maps (Chapte r 4, Figure s
4-10, 4-11, and 4-12) to follow the menu sequen c es.

Amplitude
Modulation
Operat ing
Modes

Providing
Amplitude
Modulation

The sweep gener ator has two AM operation modes—
Linear AM and Log AM. In Linear AM mode, sensi­tivity is continuously variable from 0 %/V to
100%/V. The amplitude of the RF output changes
linearly a s the ex ternal AM inpu t c han g es.

In Log AM mode, sen sitivity is c ontinu ou sly var i­able from 0 dB/V to 25 dB/V. The ampli tude of the
RF output chan ges e xpon en tially as the AM inpu t
changes.

To provide amplitude modu lation , fir st set up the ex­ternal signal generator, then connect it to either the
681XXB front or rear panel AM IN connector.

Next, press
display, press
(below) is displayed.

MODULATION . At the resu lting me nu

AM . The Ex ter nal AM Status Menu

This menu contains an external AM status window
that shows the current menu selections and the
measured AM De pth. (The AM depth measuremen t
function measu res the voltag e of the external modu ­lation signal and calcu lates the per cen tage modu la­tion value.) Th i s menu lets you perform the
followin g:

Turn AM on and off.
Select the Linear AM or Log AM oper atin g
mode.
Set the AM Sensitivity
Select the input impedance (600Ω or 50Ω ) of
the input con ne ctor.

681XXB OM 3-61

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

Select the input con ne ctor (fron t panel or rear
panel AM IN) that is connected to the external
signal source.

Press

On / Off to turn AM on and off. Both the AM
status display and AM modulation status ar ea w ill
reflect you r selec tion.

Press

Log / Linear to select the AM operating
mode. The AM status d isplay w ill r eflec t you r selec-

ERR

tion as XX dB/V (Log) or XX %/V (Linear ).

This error message is displayed
when the external AM modulating
signal exceeds the input voltage
range. The message “Reduce AM
Input Level” also appears at the bot­tom of the AM status display. AM is
turned off until the modulatin g sig­nal is within the input voltage
range.

NOTE

Refer to Appendix B, page B-5, for
the maximum FM deviation speci­fications for 681X5B models.

Frequency
Modulation
Operat ing
Modes

Press

Edit Sens to open the AM Sensitivity pa­rameter, then edit the current valu e using the cur­sor control key or rotar y data knob or enter a new
value using the keypad an d the appr opr iate termi­nator key (kHz/µs/STEPS for Linear; MHz/ms/dB for
Log). The AM Sensitivi ty range is 0 %/V to 100 %/V
in Linear and 0 dB/V to 25 dB/V in Log. To close the
open Am Sensitiv ity p arame ter, pr es s
make another menu selection .

Press

600Ω / 50Ω to select the input impedance of
the input con n ec to r. The AM status display will re­flect your selec tion.

Press

Front / Rear to select the front panel or rear
panel AM IN connector. The AM status display will
reflect you r selec tion.

The sweep gener a tor has two FM operation modes—
Locked FM and Unlocked FM. In Locked FM mode,
frequenc y modu l ation of the outpu t signal is acco m­plished by summin g the modulatin g signal in to the
FM control path of the YIG ph ase-loc k loop. Maxi­mum FM deviation i s the lesser of ±10 MHz or
Fmod x 300 for 1 kHz to 500 kHz rates.

In Unlocked FM mode, the YI G phase-lo ck loop i s
disabled to allow for peak FM deviation s of up to
100 MHz. There are two Unlock ed FM modes—Un­locked Narro w an d Unloc k ed Wide.

Edit Sens or

In Unlocked Narr ow mode, frequ en c y modulation is
obtained by apply ing the modu latin g signal to the
fine tuning coil of the YIG-tu ned osc illator. Un­locked Narro w FM mode allow s maximum dev i a­tions of ±10 MHz for DC to 500 kHz rates.

3-62 681XXB OM

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

In Unlocked W ide mode, frequ en cy modu lation is ac­complished by apply ing the modulatin g sign al to
the main tuning co il of the YIG-tu ne d oscillator. Un­locked W ide FM mode allow s maximum dev iation s
of ±100 MHz for DC to 100 Hz rates.

Providing
Frequency
Modulation

To provide frequ en cy modulation, first set up the ex­ternal signal generator, then connect it to either the
681XXB front or rear panel FM IN connector.

Next, press
display, press
(below) is displayed.

Now, press the menu soft-ke y
External FM Status Menu (below) is displayed.

MODULATION . At the resu lting me nu

FM . The External FM Status Menu

More . The additional

This menu lets you select the FM oper ating mode.
Press

UNLOCKED

When Unlocked Narrow FM or Un­locked W ide FM is sele cted ON, this
warning message is displayed on a ll
menu displays to remind the oper a­tor that the c arrier frequenc y is not
phase-locked.

Locked to select the Locked FM operating
mode; press
locked Narro w FM oper ating mode; or pres s
Unlocked Wide to select the Unloc k ed Wide FM
operating mode. The FM status display will reflect
your selection.

Press
nal FM Status Menu display (next page) .

Unlocked Narrow to select the Un-

Previous Menu to return to the main Exter-

681XXB OM 3-63

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

This menu contains an extern al FM status window
that shows the current menu selections and the
measured FM Deviation. (The FM deviation meas­urement func tion measur es the voltage of the exter ­nal modulation signal an d calc ul ates the peak
frequency deviation.) This menu lets you perform
the following :

Turn FM on/off.
Set the FM sensitivity.
Select the input impedance (600Ω or 50Ω ) of
the input con ne ctor.
Select the input con ne ctor (fron t panel or rear
panel FM IN) that is connected to the external
signal source.

ERR

This error message is displayed
when the external FM modulating
signal exceeds the input voltage
range. The message “Reduce FM
Input Leve l” also appear s at the bot­tom of the FM s tatus display. FM is
turned off until the modu lating sig­nal is within the input voltage
range.

Press

On / Off to turn FM on and off. Both the FM
status display and FM modulation status area will
reflect you r selec tion.

Press

Edit Sens to open the FM Sensitivity pa­rameter, then edit the current valu e using the cur­sor control key or rotar y data knob or enter a new
value using the keypad an d the appr opr iate termi­nator key. The FM Sensitivity range is ±1 kH z/V to
±20 MHz/V for Locked and Unlocked Narrow FM
modes and ±100 kHz/V to ±100 MHz/V for Unlocked
Wid e FM mode. To close the open FM Sensitivity pa­rameter, press
lection.

Press

600Ω/50Ω to select the input impedance of
the input connec tor. The FM status display will re­flect your selec tion.

Press

Front/Rear to selec t th e fr on t or rear pan el
FM IN connector. The FM status display will reflect
your selection.

Edit Sens or make another menu se-

3-64 681XXB OM

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

Square Wave
Modulation
Operat ing
Modes

Providing
Square Wave
Modulation

The 681XXB provides square wave (pulse) modula­tion of the output signal using modulatin g signals
from either its internal square wave generator or an
external signal generator.

The sweep generator’s internal square wave gener­ator outputs modu l a ting sig n a l s of 400 Hz, 1 kHz,

7.8125 kHz, and 27.8 kHz. Th e modulating sign al s
are selectable from a menu.

The 681XXB accepts modulating signals from an ex­ternal signal generator that are TTL-compatible
with the minimum pulse w idth of >5 µs.

The following are the menu selections necessary to
provide square wave (pulse) modulation of the out­put signal using a modulating signal from both the
internal an d exte rnal so urc es.

Press

MODULATION . At the resul ting men u dis-

play, press
Menu (below) is displayed.

SqWave . The Square Wave Status

This menu contain s the squar e wav e s tatus win dow
that shows the current menu selections. This me nu
lets you perform the follow ing :

Turn square wave modulation on/off .
Select Internal or Exter nal sou rce for the
modulation signal.
Select the polarity of the signal (Hig h or Low)
that turns the RF on.
Go to an additional menu (to select the fre­quency from the internal source or to select
the front or rear panel input connector).

681XXB OM 3-65

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

Press On/Off to turn square wave modulation on
and off. Both the Square Wave status display and
the Square Wave modulation statu s area will reflec t
your selection.

Press

Internal/External to select the sourc e of the
modul ating signal. If yo u select Internal, the status
display sho ws Sour ce a s Inter nal an d Frequency
lists the actual source frequency. If you select Exter­nal, the di splay sho ws Fr equency as Ext (extern a l)
and Source as Front or Rear to indic a te which input
connector is selected.

Press

L RF On/H RF On to select the polarity of the
signal that triggers the RF on.

Press

More to go to the additional menu.

Internal So urce Freq uen cy Select io n

If you have selected Inte rnal to use the modulating
signal from the inter nal sou rc e, then when you
press

More the menu shown below is displayed.

Use the cursor contr ol key to chose th e desired
modulating signal frequency, then press Select to
enter the selection into memor y. The Square Wave
status display will reflect your selection .

Press

Previous Menu to return to the initial
Square Wave Status Menu display.

3-66 681XXB OM

LOCAL (FRONT SIGNAL
PANEL) OPERATION MODULATION

Externa l So urce In pu t Conn ecto r Select ion

If you have selected Exter n al to use a modulating
signal from an exter nal sour ce , then when you pr ess

More the menu (below ) i s displayed.

Front/Rear to selec t th e fr on t or rear pan el

Press
IN connector. The Square Wave status display
shows your selection as Source.

Press

Previous Menu to return to the initial

Square Wave Status Menu display.

681XXB OM 3-67

LOCAL (FRONT SYSTEM
PANEL) OPERATION CONFIGURATION

3-13

SYSTEM
CONFIGURATION

The system config uration func tion provide s menu s that let you set or
select instrument co nfigu ration items; for example, display inten sity,
polarity of blanking and video marker outputs, RF on or off during re­trace or between steps, GPIB address and lin e termin ator, and incr e­ment sizes for frequ ency, power level, and time parameters. Use the
System Configu r ation men u map (Chapter 4, Figur e 4-13) to follow
the menu sequence s.

To go to the System Configuration menu , first press
System Menu display, press
(below) is displayed.

This menu lets you go to the Front Panel, Rear Pan el, R F, GPIB, and
Increment Configuration menus.

Config . The System Configu r atio n Men u

SYSTE M . At the

3-68 681XXB OM

LOCAL (FRONT SYSTEM
PANEL) OPERATION CONFIGURATION

Configuring
the Front
Panel

Configurin g the front pane l of the sweep gener ator
involves adju sting the inte nsity level of the data dis­play for ease of viewin g .

To go to the Configure Front Panel menu from the
System Configuration menu, press
The Configure Front Panel Menu (below) is dis­played.

Press

Brite (repeatedly) to increase the in tensity of

the data display to the desired level.
Press

Dim (repeatedly) to decr ease the inten sity of

the data display.

Front Panel .

When done, press
System Configuration menu.

Previous Menu to return to the

681XXB OM 3-69

LOCAL (FRONT SYSTEM
PANEL) OPERATION CONFIGURATION

Configuring
the Rear
Panel

Configurin g the rear pane l of the sweep gener ator
consists of selecting the polarity of the retrace blank­ing, bandswitch blankin g , retrac e pen lift, and video
marker outputs.

To go to the Configure Rear Panel menu from the
System Configuration menu, press
The Configu re Re ar Pan el Menu (below) is dis­played.

Press

Blanking +/– to select a +5V or –5V level for
the retrace and ban dsw itch blank ing outp uts. The
retrace blanking signal output is available at the
rear panel RETRACE BLANK OUT connector and
AUX I/O co nn ec tor. The bandswitch blanking sign a l
output is available at the rear panel AUX I/O connec-
tor. The display will reflect you r selection .

Rear Panel .

Press

Penlift to select normally-open (N/O) or nor-
mally-closed (N/C) contacts on the internal penlift
relay. The penlift relay outpu t, av ailable at the rear
panel PEN LIFT OUT connec tor, is used to lift a plot-
ter pen during retrace .Th e display will reflec t you r
selection.

Press

Marker +/– to select a +5V or –5V level for
the video marker outpu t wh en vide o mark er s are se­lected ON. The video mark er signal outpu t is avail­able at the rear panel MARKER OUT connector and
AUX I/O co nnec tor. The display w ill refle ct yo ur se ­lection.

When done, press
System Configuration menu.

Previous Menu to return to the

3-70 681XXB OM

LOCAL (FRONT SYSTEM
PANEL) OPERATION CONFIGURATION

Configuring
the RF

Configur in g the RF of the 681XX B inv olv es select­ing the state of the RF during retrace, dur ing fr e­quency swi tchin g in CW and step modes, and at
reset and selecting whe ther a sweep trig g ered by a
single or external trig g er should re st at the top or
bottom of the sweep ramp.

To go to the Configure RF menu from the System
Configuration menu, press
Menu (below) is displayed.

Press

Retrace RF to select RF On or Off durin g re-

trace. The display will ref lec t your selection .
Press

Delta-F RF to select RF On or Off during fre­quency switch in g in CW or step sweep modes. The
display will refle ct yo ur se lec tion.

RF . The Con fig ur e R F

Press

Ramp Rest to select 0 or 10 for the ramp
rest point for swee ps tr igger ed a single or external
trigger. 0 indicates that the sweep will re st at the
bottom of the sweep ramp; 10 indic ates that the
sweep will rest at the top of the sweep ramp. The
display will refle ct yo ur se lec tion.

Press

Reset State to select RF On or Off at re se t.
The display will reflect your selection.

When done, press
System Configuration menu.

Previous Menu to return to the

681XXB OM 3-71
Changed: November 1995

LOCAL (FRONT SYSTEM
PANEL) OPERATION CONFIGURATION

Configuring
the GPIB

Configur in g the GPIB for the sweep ge ne rator con­sists of the following:

Selecting a GPIB addre ss and the GPIB line
terminator for the sweep generator.
Placing the 681XX B in a sour ce lock mode for
operation with a WILTRON Model 360B Vector
Network Analy zer .
Selecting the model and GPIB address for the
power meter use d to crea te a user lev el fl at­ness correction power - offset table.
Selecting the external interface language for
remote operation of 681XXBs with Option 19.

To go to the Configure GPIB menu from the System
Configuration menu, press
GPIB Menu (below) is displayed.

GPIB . The Configure

SS MODE

When SS Mode is selected on, this
message is displayed (in the fre­quency mode title bar) on all menu
displays to remind the operator that
the 681XXB is in a source lock
mode.

Press

GPIB Address to chang e the address of the
681XXB on the bus (the sweep generator’s default
GPIB address is 5). Enter a new address, betw een 1
and 30, using the cursor contro l key or the data en­try keypad and the terminator key

Hz

ns

ADRS

The new GPIB address will appear on the display.

Line Term to select a carriage return (CR) o r

Press
a carriage re tur n and line feed ( CR/LF ) as the GPIB
data delimiter. Consult the GPIB contr oller’ s man­ual to determine whic h da ta delimiter is require d.

Press

SS Mode to place the sweep gener ator in a
source lock mode for oper ation with a WI LTRON
Model 360B Vector Netw ork An aly zer. (Refer to
paragraph 7-4 for information pertaining to operat­ing the 681XXB with a 360B VNA.) Pres s
again to turn the so urc e lock mode off .

SS Mode

3-72 681XXB OM