Avtech AVMP-3-B User manual

INSTRUCTIONS
MODEL AVMP-3-B
20 VOLT, 200 ps RISE TIME
HIGH PERFORMANCE PULSE GENERATOR
WITH IEEE 488.2 RS-232 ETHERNET CONTROL
SERIAL NUMBER: 14278
A V T E C H E L E C T R O S Y S T E M S L T D .
N A N O S E C O N D W A V E F O R M E L E C T R O N I C S
S I N C E 1 9 7 5
[e-mail]
http: www.avtechpulse.com
Tel: [phone] (USA & Canada) or [phone] (Intl)
Fax: [phone] (USA & Canada) or [phone] (Intl)
BOX 5120, LCD MERIVALE
OTTAWA, CANADA K2C3H5

WARRANTY
Avtech Electrosystems Ltd. warrants products of its manufacture to be free
from defects in material and workmanship under conditions of normal use. If,
within one year after delivery to the original owner, and after prepaid return by
the original owner, this Avtech product is found to be defective, Avtech shall at
its option repair or replace said defective item. This warranty does not apply to
units which have been dissembled, modified or subjected to conditions
exceeding the applicable specifications or ratings. This warranty is the extent of
the obligation assumed by Avtech with respect to this product and no other
warranty or guarantee is either expressed or implied.
TECHNICAL SUPPORT
Phone: [phone] (USA & Canada) or [phone] (International)
Fax: [phone] (USA & Canada) or [phone] (International)
E-mail: [e-mail]
World Wide Web: http: www.avtechpulse.com
2

TABLE OF CONTENTS
WARRANTY....................................................................................................................2
TECHNICAL SUPPORT..................................................................................................2
TABLE OF CONTENTS.................................................................................................. 3
INTRODUCTION............................................................................................................. 5
SPECIFICATIONS...........................................................................................................6
REGULATORY NOTES.................................................................................................. 7
FCC PART 18..........................................................................................................................7
EC DECLARATION OF CONFORMITY..................................................................................7
DIRECTIVE 2011/65/EU (RoHS).............................................................................................8
DIRECTIVE 2002/ 6/EC (WEEE)............................................................................................8
FIRMWARE LICENSING.........................................................................................................
INSTALLATION.............................................................................................................10
VISUAL CHECK....................................................................................................................10
POWER RATINGS................................................................................................................ 10
CONNECTION TO THE POWER SUPPLY...........................................................................10
PROTECTION FROM ELECTRIC SHOCK...........................................................................11
ENVIRONMENTAL CONDITIONS........................................................................................12
LABVIEW DRIVERS..............................................................................................................12
FUSES........................................................................................................................... 13
AC FUSE REPLACEMENT...................................................................................................13
DC FUSE REPLACEMENT...................................................................................................14
FUSE RATINGS....................................................................................................................14
FRONT PANEL CONTROLS........................................................................................ 15
REAR PANEL CONTROLS..........................................................................................17
GENERAL INFORMATION...........................................................................................19
BASIC PULSE CONTROL....................................................................................................1
TRIGGER MODES................................................................................................................ 20
GATING MODES...................................................................................................................21
OPERATION AT LOW AMPLITUDES..................................................................................21
OPTIONAL FEATURES................................................................................................22
RACK MOUNTING, "-R5" OPTION......................................................................................22
DC OFFSET, "-OS" OPTION................................................................................................22
DC OFFSET, "-OT" / "-ELA" OPTIONS...............................................................................22
3

MONITOR OUTPUT, "-M" OPTION......................................................................................22
PROTECTING YOUR INSTRUMENT............................................................................23
TURN OFF INSTRUMENT WHEN NOT IN USE...................................................................23
DO NOT EXCEED 1 MHz......................................................................................................23
USE A 50 OHM LOAD..........................................................................................................23
OPERATIONAL CHECK...............................................................................................2
PROGRAMMING YOUR PULSE GENERATOR...........................................................27
KEY PROGRAMMING COMMANDS....................................................................................27
ALL PROGRAMMING COMMANDS.....................................................................................28
MECHANICAL INFORMATION.....................................................................................30
TOP COVER REMOVAL.......................................................................................................30
RACK MOUNTING................................................................................................................30
ELECTROMAGNETIC INTERFERENCE..............................................................................30
MAINTENANCE............................................................................................................ 31
REGULAR MAINTENANCE..................................................................................................31
CLEANING............................................................................................................................ 31
WIRING DIAGRAMS.....................................................................................................32
WIRING OF AC POWER.......................................................................................................32
WIRING OF DC POWER.......................................................................................................33
PCB 158R7 - LOW VOLTAGE POWER SUPPLY................................................................34
PCB 235C - HIGH VOLTAGE DC POWER SUPPLY............................................................35
PCB 216F - PRF/PW TWEAKING PCB................................................................................36
PCB 231A - INTERNAL DC OFFSET FUNCTION................................................................37
PCB 335C - TRIGGER MULTIPLEXER................................................................................38
PCB 104H - KEYPAD / DISPLAY BOARD...........................................................................3
MAIN WIRING....................................................................................................................... 40
PERFORMANCE CHECKSHEET................................................................................. 1
Manual Reference: fileserver2 officefiles instructword avmp AVMP-3-B,ed7.odt.
Last modified September 30, 2022.
Copyright © 2022 Avtech Electrosystems Ltd, All Rights Reserved.
4

INTRODUCTION
The AVMP-3-B is a high performance, GPIB RS232 Ethernet-equipped instrument
capable of generating up to 20V into 50Ω loads at repetition rates up to 1 MHz. The
output pulse width is variable from 10 to 100 ns, and the delay is variable up to ± 1 s.
The rise and fall times are less than 200 ps (20%-80%).
A 50 Ohm load is required for proper operation.
Instruments with the "-P" model suffix can generate up to +20V, whereas instruments
with the "-N" model suffix can generate up to -20V. Instruments with the "-PN" suffix can
generate both polarities.
The AVMP-3-B is a highly flexible instrument. Aside from the internal trigger source, it
can also be triggered or gated by external TTL-level signals. A front-panel pushbutton
or a computer command can also be used to trigger the instrument.
The AVMP-3-B features front panel keyboard and adjust knob control of the output
pulse parameters along with a four line by 40-character backlit LCD display of the
output amplitude, pulse width, pulse repetition frequency, and delay. The instrument
includes memory to store up to four complete instrument setups. The operator may use
the front panel or the computer interface to store a complete “snapshot” of all key
instrument settings, and recall this setup at a later time.
This instrument is intended for use in research and development laboratories.
5

SPECIFICATIONS
Model1: AVMP-3-B
Amplitude2: 2 - 20 Volts
Pulse width (FWHM): 10 ns - 100 ns
Maximum PRF: 1 MHz
Maximum duty cycle: 10%
Rise time (20%-80%): ≤ 200 ps
Fall time (80%-20%): ≤ 200 ps
Required load impedance: 50 Ohms6
Polarity3: Positive or negative or both (specify)
GPIB and RS-232 control1: Standard on -B units.
LabView Drivers: Check http: www.avtechpulse.com labview for availability and downloads
Ethernet port, for remote
control using VXI-11.3, ssh,
telnet, & web:
Included. Recommended as a modern alternative to GPIB RS-232.
See http: www.avtechpulse.com options vxi for details.
Settings resolution: The resolution of the timing parameters (pulse width, delay, period) varies,
but is always better than 0.15% of (|set value| + 20 ns).
The amplitude resolution is < 0.1% of the maximum amplitude.
Settings accuracy: Amplitude: Typically ± (3% of setting) ± (2% of maximum).
Delay, Period: Typically ± (3% of setting ) ± (5 ns)
Pulse width: Typically ± (3% of setting ) ± (2 ns), at maximum amplitude.
As the amplitude is reduced, the pulse width may shift ± 5 ns.
For high-accuracy applications requiring
traceable calibration, verify the output with a calibrated oscilloscope7.
Propagation delay: ≤ 200 ns (Ext trig in to pulse out)
Jitter: ± 35ps ± 0.015% of sync delay
DC offset: Optional4 (except not available for the AVMP-4-B).
Apply required DC offset to back panel solder terminals (250 mA ±50V maximum )
Trigger modes: Internal trigger, external trigger (TTL level pulse, > 10 ns, 1 kΩ input impedance),
front-panel “Single Pulse” pushbutton, or single pulse trigger via computer command.
Variable delay: Sync out to main out: 0 to 1.0 seconds, for all trigger modes (including external trigger).
Sync output: > +3 Volts, > 50 ns, will drive 50 Ohm loads
Monitor output option5: Provides a 20 dB attenuated coincident replica of main output
Connectors: Out, Monitor: SMA, Trig, Sync, Gate: BNC
Power requirements: 100 - 240 Volts, 50 - 60 Hz
Dimensions: (H x W x D) 100 mm × 430 mm × 375 mm (3.9” × 17” × 14.8”)
Chassis material: Aluminum frame & handles, blue vinyl on aluminum covers
Temperature range: +5°C to +40°C
1) -B suffix indicates IEEE-488.2 GPIB and RS-232 control of amplitude, pulse width, PRF and delay (See http: www.avtechpulse.com gpib).
2) For operation at amplitudes of less than 20% of full-scale, best results will be obtained by setting the amplitude near full-scale and using external
attenuators on the output.
3) Indicate desired polarity by suffixing model number with -P or -N (i.e. positive or negative) or -PN for dual polarity option.
4) The -OS option adds an internal bias tee circuit to the output, allowing an externally-generated DC offset (±50V 250mA max) to be
added the output signal. The -OT option includes the -OS function, and adds the ability to generate a ±5V 100mA offset internally
(controlled from the front panel, or by computer command on -B units).
5) Add -M to model number for monitor option.
6) A 50 Ohm load is required. Other loads may damage the instrument. Consult Avtech ([e-mail]) if you need to drive other load
impedances.
7) These instruments are provided with a basic calibration checksheet, showing a selection of measured output parameters. These measurements are
performed with equipment that is calibrated on a regular basis by a third-party ISO IEC 17025:2005 accredited calibration laboratory. However,
Avtech itself does not claim any accreditation. For applications requiring traceable performance, use a calibrated measurement system rather than
relying on the accuracy of the pulse generator settings.
6

REGULATORY NOTES
FCC PART 18
This device complies with part 18 of the FCC rules for non-consumer industrial,
scientific and medical (ISM) equipment.
This instrument is enclosed in a rugged metal chassis and uses a filtered power entry
module (where applicable). The main output signal is provided on a shielded connector
that is intended to be used with shielded coaxial cabling and a shielded load. Under
these conditions, the interference potential of this instrument is low.
If interference is observed, check that appropriate well-shielded cabling is used on the
output connectors. Contact Avtech ([e-mail]) for advice if you are unsure
of the most appropriate cabling. Also, check that your load is adequately shielded. It
may be necessary to enclose the load in a metal enclosure.
If any of the connectors on the instrument are unused, they should be covered with
shielded metal “dust caps” to reduce the interference potential.
This instrument does not normally require regular maintenance to minimize interference
potential. However, if loose hardware or connectors are noted, they should be
tightened. Contact Avtech ([e-mail]) if you require assistance.
EC DECLARATION OF CONFORMITY
We Avtech Electrosystems Ltd.
P.O. Box 5120, LCD Merivale
Ottawa, Ontario
Canada K2C 3H5
declare that this pulse generator meets the intent of Directive 2004 108 EG for
Electromagnetic Compatibility. Compliance pertains to the following specifications as
listed in the official Journal of the European Communities:
EN 50081-1 Emission
EN 50082-1 Immunity
7

and that this pulse generator meets the intent of the Low Voltage Directive 2006 95 EC.
Compliance pertains to the following specifications as listed in the official Journal of the
European Communities:
EN 61010-1:2001 Safety requirements for electrical equipment for
measurement, control, and laboratory use
DIRECTIVE 2011 65 EU (RoHS)
We Avtech Electrosystems Ltd.
P.O. Box 5120, LCD Merivale
Ottawa, Ontario
Canada K2C 3H5
declare that, to the best of our knowledge, all electrical and electronic equipment (EEE)
sold by the company are in compliance with Directive 2011 65 EU of the European
Parliament and of the Council of 8 June 2011 on the restriction of the use of certain
hazardous substances in electrical and electronic equipment (also known as “RoHS
Recast”). In addition, this declaration of conformity is issued under the sole
responsibility of Avtech Electrosystems Ltd. Specifically, products manufactured do not
contain the substances listed in the table below in concentrations greater than the listed
maximum value.
Material/Substance Threshold level
Lead (Pb) < 1000 ppm (0.1% by mass)
Mercury (Hg) < 1000 ppm (0.1% by mass)
Hexavalent Chromium (Cr6+) < 1000 ppm (0.1% by mass)
Polybrominated Biphenyls (PBB) < 1000 ppm (0.1% by mass)
Polybrominated Diphenyl ethers (PBDE) < 1000 ppm (0.1% by mass)
Cadmium (Cd) < 100 ppm (0.01% by mass)
Bis(2-ethylhexyl) phthalate (DEHP) < 1000 ppm (0.1% by mass)
Butyl benzyl phthalate (BBP) < 1000 ppm (0.1% by mass)
Dibutyl phthalate (DBP) < 1000 ppm (0.1% by mass)
Diisobutyl phthalate (DIBP) < 1000 ppm (0.1% by mass)
DIRECTIVE 2002 96 EC (WEEE)
European customers who have purchased this equipment directly from Avtech will have
completed a “WEEE Responsibility Agreement” form, accepting responsibility for WEEE
compliance (as mandated in Directive 2002 96 EC of the European Union and local
8

laws) on behalf of the customer, as provided for under Article 9 of Directive
2002 96 EC.
Customers who have purchased Avtech equipment through local representatives
should consult with the representative to determine who has responsibility for WEEE
compliance. Normally, such responsibilities with lie with the representative, unless other
arrangements (under Article 9) have been made.
Requirements for WEEE compliance may include registration of products with local
governments, reporting of recycling activities to local governments, and financing of
recycling activities.
FIRMWARE LICENSING
Instruments with firmware versions 5.00 or higher use open-source software internally.
Some of this software requires that the source code be made available to the user as a
condition of its licensing. This source code is available upon request (contact
[e-mail]).
Earlier firmware versions do not contain any open source software.
9

INSTALLATION
VISUAL CHECK
After unpacking the instrument, examine to ensure that it has not been damaged in
shipment. Visually inspect all connectors, knobs, liquid crystal displays (LCDs), and the
handles. Confirm that a power cord, a GPIB cable, and two instrumentation manuals
(this manual and the “Programming Manual for -B Instruments”) are with the instrument.
If the instrument has been damaged, file a claim immediately with the company that
transported the instrument.
POWER RATINGS
This instrument is intended to operate from 100 - 240 V, 50 - 60 Hz.
The maximum power consumption is 57 Watts. Please see the “FUSES” section for
information about the appropriate AC and DC fuses.
This instrument is an “Installation Category II” instrument, intended for operation from a
normal single-phase supply.
CONNECTION TO THE POWER SUPPLY
An IEC-320 three-pronged recessed male socket is provided on the back panel for AC
power connection to the instrument. One end of the detachable power cord that is
supplied with the instrument plugs into this socket. The other end of the detachable
power cord plugs into the local mains supply. Use only the cable supplied with the
instrument. The mains supply must be earthed, and the cord used to connect the
instrument to the mains supply must provide an earth connection. (The supplied cord
does this.)
Warning: Failure to use a grounded outlet may result in injury or death due to
electric shock. This product uses a power cord with a ground connection. It must be
connected to a properly grounded outlet. The instrument chassis is connected to the
ground wire in the power cord.
The table below describes the power cord that is normally supplied with this instrument,
depending on the destination region:
10

Destination Region Description Option Manufacturer Part Number
United Kingdom, Hong Kong,
Singapore, Malaysia
BS 1363,
230V, 50 Hz -AC00 Qualtek 370001-E01
Australia, New Zealand AS 3112:2000,
230-240V, 50 Hz -AC01 Qualtek 374003-A01
Continental Europe, Korea,
Indonesia, Russia
European CEE 7 7
“Schuko” 230V, 50 Hz -AC02 Qualtek 364002-D01
North America, Taiwan NEMA 5-15,
120V, 60 Hz -AC03 Qualtek 312007-01
Switzerland SEV 1011,
230V, 50 Hz -AC06 Qualtek 378001-E01
South Africa, India SABS 164-1,
220-250V, 50 Hz -AC17 Volex 2131H 10 C3
Japan JIS 8303,
100V, 50-60 Hz -AC18 Qualtek 397002-01
Israel SI 32,
220V, 50 Hz -AC19 Qualtek 398001-01
China GB 1002-1 2099-1,
220V, 50 Hz -AC22 Qualtek 399012-01
PROTECTION FROM ELECTRIC SHOCK
Operators of this instrument must be protected from electric shock at all times. The
owner must ensure that operators are prevented access and or are insulated from
every connection point. In some cases, connections must be exposed to potential
human contact. Operators must be trained to protect themselves from the risk of electric
shock. This instrument is intended for use by qualified personnel who recognize shock
hazards and are familiar with safety precautions required to avoid possibly injury. In
particular, operators should:
1. Keep exposed high-voltage wiring to an absolute minimum.
2. Wherever possible, use shielded connectors and cabling.
3. Connect and disconnect loads and cables only when the instrument is turned off.
4. Keep in mind that all cables, connectors, oscilloscope probes, and loads must
have an appropriate voltage rating.
5. Do not attempt any repairs on the instrument, beyond the fuse replacement
procedures described in this manual. Contact Avtech technical support (see
page 2 for contact information) if the instrument requires servicing. Service is to
be performed solely by qualified service personnel.
11

ENVIRONMENTAL CONDITIONS
This instrument is intended for use under the following conditions:
1. indoor use;
2. altitude up to 2 000 m;
3. temperature 5 °C to 40 °C;
4. maximum relative humidity 80 % for temperatures up to 31 °C decreasing
linearly to 50 % relative humidity at 40 °C;
5. Mains supply voltage fluctuations up to ±10 % of the nominal voltage;
6. no pollution or only dry, non-conductive pollution.
LABVIEW DRIVERS
A LabVIEW driver for this instrument is available for download on the Avtech web site,
at http: www.avtechpulse.com labview. A copy is also available in National Instruments'
Instrument Driver Library at http: www.natinst.com .
12

FUSES
This instrument contains four fuses. All are accessible from the rear-panel. Two protect
the AC prime power input, and two protect the internal DC power supplies. The
locations of the fuses on the rear panel are shown in the figure below:
AC FUSE REPLACEMENT
To physically access the AC fuses, the power cord must be detached from the rear
panel of the instrument. The fuse drawer may then be extracted using a small flat-head
screwdriver, as shown below:
13
Fuses #1 and #2
(AC fuses)
Fuse #4
(DC fuse)
Fuse #
(DC fuse)
Fuse
Drawer
Pry out the fuse
drawer using a
screwdriver.

DC FUSE REPLACEMENT
The DC fuses may be replaced by inserting the tip of a flat-head screwdriver into the
fuse holder slot, and rotating the slot counter-clockwise. The fuse and its carrier will
then pop out.
FUSE RATINGS
The following table lists the required fuses for standard models:
Fuses
Nominal
Mains
Voltage
Rating Case Size
Recommended Replacement Part
Littelfuse Part
Number
Digi-Key Stock
Number
#1, #2 (AC) 100-240V 0.5A, 250V,
Time-Delay 5×20 mm 0218.500HXP F2416-ND
#3 (DC) N A 1.6A, 250V,
Time-Delay 5×20 mm 021801.6HXP F2424-ND
#4 (DC) N A 0.5A, 250V,
Time-Delay 5×20 mm 0218.500HXP F2416-ND
The recommended fuse manufacturer is Littelfuse (http: www.littelfuse.com).
Replacement fuses may be easily obtained from Digi-Key (http: www.digikey.com) and
other distributors.
14

FRONT PANEL CONTROLS
1. POWER Switch . This is the main power switch. When turning the instrument on,
there is normally a delay of 10 seconds before anything is shown on the main
display, as the internal operating system boots up.
2. OVERLOAD Indicator . When the instrument is powered, this indicator is normally
green, indicating normal operation. If this indicator is yellow, an internal automatic
overload protection circuit has been tripped. If the unit is overloaded (by operating
at an exceedingly high duty cycle or by operating into a very low impedance), the
protective circuit will disable the output of the instrument and turn the indicator light
yellow. The light will stay yellow (i.e. output disabled) for about 5 seconds after
which the instrument will attempt to re-enable the output (i.e. light green) for about
1 second. If the overload condition persists, the output will be disabled again (i.e.
light yellow) for another 5 seconds. If the overload condition has been removed, the
instrument will resume normal operation.
This overload indicator may flash yellow briefly at start-up. This is not a cause for
concern.
3. OUT CONNECTOR . This SMA connector provides the main output signal, into load
impedances of 50 Ohms.
4. SYNC OUT . This connector supplies a SYNC output that can be used to trigger
other equipment, particularly oscilloscopes. This signal leads (or lags) the main
output by a duration set by the "DELAY" controls and has an approximate
amplitude of +3 Volts to RL > 50Ω with a pulse width of approximately 100 ns.
5. LIQUID CRYSTAL DISPLAY (LCD) . This LCD is used in conjunction with the
keypad to change the instrument settings. Normally, the main menu is displayed,
which lists the key adjustable parameters and their current values. The
“Programming Manual for -B Instruments” describes the menus and submenus in
detail.
15
2
3
4
5
6
1

6. KEYPAD .
Control Name Function
MOVE This moves the arrow pointer on the display.
CHANGE This is used to enter the submenu, or to select the operating
mode, pointed to by the arrow pointer.
×10 If one of the adjustable numeric parameters is displayed, this
increases the setting by a factor of ten.
÷10 If one of the adjustable numeric parameters is displayed, this
decreases the setting by a factor of ten.
+ - If one of the adjustable numeric parameters is displayed, and
this parameter can be both positive or negative, this changes the
sign of the parameter.
EXTRA FINE This changes the step size of the ADJUST knob. In the extra-
fine mode, the step size is twenty times finer than in the normal
mode. This button switches between the two step sizes.
ADJUST This large knob adjusts the value of any displayed numeric
adjustable values, such as frequency, pulse width, etc. The
adjust step size is set by the "EXTRA FINE" button.
When the main menu is displayed, this knob can be used to
move the arrow pointer.
16

REAR PANEL CONTROLS
Note: some connectors may be in different positions than shown above, depending on
the exact combination of options ordered.
1. AC POWER INPUT . An IEC-320 C14 three-pronged recessed male socket is
provided on the back panel for AC power connection to the instrument. One end of
the detachable power cord that is supplied with the instrument plugs into this socket.
2. AC FUSE DRAWER . The two fuses that protect the AC input are located in this
drawer. Please see the “FUSES” section of this manual for more information.
3. DC FUSES . These two fuses protect the internal DC power supplies. Please see the
“FUSES” sections of this manual for more information.
4. GATE . This TTL-level (0 and +5V) logic input can be used to gate the triggering of
the instrument. This input can be either active high or active low, depending on the
front panel settings or programming commands. (The instrument triggers normally
when this input is unconnected). When set to active high mode, this input is pulled-
down to ground by a 1 kΩ resistor. When set to active low mode, this input is pulled-
up to +5V by a 1 kΩ resistor.
5. TRIG . This TTL-level (0 and +5V) logic input can be used to trigger the instrument, if
the instrument is set to triggering externally. The instrument triggers on the rising
edge of this input. The input impedance of this input is 1 kΩ. (Depending on the
length of cable attached to this input, and the source driving it, it may be desirable to
add a coaxial 50 Ohm terminator to this input to provide a proper transmission line
termination. The Pasternack (www.pasternack.com) PE6008-50 BNC feed-thru 50
Ohm terminator is suggested for this purpose.)
17
GATE
RS-232
GPIB
TRIG
MON
OS GND
8
5
2
3
6
1
410
7
9

6. GPIB Connector . A standard GPIB cable can be attached to this connector to allow
the instrument to be computer-controlled. See the “Programming Manual for -B
Instruments” for more details on GPIB control.
7. RS-232 Connector. A standard serial cable with a 25-pin male connector can be
attached to this connector to allow the instrument to be computer-controlled. A user
name (“admin”) and a password (“default”, as shipped from the factory) are required
when logging into a serial terminal session. The internal controller attempts to auto-
sense the parity setting. It may be necessary to send a few return characters before
attempting a login in order to provide enough data to allow this auto-sensing to work.
(A standard Linux “agetty” process is used to implement serial control internally.) See
the “Programming Manual for -B Instruments” for more details on RS-232 control.
8. Network Connector . This Ethernet connector allows the instrument to be remotely
controlled using the VXI-11.3, ssh (secure shell), telnet, and http (web) protocols. See
the “Programming Manual for -B Instruments” for more details.
9. M Connectors . (Optional feature. Present on "-M" units only.) The monitor output
provides an attenuated replica (20 dB down) of the voltage on the main output (but
excluding the effect of the internal range attenuator and DC offset functions).
10.OS Connector . (Optional feature. Present on units with the -OS, -OT, and -ELA
options only). This connector allows an externally generated DC offset to be added to
the output. The desired DC offset is applied to this connector, which is connected to
the output centre conductor through a high-quality RF inductor. Do not exceed ±50V,
250 mA. For units with the -OS option, this input is always active. For units with the
-OT or -ELA options, the DC offset is generated internally by default, unless the
“volt:low ext” command is sent, or the external mode is selected from the front panel
offset menu – in which case, the externally-generated DC bias is applied to this input.
18

GENERAL INFORMATION
BASIC PULSE CONTROL
This instrument can be triggered by its own internal clock or by an external TTL trigger
signal. In either case, two output channels respond to the trigger: OUT and SYNC.
OUT. This is the main output.
SYNC. The SYNC pulse is a fixed-width TTL-level reference pulse used to
trigger oscilloscopes or other measurement systems. When the delay is set to a
positive value the SYNC pulse precedes the OUT pulse. When the delay is set to
a negative value the SYNC pulse follows the OUT pulse.
These pulses are illustrated below, assuming internal triggering and a positive delay:
If the delay is negative, the order of the SYNC and OUT pulses is reversed:
The next figure illustrates the relationship between the signal when an external TTL-
level trigger is used:
19
SYNC OUT
(generated by the
internal oscillator)
100 ns, FIXED
MAIN OUTPUT
PULSE WIDTHDELAY > 0
AMPLITUDE,
VARIABLE
3V, FIXED
SYNC OUT
(generated by the
internal oscillator)
100 ns, FIXED
MAIN OUTPUT
PULSE WIDTH
DELAY < 0
AMPLITUDE,
VARIABLE
3V, FIXED

As before, if the delay is negative, the order of the SYNC and OUT pulses is reversed.
In general, the delay, pulse width, and frequency (when in the internal mode), of the
OUT pulse can be varied with front panel controls or via the GPIB or RS-232 computer
interfaces.
TRIGGER MODES
This instrument has four trigger modes:
Internal Trigger: the instrument controls the trigger frequency, and generates the
clock internally.
External Trigger: the instrument is triggered by an external TTL-level clock on the
back-panel TRIG connector.
Manual Trigger: the instrument is triggered by the front-panel “SINGLE PULSE”
pushbutton.
Hold Trigger: the instrument is set to not trigger at all.
These modes can be selected using the front panel trigger menu, or by using the
appropriate programming commands. (See the “Programming Manual for -B
Instruments” for more details.)
20
SYNC OUT
100 ns, FIXED
MAIN OUTPUT
PULSE WIDTHDELAY > 0
AMPLITUDE,
VARIABLE
3V, FIXED
> 50 ns
TTL LEVELS
(0V and 3V-5V)
TRIG
(external input)
PROPAGATION DELAY (FIXED)