Avtech AVMH-6-C User manual

INSTRUCTIONS
MODEL AVMH-6-C
65 VOLTS, 20 MHz
IMPULSE GENERATOR
WITH 0.5 – 1 ns PULSE WIDTH
SERIAL NUM ER: 14193
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] (Worldwide)
OX 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] (Worldwide)
E-mail: [e-mail]
World Wide Web: http://www.avtechpulse.com
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TA LE OF CONTENTS
WARRANTY......................................................................................................................2
TECHNICAL SUPPORT...................................................................................................2
TABLE OF CONTENTS....................................................................................................3
INTRODUCTION...............................................................................................................5
AVAILABLE OPTIONS...........................................................................................................5
SPECIFICATIONS............................................................................................................6
REGULATORY NOTES....................................................................................................7
FCC PART 18.......................................................................................................................... 7
EC DECLARATION OF CONFORMITY..................................................................................7
DIRECTIVE 2011/65/EU (RoHS ............................................................................................8
DIRECTIVE 2002/96/EC (WEEE ............................................................................................8
INSTALLATION..............................................................................................................10
VISUAL CHECK.................................................................................................................... 10
POWER RATINGS................................................................................................................ 10
CONNECTION TO THE POWER SUPPLY...........................................................................10
PROTECTION FROM ELECTRIC SHOCK...........................................................................11
ENVIRONMENTAL CONDITIONS........................................................................................12
FUSES.............................................................................................................................13
AC FUSE REPLACEMENT...................................................................................................13
DC FUSE REPLACEMENT...................................................................................................14
FUSE RATINGS.................................................................................................................... 14
FRONT PANEL CONTROLS..........................................................................................15
REAR PANEL CONTROLS............................................................................................17
GENERAL INFORMATION............................................................................................18
BASIC TEST ARRANGEMENT............................................................................................18
BASIC PULSE CONTROL....................................................................................................18
SHAPING THE IMPULSE..................................................................................................... 19
POLARITY INVERSION........................................................................................................19
MINIMIZING WA EFORM DISTORTIONS....................................................................20
USE 50Ω TRANSMISSION LINES AND LOADS.................................................................20
USE LOW-INDUCTANCE LOADS........................................................................................20
PRE ENTING DAMAGE................................................................................................20
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OPTIONS.........................................................................................................................21
-OS OPTION.......................................................................................................................... 21
-M OPTION............................................................................................................................ 21
MECHANICAL INFORMATION......................................................................................22
TOP COVER REMOVAL.......................................................................................................22
ELECTROMAGNETIC INTERFERENCE..............................................................................22
MAINTENANCE..............................................................................................................23
REGULAR MAINTENANCE..................................................................................................23
CLEANING............................................................................................................................23
WIRING DIAGRAMS.......................................................................................................24
WIRING OF AC POWER.......................................................................................................24
PCB 158R6 - LOW VOLTAGE POWER SUPPLY................................................................25
PCB 282C - HIGH-VOLTAGE POWER SUPPLY.................................................................26
PCB 219E - OSCILLATOR AND TRIGGER.........................................................................27
MAIN WIRING.......................................................................................................................28
PERFORMANCE CHECK SHEET.................................................................................29
Manual Reference: /fileserver2/officefiles/instructword/avmh/AVMH-6-C,ed1.odt.
Last modified February 4, 2022.
Copyright © 2022 Avtech Electrosystems Ltd, All Rights Reserved.
4

INTRODUCTION
The AVMH-6-C is a high performance instrument capable of generating up to 65V into
50Ω loads at repetition rates up to 20 MHz. The output pulse width may be adjusted
from 0.5 ns to 1 ns.
Instruments with the "-P" model suffix can generate up to +65V, whereas instruments
with the "-N" model suffix can generate up to -65V.
Instruments with the "-P-PN" suffix generate up to +65V at the main output, and are
supplied with an inverting transformer that can be installed on the output to generate a
negative signal.
Instruments with the "-N-PN" suffix generate up to -65V at the main output, and are
supplied with an inverting transformer that can be installed on the output to generate a
positive signal.
The output is designed to drive 50Ω loads. (A 50Ω load is required for proper
operation.) The output is AC-coupled.
This instrument is intended for use in research and development laboratories.
AVAILA LE OPTIONS
The AVMH-6-C is available with several options:
-M Option: a monitor output is provided.
-OS Option: an externally generated DC offset can be added to the output.
5

SPECIFICATIONS
Model1: AVMH-6-C
Max.5 amplitude (50Ω load4): 65 V
Pulse width: 0.5 to 1 ns
Pulse width measured at: 50% (FWHM)
PRF, internal trigger:
external trigger:
1 kHz - 20 MHz
0 - 20 MHz
Polarity2: Positive or negative or both (specify)
Propagation delay: ≤ 50 ns (Ext trig in to pulse out)
Jitter: ± 15 ps (Ext trig in to pulse out)
DC offset: Optional3: Apply the required externally-generated DC offset to
back-panel solder terminals (±50 Volts, ±250 mA max)
Trigger required:
(ext trig mode)
TTL-level (Low: 0V, High: +3V to +5V),
≥ 10 ns, RIN = 50Ω6.
Sync output: +3 Volts, width varies with PRF (always > 10 ns), drives ≥ 50Ω
Sync delay: Variable 0 to 80 ns, Sync out to pulse out
Monitor output: Optional7. Provides a ÷11 (-21 d ) attenuated
coincident replica of the main output, into 50 Ohms.
Accuracy / calibration: Not calibrated. Controls may interact. For high-accuracy applications requiring
traceable calibration, verify the output with a calibrated oscilloscope.
Connectors: Out, Monitor: SMA, Trig: NC
Power requirement: 100 - 240 Volts, 50 - 60 Hz
Dimensions (H×W×D): 100 x 430 x 375 mm (3.9” x 17” x 14.8”)
Chassis material: Anodized aluminum, with gray plastic trim.
Temperature range: +5°C to +40°C
1) -C suffix indicates stand-alone lab instrument with internal clock and line powering. (See http://www.avtechpulse.com/formats for additional details of the basic
instrument formats).
2) Indicate desired polarity by suffixing model number with -P or -N (i.e. positive or negative) or -P-PN or -N-PN for dual polarity option where the suffix preceding -PN
indicates the polarity at the mainframe output port.
3) For DC offset option add suffix -OS.
4) A 50 Ohm load is required. Other loads may damage the instrument. Consult Avtech ([e-mail]) if you need to drive other load impedances.
5) 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.
6) An input impedance of ≥1 kΩ can also be provided (-Z1K option).
7) For monitor option add the suffix -M to the model number.
8) For monitor option add the suffix -M to the model number.
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. ox 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. ox 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 iphenyls (P ) < 1000 ppm (0.1% by mass)
Polybrominated Diphenyl ethers (P DE) < 1000 ppm (0.1% by mass)
Cadmium (Cd) < 100 ppm (0.01% by mass)
is(2-ethylhexyl) phthalate (DEHP) < 1000 ppm (0.1% by mass)
utyl benzyl phthalate ( P) < 1000 ppm (0.1% by mass)
Dibutyl phthalate (D P) < 1000 ppm (0.1% by mass)
Diisobutyl phthalate (DI P) < 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.
9

INSTALLATION
VISUAL CHECK
After unpacking the instrument mainframe and the transformer module, examine to
ensure that they have not been damaged in shipment. Visually inspect all connectors,
knobs, and handles. Confirm that a power cord and an instrumentation manual (this
manual), 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:
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Destination Region Description Option Manufacturer Part Number
United Kingdom, Hong Kong,
Singapore, Malaysia
S 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 SA S 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 G 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.
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
Fuse
Drawer
Pry out the fuse
drawer using a
screwdriver.
Fuses #1 and #2
AC fuses)
Fuse #4
DC fuse)
Fuse #3
DC fuse)

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:
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 1.0A, 250V,
Time-Delay 5×20 mm 0218001.HXP F2419-ND
#4 (DC) N/A 0.8A, 250V,
Time-Delay 5×20 mm 0218.800HXP F2418-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.
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. PRF Range Switch and Fine Dial . This switch sets the pulse repetition frequency
(PRF) range of the internal oscillator. The marked value of each position is the
upper limit of the range, approximately. The fine dial directly below the switch varies
the PRF within the set range. When set to the “EXT” position, the instrument is
triggered by externally-generated pulses applied to the TRIG input.
4. DELAY Control . Controls the relative delay between the reference output pulse
provided at the SYNC output and the main output. This delay is variable over the
range of 0 to 50 ns, approximately. At high frequencies, this delay should be kept
nearly fully counter-clockwise, so that the delay does not exceed the period
(otherwise, the triggering may stop). The variable delay circuitry only functions in the
internal trigger mode. The delay is not adjustable when triggering externally.
15
7
13
259
8
4
6

5. TRIG Input . The external trigger signal is applied at this input when the PRF range
switch is in the “EXT” position.
For standard units, a TTL logic level pulse (i.e., 0V = TTL LOW, +3V to +5V = TTL
HIGH) is required to trigger this input, and the input impedance is 50Ω to ground (or
1kΩ, for units with the -Z1K option).
The input pulse width should be > 10 ns.
6. SYNC Output . This output precedes the main output, and is typically used to trigger an
oscilloscope. When triggering internally, the SYNC pulse width varies, but is always >
10 ns. When triggering externally, the SYNC output is a buffered replica of the TRIG
input. The amplitude is fixed at +3V approximately, and this output will drive 50 Ohms
or higher.
7. Pulse Width Controls . These two dials control the pulse width. The TR dial
determines the position of the impulse rising edge, and the TF dial determines the
position of the impulse falling edge. Used together, they control the pulse width.
These dials interact with the amplitude control, so they must be adjusted together.
8. Amplitude Control . This dial controls the pulse amplitude. This dial interacts with the
pulse width controls, so they must be adjusted together.
9. OUT Connector . This is the main output. (This output requires a 50Ω load to function
properly).
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. OS INPUT CONNECTOR . (Present on units with -OS option only.) A DC offset in
the range of ±50V (250 mA max) may be applied to this solder terminal. The DC
offset will appear on the output. When this feature is not used, the OS input should
be connected to ground (using the adjacent GND connector). This is especially
important when driving loads containing a diode.
5. GND CONNECTOR . This solder terminal is connected to ground. It may be used to
ground the OS input connector.
6. M OUTPUT CONNECTOR . (Present on units with -M option only.) This SMA
connector output provides a 20 d attenuated coincident replica of main output, for
monitoring purposes.
17
1
6
4
5
2
3
MON OS GND

GENERAL INFORMATION
ASIC TEST ARRANGEMENT
The AVMH-6-C should be tested with a sampling oscilloscope with a bandwidth of at
least 15 GHz to properly observe the high-speed waveform. A typical test arrangement
is shown below:
The attenuators are required to prevent damage to the sampling oscilloscope. A 40 d
attenuator with sufficient voltage rating should be used on the main output.
ASIC PULSE CONTROL
This instrument can be triggered by its own internal clock or by an external TTL trigger
signal. When triggered internally, two mainframe output channels respond to the
trigger: OUT and SYNC.
OUT. This is the main output.
SYNC. The SYNC pulse is a 3V, > 10 ns wide reference pulse used to trigger
oscilloscopes or other measurement systems.
These pulses are illustrated below:
18
AVTECH
PULSER
MAIN OUTPUT
CONNECTOR
SYNC
CONNECTOR
AC
POWER
ALL CA LES: 50 OHM COAXIAL
SAMPLING
OSCILLOSCOPE
BW > 15 GHz
50 OHM INPUT
TRIG
CONNECTOR
40 d
ATTENUATOR

Figure A
The AVMH-6-C can also be triggered by a TTL-level pulse applied to the TRIG input.
SHAPING THE IMPULSE
The amplitude, TR, and TF dials need to be adjusted together, as they all interact. The
“TR” dial controls the position of the leading edge of the impulse. The “TF” dial controls
the position of the trailing edge of the impulse.
The TR and TF dials will need to be re-adjusted if the amplitude or pulse repetition
frequency are adjusted.
Some “play” is required to generate the ideal output impulse waveform shape. The
impulse will disappear entirely for some combinations of dial settings.
Some properties of the output pulse will change as a function of the amplitude setting.
For some demanding applications, it may be desirable to use a combination of external
attenuators and the amplitude dial to achieve the desired output amplitude.
POLARITY INVERSION
Instruments with the "-P-PN" suffix generate up to +65V at the main output, and are
supplied with an AVX-2 inverting transformer that can be installed on the mainframe
output. A negative pulse is then obtained at the out port of the AVX-2 module.
Instruments with the "-N-PN" suffix generate up to -65V at the main output, and are
supplied with an AVX-2 inverting transformer that can be installed on the mainframe
output. A positive pulse is then obtained at the out port of the AVX-2 module.
When using the transformer with dual-polarity models with the “-OS” option, the external
offset must be added to the DC terminal of the inverting transformer. Do not apply the
offset to the rear-panel offset terminal on the mainframe (if present).
19
SYNC
(generated by the
internal oscillator)
> 10 ns
MAIN OUTPUT
PULSE WIDTHDELAY
AMPLITUDE,
VARIA LE
3V, FIXED

MINIMIZING WAVEFORM DISTORTIONS
USE 50 Ω TRANSMISSION LINES AND LOADS
Connect the load to the pulse generator with 50Ω transmission lines (e.g. RG-58 or RG-
174 cable).
This instrument requires a 50Ω load for proper operation. It will not properly drive a
high-impedance load. The output stage will be damaged if it is operated into an open
circuit (or any other high impedance). Failures due to improper output loading are not
covered by the warranty.
USE LOW-INDUCTANCE LOADS
Lenz’s Law predicts that for an inductive voltage spike will be generated when the
current through an inductance changes. Specifically, VSPIKE = L × dILOAD/dt, where L is
the inductance, ILOAD is the load current change, and t is time. For this reason, it is
important to keep any parasitic in the load low. This means keeping wiring short, and
using low inductance components. In particular, wire-wound resistors should be
avoided.
PREVENTING DAMAGE
The AVMH-6-C may fail if triggered at a PRF greater than 25 MHz.
This unit is designed to operate into a load impedance of 50 Ohms and the output
stage will be damaged if it is operated into an open circuit (or any other high
impedance). Failures due to improper output loading are not covered by the warranty.
The lifetime of the switching elements in the pulse generator module is proportional to the
running time of the instrument. For this reason the prime power to the instrument should
be turned off when the instrument is not in use.
20