Atec CMX25 Manual

HIGH POWER WIDE BAND AMPLIFIER
MODEL CMX25
OPERATING AND MAINTENANCE
INSTRUCTIONS
DOCUMENT NUMBER
CMX25MAN-00
SERIAL NUMBER
______________________
Provided by: www.atecorp.com
(800) 404-ATEC
Advanced Test
Equipment Corp.
®
Rentals • Sales • Calibration • Service

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TABLE OF CONTENTS
SECTION DESCRIPTION PAGE
1.0 INTRODUCTION ..................................................................................4
2.0 GENERAL DESCRIPTION...................................................................5
3.0 WARRANTY INFORMATION ............................................................ 6
4.0 GENERAL INFORMATION
4.1 Scope Of This Manual ................................................................ 7
4.2 Operation Overview....................................................................7
4.3 General Operation with System 55............................................. 8
4.4 General Specifications ................................................................8
4.5 Protection Circuits ......................................................................9
4.6 Status Indicators, Controls and Connectors.............................. 11
4.7 Data Sheets And Curves ........................................................... 15
5.0 PRINCIPALS OF OPERATION
5.1 Proper Usage And Warnings .................................................... 16
5.2 Features Of The CMX25 Amplifier.......................................... 17
5.3 Level Control Board .................................................................19
5.4 Optional Features ......................................................................20
6.0 AUTOMATIC LEVELING CONTROL (ALC )
6.1 ALC Features ............................................................................ 21
6.2 Leveling Using The "INT' Mode ..............................................23
6.3 Leveling Using The 'EXT' Mode ..............................................24
7.0 IEEE-488 INTERFACE OPTION
7.1 Introduction............................................................................... 27
7.2 Remote Initialization.................................................................27
7.3 Local And Remote Attenuation ................................................27
7.6 Status Commands......................................................................28
7.7 GPIB Address ........................................................................... 29
8.0 MAINTENANCE AND SERVICING
8.1 Periodic Maintenance................................................................ 33
8.2 Servicing The Amplifier ...........................................................33
8.3 Equipment Return Procedure....................................................33

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LIST OF FIGURES
FIGURE DESCRIPTION PAGE
1.0 CMX25 ILLUSTRATION...................................................................... 4
2.0 SYSTEM BLOCK DIAGRAM .............................................................. 7
3.0 CMX25 REAR PANEL ILLUSTRATION ..........................................12
4.0 CMX25 SCHEMATIC DIAGRAM ..................................................... 17
5.0 ‘E’ FIELD LEVELING SET-UP.......................................................... 26
LIST OF APPENDICES
APPENDIX DESCRIPTION PAGE
A CALIBRATION DATA SHEETS AND RESPONSE CURVES ........ 35
B DRAWINGS .........................................................................................36

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SECTION 1.0
INTRODUCTION
Congratulations on the purchase of your new Wide Band Amplifier from Instruments For
Industry, Inc. Your new Wide Band Amplifier incorporates the finest advancements in the state
of the art solid state electronics technology available in a compact, portable and versatile
package. Your Wide Band Amplifier's quality, performance and trouble free operation depends
on you thoroughly reading through this manual and familiarizing yourself with its proper
operation and usage.
Your Wide Band Amplifier comes with the following accessories, be sure to check your
packaging for the items listed below before disposing of the packaging.
CONTENTS
( For a typical Wide Band Amplifier )
Quantity Description
1 CMX25 High Power Wide Band Amplifier, P/N CMX25
1 A/C Line Cord
1 Operation and Instruction Manual, Doc. No. CMX25MAN
1 Calibration Data Sheets and Response Curves (Included in Manual )
FIGURE 1.0
CMX25 ILLUSTRATION

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SECTION 2.0
GENERAL DESCRIPTION
The Instruments For Industry, Inc. ( IFI ) manufactured CMX25 Wide Band Amplifier is a
Bench Top or rack mount amplifier providing 40 Watts of linear RF power from 0.01 to 10000
MHz. The CMX25 incorporates two frequency bands of operation identified as Band 1 and
Band 2 which the CMX25 features easy operator frequency band switching without changing the
RF Output connections. The Band 1 frequency range is 10 kHz to 230 MHz with Band 2
frequency range being 200 MHz to 1.0 GHz. The minimum saturated output power over the
entire operating frequency range is more than 25 Watts.
The CMX25 features a Liquid Crystal Display ( LCD ) that displays continuous forward and
reflected power in four digit metering. The display also scrolls to provide the operator with
operating status and self diagnostic fault indications.
The CMX25 has an internal electronic gain control of 40 dB and a built in leveling control which
allows the CMX25 to level on an external controlling signal or level internally by an operator
determined the Automatic leveling Control ( ALC ) setting.
The CMX25 is unconditionally stable and incorporates protection circuits that monitors and
controls the VSWR input and outputs so the amplifier cannot be damaged by any mismatched
load.
The CMX25 has an optional IEEE-488 BUS interface which allows the amplifier to be remotely
controlled through the use of as computer and a GPIB BUS.

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SECTION 3.0
WARRANTY INFORMATION
Instruments For Industry, Inc. (IFI) warrants each product of its manufacture to be free from
any defect in material and workmanship for a period of one year from shipment to the original
purchaser. All warranty returns, however, must first be authorized by our factory office
representative. Refer to the Service Section for information on how to return items for warranty
repair.
Warranty liability shall be limited to repair or replacement of, or part thereof, which proves to be
defective after inspection by IFI. This warranty shall not apply to any IFI product that has been
disassembled, modified, physically or electrically damaged or any product that has been
subjected to conditions exceeding the applicable specifications or ratings.
IFI shall not be liable for any direct or consequential injury, loss or damage incurred through the
use, or the inability to use, any IFI product.
IFI reserves the right to make design changes to any IFI product without incurring any obligation
to make the same changes to previously purchased units.
This warranty is the full extent of obligation and liability assumed by IFI with respect to any and
all IFI products. IFI neither makes, nor authorizes any person to make, any other guarantee or
warranty concerning IFI Products.

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SECTION 4.0
GENERAL INFORMATION
4.1 SCOPE OF THIS MANUAL
This manual is intended to inform a qualified transmitter operator or technician of the normal
operating and maintenance procedures for the CMX25. It is not intended to be a course of
instruction for unqualified personnel.
4.2 OPERATION OVERVIEW
The CMX25 is an integrated system with band switching capability for the frequency range
required for operation. With the CMX25 in Low Band (BAND 1) mode of operation, the input
RF signal is directed by RF Relays to the Band 1 PA and Driver section which in then to the
output. With the CMX25 in the High Band ( BAND 2 ) mode of operation, the input signal is
directed by RF Relays to the Band 2 PA and Driver section which in then to the output. Both
bands utilize only one input and output connector with the signal routed internally by RF Relays.
Refer to Figure 2.0, the System Block Diagram, for an illustration of the CMX25 band swiching
.
FIGURE 2.0
SYSTEM BLOCK DIAGRAM

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4.3 GENERAL OPERATION WITH SYSTEM 55
SYSTEM 55 is an IBM Compatible, Windows based proprietary EMC susceptibility program
specially designed to integrate the CMX25 with other IFI equipment into an efficient and flexible
automated EMC Testing System for immunity testing. It is capable for IEC801-3 testing as well
as a real time leveled sweep that maintains a desired preset field level across a given frequency
range.
4.4 GENERAL SPECIFICATIONS
The specifications listed below represent the minimum performance characteristics at the time of
delivery.
SPECIFICATIONS
Frequency Response:
Band One: 10 kHz to 250 MHz
Band Two: 200 MHz to 1000 MHz
Bandpass Ripple: + 2 dB maximum
Power Output: Minimum 25 Watts, 20W min. at <1 dB gain compression
Power Gain: 50 dB (minimum)
Input Impedance: Nominal 50 Ohms unbalanced
Output Impedance: Nominal 50 Ohms unbalanced
Input Signal Levels: < 0 dBm ( 1.0 mW ) See data sheet for specific input drive
levels
Harmonic distortion: < -20 dB at 20 Watts (Typically < -30 dB)
Gain Adjustment: Greater than 40 dB (voltage controlled) when using Level
Adjust.
Duty Factor: No limitation
RF Rise Time: Approximately 3 ns
Power Requirements: 5 to 10 Amps ( less than 1.0 KVA )

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4.5 PROTECTION CIRCUITS
The CMX25 is designed with a variety of protection circuits to provide safeguards for the
amplifier should any adverse electrical conditions occur or if the amplifier is accidentally
experiencing operator deviation of the design application. Listed below are the safeguards built
into the CMX25.
4.5.1 Over Heat Protection
The CMX25 critical components are mounted to heat sinks which are, in turn, air cooled by four
fans. Should a over heating condition occur, either through component failure or by a restricted
air flow, the CMX25 contains heat sensors that will shut down the system should an over heating
condition occur. As a result, the air inlet and outlet openings should be free of obstructions for
proper cooling of the amplifier. Operation is restored automatically when the amplifier cools to
normal temperature levels.
4.5.2 Input Protection
The CMX25 is designed to operate with less than a 0 dBm ( 1.0 mW ) input signal however, to
prevent over driving the amplifier, the Input Protection circuit will activate if the input signal
exceeds 3 dBm ( 2.0 mW ) and will automatically compensate for the increased input signal by
reducing the gain of the preamplifier. Even though the amplifier has an Input Protection Circuit,
overdriving the amplifier is not recommended, refer to paragraph 5.1.2 for more details.
4.5.3 Output Protection
The CMX25 incorporates a microprocessor controlled Output Protection Circuit which monitors
the Forward Power Meter indication and limits the out put power to 40 Watts. This feature
protects the amplifier from being over driven and causing damage to the power transistors.

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4.5.4 Power Supply Faults
The Power Supply Fault circuit monitors the 28 VDC, ± 12 VDC and 5 VDC power supplies and
produces a fault indication should any voltage level deviate from normal operating parameters.
Each power supply voltage output is monitored and Green Status LEDs are illuminated to
indicate that the power supplies are operating within design parameters. Should any power
supply voltage deviate from the design parameters, the corresponding Green Status LED will
extinguish. The Power Supply Fault Indication LED, located on the front panel of the Power
Supply / Control Module is illuminated RED only when the 28 VDC power supply fails to meet
design tolerances in addition to the extinguishing Green Status Indicator LED. A ± 12 VDC or
5 VDC power supply failure will not illuminate the Power Supply Fault Indication LED, this
indicator is reserved only for the 28 VDC supply.
4.5.5 Mismatch Protection
The CMX25 is designed to operate with a tuned 50 Ohm load and should any mismatching of the
50 Ohm occur, the Reverse Power, also called Reflective Power, will increase producing a high
VSWR. The CMX25 microprocessor monitors the Reverse Power levels by utilizing a Dual
Directional Coupler and begins to turn down the gain of the preamplifier when the Reflected
Power exceeds 25%. The Reverse Power is also displayed on the LCD Display for operator
monitoring for any mismatched load.
4.5.6 Modular Faults Indications
The CMX25 is a microprocessor controlled wide band power amplifier which the
microprocessor is designed to control and monitor critical components within it's circuitry. If the
microprocessor detects any abnormality, the microprocessor generates and stores up to 13
diagnostic fault codes which are scrolled on the LCD Display as a trouble shooting aide for the
operator. The CMX25 also has a RED Status Fault Indicator LED which illuminates when any
fault condition occurs.
4.5.7 Short Circuit Protection
The CMX25 utilizes three different power supply voltages, + 28 VDC, ± 12 VDC and the
+ 5 VDC, each of the power supplies are designed with a short circuit and overload protection
device.

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4.6 STATUS INDICATORS, CONTROLS AND CONNECTORS
The CMX25 has various controls and status indicators which are identified below and can be
visually located on Figure 1.0, CMX25 Illustration and Figure 3.0, CMX25 Rear Panel
Illustration. A narrative description for the function and purpose of each control and status
indicator is provided within paragraphs 4.6.1 and 4.6.2.
CMX25 RF AMPLIFIER
Front Panel: Rear Panel:
POWER
P.S. STATUS INDICATOR AC PWR, Standard 3 Wire Recept
+ 28 VDC On Led SAMPLE RF OUT, BNC Type
± 12 VDC On Led ALC INPUT, BNC Type
+ 5 VDC On Led RF IN, N type (Optional)
FAULT Led RF OUT, N type (Optional)
LEVEL ADJUST RF Reverse Sample Port (Optional)
GPIB REMOTE Led INTERLOCK, BNC Type (Optional)
HI VSWR Led IEEE-488, Connector
LOCAL Switch ADDRESS, Switch
AUTO LIMIT Led
ALC INT. / OFF / EXT. Switch
BAND 1 / BAND 2 Switch
RF IN, N Type
RF OUT, N Type

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FIGURE 3.0
CMX25 REAR PANEL ILLUSTRATION
4.6.1 CMX25 PANEL STATUS INDICATORS
INDICATOR FUNCTION
+ 28 LED The + 28 Green LED is provided on both the Power Supply and
the
Amplifier sections. When these LEDs are illuminated, the + 28
VDC supply is functioning properly. When these LEDs
extinguish, the +28 VDC supply has shut down. When this
condition occurs, the two cooling fans will slow down to maintain
cooling during the power failure and the PS Fault LED will
illuminate.
± 12 and +5 LED The ± 12 and the +5 Green LEDs are provided on both the Power
Supply and the Amplifier sections. . When these LEDs are
illuminated, the ± 12 and +5 VDC supplies are functioning
properly. Should either power supply voltage deviate from the
design parameters, the corresponding LED will extinguish

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4.6.1 CMX25 PANEL STATUS INDICATORS - continued
INDICATOR FUNCTION
Fault LED The Fault LED illuninates when either a Thermal, Power Supply or
Module Fault occurs.
A Thermal Fault occurs when the amplifier is operating outside
design temperatures. Should an excessive temperature condition
occur, the + 28 VDC Supply is shut down and the +28 Green LED
will extinguish. Once the thermal condition returns to the
operational limits, the Fault LED will extinguish, the +28 VDC
will activate and the +28 Green LED will illuminate.
A Power Supply Fault is illuminated when the +28 VDC Power
Supply voltage shuts down. The + 28 Green LED will extinguish
when this failure condition occurs.
A Module Fault occurs when an anomaly was detected by the
microprocessor. When this condition occurs, an error code is
stored and displayed on the LCD display of the CMX25.
Hi VSWR LED When the Hi VSWR Red LED is illuminated, the amplifier is
subjected to a condition where the Reflected Power exceeds 25%.
The microprocessor turns down the gain of the preamplifier and
displays the Reverse Power on the LCD Display.
Band 1 / Band 2 LED The Band 1 and Band 2 Red LEDs are status indicators identifying
which band mode is in operation.
Auto Limit LED The Auto Limit Red LED indicates, when illuminated, that the
output driver is exceeding the maximum input levels for the Final
Low Band Distributed Amplifier. The microprocessor turns down
the gain to design operating levels and illuminates the Auto Limit
LED. When the input gain is turned down to a appropriate level,
the Auto Limit LED will extinguish.
GPIB Remote The GPIB Green LED indicates, when illuminated, that the
amplifier is in the remote control mode of operation via the IEEE-
488 GBIP Bus.

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4.6.2 CMX25 CONTROLS
CONTROL FUNCTION
Local The Local switch is a momentary GPIB Rest switch. When
depressed, the amplifier is restored to the local control form the
GPIB mode of control.
Band 1 / Band 2 Switch The Band 1 / Band 2 switch changes the amplifier to the desired
Frequency Band of operation.
ALC Switch Automatic Leveling Control (ALC) is a three position switch
which selects the method for leveling, either internal, external or
manual.
Power ON/OFF The Power On/Off switch is circuit braker that is used as an
On/Off switch as well as a circuit protection device. This switch
turns the CMX25 either on or off.
Level Adjust The Level Adjust control is a ten turn pot which allows a minimum
of a 40 dB range of gain. Turning the control Clockwise ( CW )
produces a minimum gain.

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4.7 DATA SHEETS AND CURVES
Provided with each CMX25 are specific Calibration Data Sheets and Flatness Curves measured
from the amplifier using a calibrated 50 Ohm Pad to assist the operator in maximizing the
performance of the Wide Band Amplifier.
The accuracy of the Metering is ± .5 dB ( nominal ) so to provide the operator with the ability to
maximize the performance of the wide band amplifier, Calibration Data Sheets are provided with
each amplifier exhibiting the actual metering indication required to produce a 25 Watt output.
The actual metering values were derived by measuring the power output of the amplifier using a
calibrated Power Meter and a calibrated 30 dB Attenuator Pad by inducing an appropriate input
signal level to obtain a 25 Watt output. Once the appropriate signal level has been determined to
obtain the 25 Watt power level, the actual Front Panel Metering Indication that correlates to the
calibrated 25 Watt indication was recorded for operator reference.
The Flatness Curve provides the operator with the over all frequency response of the amplifier in
perspective to the amplifier operating frequency range. The Flatness Curve provides the operator
with the actual gain of the amplifier over the frequency band.
The Calibration Data Sheets and Curves are located within Appendix A

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SECTION 5.0
PRINCIPLES OF OPERATION
5.1 PROPER USAGE AND WARNINGS
5.1.1 Controlling Power Output
With a nominal 50 ohm resistive load and an input signal appropriate to produce a power output
within the limitations specified above, the amplifier may be placed in operation. To interrupt the
output, simply interrupt the input signal or increase the input attenuation setting to produce
commensurate output level reduction. The amplifier may be run indefinitely at rated output.
Output power is usually measured with a power meter and suitable power attenuators.
5.1.2 Input Signal Levels
The CMX25 is designed to operate with less than a 0 dBm ( 1.0 mW ) input signal however, to
prevent over driving the amplifier, the Input Protection circuit will activate if the input signal
exceeds 3 dBm ( 2.0 mW ) and will automatically compensate for the increased input signal by
reducing the gain of the preamplifier.
It is not advisable to over drive any amplifier and depend on protection circuits to maintain
proper gain control. IFI makes available with each shipped amplifier specific data and curves so
the operator will know the proper input signal levels to more efficiently operate the amplifier,
refer to Paragraph 4.7 herein.
5.1.3 Band Switching Cautions
The CMX25 amplifier incorporates two bands with one input and output connector. Switching
between bands is accomplished with a front panel toggle switch which operates internal solenoid
coaxial switches. Switching while driving RF power is not recommended as it may cause arcing
and pitting on the coaxial relay contacts. This arcing condition can be avoided by turning down
the output power before switching the bands. Taking this precaution will extend the operating
life of the coaxial switches.
5.1.4 Sample RF Output Cautions
The CMX25 Sample RF Output connector located on the rear panel must be terminated with the
supplied 50 Ohm load if the output is not being used. Should the CMX25 be operated without a
termination on the Sample RF Output connection, the lack of loading will jeopardize the
accuracy of the metering and output protection which are based on the Forward Power Readings.

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5.2 FEATURES OF THE CMX25 AMPLIFIER
The CMX25 amplifier is intended for applications requiring high gain and power output to 20
Watts, over a wide range of frequencies, without tuning adjustments. Through the utilization of
two frequency bands identified as Band 1 and Band 2, the CMX25 amplifies a input signal
source over the frequency range from 10 kHz to 1000 MHz and at a minimum gain of 50 dB.
The operational description of each frequency band is identified in Paragraph 5.2.1 and 5.2.2,
refer to Figure 4.0, CMX25 Schematic Diagram for an illustration of the CMX25 circuitry.
FIGURE 4.0
CMX25 SCHEMATIC DIAGRAM
5.2.1 Band 1
Band 1 is designed for operation between 0.01 to 230 MHz. Band 1 circuitry consists of a single
module driven by a Preamplifier/Attenuator.

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5.2.1.1 Preamplifier / Attenuator
This module is both a preamplifier and a voltage controlled, broad band attenuator. It provides
the CMX25 with remote level control and leveling capability over the entire 0.01 to 1000 MHz
frequency range. With the front panel level control set at maximum output it has a nominal 7 dB
gain and can be adjusted with the front panel level control over a greater than 40 dB range.
The preamplifier is powered from a low voltage power supply that is independent of the main
power supply.
5.2.1.2 Power Amplifier
This amplifier consists of three amplification sections, the final stage having two cascaded high-
power, push-pull devices operating in parallel and combined through a transmission type
impedance transformer.
5.2.2 Band 2
5.2.2.1 Preamplifier / Attenuator - Same amplifier as 5.2.1.1.
5.2.2.2 Driver Amplifier
This amplifier module consists of three cascaded single ended amplification stages and one push-
pull output stage. It can provide up to 10 Watts of drive power to the Power Amplifiers (PA).
5.2.2.3 Power Amplifier
This amplifier consists of two high power push - pull devices, operating in parallel and combined
through transmission type impedance transformers.

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5.3 LEVEL CONTROL BOARD
All level control functions (manual and automatic), for both bands, are conditioned and
processed through the circuitry contained on this board. These include:
l. Manual Level Control
2. Automatic Leveling Control (closed loop gain control)
3. Automatic Drive Limit Function ( to higher power external stages )
5.3.1 Manual Level Control
Manual level control is accomplished by adjusting the front panel ten turn potentiometer, located
on the power supply control unit, to a reference voltage setting between 0 to 5 volts.
5.3.2 Automatic Level Control
In this mode, the CMX25 serves as the voltage comparator and variable gain stage. It will
enable the maintaining of a constant RF voltage vs. frequency at the input to an imperfect load or
a virtually constant E-Field at a measurement point in space. For further information regarding
the ALC operation, refer to Section 6.0

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5.4 OPTIONAL FEATURES
5.4.1 Automatic Drive Limit Function ( Auto Limit )
The Auto Limit is an optional feature that can be used when the CMX25 is used as a driver for
higher power amplifiers available from IFI. The IFI series of high power amplifiers have
provisions for continuously sampling plate and screen currents for front panel metering and to
establish current limits which the amplifier will not be permitted to exceed. When either of these
critical currents are reached, the power amplifier system is automatically switched from the
OPERATE condition to the STANDBY condition and a status light (OVERLOAD) flashes to
show that an overload condition occurred. While this is necessary for protection of the power
tubes, it can be an inconvenience for the operator, particularly when sweeping through frequency
to reduce testing time.
The Auto Limit feature will prevent the amplifier from exceeding the preset current limits by
automatically reducing amplifier gain as necessary. This "turn down" action will prevent
unnecessary overload conditions and enable maximum possible RF output power within safe
operating limits. A front panel LED, on the CMX25 will light whenever the Auto Limit is acting
to limit RF drive.
To determine whether the Auto Limit Feature is included in the operator's CMX25, The Auto
Limit feature can be identified by a Auto Limit BNC Connector located on the rear panel of the
CMX25 Power Supply / Control Module. The lack of the BNC connector means that this option
has not been installed, however should the operator desire this optional feature, the amplifier can
be returned to IFI for installation. Refer to Section 8.0 for Equipment Return Procedure.
5.4.2 Door Ajar Feature
The Door Ajar Feature is an option for the CMX25 that utilizes an Electro Magnetic Interference
(EMI) Testing Room door switch that is mounted to the door in such a manner that when opened,
the switch will automatically induce an ordered shut down of the amplifier and produce a
STAND-BY MODE indication on the LCD Metering Display. When the door is closed, the
amplifier resumes previous testing conditions.
The advantage to this feature is providing an additional safety feature for the growing concerns
for potential hazards due to exposure to EMI Fields. With the Door Ajar option, all Testing
Personnel will be protected from accidental exposure to EMI Fields. Should the operator desire
this optional feature, the amplifier can be returned to IFI for installation. Refer to Section 8.0 for
Equipment Return Procedure.