MPD Technologies FFPA8689-120 Manual

M P D T E C H N O L O G I E S , I N C .
49 WIRELESS BOULEVARD HAUPPAUGE, NEW YORK 11788 [phone] FAX [phone]
MODEL FFPA8689-120
INSTALLATION, OPERATION AND
MAINTENANCE INSTRUCTIONS
FOR
FEED FORWARD
POWER AMPLIFIER
PREPARED
SEPTEMBER 1, 1999
NOTICE
PROPRIETARY AND PRIVATE
The information contained in this document is the property of
Microwave Power Devices, Inc. (MPD), and shall be kept in strict
confidence. Except with the written permission of MPD, such
information shall not be published, or disclosed to others, or used
for manufacture or sale or for any other purpose. This document
shall not be duplicated in whole or in part. Any recipient so agrees
by acceptance of this document.

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1. Publication # & Edition
MPD Technologies Incorporated
49 Wireless Boulevard
Hauppauge NY USA 11788.
MPD Technologies Incorporated provides this manual “as is” without warranty of
any kind, either expressed or implied. MPD Technologies may make improvements
or changes in the product and manual at any time without notice.
This manual may include technical inaccuracies or typographical errors. Changes
are periodically made to the information herein, these changes may be
incorporated in new editions of this publication.
MPD Technologies is interested in receiving comments from the users of this
manual in order to improve its usefulness. All comments should directed to the
address listed below. MPD Technologies may use or distribute any of the
information supplied in any way it believes appropriate, without incurring any
obligations.
All specifications are subject to change without notice.
Warning - If the equipment appears to be damaged in any way, remove all power
to the unit and it serviced as soon thereafter as possible. The use of an earth
ground is required to ensure safety.

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Warranty
MPD Technologies offers a Limited Warranty of 12 months from the date of original
shipment unless otherwise agreed to in writing.
Any warranty is void (1) if the equipment has been subject to unauthorized alteration,
modification or repair or (2) defects or failures resulting from improper handling,
storage, operation, interconnection or installation; failure to continually provide a
suitable installation and operational environment; or any other cause beyond the range
of normal usage for the equipment (except, in all of the foregoing cases, when caused
by MPD).
Return Procedures
Your MPD amplifier has been extensively tested and inspected prior to shipment to
ensure proper operation at time of delivery and beyond. However, should your
equipment fail to operate properly, return the failed unit to MPD using a Return
Authorization number.
To obtain a Return Authorization number, contact the customer service department
during business hours 8 A.M. to 5 P.M. Eastern Standard Time.
The customer shall be responsible for the return of the equipment to MPD and packed
to ensure safe arrival. MPD shall return repaired, amended or altered equipment,
packed to ensure safe arrival to the Customer’s designated location.
Limitation of Liability
In no event will MPD Technologies be liable to customer or anyone else for special
collateral, exemplar, indirect, incidental or consequential damages, loss of goodwill,
loss of profits or revenues, loss of savings, loss of life, interruptions of business, and
claims of customers, whether such damages occur prior or subsequent to or are alleged
as a result of tortuous conduct, even if MPD Technologies has been advised of the
possibility of such damages.
Table of Contents
1. GENERAL DESCRIPTION.......................................................................................................5
1.1 Introduction...........................................................................................................................................5

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1.2 General Description ..............................................................................................................................6
1.3 Equipment Functional and Physical Specifications...........................................................................8
1.4 Mechanical Description........................................................................................................................8
2. INSTALLATION ........................................................................................................................9
2.1 Introduction...........................................................................................................................................9
2.2 Electrical Service Recommendations ................................................................................................10
2.3 Receiving, Unpacking and Inspection ...............................................................................................10
2.4 Repackaging for Shipment.................................................................................................................11
2.5 Environmental Limitations................................................................................................................11
2.6 Installation...........................................................................................................................................11
2.7 Cable Interconnections.......................................................................................................................12
2.8 I/O Connector Wiring.........................................................................................................................12
2.9 Verify Connections..............................................................................................................................12
2.10 Verify DC Supply Voltage................................................................................................................12
3. OPERATING INSTRUCTIONS..............................................................................................13
3.1 Safety Precautions...............................................................................................................................13
3.2 Controls and Indicators......................................................................................................................14
3.2.1 Local Controls and Indicators........................................................................................................14
3.2.2 Remote Control/Status Interface....................................................................................................18
3.3 Initial Turn On Procedure .................................................................................................................18
3.4 Normal Operation...............................................................................................................................19
3.5 Shut Down Procedure.........................................................................................................................19
4. PRINCIPLES OF OPERATION.............................................................................................19
4.1 Introduction.........................................................................................................................................19
4.2 RF Input Signal ...................................................................................................................................19
4.3 RF Output Load..................................................................................................................................19
4.4 System Functional Description ..........................................................................................................19
4.4.1 Main Amplifier ..............................................................................................................................20
4.4.2 Error Amplifier ..............................................................................................................................20
4.4.3 Amplitude and Phase Adjustment..................................................................................................21
4.4.4 Amplifier Module Cooling ............................................................................................................21
4.5 Power Distribution..............................................................................................................................21
4.6 Intermodulation...................................................................................................................................21
4.6.1 Two tone Intermodulation..............................................................................................................21
4.7 Alarms..................................................................................................................................................21
5. MAINTENANCE......................................................................................................................23
5.1 Introduction.........................................................................................................................................23

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5.2 Periodic Maintenance .........................................................................................................................23
5.3 Cleaning Air Inlets/Outlets.................................................................................................................24
5.4 Test Equipment Required ..................................................................................................................24
5.5 Performance Tests...............................................................................................................................24
List of Figures
Figure 1. Model FFPA8689-120 Feed Forward Linear Power Amplifier.............................................7
Figure 2. MPD Technologies, Inc. Model FFPA8689-120 Outline/Installation Drawing ...................9
Figure 3. Model FFPA8689-120 Local Controls and Indicators ..........................................................15
Figure 4. Block Diagram, Model FFPA8689-120 FFPA........................................................................22
Figure 5. Front View FFPA8689-120…………………………………………………………………..
25
Figure 6. Back View FFPA8689-120……………………………………………………………………26
List of Tables
Table 1. Performance Characteristics, Model FFPA8689-120 Linear Power Amplifier ....................6
Table 2. Periodic Maintenance Tasks......................................................................................................23
Table 3. Test Equipment Required..........................................................................................................24
Table 4. Blind Mate Connector
Assignments…………………………………………………………..27
1. GENERAL DESCRIPTION
1.1 Introduction
This manual provides information for the installation, operation and maintenance of
MPD Technologies, Inc. model FFPA8689-120 feed forward linear power amplifier.
The manual is organized in 5 sections as follows:
•Section 1. General Description

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•Section 2. Installation
•Section 3. Operating Instructions
•Section 4. Principles of Operation
•Section 5. Maintenance
1.2 General Description
The FFPA8689-120 (Figure 1-1) is a microprocessor-controlled linear power amplifier
(FFPA) which operates over the frequency range of 869 to 894 MHz with a rated output
power of 120 watts total (average). At rated output, the amplifier provides
intermodulation products of better than 65 dBc. The design of the FFPA is entirely solid
state, providing trouble free operation and a minimum of maintenance. The FFPA8689-
120 includes a high-speed I/O port to receive commands from the host controller. An
internal transmitter sends data to the host controller regarding the performance and
health of the FFPA8689-120. The FFPA8689-120 is equipped with microprocessor
controlled status monitoring and control circuitry which monitors key FFPA operating
conditions and provides remote status output via the rear panel I/O connector. Local
operating status is provided via front panel LED indicators. The FFPA8689-120 is
powered by an external (customer supplied) 24-28 vdc power supply.

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Figure 1. Model FFPA8689-120 Feed Forward Power Amplifier

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1.3 Equipment Functional and Physical Specifications
Table 1 lists the functional and physical specifications of the FFPA8689-120 linear
power amplifier.
Table 1. Performance Characteristics
Model FFPA8689-120 Linear Power Amplifier
PERFORMANCE CHARACTERISTICS
Parameter Specification
Frequency 869 - 894 MHz
RF Output Power 120 Watts Average
Intermodulation Distortion 65 dBc minimum
when measured with 50 random phase sets.
Gain 61±0.25 dB
Modulation Format Any
Input Return Loss 18 dbr Minimum
Load Stability VSWR unconditional, all phases
Current Consumption 50 amperes nominal @ 27 Vdc
DC Input Fully operational from 24 to 28 VDC
Operating Temperature 0° to 50° C
Operating Humidity 20% to 80% RH, non condensing
Storage Humidity 20% to 95% RH, non condensing
Dimensions 349.5 mm H x 130 mm W x 422.4 mm D
(Optional Configuration Available)
RF, DC, and I/O interface Blindmate 24W7 Sub-miniature connector
LED Status Monitoring Loop Alarm, VSWR Alarm, Temperature Alarm, Power
Supply Alarm, Fan Alarm, Over Power Alarm, and DC
On
1.4 Mechanical Description
The FFPA8689-120 is contained in a 19-inch rack mountable enclosure. A central
heatsink is permanently mounted as part of the assembly (casting/housing). Cooling is
provided by 2 integral rear mounted fans which are easily replaced without the need for
chassis disassembly. Airflow through the FFPA is from front through the rear of the unit.
2. INSTALLATION

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Figure 2, is the outline/installation drawing for the FFPA8689-120 linear power amplifier.
Figure 2. MPD Technologies, Inc.
Model FFPA8689-120
Outline/Installation Drawing
INSTALLATION (cont.)
2.1 Introduction
This section contains receiving, unpacking and installation recommendations for the
model FFPA8689-120 feed forward linear power amplifier. Carefully read and review all

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of the information contained in this section before attempting to install or operate the
FFPA. In addition, read and review the operating instructions contained in Section 3
before operating the equipment.
2.2 Electrical Service Recommendations
MPD Technologies strongly recommends the use of AC line conditioning and surge
suppression devices at the primary AC input to the power source for the FFPA. All
electrical connections should be in accordance with National Electric Code, and any
applicable state and local codes. In addition, lightning protection for all systems is
strongly recommended. Lightning arrestors are recommended at the service entrance
as well. The electric service must be well grounded.
The amplifier power source should be equipped with a separate circuit breaker,
installed in a load center with a separate mains switch or breaker. This arrangement
permits service and maintenance of the FFPA without the necessity for removing power
to the entire site.
2.3 Receiving, Unpacking and Inspection
The FFPA has been tested and calibrated at the factory prior to shipment. No
additional readjustment is required prior to installation.
The FFPA is shipped in a single container. Check the exterior of the shipping container
for any visible signs of damage. If possible, open the container in the presence of the
delivery agent. Carefully unpack the FFPA and save all packing material for possible
reshipment. After removal from the container, check the FFPA for physical damage
such as scratched panels, damaged connectors, etc. If damage is noted, immediately
file claim with the delivery agent or freight carrier.

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2.4 Repackaging for Shipment
Should it ever become necessary to return the FFPA for service or repair, the following
procedure should be followed.
a. Use the original container, if possible.
b. Wrap the item in heavy paper or plastic before placing it in the shipping container.
c. Use packing material around all sides of the item.
d. Use a heavy cardboard box or a wooden container to house the item. Seal the
container with heavy duty tape (Fiberglas) or strap the container with metal bands.
e. Mark the container: "FRAGILE - DELICATE INSTRUMENT". If the item is to be
shipped to MPD for service or repair, attach a tag identifying the owner and include a
description of the difficulty. Refer to the Notification of Returned Goods at the rear of
this manual. In all correspondence regarding the unit, identify the assembly by both
model and serial number, noting the difficulty in detail.
2.5 Environmental Limitations
The FFPA is designed to operate in an environment as noted in Table 1 of this manual.
The FFPA must be installed in an area where an adequate and unrestricted supply of
air is available for cooling. Adequate clearance must be provided to prevent obstruction
of airflow. Confirm that proper dc power is available for the equipment.
2.6 Installation
Refer to the outline and installation drawing contained in Appendix A and the following
paragraphs for installation details.
The FFPA is designed for rack mounting in a standard 19-inch rack. It is secured in the
rack at each corner of the front panel. Install the FFPA in the desired location in the
rack, making sure that an unrestricted supply of air is available at the front and rear of
the enclosure.

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2.7 Cable Interconnections
!! CAUTION !!
DO NOT CONNECT AC POWER TO FFPA UNTIL
PROPER AC POWER OUTPUT HAS BEEN VERIFIED.
DAMAGE TO THE FFPA CAN OCCUR IF IMPROPER
VOLTAGES ARE APPLIED.
2.8 J1 – I/O Connector and Wiring
The RF, DC, and I/O interface is incorporated on one connector. It is a 24W7 Blind
Mate “D” sub-miniature connector. Connections are as shown in the Table 4.
2.9 Verify Connections
Recheck all connections. Make certain that all connections are correct and secure.
2.10 Verify DC Supply Voltage
Measure the DC supply voltage which will power the FFPA. The voltage must be 27
vdc ±0.5 vdc. Refer to Section 3 for operating instructions.
!! CAUTION !!
DO NOT OPERATE FFPA WITH A DC SUPPLY VOLTAGE
OUTSIDE OF THESE LIMITS. DAMAGE WILL OCCUR TO
THE FFPA FROM IMPROPER SUPPLY APPLICATION.

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3OPERATING INSTRUCTIONS
3.1 Safety Precautions
During normal FFPA operation, personnel must be cognizant of the intrinsic hazards
related to electronic equipment in general, and RF power amplifiers in particular. This
amplifier subsystem generates high RF power (120 watts) which is dangerous and can
cause serious RF burns if contacted. Caution must be exercised when working with this
amplifier. While every practicable safety precaution has been incorporated into this
amplifier, the following rules must be strictly observed:
!! WARNING !!
Keep Away From Live Circuits
Operating personnel must observe all safety regulations at
all times. Do not make adjustments inside equipment with
hazardous voltages present. Do not operate the amplifier
without proper RF termination.
Do Not Service or Adjust Alone
Under no circumstances should any person reach within or
enter any enclosure for purposes of servicing or adjustment
without the immediate presence and assistance of another
person capable of rendering aid. Knowledge of first aid for
electrical shock and burns is necessary.
Personnel
Only trained personnel are to service and adjust the
amplifier. Personnel must be trained in the maintenance of
equipment with hazardous RF power, and must be familiar
with this amplifier. In addition, the following precautions must
be observed during operation.
!! WARNING !!
Maintain proper termination at the output port of the FFPA.
Do not remove or exchange RF cables of the output load
circuit while the FFPA is in operation. Dangerous RF voltage
may exist at the foremost terminal of the interrupted load
circuit during operation.
!! CAUTION !!

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All interconnecting cables must be connected prior to
application of RF power. Although the FFPA is designed to
withstand all output load conditions including open and short
circuit conditions, it is recommended to connect an
appropriate RF load to the output port of the FFPA prior to
application of RF power.
!! CAUTION !!
Maintain proper RF input to the amplifier. Damage to the
amplifier may occur if excessive RF input is applied.
3.2 Controls and Indicators
The FFPA is equipped with local controls and indicators on the front panel, and a rear
panel I/O interface for remote status monitoring and control. The following paragraphs
detail these features.
3.2.1 Local Controls and Indicators
Figure 3 is the front view of the FFPA, and the following controls and indicators:

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Figure 3 Model FFPA8689-120
Local Controls and Indicators

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FFPA Status & Alarms
POWER ON/OFF** - line switch/circuit breaker, turns on high power +27V power supply
circuitry.
DC ON** - Green LED indicating presence of DC from high power +27V power supply.
This is located on the ON/OFF switch.
ENABLE ON** - Green LED indicates unit is ENABLED and biased on.
FAN ALARM - Yellow LED indicating a blocked or non-functioning fan.
LOOP ALARM - Red LED indicating control loops can no longer minimize IMD
performance.
VSWR ALARM - Red LED indicating load VSWR is greater than 3.0:1.
POWER SUPPLY ALARM - Red LED indicating a power supply generated voltage is
out of range.
TEMP WARNING/ALARM – Bi-Polar LED. Yellow indicating excessive temperature of
approximately 808C as monitored on the heatsink. Red
indicating excessive temperature of approximately 908C as
monitored on the heatsink.
OVERPOWER ALARM - Red LED indicating that the RF output power from the FFPA
is greater than 2 dB above nominal operating power level.
NOTE: Loop, VSWR, Power Supply, Temperature, and Overpower alarms will shut the
FFPA down.
**See the note on the following page regarding the ON/OFF sequence of the FFPA**

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ON/OFF Sequence of the FFPA Module
ON/OFF Sequence Summary: First, the FFPA module’s high power +27 VDC and +15
VDC bias are both off. After depressing the On/Off switch once, the high power
+27 VDC is on while +15 VDC bias voltage is off. Typical current is 3.5 amps.
After depressing the On/Off switch a second time, both the +27 VDC and +15
VDC bias are on. Typical current without any RF applied to the FFPA is 18
amps. Pressing the On/Off switch a third time will bias off the Module. Pressing
the On/Off switch a fourth time will turn off the FFPA module completely.
27 Volts 15 Volts Bias
OFF
ON
ON
ON
OFF
OFF
ON
OFF
Mode
Mode
Mode
Mode
All Off
High Power +27 on,
Typical current 3.5 amps
Module bias on, any RF
signal will be amplified,
typical current w/o any
RF 18 amps
Biased Off

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3.22 Remote Control/Status Interface
The FFPA is equipped with control inputs as well as built-in-test (BIT) status outputs at
I/O connector J4. Table 3 details the interface and describes the signals.
3.3 Initial Turn On Procedure
The following procedure is intended to verify operation of the FFPA following installation
or repair/replacement.
!! WARNING !!
Equipment operators must be familiar with all safety
precautions outlined at the beginning of this section prior to
operating the FFPA. Operator injury and/or equipment
damage will result from improper operation.
a. Verify that all connections to the FFPA have been properly made in accordance with
Section 2 of this manual, and the outline and installation drawing, Figure 2.
b. With no RF applied to the FFPA, press the POWER ON/OFF switch once. The DC
ON LED on the ON/OFF switch will be illuminated, and the fans will be activated.
c. Observe that only the following indicators are illuminated on the front panel of the
FFPA:
DC ON
d. Press the ON/OFF switch a second time. The DC on and Enable LEDs will both be
illuminated.
e. Observe that the following indicators are illuminated on the front panel of the FFPA:
DC ON
ENABLE
f. Apply reduced RF input (-60 dBm) to the FFPA RF IN connector within the 869-894
MHz frequency range, and observe that all indicators remain as in step e.
!! CAUTION !!
Maintain proper RF input level within the 869-894 MHz
operating band. Improper RF input may cause severe FFPA
damage.
g. Increase input level to between -15 and -11 dBm, and observe that only the following
indicators are illuminated on the front panel of the FFPA:
DC ON

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ENABLE
3.4 Normal Operation
The FFPA requires minimum attention during normal operation. Monitoring of the BIT
status output and output meter provides an overall indication of FFPA health.
3.5 Shut Down Procedure
a. Reduce RF input signal level to minimum (-60 dBm).
b. Press the PWR ON/OFF switch once to disable the bias voltage, two times to shut
down the module altogether.
c. If maintenance or service is to be performed on the FFPA, deactivate prime dc power
to the FFPA.
4.0 PRINCIPLES OF OPERATION
4.1 Introduction
This section contains a functional description of the Feed Forward linear SMR Power
Amplifier. Refer to the block diagram of the FFPA8689-120 FFPA, Figure 4.
4.2 RF Input Signal
The maximum input signal for all carrier frequencies should not exceed the limits
specified in the electrical specifications. The input VSWR should be 2:1 maximum (or
better).
4.3 RF Output Load
The load impedance should be as good as possible (1.5:1 or better) in the operating
frequency band for good RF power transfer to the load.
4.4 System Functional Description
The FFPA8689-120 amplifier is a linear, feed forward power amplifier which operates
from 869 to 894 MHz with a rated output power of 120W total (average). The amplifier
produces better than 65 dBc intermodulation products. The amplifier operates from a
24-28 vdc input power source, and provides a rear I/O interface to report all faults and
alarms. The front panel of the amplifier contains the DC ON/OFF switch, and the status
LEDs.

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The amplifier is comprised of the following:
Carrier Cancellation
Main/Error Driver Amplifier
Main Amplifier
Error Amplifier
DC/DC Function
Microprocessor Control
Loop Processor
Pre-distorter
The main amplifier employs class AB amplification for maximum efficiency and low
intermodulation distortion. The error amplifier and main/error driver amplifiers operate
class A mode. The input RF signal is amplified by the carrier cancellation and then split
into a signal and a reference path. The signal path is sent through the main driver
amplifier where the amplitude and phase are modified based on the reference signal,
and then amplified by the main amplifier. The signal is coupled off to the carrier
cancellation where the 180 degree converted amplified signal meets the reference
signal. At this point the combined signal which has a canceled carrier (called the IMD
signal) is sent to the IMD leg of the feed forward amplifier.
The IMD signal is sent to the error driver amplifier and error amplifier. The signals
amplitude and phase are adjusted from the input by the loop processor. The signal is
re-injected into the main amplifier output signal and the combined signal yields
intermodulation suppression of 65 dBc minimum.
4.4.1 Main Amplifier
The main amplifier operates class AB that provides approximately 22 dB of gain over
the operating frequency band of 869-894 MHz. The main amplifier operates on 27.0
VDC, and utilizes 15V DC to derive bias. The main amplifier is directly mounted to the
heatsink. Within the main amplifier are the temperature sensors, which detect the
baseplate temperature.
4.4.2 Error Amplifier
The main function of the error amplifier is to amplify the distortion products generated
by the main amplifier, so they can be canceled when the signal is coupled onto the
main signal at the output of the amplifier. The error amplifier operates class A, has 47
dB of gain, and produces a 2W output. The amplifier operates on 27.0 VDC, and