AR 2000TP2G8B Service manual

Operating and
Service Manual
2000TP2G8B
Model
10013130
Part Number
Serial Number
160 School House Road, Souderton, PA 18964 • 215-723-8181 • Fax [phone] • www.ar-worldwide.com

EC Declaration of Conformity
We; AR RF/Microwave Instrumentation
160 School House Road
Souderton, PA 18964
declare that our product;
the Model 2000TP2G8B amplifier
to which this declaration relates is in compliance with the requirements of the EEC EMC
Directive (89/336/EEC) and Low Voltage Directive (73/23/EEC) in accordance with the
relative standards listed below:
EMC:
EN 50082-1: 1992
Electromagnetic compatibility – Generic immunity standard
EN 50081-1: 1992
Electromagnetic emissions requirements for Industrial, Scientific, and
Medical (ISM) Equipment
Safety:
EN 60950 (1995)
The CE marking is affixed on the device according to the EC Directives.
Donald R. Shepherd
President

INSTRUCTIONS FOR SAFE OPERATION
BEFORE APPLYING POWER
Review this manual and become familiar with all safety
markings and instructions.
Verify that the equipment line voltage selection is
compatible with the main power source.
Protection provided by the equipment may be impaired if
used in a manner not specified by Amplifier Research.
INTENDED PURPOSES
This equipment is intended for general laboratory use in a
wide variety of industrial and scientific applications. It is
designed to be used in the process of generating, controlling,
and measuring high levels of electromagnetic Radio Frequency
(RF) energy. Therefore, the output of the amplifier must be
connected to an appropriate load such as an antenna or field-
generating device. It is the responsibility of the user to assure
that the device is operated in a location which will control the
radiated energy such that it will not cause injury and will not
violate regulatory levels of electromagnetic interference.
HAZARDOUS RF VOLTAGES
The RF voltages on the center pin of the RF output connector
can be hazardous. The RF output connector should be
connected to a load before AC power is applied to the
amplifier. Do not come into contact with the center pin of the
RF output connector or accessories connected to it. Place the
equipment in a non-operating condition before disconnecting
or connecting the load to the RF output connector.
SAFETY GROUND
This equipment is provided with a protective earth terminal.
The main power source to the equipment must supply an
uninterrupted safety ground of sufficient size to the input
wiring terminals, power cord, or supplied power cord set. The
equipment MUST NOT BE USED if this protection is
impaired.
PHYSICAL DAMAGE
The RF amplifier should not be operated if there is physical
damage, missing hardware, or missing panels.
MAINTENANCE CAUTION
Adjustment, maintenance, or repair of the equipment must be
performed only by qualified personnel. Hazardous energy may
be present while protective covers are removed from the
equipment even if disconnected from the power source.
Contact may result in personal injury. Replacement fuses are
required to be of specific type and current rating.
SAFETY SYMBOLS
This symbol is marked on the equipment
when it is necessary for the user to refer to
the manual for important safety information.
Dangerous voltages are present. Use extreme
care.
CAUTION: The caution symbol denotes a
potential hazard. Attention must be given to
the statement to prevent damage, destruction,
or harm.
Indicates protective earth terminal.
RANGE OF ENVIRONMENTAL CONDITIONS
This equipment is designed to be safe under the following
environmental conditions:
•Indoor use
•Altitude up to 2000M
•Temperature of 5°C to 40°C
•Maximum relative humidity 80% for temperatures up to
31°C. Decreasing linearly to 50% at 40°C.
•Main supply voltage fluctuations not to exceed ± 10% of
the nominal voltage or minimum and maximum
autoranging values.
•Pollution degree 2: Normally non-conductive with
occasional condensation. While the equipment will not
cause hazardous condition over this environmental range,
its performance may vary.
COOLING AIR
Care should be exercised not to block the cooling air inlets or
outlets. Cooling air blockage can result in damage to the RF
amplifier or intermittent shut-downs.

ADDITIONAL WARNINGS & NOTES
WARNING:
This equipment operates at potentially lethal voltages. Only trained,
qualified personnel should operate, maintain, or service it.
Hazardous energy may be present while protective covers are removed
from the equipment even if disconnected from the power source. Contact
may result in personal injury.
CAUTION:
Adjustment, maintenance, or repair of the equipment must be performed
only by qualified personnel.
CAUTION:
Replacement fuses are required to be of specific type and current rating.
CAUTION:
The information in this document was obtained from reliable sources and
was believed to be accurate at the time of publication. Since subsequent
modifications to the machine may have been made, use this information
only as a guide. Carefully compare the unit's actual configuration and
operation to the descriptions in this manual before you undertake to
operate, service, or modify this machine. Any variance or modification
should be noted, dated, and initialed in the discrepant part of all manuals
on hand for future reference. If you have technical or editorial comments
you wish to make to the manufacturer, please write them on photocopies
of the relevant sheets.
NOTE: The contents of this document are the property of the manufacturer and this document is delivered
on the express condition that it not be disclosed, reproduced in whole or in part, or used for manufacture for
anyone other than the manufacturer without its written consent, and that no right is granted to disclose or
so use any information in this document.

TABLE OF CONTENTS
TABLE OF CONTENTS ..................................................................................................i
1. DESCRIPTION AND SPECIFICATIONS.......................................................1
1.1 TWTA Description................................................................................................1
1.2 Suggested Applications .........................................................................................1
1.3 Specifications.........................................................................................................1
1.4 Accessories............................................................................................................ 1
1.5 Test Data Sheet......................................................................................................2
2. THEORY OF OPERATION..............................................................................7
2.1 Design of the Amplifier.........................................................................................7
2.2 Description of the RF Circuit (A27502-318) ........................................................7
2.3 Description of the Power Supply (A22826-018)...................................................8
3. OPERATION.......................................................................................................9
3.2 Installation.............................................................................................................9
3.2.1 Unpacking .......................................................................................................9
3.2.2 Mounting and removing................................................................................10
3.2.3 Cooling Requirements...................................................................................11
3.2.4 AC Line Power Connections.........................................................................11
3.2.5 RF Connections.............................................................................................11
3.2.6 External Interlock Connector........................................................................12
3.2.7 Video Input (Pulse Gate) Connection...........................................................12
3.2.8 Optional External Filter/Switch Connection.................................................13
3.3 Front Panel Features............................................................................................14
3.4 Front Panel Display and Soft Keys......................................................................15
3.5 Rear Panel Features.............................................................................................19
3.6 Initial Turn On and Warm-up Procedure.............................................................20
3.7 Remote IEEE-488 Operation...............................................................................21
3.8 TWTA General Considerations...........................................................................27
4. MAINTENANCE...............................................................................................29
4.1 Safety Warning....................................................................................................29
4.2 Unauthorized Repairs ..........................................................................................29
4.3 Preventive Maintenance ......................................................................................29
4.4 Troubleshooting...................................................................................................30
4.5 Non-Repairable Modules.....................................................................................30
5. TECHNICAL DOCUMENTATION ...............................................................31
5.1 Top Level Build Tree ..........................................................................................33
5.2 Schematics........................................................................................................... 35
5.3 Parts Lists ............................................................................................................37
5.3.1 Parts List, HPA Logic and Control Module, A16485-000............................38
5.3.2 Parts List, Pulsed TWT Power Supply (PFC), A22826-018......................... 40
5.3.3 Parts List, Emergency Bypass Board, A24830-000......................................41
5.3.4 Parts List, HPA Interface Board 200UM Glass, A25444-001......................42
5.3.5 Parts List, HPA Assy 13PSC, 1 KW Pulsed 2-4 GHZ, A27500-913...........45
5.3.6 Parts List, Microwave Power Assy 2 - 4 GHZ, A27502-318........................46
i

Model 2000TP2G8B
5.3.7 Parts List, HPA Wiring Kit, Single Phase 13PSC, A27507-913.................47
5.3.8 Parts List, 200W SC External Filters, A30528-000......................................50
5.4 Recommended Spare Parts ..................................................................................51
5.5 Sample Program for IEEE-488 Communication ................................................. 52
APPENDIX, Application Note 35
FIGURES
3-1 Mounting Support Holes .....................................................................................10
3-2 Front Panel Features............................................................................................14
3-3 Front Panel Display Screens................................................................................15
3-4 Rear Panel Features.............................................................................................19
TABLES
3-1 Front Panel Features............................................................................................14
3-2 Rear Panel Features.............................................................................................19
3-3 Catalog of IEEE-488 Commands.........................................................................22
3-4 Catalog of Status Codes.......................................................................................24
3-5 Catalog of Fault Codes ........................................................................................24
3-6 Catalog of System State Codes............................................................................ 25
3-7 Catalog of *STA?; Response Codes....................................................................25
3-8 Catalog of *STB?; Response Codes....................................................................26
3-9 Catalog of Heater Auto Off Time Delay Codes..................................................26
ii

Rev - 1
1. DESCRIPTION AND SPECIFICATIONS
This manual provides operating, interfacing and selected service information pertinent to AR
RF/Microwave Instrumentation Model 2000TP2G8B Broadband Microwave Amplifier. The Model
2000TP2G8B is a 2,000 watt pulse only SC band traveling-wave tube amplifier (TWTA).
1.1 TWTA DESCRIPTION
The amplifier uses a broadband traveling-wave tube to provide a minimum of 2,000 watts peak pulsed output
power over the amplifier's full bandwidth. The amplifier is well suited for pulse susceptibility and general
laboratory testing where instantaneous bandwidth and high gain are required.
For bench top use the amplifier is supplied in an enclosure with integral carrying handles.
The amplifier is completely self-contained and packaged for standard 19-inch rack mounting or bench top
use. The front panel of the rack mountable amplifier is 8.75 inches high, and the overall unit is 25 inches
deep, excluding the rear-panel connectors.
Primary power is 190-260VAC, 50/60 Hz, single phase. An efficient switching power supply design
provides minimum power consumption. A fast regulation control loop and a high degree of filtering ensure
performance within specifications over a wide range of operating conditions. The amplifier is fully enclosed,
and the upper and lower panels of the enclosure are interlocked to reduce the likelihood of accidental contact
with high voltage.
1.2 SUGGESTED APPLICATIONS
•Pulse RF Susceptibility testing
•Antenna and component testing
•Equipment calibration
•General laboratory pulse RF instrumentation
1.3 SPECIFICATIONS
Refer to the AR RF/Microwave Instrumentation Data Sheet on the following pages for detailed
specifications.
1.4 ACCESSORIES
AR RF/Microwave Instrumentation offers a number of accessories for use with this amplifier including:
•Directional coupler
•Antenna
•Flexible transmission line
Refer to a current AR catalog for Microwave Accessories.

Model 2000TP2G8B
2 Rev -
1.5 TEST DATA SHEET
A Test Data Sheet for a specific unit is prepared at the time of manufacture and is included with the unit's
copy of this manual.

Approved for public release by AR RF/Microwave Instrumentation 011712
160 School House Road Souderton, PA 18964-9990 • 215-723-8181 • www.ar-worldwide.com Page 1 of 3
2000TP2G8B,
M1 through M5
2000 Watts Pulse
2.5-7.5GHz
The Model 2000TP2G8B is a self contained, forced air cooled, broadband traveling wave tube (TWT)
microwave amplifier designed for pulse applications at low to moderate duty factors where instantaneous
bandwidth and high gain are required. A reliable TWT provides a conservative 2000 watts minimum peak RF
pulse power at the amplifier output connector. Stated power specifications are at fundamental frequency.
The amplifier's front panel digital display shows forward and reflected average power output or forward and
reflected peak power, plus extensive system status information accessed through a series of menus via soft
keys. Status indicators include power on, warm-up, standby, operate, faults, excess average or peak reflected
power warning and remote. Standard features include a built-in IEEE-488 (GPIB) interface, 0dBm input, TTL
Gating, VSWR protection, gain control, RF output sample port, auto sleep, plus monitoring of TWT helix
current, cathode voltage, collector voltage, heater current, heater voltage, baseplate temperature and cabinet
temperature. Modular design of the power supply and RF components allow for easy access and repair. Use
of a switching mode power supply results in significant weight reduction.
Housed in a stylish contemporary cabinet, the Model 2000TP2G8B provides readily available pulsed RF power
for a variety of applications in Test and Measurement, (including EMC RF pulse susceptibility testing), Industrial
and University Research and Development, and Service applications. AR also offers a broad range of
amplifiers for CW (Continuous Wave) applications. See Model Configurations for alternative packaging and
external harmonic filters.
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
WATTS
2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8
FRE
Q
UENCY
(
GHz
)
2000T2G8B TYPICAL POWER OUTPUT
PEAK PULSE

Page 2 of 3
SPECIFICATIONS
POWER (fundamental), PEAK PULSE, @ OUTPUT CONNECTOR
Nominal ................................................................2200 watts
Minimum ...............................................................2000 watts
FLATNESS.....................................................................±13 dB maximum, equalized for
±4 dB maximum at rated power
FREQUENCY RESPONSE ...............................................2.5–7.5 GHz instantaneously
INPUT FOR RATED OUTPUT..........................................1.0 milliwatt maximum
GAIN (at maximum setting) ...........................................63 dB minimum
GAIN ADJUSTMENT (continuous range).........................35 dB minimum
INPUT IMPEDANCE.......................................................50 ohms, VSWR 2.5:1 maximum
OUTPUT IMPEDANCE ...................................................50 ohms, VSWR 2.5:1 typical
MISMATCH TOLERANCE...............................................Output pulse width foldback protection at peak reflected power exceeding 1000
watts. Will operate without damage or oscillation with any magnitude and phase
of source and load impedance. May oscillate with unshielded open due to
coupling to input. Should not be tested with connector off.
PULSE CAPABILITY
Pulse Width............................................................0.07–30 microseconds.
Pulse Rate (PRF)......................................................100 kHz maximum
Duty Cycle .............................................................4% maximum.
RF Rise and Fall......................................................30 ns max (10% to 90%).
Delay.....................................................................300 ns maximum from pulse input to RF 90%
Pulse Width Distortion.............................................±30 ns maximum (50% point of output pulse width compared to 50% points of
input pulse width)
Pulse Off Isolation ..................................................80 dB minimum, 90 dB typical
Pulse Input .............................................................TTL Level, 50 Ohm nominal termination
NOISE POWER DENSITY
(pulse on) ..............................................................Minus 70 dBm/Hz (maximum), minus 72 dBm/Hz (typical)
(pulse off) ..............................................................Minus 140 dBm/Hz (typical)
HARMONIC DISTORTION.............................................Minus 0 dBc maximum, Minus 1.5 dBc typical
PRIMARY POWER ..........................................................190-260 VAC, single phase
50/60 Hz
1.2 KVA maximum
CONNECTORS
RF input .................................................................Type N female on rear panel
RF output ...............................................................Type N female on rear panel
RF output sample port ............................................Type N female on rear panel
Pulse input .............................................................Type BNC female on rear panel
GPIB......................................................................IEEE-488 female on rear panel
Interlock ................................................................DB-15 female on rear panel
COOLING....................................................................Forced air (self-contained fans), air entry and exit in rear.
EXPORT CLASSIFICATION .............................................ITAR. This document contains specifications for a commodity whose export is
governed by the U.S. International Traffic in Arms Regulations (ITAR). This
commodity must not be transferred to a foreign person/entity without proper
authorization of the U.S. Government. Violations may result in administrative,
civil or criminal penalties.

Page 3 of 3
MODEL CONFIGURATIONS
EMust select one enclosure type from the following [E1 or
E2 or E2S]:
E1 Removable outer enclosure, size 50.3 x 25.4 x 82 cm
(19.8 x 10 x 32 in). Add approximately 14 kg (30 lbs)
to weight of E2.
E2 Without outer enclosure, size 48.3 x 22.2 x 69 cm (19 x
8.75 x 27 in). Weight approximately 39 kg (85 lbs).
E2S Enclosure removed for rack mounting; slides and front
handles installed, size same as E2. Add approximately
2 kg (5 lbs) to weight of E2.
SMay select a special feature (extra cost) from the
following [S2K]:
S2K Supplied with two TF-type externally-mountable
harmonic filters and a switch kit that allows the user to
select an appropriate filter band, high or low, via this
TWTA. Insertion loss when used with filters is maximum
1.5 dB. See TF Type Filter Specifications table below.
Add filter weights, plus add 1 kg (2 lbs) for switch kit.
Model Number Features
2000TP2G8B E S
2000TP2G8B E1 -
2000TP2G8B M1 E2 -
2000TP2G8BM2 E2S -
2000TP2G8BM3 E1 S2K
2000TP2G8BM4 E2 S2K
2000TP2G8BM5 E2S S2K
S2K – TF FILTER TYPE SPECIFICATIONS
Microwave
Filter Model For Use with AR TWTA
Model
Pass
Band
(GHz)
Insertion
Loss(dB
max)
Reject
Band
(GHz)
Rejection
(dB min) Power (fundamental
& harmonic,
watts, max)
Input
Connector Output connector Size L x W x D
(cm, in max)
Weight
(kg, lbs
typical)
Input
VSWR in
Pass
band
(typical)
Input
VSWR in
Reject
band
(typical)
TF type
filter 1 2000TP2G8B
with N
connector,
requires two
filters
2.5-4.2 0.5 5.0 - 8.4 25 150 & 100
average,
3000 & 2000
peak
N male (or N
female plus
supplied
adapter or
short cable)
N female 19 x 8 x 13
7.5 x 3 x 5 1, 2 1.3:1 2.5:1
filter 2 4.2-7.5 0.5 8.4 - 15 25 150 & 100
average,
3000 & 2000
peak
13 x 8 x 9
5 x 3 x 3.5 0.5, 1 1.3:1 2.5:1

6 Rev -

Rev - 7
2. THEORY OF OPERATION
2.1 DESIGN OF THE AMPLIFIER
The Model 2000TP2G8B TWT amplifier consists of three main parts, the microwave power assembly, the
power supply, and the control. These will be described in greater detail below.
The heart of the microprocessor control system is the control head assembly (A27509-301), which consists of
the CPU board (A25450-000) and the data link board (A22488-013). The microprocessor control system
supervises the power supply, provides metering display, processes operator front panel inputs, and enables
communication with a host computer over the IEEE-488 interface. Communication from the front panel is
through the HPA display board (A25425-001).
The control head is provided with its own power supply and, other than through the IEEE-488 interface bus,
is electrically isolated from the amplifier. Communication with the amplifier is via fiberoptic links to the
HPA interface board (A25444-001).
2.2 DESCRIPTION OF THE RF CIRCUIT (A27502-318)
The TWTA consists of two stages of RF amplification: a solid state preamp assembly with adjustable gain
(E01136-000) and the traveling-wave tube assembly (E01037-000).
The type N RF input connector is located on the rear panel. The RF input is fed to the input connector on the
solid state pre-amp. The solid state pre-amp's output drives the RF input of the TWT. The RF output of the
TWT is a type SC connector. The output is directed through a coax cable assembly to a dual (-30 dB/-40 dB)
directional coupler. The RF Output connector on the rear panel is Type-N female.
An optional external harmonic filter / switch assembly may be used to further reduce harmonic power in a
sub-band. The TWTA output connects to the input of a two-position switch via a coax cable. Switching is
controlled locally, through the TWTA front panel, or remotely over the TWTA’s GPIB interface. The switch
routes the RF to the appropriate band depending upon the sub-band selected:
•LOW band selection: routes to a low pass filter for operation from 2.5 – 4.6 GHz.
•HIGH band selection: routes to a low pass filter for operation from 4.6 – 7.5 GHz.
The reflected signal from the directional coupler is connected to a detector diode, whose output is used for
VSWR protection by the power supply logic board, for VSWR measurement in the leveling loop, and for
reflected power measurement on the HPA interface board.
The VSWR detection and reflected power Foldback circuit is provided to protect the tube from high reflected
peak power that may result from progressive failure or mismatch of the output load. The Foldback circuit
reduces the maximum pulse width of the output signal when the reflected power exceeds the factory set
value. FOLDBACK ACTIVE appears on Menu 1 of the front panel display when the Foldback activates.
When the reflected power is below the Foldback setting, the Foldback circuit de-activates.
The forward port output is split by a -10 dB coupler. The direct output is connected to a detector diode. The
output of the detector diode is used on the HPA interface board to measure forward power. The side port of
the coupler is connected to the forward type N RF sample port on the rear panel.

Model 2000TP2G8B
8 Rev -
Forward and reflected power monitoring, both peak reading and average reading, are designed for use when a
CW RF input is present during the entire period of the pulses applied to the external pulse input.
Amplifier gain is determined by the solid state pre-amp (SSPA), which has a voltage-controlled attenuator.
The control head determines the output of a digital-to-analog converter (DAC) on the HPA interface board.
The output of the DAC controls the SSPA attenuator. The emergency bypass board mounted behind the front
panel is provided with a circuit for control head bypass in the event of a failure. In emergency bypass
operation the attenuator signal is provided locally by means of a potentiometer on the emergency bypass
board.
RF pulsing characteristics are protected by the Pulse Monitor Board (A30750-000). This board protects the
HPA from over duty and over pulse width operation. The settings of these faults are factory set prior to
shipment. This board also allows for user settable warnings for over peak forward or reflected power. These
warnings can be set locally or remotely.
2.3 DESCRIPTION OF THE POWER SUPPLY (A22826-018)
The TWT power supply assembly is of modular construction. Low voltage power for logic and for control of
the entire power supply assembly is provided by the low voltage power supply module (A23687-001).
Control logic and TWT protection circuits are contained in the HPA Logic and Control Assembly (A16485-
000).
The Heater Power Supply Module (A10010-000) powers the TWT DC heater. Bias and pulse top voltage for
the TWT grid are provided by the Modulator Assembly (A23684-101).
The high voltage power supply consists of the following: the Power Factor Correction module (A23683-100)
converts line voltage to DC for the high voltage switching supply. Switching transistors are on the Power
Board Assembly (A16487-382), and switching is controlled by the Regulation Board. The high voltage
transformer and rectifiers are contained in the HV Diode/Cap Assembly (A21425-020). The high voltage DC
is filtered in the HV Filter Assembly (A21458-004).
Interconnects between the power supply modules are either through a motherboard or interconnected wiring
harnesses. The motherboard is installed in the power supply base plate so that the entire area of the finned
heat sink is available for heat transfer. The cooling air is provided by a 400 Hz fan. Air enters through the air
intake filter on the rear panel. The Motherboard assembly is A23280-000.
The HPA interface board permits the control module to control the power supply and monitor analog values
and fault status. Control is through the F/O to RS-485 board, which converts the electrical data from the
control module back to fibers to the HPA interface board.

Rev - 9
3. OPERATION
Throughout this manual, the symbol:
WARNING:
indicates that a hazard exists that may result in personal injury or loss of life.
CAUTION:
indicates that failure to follow procedures may result in damage to the
equipment.
WARNING: DANGER - High Voltage Present:
Electrical equipment in this TWTA generates and stores high-voltage
energy that can result in fatal electrocution. Do not operate the TWTA
with covers or the front panel removed.
Service work must be performed only by technicians thoroughly familiar
with the high-voltages present in microwave tube amplifiers in general,
and with this equipment in particular.
Never handle the TWT leads or the high-voltage connectors unless the
unit has been unplugged and it has been positively established that the
high-voltage filter capacitors have been discharged to a known safe level.
WARNING: Safety Ground
Improper grounding of this equipment can result in electric shock. The
TWTA must be operated only with a line cord with a safety ground wire.
It is the user's responsibility to ascertain that the power connector is
properly wired and that the power outlet is grounded.
WARNING: Explosive Atmosphere
To avoid explosion, never operate this TWTA in an explosive atmosphere.
This equipment is not certified for operation in an explosive atmosphere.
3.2 INSTALLATION
3.2.1 Unpacking
Upon receiving the TWTA, inspect the shipping container for obvious signs of external damage. If damage
is observed, notify the carrier and contact an authorized service representative.
Save and store the shipping container in case the unit needs to be returned to the manufacturer for repair.

Model 2000TP2G8B
10 Rev -
3.2.2 Mounting and removing
The TWTA may be operated as a standalone benchtop unit, or it may be installed in a 19" rack.
If rack mounting is desired, first remove the module from the cabinet, then install the module in the rack.
NOTE: Due to the weight of the unit, the installation or removal of the amplifier is a two person operation.
Before removing the amplifier, disconnect power, RF, and any other external interface connectors. On the
rear of the unit, remove any screws used to connect support brackets to the amplifier. On the front of the unit,
remove all of the screws holding the front panel to the cabinet. Carefully slide the entire amplifier out of the
front of the cabinet.
CAUTION:
Never rack mount the TWTA using the front panel alone. The chassis is
likely to be damaged unless its weight is supported. Bottom support rails
or side slide rails must be used in a rack mount configuration.
See Figure 3-1 (below) for the locations of threaded holes which may be used for supplementary support of
the rear of the TWTA.
Figure 3-1. Mounting Support Holes
If bottom supports are used for rack mount installation of multiple units, the amplifiers should be separated
vertically by at least 1 3/4 inches. This will allow room for necessary support rails and facilitate installation
and removal of the units.