Xicom XT-50 User manual

OPERATION AND INSTALLATION MANUAL
XT-50, XT-80 AND XT-100
ANTENNA MOUNT TWT POWER AMPLIFIERS

OPERATION & INSTALLATION MANUAL
XT-50, XT-80, AND XT-100
ANTENNA-MOUNT TWT POWER AMPLIFIERS
Document No. 802-0111-001
Revision E
September 2001
3550 Bassett Street
Santa Clara, CA 95054
Phone [phone] ·Fax [phone]

Notice
Copyright 2001
This document contains propriety information which is protected by copyright. All rights are
reserved.
The information in this document is subject to change without notice.
Xicom Technology reserves the right to revise this publication and to make changes from time
to time in the content hereof without obligation of Xicom Technology to notify any person of
such revision or changes.
Xicom Technology makes no warranty of any kind with regard to this material, including, but
not limited to, the implied warranties of fitness for a particular purpose. Xicom Technology
shall not be liable for errors contained herein or for incidental consequential damages in
connection with the furnishing, performance, or use of this material.
Printing History
EDITION DATE ECO DOCUMENT NUMBER
Edition 5 09/07/01 8861 802-0111-001 Rev. E
Edition4 05/05/01 8374 802-0111-001 Rev. D
Edition 3 02/20/98 802-0000-000 Rev. C
Edition 2 10/97 802-0000-000 Rev. B
Edition 1 07/97 802-0000-000 Rev. A

XT-50, XT-80, and XT-100 Amplifiers iii
TABLE OF CONTENTS
1. General Description............................................................................................ 1-1
Overview ............................................................................................................... 1-1
Control and Status Interface................................................................................ 1-2
Performance Specifications.................................................................................. 1-2
2. Installation............................................................................................................ 2-1
Introduction........................................................................................................... 2-1
Unpacking and Inspection................................................................................... 2-1
Mechanical Installation........................................................................................ 2-1
Waveguide Connection.............................................................................. 2-2
Air Ducting.................................................................................................. 2-3
Prime Power Connections ................................................................................... 2-3
AC Prime Power, 100 to 260 VAC, Single Phase.............................................. 2-3
Fuses ...................................................................................................................... 2-4
Controller Connections........................................................................................ 2-4
Control and Monitor Interfaces........................................................................... 2-5
Control Interfaces.................................................................................................. 2-6
Digital Status Circuits........................................................................................... 2-9
Analog Status Circuits........................................................................................ 2-11
Output Voltage Circuits..................................................................................... 2-11
Detected Power Calibration .............................................................................. 2-13
Standard Interconnect Cable............................................................................. 2-13
RF Connectors..................................................................................................... 2-16
3. Operation .............................................................................................................. 3-1
General ............................................................................................................. 3-1
Operating Modes.................................................................................................. 3-1
Heater Delay Mode............................................................................................... 3-1
Heater Standby Mode.......................................................................................... 3-1
Standby Mode....................................................................................................... 3-2
High Voltage ON Mode....................................................................................... 3-2
Fault Mode............................................................................................................. 3-2
Clearing Faults...................................................................................................... 3-3
Control and Status Signals................................................................................... 3-3
Control Signals...................................................................................................... 3-3
Status, Digital........................................................................................................ 3-3
Status, Analog ....................................................................................................... 3-4
Initial Turn-On...................................................................................................... 3-5
Pre-Power Check................................................................................................... 3-5
Turn-On Sequence................................................................................................ 3-5
Turn-Off ............................................................................................................. 3-6

iv XT-50, XT-80, and XT-100 Amplifiers
4. Maintenance and Service................................................................................... 4-1
Preventative Maintenance ................................................................................... 4-1
Remove Lower Deck Cover.................................................................................4-1
Service and Repair................................................................................................ 4-1
Return Authorization........................................................................................... 4-2
Re-Shipment .......................................................................................................... 4-2
List of Figures
1-1 TWT Block Diagram...................................................................................1-1
2-1 Amplifier Outline Drawing.......................................................................2-1
2-2 “Output End”.............................................................................................. 2-2
2-3 Typical Tightening Pattern........................................................................ 2-3
2-4 Location of Prime Power Connector ........................................................2-3
2-5 Connector J2 AC Pinouts ........................................................................... 2-3
2-6 Location of Fuses.........................................................................................2-4
2-7 Location of Controller Interface Connector J1.........................................2-4
2-8 Interface Connector Pinouts...................................................................... 2-5
2-9 Internal Supply Control Circuits...............................................................2-7
2-10 External Supply Control Circuits.............................................................. 2-8
2-11 Digital Status Circuit Isolation.................................................................. 2-9
2-12 TWT Temperature: Temperature vs. Voltage......................................2-12
2-13 Detected Power Calibration.....................................................................2-13
2-13 Interconnect Cable.................................................................................... 2-14
2-14 Interface Cable “D” Connector Pinouts................................................. 2-15
List of Tables
1-1 Models Available........................................................................................1-1
1-2 C-Band Performance Specifications .........................................................1-3
1-3 X-Band Performance Specifications.......................................................... 1-4
1-4 Ku-Band Performance Specifications.......................................................1-5
1-5 Environmental Specifications, All Models...............................................1-6
1-6 Interface Specifications, All Models......................................................... 1-6

XT-50, XT-80, and XT-100 Amplifiers v
High Voltage Hazards
This amplifier utilizes high voltage that can be lethal if contacted. The amplifier should not be
operated without its cover unless you are thoroughly familiar with its operation and are experienced
with high voltage.
RF Radiation Hazards
Prior to operation of the TWTA, ensure that all microwave connections are securely fastened. Check
that there is no microwave leakage from them. Never operate the amplifier with an open waveguide.
This amplifier is capable of generating high power microwave radiation, which can cause bodily
harm.
Safety Summary
Equipment of this nature has inherent hazards. Operator or service technicians should have training
on the XT-50, XT-80, or XT-100 power amplifiers. When the amplifier’s cover is removed, the high
voltage power supply for the TWT has multiple exposed high voltage points. Use extreme care when
operating the amplifier with its cover removed.

XT-50, XT-80, and XT-100 Amplifiers General Description 1-1
CHAPTER 1: GENERAL DESCRIPTION
Overview
This operation manual discusses Xicom Technology antenna-mount power amplifiers with power
levels ranging from 50 Watts to 170 Watts. These antenna-mount units are designed for outdoor
mounting directly to an antenna structure. The standard components of each amplifier include: a
Traveling Wave Tube (TWT), an integral high voltage power supply, and a forced air cooling system.
For a brief product description and typical block diagram, see the table and figure below.
Model Name Frequency Range Band Rated Power @ HPA Flange
XT-50C 5.85 to 6.425 GHz C-Band 50 Watts
XT-100C 5.85 to 6.425 GHz C-Band 140 Watts
XT-50X 7.9 to 8.4 GHz X-Band 50 Watts
XT-100X 7.9 to 8.4 GHz X-Band 125 Watts
XT-50K 14.0 to 14.5 GHz Ku-Band 50 Watts
XT-80K 14.0 to 14.5 GHz Ku-Band 70 Watts
XT-100K 13.75 to 14.5 GHz Ku-Band 100 Watts
Table 1-1 Models Available
Figure 1-1 TWT Block Diagram

1-2General Description XT-50, XT-80, and XT-100 Amplifiers
Control and Status Interface
The XT-50, XT-80, and XT-100 amplifiers are externally controlled. These amplifiers do not include any
control switches or status indicators for operator use. The external control and status indicator
interfaces are detailed in Chapter 2 of this manual.
Performance Specifications
The performance specifications of the C-Band, X-Band, and Ku-Band models are shown in Tables 1-2, 1-
3, and 1-4 respectively. Environmental specifications for all models are summarized in Table 1-5.
Interface specifications are shown in Table 1-6.

XT-50, XT-80, and XT-100 Amplifiers General Description 1-3
Table 1-2 C-Band Performance Specifications
Parameter XT-50C Specifications XT-100C Specifications
FREQUENCY RANGE 5.850 GHz to 6.425 GHz 5.850 GHz to 6.425 GHz
OUTPUT POWER TWT
@ Amplifier Flange 55 Watts 50 Watts 170 Watts 140 Watts
GAIN, Small Signal, Minimum 45 dB 46 dB
GAIN, Large Signal, Minimum 40 dB 40 dB
GAIN VARIATION, SSG
Narrow Band, Maximum
Full Band, Maximum 1.5 dB over any 40 MHz band 2.5 dB 1.0 dB over any 40 MHz band 2.5 dB
GAIN SLOPE, Maximum ±0.04 dB/MHz ±0.04 dB/MHz
GAIN STABILITY IN ANY 24
HOUR PERIOD, Maximum ±0.25 dB ±0.25 dB
GAIN STABILITY OVER
TEMPERATURE ±1.0 dB maximum over operating
temperature range at any frequency ±1.0 dB maximum over operating temperature range at any frequency
INTERMODULATION WITH
TWO EQUAL SIGNALS -18 dBc maximum with two equal carriers at 4 dB total output backoff -18 dBc maximum with two equal carriers at 4 dB total output backoff
HARMONIC OUTPUT,
Maximum -60 dBc -60 dBc
AM TO PM CONVERSION,
Maximum 2.5°/dB at 6 dB below rated power 2.5°/dB at 6 dB below rated power
NOISE POWER
Transmit Band, Maximum
Receive Band, Maximum -70 dBw/4 KHz -150 dBw/4 KHz
3.7 GHz to 4.2 GHz
-80 dBw/4 KHz
-160 dBw/4 KHz
3.7 GHz to 4.2 GHz
GROUP DELAY, Maximum
Bandwidth
Linear
Parabolic
Ripple
Any 40 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
Any 40 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
RESIDUAL AM NOISE,
Maximum -50 dBc to 10 KHz -20 (1.5+logf) dBc 10 to 500 KHz
-85 dBc above 500 KHz
-50 dBc to 10 KHz
-20 (1.5+logf) dBc 10 to 500 KHz
-85 dBc above 500 KHz
PHASE NOISE, Maximum 10 dB below IESS phase noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
10 dB below IESS phase noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
VSWR, Maximum
Input
Output 1.3:1 2.2:1 1.3:1 2.2:1

1-4General Description XT-50, XT-80, and XT-100 Amplifiers
Table 1-3 X-Band Performance Specifications
Parameter XT-50X Specifications XT-100X Specifications
FREQUENCY RANGE 7.90 GHz to 8.40 GHz 7.90 GHz to 8.40 GHz
OUTPUT POWER, TWT
@ Amplifier Flange 55 Watts 50 Watts 140 Watts 125 Watts
GAIN, Small Signal, Minimum 53 dB 46 dB
GAIN, Large Signal, Minimum 49 dB 40 dB
GAIN VARIATION, SSG
Narrow Band, Maximum
Full Band, Maximum 1.3 dB over any 40 MHz band 2.5 dB 1.0 dB over any 40 MHz band 2.5 dB
GAIN SLOPE, Maximum ±0.04 dB/MHz ±0.04 dB/MHz
GAIN STABILITY IN ANY 24
HOUR PERIOD, Maximum ±0.25 dB ±0.25 dB
GAIN STABILITY OVER
TEMPERATURE ±1.0 dB maximum over operating
temperature range at any frequency ±1.0 dB maximum over operating temperature range at any frequency
INTERMODULATION WITH
TWO EQUAL SIGNALS -18 dBc maximum with two equal carriers at 4 dB total output backoff -18 dBc maximum with two equal carriers at 4 dB total output backoff
HARMONIC OUTPUT,
Maximum -60 dBc -60 dBc
AM TO PM CONVERSION,
Maximum 2.5°/dB at 6 dB below rated power 2.5°/dB at 6 dB below rated power
NOISE POWER
Transmit Band, Maximum
Receive Band, Maximum -70 dBw/4 KHz -70 dBw/4 KHz
7.25 - 7.75 GHz
-80 dBw/4 KHz
-80 dBw/4 KHz
7.25 - 7.75 GHz
GROUP DELAY, Maximum
Bandwidth
Linear
Parabolic
Ripple
Any 40 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
Any 40 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
RESIDUAL AM NOISE,
Maximum -50 dBc to 10 KHz -20 (1.5+logf) dBc 10 to 500 KHz
-85 dBc above 500 KHz
-50 dBc to 10 KHz
-20 (1.5+logf) dBc 10 to 500 KHz
-85 dBc above 500 KHz
PHASE NOISE, Maximum 10 dB below IESS phase noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
10 dB below IESS phase noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
VSWR, Maximum
Input
Output 1.3:1 2.2:1 1.3:1 2.2:1

XT-50, XT-80, and XT-100 Amplifiers General Description 1-5
Table 1-4 Ku-Band Performance Specifications
Parameter XT-50K XT-80K XT-100K
FREQUENCY RANGE 14.0 GHz to 14.5 GHz 14.0 GHz to 14.5 GHz 13.75 GHz to 14.5 GHz
OUTPUT POWER, TWT
@ Amplifier Flange 55 Watts 50 Watts 80 Watts 70 Watts 125 Watts 100 Watts
GAIN, Small Signal, Minimum 53 dB 50 dB 46 dB
GAIN, Large Signal, Minimum 49 dB 46 dB 40 dB
GAIN VARIATION, SSG
Narrow Band, Maximum
Full Band, Maximum 1.3 dB per 80 MHz 2.5 dB 1.3 dB per 80 MHz 2.5 dB 1.0 dB per 80 MHz 2.5 dB
GAIN SLOPE, Maximum ±0.04 dB/MHz ±0.04 dB/MHz ±0.04 dB/MHz
GAIN STABILITY IN ANY 24
HOUR PERIOD, Maximum ±0.25 dB ±0.25 dB ±0.25 dB
GAIN STABILITY OVER
TEMPERATURE ±1.0 dB maximum over
operating temperature
range at any frequency
±1.0 dB maximum over
operating temperature
range at any frequency
±1.0 dB maximum over
operating temperature
range at any frequency
INTERMODULATION WITH
TWO EQUAL SIGNALS -18 dBc maximum with two equal carriers at 4 dB
total output backoff
-18 dBc maximum with
two equal carriers at 4 dB
total output backoff
-18 dBc maximum with
two equal carriers at 4 dB
total output backoff
HARMONIC OUTPUT,
Maximum -60 dBc -60 dBc -60 dBc
AM TO PM CONVERSION
Maximum 2.5°/dB at 6 dB below
rated power 2.5°/dB at 6 dB below rated power 2.5°/dB at 6 dB below rated power
NOISE POWER
Transmit Band, Maximum
Receive Band, Maximum -70 dBw/4 KHz -150 dBw/4 KHz
10.95 GHz to 12.75 GHz
-70 dBw/4 KHz
-150 dBw/4 KHz
10.95 GHz to 12.75 GHz
-80 dBw/4 KHz
–160 dBw/4 KHz
10.95 GHz to 12.75 GHz
GROUP DELAY, Maximum
Bandwidth
Linear
Parabolic
Ripple
Any 80 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
Any 80 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
Any 80 MHz
0.01 nS/MHz
0.005 nS/MHz2
0.5 nS/Pk-Pk
RESIDUAL AM NOISE,
Maximum -50 dBc to 10 KHz -20 (1.5+logf) dBc 10 to
500 KHz
-85 dBc above 500 KHz
-50 dBc to 10 KHz
-20 (1.5+logf) dBc 10 to
500 KHz
-85 dBc above 500 KHz
-50 dBc to 10 KHz
-20 (1.5+logf) dBc 10 to
500 KHz
–85 dBc above 500 KHz
PHASE NOISE, Maximum 10 dB below IESS phase
noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
10 dB below IESS phase
noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
10 dB below IESS phase
noise profile
AC fundamental -50 dBc
Sum of all spurs -47 dBc
VSWR, Maximum
Input
Output 1.3:1 2.2:1 1.3:1 2.2:1 1.3:1 2.2:1

1-6General Description XT-50, XT-80, and XT-100 Amplifiers
Table 1-5 Environmental Specifications, All Models
Parameter Specifications
NON-OPERATING TEMPERATURE RANGE -50°C to + 70°C
OPERATING TEMPERATURE RANGE -40°C to + 50°C
HUMIDITY Up to 100% condensing
ALTITUDE 10,000 feet MSL maximum
SHOCK AND VIBRATION Normal transportation
COOLING Forced air
Table 1-6 Interface Specifications, All Models
Parameter Specifications
PRIME POWER, STANDARD 100-260 VAC
47 Hz to 63 Hz
XT-50, maximum value
XT-80, maximum value
XT-100 maximum value
400 VA Maximum/.95 Minimum Power Factor
525 VA Maximum/.95 Minimum Power Factor
675 VA Maximum/.96 Minimum Power Factor
CONTROLS High Voltage ON/OFF
Fault Reset
Heater Standby
MONITOR, DIGITAL High Voltage ON
Filament Time Delay
Standby
Summary Fault
Helix Current/Arc Fault
Helix Latched Fault
Temperature Fault
High Voltage Fault
Fan Fault
MONITOR, ANALOG Helix Current (2 mA/V)
Cathode Voltage (1000:1 V/V)
TWT Temperature
RF Output Power (Optional)
AUXILIARY VOLTAGES + 15 VDC (100 mA max)
+24 VDC (100 mA max)
*Heater standby reduces the TWT heater voltage for situations where the high voltage
is off for extended periods.

XT-50, XT-80, and XT-100 Amplifiers Installation 2-1
CHAPTER 2: INSTALLATION
Introduction
This chapter describes the procedures for unpacking, inspecting, and installing the XT-50, XT-80,
and XT-100 amplifiers.
Unpacking and Inspection
Upon receiving the amplifier, inspect both the inside and outside of the shipping container for signs
of damage. If any shipping damage is detected, call the shipping carrier and submit a damage
report.
Compare the packing list to the contents of the container to be certain that all material has been
received. Save all data sheets. They will be useful during any maintenance actions. Save the
packing material and use it if you need to reship the unit.
Inspect all items for any damage received during shipment. If shipping damage is detected, submit a
damage report to the shipping carrier. Failure to submit a report may invalidate any future claims.
Mechanical Installation
The power amplifier can be mounted any place that is convenient for the user, subject to the
conditions noted later in this section for unobstructed intake and exhaust air flow.
Standard mounting brackets come with the unit. Alternative mounting brackets can be designed
using the mounting dimensions shown in Figure 2-1.
Figure 2-1. Amplifier Outline Drawing

2-2Installation XT-50, XT-80, and XT-100 Amplifiers
Waveguide Connection
The RF output waveguide port (C-Band and X-Band CPR-137G, or Ku-Band WR-75) is located on the
“output end” of the amplifier as shown in Figure 2-2.
Figure 2-2. “Output End”
Proceed as follows:
1. Ensure that the proper matching waveguide flange and gaskets are used to
connect the RF output to the feed system or antenna.
2. Position the interconnecting waveguide flange parallel to the output
waveguide flange. Make sure that the flanges can be mated without strain
or torsion.
3. If the two flanges cannot be properly aligned or if the installation is subject
to vibration, a flexible waveguide section should be utilized to eliminate
potential strain on the waveguide connection.
4. Insert any necessary gasket and/or window between the two flanges.
If the connecting waveguide is to be pressurized at greater than 5
psi, a waveguide window must be installed at the output flange of
the amplifier.
5. Install and hand tighten all mounting screws (#6-32 for Ku-Band and #10-
32 for C-Band and X-Band).
Do not overtighten the waveguide mounting screws.
Overtightening may strip the threads in the waveguide flange.
6. Tighten all mounting screws to the torque values shown in Figure 2-3. A
typical sequence is indicated by the numbers in the grayed areas of Figure
2-3. Proceed as follows:
a. Partially tighten one of the screws (#1).
b. Move the tool to the screw that is diagonally opposite to the screw
tightened in step 1 (#2) and partially tighten that screw.
c. Move clockwise to the next screw to be tightened (#3) and partially tighten
that screw.
d. Move to the screw diagonally opposite screw #3 and partially tighten that
screw (#4).
e. Repeat this process for the remaining screws (#5-#6, #7-#8).
f. When you reach the first screw tightened in step a (#1) increase the torque
on the screw and repeat the process of steps (1) through (5) until the
screws have all been tightened to the torque levels included in Figure 2-3.

XT-50, XT-80, and XT-100 Amplifiers Installation 2-3
Figure 2-3. Typical Tightening Pattern
Air Ducting
The location of the air inlet and exhaust ports were shown in Figure 2-1. A minimum clearance of
two inches is required for the air inlets and exhaust ports. If the amplifier is mounted in an enclosed
chamber, duct the exhaust air to the outside of the chamber. Do not recirculate the exhaust air back
into the amplifier. Use an exhaust duct that is not smaller than the exhaust port of the amplifier and
one that has smooth bends and transitions.
Prime Power Connections
The location of the prime power input connector is shown in Figure 2-4.
WHEN THE CONTROLLER IS DISCONNECTED OR SET TO AC OFF,
PRIME POWER IS STILL PRESENT IN THE INTERIOR OF THE TWTA.
DISCONNECT PRIME POWER BEFORE SERVICING THE UNIT.
Figure 2-4. Location of Prime Power Connector
AC Prime Power, 100 to 260 VAC, Single Phase
The HPA will operate over the entire range of 100 to 260 VAC, 47 Hz to 63 Hz. Connector J2 pinouts
are shown in Figure 2-5.
Figure 2-5. Connector J2 AC Pinouts
100-260 VAC
Ground
(PE)
Neutral
Prime Power Connector-
Amphenol T3110-003 Mating Plug Amphenol T3109-013

2-4Installation XT-50, XT-80, and XT-100 Amplifiers
THE AMPLIFIER SHOULD BE SECURELY GROUNDED FOR PERSONNEL
AND EQUIPMENT SAFETY.
BE CERTAIN THAT THE AC VOLTAGE CABLE HAS THREE WIRES
WHERE THE THIRD WIRE IS A SAFETY GROUND.
Fuses
Input AC power fuses are 13” AGC type related at 8 amperes. They are replaceable through the
screw-on sealing caps next to the prime power connector.
Figure 2-6. Location of Fuses
Controller Connections
Connector J1 (Figure 2-6) on the “Input End” of the amplifier connects to the external controller. A
description of the functions of this connector follows Figure 2-6. The standard connecting cable and
the controller end of the cable are described in the paragraphs following the description of connector
J1.
Figure 2-7. Location of Controller Interface Connector J1

XT-50, XT-80, and XT-100 Amplifiers Installation 2-5
Control and Monitor Interfaces
The control interface connector (J1) pinouts are shown in Figure 2-8. There are five classes of
interfaces:
•Controls •Analog Signals
•Digital Status •DC Bias Voltages
•External Voltage
Item Pin Functions
Controls
(Commands)
All circuits
active low
a
F
J
X
Z
AC Power ON
High Voltage ON
Heater Standby
Fault Reset
AC Command Return
Status, Digital
(Indicators)
All circuits
active low.
A
C
G
H
K
M
R
S
T
U
W
Helix/Arc Fault Latched
Helix/Arc /Fault
Heater Timer Complete
TWT Temperature Fault
High Voltage ON
Fan ON
High Voltage Fault
Fan ON High
Summary Fault
Fan Lock
Control/Status Return
Signals, Analog b
D
L
N
P
RF Output Power
Helix Current
High Voltage Monitor
Analog Signal Return
TWT Temperature
Output Voltages E
V+15 VDC (100 mA maximum) +24 VDC (100 mA maximum)
External Voltage YExternal Supply (+5/15 VDC)
Figure 2-8. Interface Connector Pinouts

2-6Installation XT-50, XT-80, and XT-100 Amplifiers
Control Interface
There are five control inputs as follows:
•AC Power ON (Pin a). Connect Pin a to ground (Pin Z) to enable operation
of the TWTA and turn the TWT's heater on.
•High Voltage ON (Pin F). Connect Pin F to ground (Pin W) to turn high
voltage on.
•Heater Standby (Pin J). Connect Pin J to ground (Pin W) to reduce the
voltage applied to the TWT's heater. This feature is provided to extend the
life of the TWT when the amplifier is the back-up unit in a redundant
configuration. The High Voltage ON overrides the Heater Standby
command and returns the TWT's heater voltage to its normal operating
value.
•Fault Reset (Pin X). Momentarily connect Pin X to ground (Pin W) to reset
the high voltage fault and helix current fault.
Turning the High Voltage OFF will also clear these faults.
•AC Command Return (Pin Z). Common return.
Operation Without a Controller
To implement operation without a controller, the following jumper connections need to be made.
These connections can be made in the control connector mate: PT06E 18-32P.
1. Connect Pin a to Pin Z
2. Connect Pin F to Pin W
3. Connect Pin E to Pin Y
With these connections, the amplifier will be operational within 3 minutes of applying AC Power. If
the amplifier has a Latching Type Fault, it can be reset by momentarily turning off the AC Power.
Bias for the external control inputs need to be implemented with either the internal +15 VDC of the
amplifier or from an external DC supply. Both configurations are described in the following
paragraphs.
Using the Internal +15 VDC for Control (Connect E to Y): The control circuits for
systems that use the internal +15 VDC supply of the power amplifier are shown in Figure 2- 9.
Using an External DC Supply for Control into Pin Y:The control circuits for systems that use an
external +10 to +15 VDC supply are shown in Figure 2- 10.
These figures include the pinouts (a., b., c., etc.) of power amplifier connector J1. The equivalent “D”
connector pinouts for interconnect cable 350-0017-XXX, which is normally used to connect the
power amplifier to a TWTA controller are shown later in this chapter in Figure 2-14.
The operation of either configuration is the same. The control system connections are fail-safe.
Removal of the interconnect cable inhibits operation of the power amplifier.

XT-50, XT-80, and XT-100 Amplifiers Installation 2-7
Figure 2-9. Internal Supply Control Circuits

2-8Installation XT-50, XT-80, and XT-100 Amplifiers
Figure 2-10. External Supply Control Circuits