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DATA SHEET
HIGH POWER TRAVELING WAVE TUBE
FOR DBS GROUND TERMINALS
LD7237
DBS Band, 400 W CW, PPM FOCUSING, HIGH POWER GAIN
GENERAL DESCRIPTION
NEC LD7237 is PPM-focused traveling wave tube designed for use as final amplifier in the earth-to-satellite
communications transmitter.
This is capable of delivering an output power of 400 W over the range of 17.3 to 18.1 GHz and provides a high
power gain of 53 dB at 400 W output power.
Furthermore, this is of rugged and reliable design offering long-life service.
LD7237 is fully compatible with TH3694B.
FEATURES
™ High Power Gain
The power gain is typically 53dB at 400 W level.
™ Simple Cooling System
The tube is forced-air-cooled, so that the cooling systems are greatly simplified.
™ PPM Focusing
The tube is PPM (Periodic Permanent Magnet)-focused, eliminating entirely the focusing power supplies and
interlock circuits.
™ Rugged Construction
The tube is designed to be rugged, therefore it is suitable for the transportable systems.
™ Long Life and High Stability
The tube employs an advanced impregnated cathode with a low operating temperature for long life.
™ Microdischarge Free
The tube is carefully designed to be free from microdischarge in the electron gun for long term operation,
therefore it is suitable for digital communication service.
For safe use of microwave tubes, refer to NEC document “Safety instructions to all personnel
handling electron tubes” (ET0048EJ∗V∗UM00)
Document No. ET0159EJ2V1DS00
Date Published August 1998 M
Printed in Japan
The information in this document is subject to change without notice.
©
1996
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LD7237
GENERAL CHARACTERISTICS
ELECTRICAL
Frequency .................................................................................. 17.3 to 18.1 GHz
Output Power ............................................................................ 400 W
Heater Voltage........................................................................... 6.3 V
Heater Current........................................................................... 1.4 A
Type of Cathode........................................................................ Indirectly heated, Impregnated
Cathode Warm-up Time ........................................................... 300 s
MECHANICAL
Dimensions................................................................................ See Outline Drawing
Weight........................................................................................ 6.0 kg approx.
Focusing .................................................................................... Periodic Permanent Magnet
Mounting Position .................................................................... Any
Electrical Connections .............................................................. AMP 861647-8 multi-pin connector
Heater, Heater-Cathode
Helix, Anode, Collector
and Thermal Protection
RF Connections
Input ................................................................................... Mates with SMA-Female
Output ................................................................................ Mates with UBR-140 Flange
Cooling....................................................................................... Forced Air
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LD7237
ABSOLUTE RATINGS
ELECTRICAL
Heater Voltage.................................................................. 6.0 6.6 V
Heater Surge Current ...................................................... – 4.5 A
Heater Current.................................................................. – 3.0 A
Heater Warm-up Time ..................................................... 300 – s
Helix Voltage .................................................................... 9.5 10.75 kV
Helix Current .................................................................... – 15 mA
Anode Voltage.................................................................. 8.55 10.25 kV
Anode Current.................................................................. – 0.5 mA
Collector Voltage.............................................................. 4.0 5.5 kV
Cathode Current............................................................... – 350 mA
RF Drive Power ................................................................ – 25 mW
Load VSWR ...................................................................... – 1.5
MECHANICAL
Temperature at output Flange ........................................ – 100 ˚C
Air Flow ............................................................................ 195 – kg/hr
Ambient Temperature
Storage ..................................................................... –40 +80 ˚C
Operation.................................................................. –10 +50 ˚C
(Note 1, 2 and 3)
Min. Max. Unit
Min. Max. Unit
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LD7237
TYPICAL OPERATION
Frequency ............................................................................... 17.3 to 18.1 GHz
Output Power ......................................................................... 400 W
Heater Voltage (Note 4)........................................................ 6.3 V
Heater Current ........................................................................ 1.4 A
Helix Voltage........................................................................... 10 kV
Helix Current........................................................................... 2 mA
Anode Voltage........................................................................ 9.5 kV
Anode Current ........................................................................ 0.1 mA
Collector Voltage.................................................................... 4.7 kV
Cathode Current ..................................................................... 290 mA
Power Gain
at small signal .................................................................. 58 dB
at rated output power ..................................................... 53 dB
Gain Variation at small signal............................................... 2 dB /800 MHz
Gain Slope at small signal .................................................... 0.01 dB/MHz
AM-PM Conversion
at small signal .................................................................. 0.5 °/dB
at rated output power ..................................................... 2.0 °/dB
3rd Order Intermodulation
(two equal carriers, 40 W total) ...................................... –32 dBc
Cooling Air Flow .................................................................... 195 kg/hr
Pressure Drop......................................................................... 650 Pa
(Note 2, 3 and 5)
Unit
Note 1 : Absolute rating should not be exceeded under continuous or transient conditions.
A single absolute rating may be the limitation and simultaneous operation at more than one absolute
rating may not be possible.
Note 2 : The tube body is at ground potential in operation.
Note 3 : All voltages are refferred to the cathode potential except the heater voltage.
Note 4 : The optimum operating parameters are shown on atest performance sheet for each tube.
Note 5 : These characteristics and operating values may be changed as a result of additional information or product
improvement. NEC should be consulted before using this information for equipment design.
This data sheet should not be referred to a contractual specification.
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LD7237 OUTLINE (Unit in mm)
RF INPUT
SMA FEMALE
AMP861647-8
MULTI-PIN CONNECTOR
LD7237
85 MAX.
900± 50
157
210 MAX. 29
RF OUTPUT
Mates with UBR-140 FLANGE
505 MAX.
98
4-M3
178
175
66
110 MAX.
φ
86
83
55
4-M4
10- 6
6
87.5 MAX.
AIR OUTLET
10110110119
φ
111
127 MAX.
PIN CONNECTION
71
2
6
5
AMP861647-8 CONNECTOR
3
4
PIN ASSIGNMENT
Pin No. LEAD NAME
1 HEATER / CATHODE
2 HEATER
3 COLLECTOR
4 THERMAL PROTECTION
5 OPEN (NO CONNECTION)
6 HELIX (GROUND)
7 ANODE
NOTE THERMAL PROTECTION : N/ C (Normally
Closed) CONTACT
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LD7237
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LD7237
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LD7237
No part of this document may be copied or reproduced in any form or by any means without the prior
written consent of NEC Corporation. NEC Corporation assumes no responsibility for any errors which may
appear in this document.
NEC Corporation does not assume any liability for infringement of patents. copyrights or other intellectual
property rights of third parties by or arising from use of a device described herein or any other liability arising
from use of such device. No license, either express, implied or otherwise, is granted under any patents,
copyrights or other intellectual property rights of NEC Corporation or others.
While NEC Corporation has been making continuous effort to enhance the reliability of its Electronic
Conponents, the possibility of defects cannot be eliminated entirely. To minimize risks of damage or injury to
persons or property arising from a defect in an NEC Electronic Conponents, customers must incorporate
sufficient safety measures in its design, such as redundancy, fire-containment, and anti-failure features.
NEC devices are classified into the following three quality grades:
“Standard”, “Special”, and “Specific”. The Specific quality grade applies only to devices developed based
on a customer designated “quality assurance program” for a specific application. The recommended
applications of a device depend on its quality grade, as indicated below. Customers must check the quality
grade of each device before using it in a particular application.
Standard: Computers, office equipment, communications equipment, test and measurement equipment, audio
and visual equipment, home electronic appliances, machine tools, personal electronic equipment and industrial
robots
Special: Transportation equipment (automobiles, trains, ships, etc.), traffic control systems, anti-disaster
systems, anti-crime systems, safety equipment and medical equipment (not specifically designed for life
support)
Specific: Aircrafis, aerospace equipment, submersible repeaters, nuclear reactor control systems, life support
systems or medical equipment for life support, etc.
The quality grade of NEC devices is “Standard” unless otherwise specified in NEC's Data Sheets or Data
Books.
If customers intend to use NEC devices for applications other than those specified for Standard quality
grade, they should contact an NEC sales representative in advance.
Anti-radioactive design is not implemented in this product.
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