NEC LD7261 Datasheet

DATA SHEET

HIGH POWER TRAVELING WAVE TUBE

FOR COMMUNICATIONS

LD7261

20 GHz, 250 W CW, PPM FOCUSING, HIGH POWER GAIN

GENERAL DESCRIPTION

The NEC LD7261 is a 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 250 W over the range of 18.0 to 21.7 GHz and provides a

power gain of more than 40 dB at 250 W.

Furthermore, it is rugged and reliable design offers long-life service.

FEATURES

™ High Power Gain

The power gain is typically 40 dB at 250 W level.

™ Simple Cooling System

All the tubes are 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 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)

The information in this document is subject to change without notice.

Document No. ET0397EJ1V0DS00
Date Published August 1998 M
Printed in Japan

©

1998

GENERAL CHARACTERISTICS

ELECTRICAL

Frequency ……………………………………………… 18.0 to 21.7 GHz
Output Power ………………………………………… 250 W
Heater Voltage ………………………………………… 6.3 V
Heater Current ………………………………………… 1.42 A
Type of Cathode ……………………………………… Indirectly heated, Impregnated
Cathode Warm-up Time …………………………… 300 s

MECHANICAL

Dimensions …………………………………………… See Outline
Weight ………………………………………………… 6.0 kg approx.
Focusing ………………………………………………Periodic Permanent Magnet
Mounting Position …………………………………… Any
Electrical Connections ……………………………… Flying Leads
RF Connections

Input ………………………………………………… SMA Female
Output ……………………………………………… Mates with WR-51 waveguide (see outline)

Cooling ………………………………………………… Forced Air

LD7261

ABSOLUTE RATINGS (Note 1, 2 and 3 )

ELECTRICAL

Heater Voltage ……………………………………… 6.0 6.6 V
Heater Surge Current …………………………… – 2.5 A
Heater Current ……………………………………… – 1.8 A
Heater Warm-up Time …………………………… 300 – s
Helix Voltage ……………………………………… 9.5 10.8 kV
Helix Current ……………………………………… – 15.0 mA
Anode Voltage ……………………………………… 8.0 10.25 kV
Anode Current ……………………………………… – 0.5 mA
Collector Voltage …………………………………… 4.0 5.8 kV
Collector Current…………………………………… – 350 mA
Cathode Current …………………………………… – 350 mA
RF Drive Power …………………………………… – 25 mW
RF Output Power ………………………………… – 400 W
Load VSWR ………………………………………… – 1.2 : 1 –

ENVIRONMENTAL

Temperature at output Flange…………………… –40 +110 ˚C
Air Flow ……………………………………………… 195 – kg/hour
Ambient Temperature

Storage …………………………………………… –40 +80 ˚C
Operation ………………………………………… –10 +50 ˚C

Min. Max. Unit

Min. Max. Unit

2