Datasheet LD7246A Datasheet (NEC)

DATA SHEET

HIGH POWER TRAVELING WAVE TUBE

FOR GROUND TERMINALS

LD7246A

14 GHz, 123 W CW, CONDUCTION COOLING, MINIMUM SIZE

GENERAL DESCRIPTION

NEC LD7246A 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 130 W over the range of 13.75 to 14.5 GHz.
It provides a high power gain of 53 dB at 123 W output power.
Furthermore, this is of rugged and reliable design offering long-life services.

FEATURES

™ Light weight, Compact and Efficient

The tube has dual-depressed collectors and is designed to operate at high efficiency across wide power
output range. It features state-of the art techniques to optimize size and efficiency.

™ High Power Gain

The power gain is typically 53 dB at 123 W level.

™ Simple Cooling System

The tube is conduction-cooled, so that the cooling system is greatly simplified.

™ PPM Focusing

The tube is PPM (Periodic Permanent Magnet) -focused, eliminating entirely 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)

Document No. ET0205EJ1V1DS00
Date Published August 1998 M
Printed in Japan

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

©

1996

GENERAL CHARACTERISTICS

ELECTRICAL

Frequency ……………………………………………… 13.75 to 14.5 GHz
Output Power ………………………………………… 123 W
Heater Voltage…………………………………………4.5 V
Heater Current ………………………………………… 1.0 A
Type of Cathode ……………………………………… Indirectly heated, Impregnated
Cathode Warm-up Time …………………………… 180 s

MECHANICAL

Dimensions …………………………………………… See Outline
Weight ………………………………………………… 1.3 kg approx.
Focusing ………………………………………………Periodic Permanent Magnet
Mounting Position …………………………………… Any
Electrical Connections ……………………………… Flying Leads

Heater, Heater-Cathode,
Helix, Collector-1, Collector-2

RF Connections

Input ………………………………………………… SMA-Female
Output ……………………………………………… Mates with UBR-120 Flange

Cooling ………………………………………………… Conduction

LD7246A

ABSOLUTE RATINGS ( Note 1, 2 and 3 )

ELECTRICAL

Heater Voltage……………………………………… 4.2 4.8 V
Heater Surge Current …………………………… – 2.5 A
Heater Current ……………………………………… – 1.3 A
Heater Warm-up Time …………………………… 180 – s
Helix Voltage ……………………………………… 6.0 6.4 kV
Helix Current ……………………………………… – 5.0 mA
Collector-1 Voltage ………………………………… 3.1 3.3 kV
Collector-2 Voltage ………………………………… 1.5 1.7 kV
Cathode Current …………………………………… – 140 mA
RF Drive Power …………………………………… – 1.0 dBm
Load VSWR ………………………………………… – 1.5 : 1

MECHANICAL

Baseplate Temperature

Storage …………………………………………… –30 +110 ˚C
Operation ………………………………………… –30 +110 ˚C

Min. Max. Unit

Min. Max. Unit

2

TYPICAL OPERATION (Note 2, 3 and 5)

Frequency ……………………………………………… 13.75 to 14.5 GHz
Output Power ………………………………………… 130 W
Heater Voltage (Note 4) ……………………………… 4.5 V
Heater Current ………………………………………… 1 A
Helix Voltage…………………………………………… 6.2 kV
Helix Current …………………………………………… 3 mA
Collector Voltage-1 …………………………………… 3.2 kV
Collector Current-1 …………………………………… 80 mA
Collector Voltage-2 …………………………………… 1.6 kV
Collector Current-2 …………………………………… 42 mA
Cathode Current ……………………………………… 125 mA
Power Gain at 6 W ………………………… 58 dB

at 130 W ……………………… 53 dB
Gain Variation at 13 W ……………………… 2 dB/750 MHz
Gain Slope at 13 W ……………………… 0.03 dB/MHz
AM-PM Conversion at 130 W ……………………… 3.5 deg./dB
3rd Order Intermodulation
(two equal carriers, 13 W total) …………………… –32 dBc
Efficiency ……………………………………………… 38 %

LD7246A

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 referred to the cathode potential exept the heater voltage.
Note 4 : The optimum operating parameters are shown on a test 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.

3

LD7246A OUTLINE (Unit in mm)

30

20

40
34

38

RF Out put
Mates With

UBR-120 Flange

LD7246A

38

9.6

13.2113.21

19

14.25 14.25

Output Flange

42

7

295

275

90

80

40

93

230

50 Max.

315

RF Input
SMA Female

HV Lead Wires
Length : 300

35

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.