Document No. ET0454EJ1V0DS00
Date Published August 1999 M
Printed in Japan
30 GHz, 40 W CW, Conduction Cooling, Mimimum Size
MIDIUM POWER TRAVELING WAVE TUBE
FOR COMMUNICATIONS
LD7714
The information in this document is subject to change without notice.
1999
For safe use of microwave tubes, refer to NEC document "Safety instructions to all personnel
handling electron tubes" (ET0048EJ
V
UM00)
GENERAL DESCRIPTION
The NEC LD7714 is a PPM-focused traveling wave tube designed for use as final amplifier in the earth-to-
satellite communications transmitter, LMDS (Local Multipoint distribution service) and other advanced
communication systems.
This is capable of delivering an output power of 40 W over the range of 27.5 to 30.0 GHz and provides a power
gain of more than 40 dB at 40 W level.
Furthermore, it is of rugged and reliable design offering long-life service.
FEATURES
TM Lightweight, Compact and Efficient
The tube has a dual-depressed collectors and designed to operate at high efficiency across the power output
range. It features state-of-the-art techniques to optimize size and efficiency.
TM Low Distortion
Distortion is a very important factor in multiplex digital signals transmission. NEC has developed techniques
for the correction of non-linear distortion and phase generated in a TWT. As a result, the TWT has an optimum
performance across a broad power range and is ideally suited for multi-carrier trancmission systems.
TM Simple Cooling System
The tube is conduction cooled, so that the cooling system is simplified.
TM Rugged Construction
The power gain is designed to be rugged, therefore it is suitable for transportable systems.
TM Long Life and High Stability
The tube employs an advanced impregnated cathode with a low operating temperature for long life.
TM Micro-discharge 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.
DATA S H E E T
LD7714
2
DATA SHEET ET0454EJ1V0DS00
GENERAL CHARACTERISTICS
ELECTRICAL
Frequency ...................................................... 27.5 to 30.0 GHz
Output Power ................................................ 40 W
Heater Voltage ................................................ 6.3 V
Heater Current ................................................ 0.82 A
Heater Surge Current
.................................... 2.5 A
Type of Cathode ............................................. Indirectly heated, Impregnated
Cathode Warm-up Time
................................. 180 s
MECHANICAL
Dimensions ................................................... See Outline
Weight ......................................................... 700 g approx.
Focusing
...................................................... Periodic Permanent Magnet
Mounting Position .......................................... Any
Electrical Connections .................................... Flying Leads
RF Connections
Input ......................................................... Mates with UG-599/U Flange or K connector Female
Output ...................................................... Mates with UG-599/U Flange
Cooling ......................................................... Conduction
ABSOLUTE RATINGS (Note 1, 2 and 3 )
ELECTRICAL
Min.
Max.
Unit
Heater Voltage .............................................
6.0
6.6
V
Heater Surge Current
.................................
2.5
A
Heater Current .............................................
1.2
A
Heater Warm-up Time .................................
180
s
Helix Voltage
.............................................
7.8
8.5
kV
Helix Current
.............................................
5.0
mA
Collector1 Voltage
....................................
3.0
3.3
kV
Collector1 Current
....................................
40
mA
Collector2 Voltage
....................................
1.5
1.7
kV
Collector2 Current
....................................
65
mA
RF Drive Power ..........................................
6
dBm
Load VSWR ................................................
1.5 : 1
ENVIRONMENTAL
Heat Sink Temperature
30
+90
C
Storage Temperature
40
+90
C
LD7714
3
DATA SHEET ET0454EJ1V0DS00
TYPICAL OPERATION (Note 2, 3 and 5)
Unit
Frequency ...................................................
28.0
GHz
Output Power .............................................
47
W
Heater Voltage (Note 4) .................................
6.3
V
Heater Current .............................................
0.82
A
Collector1 Voltage
....................................
3.0
kV
Collector1 Current
....................................
32.0
mA
Collector2 Voltage
....................................
1.5
kV
Collector2 Current
....................................
23.0
mA
Cathode Current ..........................................
57.0
mA
Helix Voltage
.............................................
8.0
kV
Helix Current
.............................................
2.0
mA
Power Gain
(SSG) ..............................
52
dB
(LSG) ..............................
45
dB
Gain Variation
at 4 W ..............................
2.5
dB/2.5 GHz
Gain Slope
at 4 W ..............................
0.025
dB/MHz
AM-PM Conversion
....................................
3.5
deg./dB
3rd Order Intermodulation ...........................
31
dBc
(two equal carriers, 4 W total)
Spurious
...................................................
60
dBc
Noise Figure ................................................
32.5
dB
Overall Efficiency
.......................................
31
%
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 except 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.
LD7714
4
DATA SHEET ET0454EJ1V0DS00
LD7714 OUTLINE (Unit in mm)
19
0.5
6 4.5
RF OUTPUT
UG-599/U FLANGE WITH
M3 THREADED HOLES
RF INPUT
TYPE K CONNECTOR FEMALE
19.3
0.5
38.3
0.5
100
0.3
151
0.3
70
1
183
18
2
1
260
2
5.5
0.5
265.5
2
24.5
0.3
21
1
30
1
27
1
36
1
LEAD COLOR
LEAD CONNECTIONS
LENGTH
BROWN
HEATER
500 mm MIN.
YELLOW
HEATER-CATHODE
500 mm MIN.
RED
COLLECTOR-1
500 mm MIN.
GREEN
COLLECTOR-2
500 mm MIN.
BLACK
HELIX (GROUND)
500 mm MIN.
LD7714
5
DATA SHEET ET0454EJ1V0DS00
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