GENERAL DESCRIPTION
NEC LD7249 series of PPM-focused traveling wave tube are designed for use as final amplifiers in the earth-to-
satellite communications transmitter.
Two models of the LD7249 series are capable of delivering an output power of 350 W and 400 W over the range
of 13.75 to 14.5 GHz and provide a high power gain of more than 47 dB at the rated output power level.
Furthermore, this is of rugged and reliable design offering long-life service.
FEATURES
TM High Power Gain
The power gain is typically 54 dB at the rated output power level.
TM Simple Cooling System
The tube is conduction-cooled so that the cooling system is greatly simplified.
TM PPM Focusing
The tube is PPM (Periodic Permanent Magnet) -focused, eliminating entirely the focusing power supplies and
interlock circuits.
TM Rugged Construction
The tube 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 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.
DATA S H E E T
Document No. ET0221EJ5V0DS00 (5th edition)
Date Published August 1999 M
Printed in Japan
14 GHz, 350 W/400 W CW, CONDUCTION COOLING, HIGH POWER GAIN
The information in this document is subject to change without notice.
1997
HIGH POWER TRAVELING WAVE TUBE
FOR GROUND TERMINALS
LD7249 SERIES
For safe use of microwave tubes, refer to NEC document "Safety instructions to all personnel
handling electron tubes" (ET0048EJ
V
UM00)
2
LD7249 SERIES
DATA SHEET ET0221EJ5V0DS00
GENERAL CHARACTERISTICS
ELECTRICAL
Frequency ...................................................... 13.75 to 14.5 GHz
Output Power
LD7249 ...................................................... 350 W
LD7249U ................................................... 400 W
Heater Voltage ................................................ 6.3 V
Heater Current ................................................ 1.2 A
Type of Cathode ............................................. Indirectly heated, Impregnated
Cathode Warm-up Time
................................. 180 s
MECHANICAL
Dimensions ................................................... See outline
Weight ......................................................... 4 kg approx.
Focusing
...................................................... Periodic Permanent Magnet
Mounting Position .......................................... Any
Electrical Connections .................................... Flying Leads
Heater, Heater-Cathode,
(Optionally, the HV lead out let position can be changeable)
Helix, Collector-1, Collector-2
and Thermal Protection
RF Connections
Input ......................................................... Type SMA Female
Output ...................................................... Mates with UBR-120 Flange, Waveguide : WR-75
Cooling ......................................................... Conduction
ABSOLUTE RATINGS (Note 1, 2 and 3 )
ELECTRICAL
min.
max.
Unit
Heater Voltage .............................................
6.0
6.6
V
Heater Surge Current
.................................
3.0
A
Heater Current .............................................
1.0
2.0
A
Heater Warm-up Time .................................
180
s
Helix Voltage
.............................................
8.0
9.2
kV
Helix Current
.............................................
0
10
mA
Collector-1 Voltage .......................................
4.0
4.6
kV
Collector-1 Current .......................................
180
mA
Collector-2 Voltage .......................................
2.3
3.1
kV
Collector-2 Current .......................................
290
mA
Cathode Current ..........................................
200
290
mA
RF Drive Power ..........................................
5
mW
Load VSWR ................................................
1.5 : 1
MECHANICAL
Min.
Max.
Unit
Heat Sink Temperature .................................
40
+115
C
ENVIRONMENTAL
Min.
Max.
Unit
Ambient Temperature
Storage ...................................................
50
+90
C
Operating ................................................
40
+100
C
3
LD7249 SERIES
DATA SHEET ET0221EJ5V0DS00
TYPICAL OPERATION (Note 2, 3 and 5)
LD7249
LD7249U
Unit
Frequency ......................................................
14.25
14.25
GHz
Output Power ................................................
350
400
W
Heater Voltage (Note 4) ....................................
6.3
6.3
V
Heater Current ................................................
1.2
1.2
A
Helix Voltage ...................................................
8.6
8.8
kV
Helix Current ...................................................
1.5
2.4
mA
Collector-1 Voltage ..........................................
4.3
4.4
kV
Collector-1 Current ..........................................
141
147
mA
Collector-2 Voltage ..........................................
2.7
2.8
kV
Collector-2 Current ..........................................
94
100
mA
Cathode Current .............................................
237
250
mA
Power Gain
at 20 W ...........................
62
58
dB
at 350 W ...........................
58
54
dB
Gain Variation
at 20 W ...........................
0.86
1.02
dB/750MHz
Gain Slope
at 40 W ...........................
0.006
0.006
dB/MHz
AM-PM ConversioN
Less than 100 W .................................
0.3
0.3
deg./dB
at 350 W .............................................
2.5
2.5
deg./dB
3rd Order Intermodulation
..............................
23
24
dBc
(two equal carriers, 100 W total)
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.
4
LD7249 SERIES
DATA SHEET ET0221EJ5V0DS00
LD7249 OUTLINE (Unit in mm)
LEAD COLOR
BROWN
YELLOW
RED
BLUE
BLACK
BLUE (SLIM CABLE)
GREEN (SLIM CABLE)
LEAD CONECTIONS
HEATER
HEATER-CATHODE
COLLECTOR-1
COLLECTOR-2
HILIX (GROUND)
THERMAL SWITCH-1
THERMAL SWITCH-2
LENGTH
650 mm
650 mm
650 mm
650 mm
650 mm
650 mm
650 mm
76
1
85 max.
WITH 8. LENGTH 14
(8 SLOTS)
8
4.85
THRU
+ 0.1
0.0
10
5 THRU
+ 0.1
0.0
No.6-32 UNC-2B
9 DEEP
BOTHSIDE
RF INPUT
SMA FEMALE
RF OUTPUT
UBR-120 FLANGE
WITH No.6-32 UNC-2B
THREADED HOLES
38
0.3
19
0.3
6
0.3
45.5
0.8
57 max.
45.7
0.3
54
0.3
22.4
0.2
431.8
0.8
416.1
0.2
352.6
0.2
289.1
0.2
225.6
0.2
162.1
0.2
322.8
1.5
175
0.8
39.9
0.8
55.9
1
47.8
0.2
73.2
0.2
117.6
0.2
127
0.8
55.9
0.8
77.2
1.3
60
0.8
43.5
0.3
11.5
1
38
0.8
P
ARAMETER
LEBEL
IDENTIFICA
TION
LEBEL
BeO CAUTION LEBEL
5
LD7249 SERIES
DATA SHEET ET0221EJ5V0DS00
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