DATA S HE E T MEDIUM POWER TRAVELING WAVE TUBE FOR GROUND TERMINALS LD7710 14GHz, 40 W CW PPM FOCUSING, MINIMUM SIZE GENERAL DESCRIPTION The NEC LD7710 is a PPM focused traveling wave tube designed for final amplifier tube in the earth-to-satellite communication's transmitter. This is capable of delivering an output power of 40 W over the range of 13.75 to 14.5 GHz. It provides a mid power gain of 26 dB at 40 W level. Furthermore, this is of rugged and reliable design offering long life services. FEATURES ™ Lightweight, Compact and Efficient The tube has a dual-depressed collectors and is designed to operate at high efficiency across the power output range. It features state-of-the-art techniques to optimize size and efficiency. ™ Low Distortion Distortion is a very important factor in multiplex digital signals transmission. NEC has developed techniques for the correction of non-linear distortion of gain 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 transmission systems. ™ Right Power Gain for Minimum Size The power gain is designed into 26 dB at 40 W level in order to keep the tube length minimum. ™ Simple Cooling System The tube is conduction cooled, so that the cooling system is 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 the low operating temperature for long life. The TWT is designed to have a lifetime of 100,000 hours or more. ™ Microdischarge Free The tube is carefully designed to be free from microdischarge in the electron gun for long time operation, therefore it is suitable for digital communication services. For safety 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. ET0199EJ2V0DS00 (2nd edition) Date Published May 1997 M Printed in Japan © 1996 LD7710 GENERAL CHARACTERISTICS ELECTRICAL Frequency …………………………………………… 13.75 to 14.5 GHz Output Power ……………………………………… 40 W Heater Voltage ……………………………………… 6.3 V Heater Current ……………………………………… 0.81 A Heater Surge Current 2.5 A …………………………… Type of Cathode …………………………………… Indirect-Heated Impregnated Cathode Warm-up Time ………………………… 180 s MECHANICAL Dimensions ………………………………………… See Outline Drawing Weight ……………………………………………… 350 g approx. Focusing …………………………………………… Periodic Permanent Magnet Mounting Position ………………………………… Any Cooling ……………………………………………… Conduction Electrical Connections …………………………… Flying Leads Heater, Heater-Cathode, Helix, Collector-1, Collector-2 RF Connections Input ……………………………………………… SMA-Female Output …………………………………………… SMA-Female ABSOLUTE RATINGS (Note 1, 2 and 3) ELECTRICAL Heater Voltage ……………………………………… Heater Surge Current Min. Max. Unit 6.0 6.6 V …………………………… – 2.5 A Heater Current ……………………………………… – 1.2 A Heater Warm-up Time …………………………… 180 – s Helix Voltage ……………………………………… 2.95 3.45 kVdc Helix Current ……………………………………… – 5.0 mAdc Collector-1 Voltage ………………………………… 1.6 2.0 kVdc Collector-1 Current ………………………………… – 70 mAdc Collector-2 Voltage ………………………………… 0.8 1.0 kVdc Collector-2 Current ………………………………… – 110 mAdc Drive Power ………………………………………… – 23 dBm Load VSWR ………………………………………… – 1.5 : 1 – Min. Max. Unit Heat Sink Temperature …………………………… –30 +90 ˚C Storage Temperature ……………………………… –40 +90 ˚C MECHANICAL 2 LD7710 TYPICAL OPERATION (Note 2, 3 and 5) Unit Frequency 13.75 to 14.5 GHz Saturated Output Power 45 W Heater Voltage (Note 4) 6.3 V Heater Current 0.81 A Helix Voltage 3.2 kVdc Helix Current 2.0 mAdc Collector-1 Voltage 1.8 kVdc Collector-1 Current 55 mAdc Collector-2 Voltage 0.9 kVdc Collector-2 Current 43 mAdc Cathode Current 100 mAdc Power Gain at 4 W ……………………… 34 dB at 40 W ……………………… 29 dB Gain Variation at 4 W ……………………… 2.5 dB/750 MHz Gain Slope at 4 W ……………………… 0.02 dB/MHz AM-PM Conversion at 40 W ……………………… 3.5 deg./dB (two equal carriers, 8 W total) ……………………… –29 dBc Overall Efficiency 31 % 3rd Order Intermodulation ……………………………… 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 for a contractual specification. 3 LD7710 LD7710 OUTLINE (Unit in mm) 25 33 23.8 6- φ 4.5 85 61 4 17 RF Output 178 57.7 SMA-Female RF Input 4 59.3 85 SMA-Female High Voltage Connection Lead Length = 300 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.