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Technical Operations Manual
The most important thing we build is trust.
100-M0167X2
GMS Inc. doing business as Cobham Tactical Communications and Surveillance
VEPA-2W Linear Power Amplifier
1 of 21
Cobham Tactical Communications and Surveillance
1916 Palomar Oaks Way, Suite 100, Carlsbad, CA 92008
Tel: 760-496-0055
FAX: 760-496-0057
www.cobham.com/tcs
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Table of Contents
Related Manuals for COBHAM VEPA-2W
Summary of Contents for COBHAM VEPA-2W
- Page 1 The most important thing we build is trust. VEPA-2W Linear Power Amplifier Cobham Tactical Communications and Surveillance 1916 Palomar Oaks Way, Suite 100, Carlsbad, CA 92008 100-M0167X2 1 of 21 Tel: 760-496-0055 FAX: 760-496-0057 www.cobham.com/tcs GMS Inc. doing business as Cobham Tactical Communications and Surveillance...
- Page 2 REVISION HISTORY Version Date Author Comments 10/01/11 Nathan Moore / Marcio Koptcke Initial release. 02/15/12 Nathan Moore Release to include C2 Band 100-M0167X2 2 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs...
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Page 3: Table Of Contents
Table 1 – ABSOLUTE MAX RATINGS ............................. 7 Table 2 – General Specifications: ..............................7 Table 3 – Frequency Specific Specifications: .......................... 8 100-M0167X2 3 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... - Page 4 LIST OF FIGURES Figure 1 – VEPA-2W PA External Connections ........................10 Figure 2 – PA on small Heat-sink with Test Cable and Isolator (Isolator Optional) ........ 12 Figure 3 – VEPA-2W PA with VMT ..............................13 ...
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Page 5: Cautions And Warnings
The VEPA-2W incorporates a fast switching PA Enable (PIN-5) function. This PIN is LVTTL compatible (3-5Vdc) and must be tied logic high for the VEPA-2W to operate. The +5VDC output (PIN-4) can be tied to the PA_ENABLE (PIN-5) if the user does not need to access the PA Enable functionality. The voltage on this pin should not exceed 5.5VDC. -
Page 6: Heatsink
1.7. OVER TEMPERATURE AUTOMATIC SHUTDOWN The VEPA-2W is designed and specified to operate up to a maximum of 70°C baseplate temperature. Operating the PA at higher temperatures than specified can damage the PA or cause the MTTF to drop significantly. -
Page 7: Absolute Max Ratings
To select High Linearity MODE (HIGH MER) connect Pins 3 and 4. Or connect 3-5 Vdc to Pin3. PA ENABLE is LVTTL compatible. Pins 8 and 9 are internally connected to chassis. 100-M0167X2 7 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 8: Table 3 - Frequency Specific Specifications
MER measurements were performed using a Rhode & Schwartz EFA Test RCVR mod 2067 in Stationary mode. DVB-T test signal generated with an Agilent MXG Vector Signal Generator. EVM specification valid for QPSK modulation only. 100-M0167X2 8 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 9: Power Amplifier Features
4.2. PA ENABLE (Fast Switching Capable) The VEPA-2 W amplifier was designed have a LVTTL compatible enable pin (PIN 5). The VEPA-2W was designed for fast switching applications with an ON time <100ns and an OFF time of <50ns (For C2 band: ON time <150ns and an OFF time of <100ns). -
Page 10: Operational Instructions
VSWR and OVERDRIVE protection in that it does not need a power cycle to correct. The OVER TEMPERATURE shutdown will allow normal operation when the VEPA-2W baseplate temperature has dropped by 5°C from the trip point of 75°C. In Normal operation the green LED (see fig. -
Page 11: Connecting & Disconnecting The Power Amplifier
The VEPA-2W will draw ~110mA when in standby mode (LVTTL logic low). The VEPA-2W PA draws about 1.5 A at 12 Vdc when in 2W High Linearity mode, with the PA_ENABLE logic high (Current will vary with frequency band). At lower voltages the current will be higher. -
Page 12: Figure 2 - Pa On Small Heat-Sink With Test Cable And Isolator (Isolator Optional)
(High Linearity or High Efficiency). The picture also shows an external isolator, the isolator is an optional addition, and is generally not needed. The C2 band VEPA-2W incorporates an internal isolator. 100-M0167X2 12 of 21 GMS Inc. -
Page 13: Vepa-2W / Vmt Combination
The only undesirable effect was an increase in harmonics emission, problem which was solved by using a low pass filter. 100-M0167X2 13 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 14: The New Digital Modulation Approach
VALID FOR DIGITAL MODULATION. 5.4.2. The NEW Digital Modulation approach Cobham/GMS transmitters are designed for operation with COFDM–DVBT type signal. In this type of modulation the information is contained in the phase and amplitude of multiple carriers which are transmitted simultaneously. - Page 15 CAUTION: WHEN COMBINING A TRANSMITTER WITH A PA FOR THE FIRST TIME THE CUSTOMER SHOULD ALWAYS MAKE SURE THAT THE POWER OUTPUT OF THE TRANMITTER IS COMPATIBLE WITH THE MAX ABSOLUTE RATING OF THE POWER AMPLIFIER. 100-M0167X2 15 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs...
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Page 16: Typical Power Amplifier Performances
6. TYPICAL POWER AMPLIFIER PERFORMANCES This chapter gives typical power amplifier performances for the VEPA-2W frequency bands. The PA has repeatable performances from unit to unit. 6.1. GAIN @ 2W COFDM Output Figure 4 – LD Band Gain Figure 6 – L2 Band Gain Figure 8 –... -
Page 17: Figure 14 - C2 Band Gain
Figure 14 – C2 Band Gain Figure 15 – C2 Band Gain Change over Temp 100-M0167X2 17 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 18: Current @ 2W Cofdm Output, 12 Vdc
Figure 17 – L2 Band Current Figure 18 – W7 Band Current Figure 19 – S2 Band Current Figure 20 – SK Band Current Figure 21 – C2 Band Current 100-M0167X2 18 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 19: Mer @ 2W Cofdm Output
Figure 23 – L2 Band MER Figure 24 – W7 Band MER Figure 25 – S2 Band MER Figure 26 – SK Band MER Figure 27 – C2 Band MER 100-M0167X2 19 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 20: Small Signal S-Parameter (High Efficiency Mode)
Figure 29 – L2 Band S-Parameters Figure 30 – W7 Band S-Parameters Figure 31 – S2 Band S-Parameters Figure 32 – SK Band S-Parameters Figure 33 – C2 Band S-Parameters 100-M0167X2 20 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs... -
Page 21: Appendix 1 - Acronyms
Radio Frequency Serial Number SDMT Standard Definition Messenger Transmitter Test Data Record Transmitter VEPA Very Efficient Power Amplifier VETA Miniature Transmitter VSWR Voltage Standing Wave Ratio 100-M0167X2 21 of 21 GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs...
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