operations manual - cobham plc · vepa 10w linear power amplifier . 100-m0135x6 17 apr 2012 2 of 32...

100-M0135X6 17 Apr 2012 1 of 32

Cobham Tactical Communications and Surveillance 1916 Palomar Oaks Way, Suite 100, Carlsbad, CA 92008 Tel: 760-496-0055 FAX: 760-496-0057

GMS Inc. doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs

Operations Manual

The most important thing we build is trust.

VEPA 10W Linear Power Amplifier

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REVISION HISTORY Version Date Author Comments

X1 April 23 2010 Silvano Padoan Initial release. X2 June 14 2010 Silvano Padoan Added paragraph 4.4 X3 Oct. 20 2010 Silvano Padoan Adapted for rev X3 of the product X4 Nov. 20 2010 Silvano Padoan Added data for L2-band and SK-band 1 Apr. 23 2011 Owen de Meyer Transferred from 100-M0135X4

X6 Apr. 17 2012 Marcio Koptcke Updated pictures

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TABLE OF CONTENTS

1.0 CAUTIONS AND WARNINGS ............................................................................................................................................................ 5

1.1 ELECTROMAGNETIC RADIATIONS .......................................................................................................................................... 5 1.2 SUPPLY VOLTAGE AND CURRENT ............................................................................................................................................ 5 1.3 LOAD TERMINATION ......................................................................................................................................................................... 5 1.4 HEATSINK .................................................................................................................................................................................................. 5 1.5 RF OVERDRIVE ........................................................................................................................................................................................ 6 1.6 POWER MEASUREMENT .................................................................................................................................................................. 7

2.0 ABSOLUTE MAX RATINGS .................................................................................................................................................................. 7

3.0 SPECIFICATIONS ...................................................................................................................................................................................... 8

4.0 OPERATIONAL INSTRUCTIONS ...................................................................................................................................................... 9

4.1 USING A TRANSMITTER/PA COMBINATION ................................................................................................................... 9 4.1.1 The old FM approach ................................................................................................................................................................ 9 4.1.2 The NEW Digital Modulation approach ....................................................................................................................... 9 4.1.3 Matching a Transmitter to a PA ..................................................................................................................................... 10

4.2 EXTERNAL CONNECTIONS AND INDICATORS ............................................................................................................ 11 4.2.1 RF-IN ................................................................................................................................................................................................. 13 4.2.2 RF-OUT ............................................................................................................................................................................................. 13 4.2.3 Vcc ...................................................................................................................................................................................................... 13 4.2.4 GND LUG and NEG RTRN .................................................................................................................................................... 13 4.2.5 PA Enable ....................................................................................................................................................................................... 13 4.2.6 0-15dB INPUT ATTENUATOR .......................................................................................................................................... 13 4.2.7 REMOTE ATTEN. CONTROL ............................................................................................................................................... 14 4.2.8 10W COFDM OR 20W FM OVERDRIVE IDENTIFIER ....................................................................................... 14 4.2.9 TEMPERATURE DETECTOR ................................................................................................................................................ 14 4.2.10 ID LABEL .................................................................................................................................................................................... 14

4.3 CONNECTING & DISCONNECTING THE POWER AMPLIFIER ............................................................................ 16 4.4 OVERDRIVE PROTECTION CIRCUIT .................................................................................................................................... 18

5.0 TYPICAL POWER AMPLIFIER PERFORMANCES ................................................................................................................ 19

5.1 GAIN ........................................................................................................................................................................................................... 19 5.1.1 S2 BAND ......................................................................................................................................................................................... 19 5.1.2 L2 BAND .......................................................................................................................................................................................... 20 5.1.3 SK BAND ......................................................................................................................................................................................... 21 5.2 CURRENT .................................................................................................................................................................................................. 22 5.2.1 S2-BAND ................................................................................................................................................................................................ 22 5.2.2 L2-BAND ................................................................................................................................................................................................ 23 5.2.3 SK-BAND ................................................................................................................................................................................................ 24

5.3 LINEARITY ................................................................................................................................................................................................... 25 5.3.1 S2-BAND ................................................................................................................................................................................................ 25 5.3.2 L2-BAND ............................................................................................................................................................................................... 26 5.3.3 SK-BAND ................................................................................................................................................................................................ 27

5.4 POWER VARIATION OVER TEMPERATURE ........................................................................................................................... 28 5.5.1 S2-BAND ................................................................................................................................................................................................ 29 5.5.2 L2-BAND ................................................................................................................................................................................................ 30

LIST OF TABLES Table 1 - ABSOLUTE MAX RATINGS 1 ................................................................................................................................... 7 Table 2 - SPECIFICATIONS .......................................................................................................................................................... 8 Table 3 Power supply recommended power capability ....................................................................................... 16

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Table 4 - Current values to be used as indication of output power when a PWR meter is not available .......................................................................................................................................................................................... 17

LIST OF FIGURES Figure 1- VEPA-10W PA EXTERNAL CONNECTIONS ................................................................................................ 13 Figure 2 – GAIN AT 10W COFDM S2-BAND ................................................................................................................... 19 Figure 3– GAIN AT 20 W FM S2-BAND .............................................................................................................................. 19 Figure 4 - GAIN AT 10W COFDM L2-BAND .................................................................................................................... 20 Figure 5 - GAIN AT 20 W FM L2-BAND ............................................................................................................................. 20 Figure 6 –GAIN AT 10W COFDM SK-BAND .................................................................................................................... 21 Figure 7 – GAIN AT 20W FM SK-BAND ............................................................................................................................. 21 Figure 8 – CURRENT AT 10W COFDM S2-BAND ......................................................................................................... 22 Figure 9– CURRENT AT 20 W FM S2-BAND ................................................................................................................... 22 Figure 10 – Current 10W COFDM L2-BAND .................................................................................................................... 23 Figure 11 – Current 20W FM L2_BAND ............................................................................................................................. 23 Figure 12 – Current 10W COFDM SK-Band ..................................................................................................................... 24 Figure 13 – Current 20W FM SK-Band ................................................................................................................................ 24 Figure 14– MER AT 8W S2-BAND .......................................................................................................................................... 25 Figure 15 –MER AT 10W S2-BAND ....................................................................................................................................... 25 Figure 16 – MER AT 8W L2-BAND ......................................................................................................................................... 26 Figure 17 – MER AT 10W L2-BAND ...................................................................................................................................... 26 Figure 18 – MER AT 8W SK-BAND ......................................................................................................................................... 27 Figure 19 – MER AT 10W SK-BAND ...................................................................................................................................... 27 Figure 20 - Power Variation Over Temperature ........................................................................................................... 28 Figure 21 – S-PARAMETERS NARROW S2-BAND ........................................................................................................ 29 Figure 22 - S-PARAMETERS S2-BANDWIDE VIEW .................................................................................................... 29 Figure 23 –S-PARAMETERS L2-BAND NARROW VIEW ........................................................................................... 30 Figure 24- S-PARAMETERS L2-BAND WIDE VIEW .................................................................................................... 30 Figure 25 – S-PARAMETERS SK-BAND NARROW VIEW ......................................................................................... 31 Figure 26 - S-PARAMETERS SK-BAND WIDE VIEW .................................................................................................. 31

APPENDICES APPENDIX 1 – ACRONYMS ....................................................................................................................................................... 32

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1.0 CAUTIONS AND WARNINGS

1.1 ELECTROMAGNETIC RADIATIONS There is no consensus in the scientific community about the potential harmful effect of electromagnetic radiations. This power amplifier will radiate an average 10W power with peak powers 14dB higher when operating with a COFDM –DVBT transmitter. It is recommended that the operator minimizes exposure to electromagnetic radiations by: 1.1.1 Avoid direct proximity to the antenna when the transmitter is turned ON. 1.1.2 Use a low leakage attenuator when the transmitter is operated for testing on a bench. 1.2 SUPPLY VOLTAGE AND CURRENT

The amplifier is designed for a wide input voltage (9-32Vdc). Make sure that the power supply has a voltage within this range and is capable of providing the current needed with some margin. At 12 Vdc the amplifier will draw less than 4.5A when the input power is properly set to deliver 10W COFDM. For 20W FM the current is usually below 7A. The efficiency of the amplifier remains about constant as the voltage changes. Therefore the current draw at 24Vdc will be about half the current draw at 12Vdc and the current draw at 9VDc will be about 30% more. Make sure your power supply is capable of delivering the current needed. Current limiting should be avoided as it may induce oscillatory voltage fluctuations that might damage the amplifier. The Power Amplifier is reversed polarity protected. 1.3 LOAD TERMINATION

Always terminate properly the RF output port into a well matched antenna. The amplifier is protected against excessive VSWR by an isolator. However the reflected power will decrease the link range and will be dissipated internally in the PA thus increasing the size of the heat-sink needed. On the bench make sure to use a 20-30dB attenuator rated for 20W (or more). 1.4 HEATSINK

Use an adequate heat-sink to keep the temperature of the PA below 65OC (149 F). Depending on customer requirements the PA might be shipped mounted on different size heat-sinks. One typical heat-sink has 15 fins 2.2” (55mm) long on a 0.35” (8.9mm) plate. The temperature will raise about 40 OC (45 F) at 10W COFDM when this heat-sink is kept with the fins down on a test bench (temperature raise will vary depending on the amount of air flow in the surrounding area). For 20W operation and also for 10W, depending on the operational environment (ambient temperature, sun exposure etc.) larger heat-sink and/or forced cooling will be required. An over temperature detector sticker is applied externally and internally to the PA. The sticker has five white dots which turn black when the temperature reaches 60, 65, 71, 77, 82 OC (140, 149, 160, 171, 180 F). A black 71 OC (160 F) dot will void the warranty. INSTALL THE HEATSINK ON THE SIDE OPPOSITE TO THE LABELS.

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1.5 RF OVERDRIVE

The PA is designed to operate at up to 10W average power with COFDM signals having PAR ratios up to 14dB. To achieve the best efficiency the PA operates at the highest power that will allow the desired linearity without damaging the devices. Therefore it is important not to overdrive the PA or damage might occur. This PA implements an overdrive protection circuit which automatically and suddenly increases the input attenuation when the overdrive exceeds 3dB. However the circuit has a discrete intervention time and very large overdrives might still be able to damage the PA. The PA can also be operated in FM; because in FM the PAR is low, the PA can be operated at 20W average power. However this requires the overdrive protection to be set higher. This will allow the operator to use it at COFDM levels which might be damaging. Therefore the PA is shipped in two possible configurations: 10W COFDM or 20W FM. The PA configured for 10W COFDM operation has internal protection circuits which will intervene if the PA is overdriven 2-3dB over the nominal 10W. This PA is not capable of operating at 20W FM because this power will trigger the protection circuit but operation at 10W FM is possible. This is indicated in a Caution label on the bottom cover:

The PA configured for 20W operation has internal protection circuits which will intervene if the PA is overdriven 2-3dB over the nominal 20W. This PA can be operated normally in COFDM provided the COFDM average power does not exceed 10W average. Operations at COFDM powers higher than 10W will not be detected by the protection circuit and might cause permanent damage. This is indicated in a Caution label on the bottom cover: The operator should carefully set the input power accordingly. The PA is equipped with a variable attenuator controlled by a rotary switch on the front panel or remotely through the wiring in the front panel connector. When shipped by itself the PA attenuator is set at midrange (8dB). This allows the operator to adjust the power in 1dB steps until it reaches the desired level. During set up it is recommended that the output power be monitored with a power meter. If a power meter is not available a gross indication of power can be assessed by monitoring the current. At 12 Vdc (measured at the terminals of the PA) the current will average typically 4.2A for 10W of COFDM output power and will be 400-500mA lower for 8W output power. At 20W FM the current will average typically 6.6A. CAUTION: 1) If the voltage is higher than 12VDc the current limits will be lower. 2) Read section 6.2 carefully for the safest set up procedure.

CAUTION: CIRCUIT PROTECTION SET FOR 10W OPERATION

CAUTION: CIRCUIT PROTECTION SET FOR 20W FM. OVERDRIVING OVER 10W COFDM VOIDS THE WARRANTY

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1.6 POWER MEASUREMENT

Using a reliable power meter is recommended for initial power set up. Using in-line power meter is not recommended especially with antennas for initial set up because an antenna will create a standing wave. The power meter readings will vary depending on the position of the power meter in the line and it’s possible to have readings lower and higher than the actual power delivered by the PA.

Cobham/GMS PA has fairly repeatable performances: the current readings can be used as an approximate indication of power in absence of a reliable power meter (see table 4).

2.0 ABSOLUTE MAX RATINGS

Table 1 - ABSOLUTE MAX RATINGS 1

MAX RF INPUT COFDM ( See note 2) below) ATTENUATOR SET TO 0 < 4dBm Other attenuator settings < (4dBm + att setting) MAX CONTINUOUS COFDM OUTPUT PWR 12W MAX CONTINUOUS FM OUTPUT PWR 25W MAX SUPPLY VOLTAGE 35 Vdc MAX BASEPLATE TEMPERATURE 65 oC

1) The absolute max rating indicates values which, if exceeded, could and/or will damage the PA.

2) Both the max input power and the PA gain depend on the attenuator setting. In all cases it is recommended not to exceed the normal operating power, because this will drive the PA to operate with decrease of linearity and increase current /heat. Since the gain might vary from unit to unit and from channel to channel consult the TDR for your unit to determine what is the correct gain and then adjust the input power accordingly.

For example in S2-band the gain is about 42 dB. To operate at 10W COFDM the input power is about -2dBm. For units set to operate at 20W FM the input power is 1 dBm. With the input attenuator set to 0 never exceed 3dBm at the input. When the attenuator is set to values other than zero the max RF input power increases accordingly.

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3.0 SPECIFICATIONS

Table 2 - SPECIFICATIONS

Parameter Specification

Frequency (GHz) 1.7 - 1.85 2.2-2.4 1.99-2.5 2.2-2.7

Frequency Band L2 S1 S2 SK Linear Gain (dB center band with attenuator set to 0). (gain is adjustable through front panel switch or remote control) 1

45 41.5 41.5 44.5

Gain Adjustment Range (dB) 0 to -15 0 to -15 0 to -15 0 to -15

Adjustment Resolution (dB) 1 1 1 1

Flatness (dB) +/- 0.75 +/-0.5 +/-0.7 +/- 0.7

P1dB (dBm) 45 45 45 45

Input / Output VSWR2 1.5:1/1.3:1 1.3:1 1.4:1 1.4:1

Rated COFDM Output PWR 10W 10W 10W 10W

Rated FM Output PWR 20W 20W 20W 20W

MER Stationary QPSK (dB)3 8 W 31 31 30 31

10W 28.5 29 28 28.5

Current (A@ 12 VDC)3

8 W COFDM 3.2 3.7 3.7 3.6

10W COFDM 3.6 4.1 4.1 4.0

20 W FM 5.7 6.5 6.5 6.4

Efficiency (%) 10W COFDM 23 21 20 21

20 W FM 28 25 25 25

DC input voltage (Vdc) 9-32

Mechanical Dimension (without heatsink) 7.5"L x 4"W x 0.79"H

Weight lbs. 1.62

grams 735

Base-plate Temperature -10 °C to + 65 °C

Operating Humidity 95% Non-condensing

Control Connector (Pins 1 through 5 enable low)

ODU-G50L0C-P06LCC0-0000

Pin 1: 1dB Pin 2: 2dB Pin 3: 4dB Pin 4: 8dB Pin 5: NC

pin 6: GND

DC Power Connector Solder pins RF Connectors SMA Female

1 Average gain among units at the center of the band. See graphs for more details 2 90th Percentile (90th percent of the test samples are equal or better to this value). 3 Typical value across the band (the average value of the 10th and 90th percentile i.e. the average of the data sample after the best and the worst 10% of data samples are discarded)

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4.0 OPERATIONAL INSTRUCTIONS

Read this section carefully and section 1 (CAUTIONS AND WARNINGS) before operating the Power Amplifier.

4.1 USING A TRANSMITTER/PA COMBINATION

4.1.1 The old FM approach The methodology of interfacing a digital transmitter with a linear PA is somewhat different that the methodology used for constant envelope type modulation such as FM. In the days of FM modulation the last stage of a transmitter was driven into compression to obtain the best efficiency. The non-linearity caused by this approach did not affect the quality of the link because the information was contained in the frequency and deviation of the carrier and not in its amplitude and phase. The only undesirable effect was an increase in harmonics emission, problem which was solved by using a low pass filter. In the FM world it made sense to mate a transmitter operating at its RF rated output power to an external Power Amplifier in order to extend its range of operation. There was no need to modify the Power output of the transmitter if the PA had the correct gain. For example GMS sold a 200mW FM transmitter and an additional 10dB gain amplifier to boost the Power to 2W. The operator had only to connect the TX output to the PA RF input. THIS APPROACH IS NO LONGER VALID FOR DIGITAL MODULATION.

4.1.2 The NEW Digital Modulation approach Newer 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. These carriers, being spaced at regular frequency interval, combine in amplitude thus creating very large amplitude peaks. The result is that the Peak to Average Amplitude Ratio (PAR) is very large (typically limited to 14dB by the DAC in the modulator). Unlike the FM world neither the amplitude nor the phase can be distorted or the quality of the information will be degraded. In order to avoid this distortion, in the digital modulation world the Power Amplifier operates at a certain level of back OFF meaning that the average power transmitted is several dB lower than the P1dB of the various stages of the amplifier. But this has a price in term of power consumption and therefore transmitters are always designed with the least amount of back off which will give the required linearity. For the sake of example a 200mW (23 dBm) amplifier deigned to perform with a 25dB MER will use as final stage a device which has a P1dB around 29dBm. If we had chosen to use a device with greater P1dB the MER would have been greater at the expense of extra current. It would be convenient if we could couple this transmitter with a 10dB gain amplifier and obtain a 2W transmitting system, but this is NOT the approach that provides the best results. Let’s say that our amplifier has an MER of 28 dB. If we connect a 25dB MER signal into it the 3rd order product and harmonics of the transmitter will further re-grow in the PA. The resulting MER will be lower than 25dB and therefore the system will no longer be capable of transmitting higher order constellations. In order to obtain a resulting 25dB MER (same MER as the transmitter by itself) we would be forced to overdesign the transmitter by considerably degrading its efficiency. The proper approach to solve this problem and obtain the best linearity (MER) and efficiency in all cases is to: 1) Make a transmitter which has 25dB MER when operating at 200mW 2) Use a PA with higher gain and an MER a little higher than 25dB 3) When the transmitter is used in combination with the PA, the transmitter Power is “Backed OFF” (i.e. an internal attenuator is set higher). By doing so the Transmitter is operating at a larger Back OFF from the P1dB and the linearity increases. (typically around 31dB MER). With a 31dB MER input the PA will see little third order product at its input and the total MER combination will be higher than 25dB as required for best system performance.

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Cobham/GMS transmitters are factory calibrated with the proper amount of Back OFF when shipped in combination with the PA. 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.

4.1.3 Matching a Transmitter to a PA Cobham/GMS transmitters are calibrated at the factory to provide a constant output power over the frequency bands. The I&Q lines also are calibrated to optimize residual carrier leakage and phase unbalances. When the transmitter is installed in combination with a PA the matched pair is usually retuned at the factory. to achieve the same goals. As explained in paragraph 4.1.2 above the transmitter output power is “BACKED OFF” by a fixed number of dB reserved as “User attenuation” by Selecting “Low Power “Mode. If the customer desires to operate the transmitter by itself all he has to do is reduce the User Attenuation to 0 by selecting the “High Power” mode. CAUTION: Failure to select “Low Power Mode” when the TX is used in combination with the PA will cause a large overdrive, and will trigger the Overdrive Protection and/or damage the PA An example will help clarify the issue. Cobham/GMS sells a transmitter call M2T which provides a 200mW (23dBm) COFDM output power. This transmitter is sold by itself or installed in a rack mount combination (called CMT-R) with a 10W PA. Since the PA has about 40 dB gain the output power of the transmitter is reduced by 7dB and the PA input attenuator is set to 15dB. There is an additional 1dB loss in cables and adapters. Therefore the output power would be: Pout dBm = P TX - Att user - PAat t + PAGAIN – Losses = 23 – 7 – 15 + 40 – 1 = 40 dBm If the customer desired to operate the TX by itself he/she would set the User attenuation to zero and the TX would have again 23dBm power at the output. If all elements in the system were perfect there would be no need for calibration. In practice there are several elements that need to be taken in account: Gain, flatness of the PA, cable losses and accuracy of the attenuators in the TX and in the PA are some of the factors. Because of the above if the transmitter were not calibrated with the PA there would be:

1) Large swing in Pout from unit to unit and from frequency to frequency 2) Imperfect IQ lines calibration (lower MER)

The consequences are that the transmitter will not be exactly at 23 dBm when operating by itself and the IQ will not be optimal. The customer should expect the transmitter to have powers ranging from 20-23 dBm typically. At the time this manual was written Cobham/GMS is investigating the process of implementing a system so that dual calibration factors could be stored in the transmitters. This will allow optimizing the TX-PA combination and also the TX when operated in stand-alone mode.

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4.2 EXTERNAL CONNECTIONS AND INDICATORS

GND LUG AND NEG .RTRN

+Vcc

RF Out, Antenna Port

0-15dB INPUT ATTENUATOR

REMOTE ATTEN. CONTROL

PA ENABLE

HEATSINK SIDE

LED STATUS INDICATOR

TEMPERATURE DETECTOR

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RF INOVERDRIVE WARNING

TEMPERATURE DETECTOR

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Figure 1- VEPA-10W PA EXTERNAL CONNECTIONS

4.2.1 RF-IN SMA Input from signal source

4.2.2 RF-OUT SMA Output to the antenna. This output is protected by an internal isolator

4.2.3 Vcc Power supply input. Operating voltage ranges from 9Vdc to 32 Vdc. The input is reverse polarity protected.

4.2.4 GND LUG and NEG RTRN This terminal is connected to chassis. Apply here the Negative of the power supply and the return of the Enable signal.

4.2.5 PA Enable

Enable Pin Input Voltage High : Min 2.5Vdc Enable Pin Input Voltage Low : Max 0.8Vdc Enable Pin Input Voltage Max : 5Vdc or < Vcc with a 10k -100k resistor. Input current: 30uA to 40uA The PA can be enabled by connecting a 10k -100k resistor from the Enable pin to the Vcc pin.

4.2.6 0-15dB INPUT ATTENUATOR

10W COFDM OR 20W FM OVERDRIVE IDENTIFIER

ID LABEL

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16 position rotary attenuator 0 to 15dB. This is factory set before shipment at 8dB. The customer should apply input power consistent with the specified gain of the PA (see specifications in Table 2) and then lower the attenuator setting until the desired output power is achieved.

4.2.7 REMOTE ATTEN. CONTROL

The attenuation is set by grounding pins 1 to 4. This will allow attenuation values ranging from 0 to 15dB. Pin 5 is not connected . Pin 6 is GND.

Pin Number Attenuation (dB)

4 3 2 1 Open Open Open Open 0 Open Open Open GND 1 Open Open GND Open 2 Open Open GND GND 3 Open GND Open Open 4 Open GND Open GND 5 Open GND GND Open 6 Open GND GND GND 7 GND Open Open Open 8 GND Open Open GND 9 GND Open GND Open 10 GND Open GND GND 11 GND GND Open Open 12 GND GND Open GND 13 GND GND GND Open 14 GND GND GND GND 15

4.2.8 10W COFDM OR 20W FM OVERDRIVE IDENTIFIER The label identifies if the product is factory set for 10W COFDM operation or for 20W FM. See paragraph 1.5 for a full explanation.

4.2.9 TEMPERATURE DETECTOR The temperature detector sticker has five white dots which turn black when the temperature reaches 60, 65, 71, 77, 82 OC (140, 149, 160, 171, 180 F). A black 71 OC (160 F) dot will void the warranty. Identical stickers are placed inside the unit.

4.2.10 ID LABEL

The label identifies the P/N, model number and S/N of the unit

PROD: VEPA 10W (VERY EFFICIENT PA) 1.99 2.5GHz

ITEM : 800-A1088X3 M/N : VEPA10WS2 S/N : XXXXXX-XX

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The label above shows that the PA operates in the S2 band between 1.99 and 2.5GHz. The power shown (10W) is the operating power for COFDM.

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4.3 CONNECTING & DISCONNECTING THE POWER AMPLIFIER

When Connecting the Power Amplifier, follow the following steps for best results and to avoid damaging the amplifier. 1) Apply the load to the amplifier (make sure a good load is ALWAYS present when working with any

power amplifier). For operational set up, use an antenna with a good VSWR (< 1.5:1 recommended). The PA is protected by an internal isolator against any mismatch; however the reflected power will decrease the efficiency of the link and will also cause extra heat to be dissipated internally to the PA. For bench tests use a 20-30 dB attenuator rated at least at 20W connected directly at the RF Out port.

2) Measure the signal level from your transmitter or signal generator before connecting it to the input port. AN EXCESSIVE INPUT POWER MIGHT DAMAGE THE PA. The input level should be conservatively set lower and then raised while monitoring the output power and/or current. When using a COFDM transmitter such as COBHAM/GMS VMT, M2T and M2TE use the low power mode for best results. It is necessary to attenuate the power internally to the transmitter rather than placing an attenuator at the transmitter output because the linearity of the transmitter will be better. Consult the transmitter’s manual for operation at low power. If needed add also external attenuator to the transmitter or signal generator until the desired power is obtained Start with an input power to the PA set at –3 dBm or lower

3) Verify that the PA input attenuator is set at about mid-range. The PA is factory shipped with the input attenuator set at 8. This will allow some margin for error if a mistake was made in the transmitter settings.

4) Set your supply at the desired operation voltage within the 9-32Vdc range. Make sure the power

supply is capable of supplying the current required. The following table 1 gives current values as function of voltage. A small margin for a possible current surge at start up is included.

Table 3 Power supply recommended power capability

Voltage (Vdc)

Recommended Supply Current capability (A)

10W 20W FM

9 8.0 12.0 10 7.0 11.0 12 6.0 9.0 14 5.0 8.0 16 5.0 7.0 18 4.0 6.0 20 4.0 5.5 22 4.0 5.5 24 3.0 4.5 26 3.0 4.5 28 3.0 4.0

30 3.0 4.0

32 3.0 3.5

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5) Connect the power supply to the PA using adequate AWG wire. Keep in mind that the voltage drop in

the wire will reduce the voltage at the PA supply terminal and therefore will cause an increase in current. The current consumption indicated in the specification sheet and in Table 3 is valid when the voltage is measured at the PA input terminals.

6) Connect a power meter at the RF port (after the attenuator). If a power meter is not available use the current meter to get an (approximate) indication of power.

7) Connect the RF input to the Power Amplifier. The power should be less than desired. If the power exceeds 10W (for COFDM) or 20W (for FM) an error was made in the setup of input power: DISCONNECT THE RF INPUT IMMEDIATELY and recheck the power at the output of the transmitter.

8) Adjust the PA RF input attenuator until the desired power is reached. If a PWR meter is not available use the current indication for an approximate estimate of power. Table 4 gives conservative current indications for various voltages and powers.

Table 4 - Current values to be used as indication of output power when a PWR meter is not available

The current varies somewhat with frequency and from unit to unit. Consult the data sheet for more accurate information.

Current indication (A) to be used to estimate PWR when a PWR meter is not available S1 and S2-band

Voltage (Vdc)

For 10W COFDM For 20W FM

Frequency (GHz) Frequency (GHz)

2.0 2.1 2.2 2.3 2.4 2.5 2.0 2.1 2.2 2.3 2.4 2.5

9 5.6 5.6 5.5 5.3 5.5 5.3 8.8 8.8 8.6 8.4 8.6 8.4 10 5.0 5.0 4.9 4.8 4.9 4.8 8.0 8.0 7.8 7.6 7.8 7.6 12 4.2 4.2 4.1 4.0 4.1 4.0 6.6 6.6 6.5 6.3 6.5 6.3 14 3.6 3.6 3.5 3.4 3.5 3.4 5.7 5.7 5.6 5.4 5.6 5.4 16 3.2 3.2 3.1 3.0 3.1 3.0 5.0 5.0 4.9 4.7 4.9 4.7 18 2.8 2.8 2.7 2.7 2.7 2.7 4.4 4.4 4.3 4.2 4.3 4.2 20 2.5 2.5 2.5 2.4 2.5 2.4 4.0 4.0 3.9 3.8 3.9 3.8 22 2.3 2.3 2.2 2.2 2.2 2.2 3.6 3.6 3.5 3.4 3.5 3.4 24 2.1 2.1 2.1 2.0 2.1 2.0 3.3 3.3 3.2 3.2 3.2 3.2 26 1.9 1.9 1.9 1.8 1.9 1.8 3.1 3.1 3.0 2.9 3.0 2.9 28 1.8 1.8 1.8 1.7 1.8 1.7 2.8 2.8 2.8 2.7 2.8 2.7 30 1.7 1.7 1.6 1.6 1.6 1.6 2.7 2.7 2.6 2.5 2.6 2.5

32 1.6 1.6 1.5 1.5 1.5 1.5 2.5 2.5 2.4 2.4 2.4 2.4

Current indication(A) to be used to estimate PWR when a PWR meter is not available L2-band

Voltage (Vdc)



1.7 1.75 1.8 1.85 1.7 1.75 1.8 1.85

9 4.87 4.73 4.60 4.60 7.87 7.47 7.40 7.40 10 4.38 4.26 4.14 4.14 7.08 6.72 6.66 6.66 12 3.65 3.55 3.45 3.45 5.9 5.6 5.55 5.55 14 3.13 3.04 2.96 2.96 5.06 4.80 4.76 4.76 16 2.74 2.66 2.59 2.59 4.43 4.20 4.16 4.16 18 2.43 2.37 2.30 2.30 3.93 3.73 3.70 3.70

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Current indication(A) to be used to estimate PWR when a PWR meter is not available L2-band

Voltage (Vdc)



1.7 1.75 1.8 1.85 1.7 1.75 1.8 1.85

20 2.19 2.13 2.07 2.07 3.54 3.36 3.33 3.33 22 1.99 1.94 1.88 1.88 3.22 3.05 3.03 3.03 24 1.83 1.78 1.73 1.73 2.95 2.80 2.78 2.78 26 1.68 1.64 1.59 1.59 2.72 2.58 2.56 2.56 28 1.56 1.52 1.48 1.48 2.53 2.40 2.38 2.38 30 1.46 1.42 1.38 1.38 2.36 2.24 2.22 2.22

32 1.37 1.33 1.29 1.29 2.21 2.10 2.08 2.08

Current indication (A) to be used to estimate PWR when a PWR meter is not available SK-band

Voltage (Vdc)



2.2 2.3 2.4 2.5 2.6 2.7 2.2 2.3 2.4 2.5 2.6 2.7

9 5.39 5.29 5.19 5.13 5.08 5.16 8.62 8.47 8.30 8.21 8.13 8.26 10 4.848 4.764 4.668 4.62 4.572 4.644 7.76 7.62 7.47 7.39 7.32 7.43 12 4.04 3.97 3.89 3.85 3.81 3.87 6.46 6.35 6.22 6.16 6.10 6.19 14 3.46 3.40 3.33 3.30 3.27 3.32 5.54 5.44 5.33 5.28 5.23 5.31 16 3.03 2.98 2.92 2.89 2.86 2.90 4.85 4.76 4.67 4.62 4.57 4.64 18 2.69 2.65 2.59 2.57 2.54 2.58 4.31 4.23 4.15 4.11 4.06 4.13 20 2.42 2.38 2.33 2.31 2.29 2.32 3.88 3.81 3.73 3.70 3.66 3.72 22 2.20 2.17 2.12 2.10 2.08 2.11 3.53 3.46 3.39 3.36 3.33 3.38 24 2.02 1.99 1.95 1.93 1.91 1.94 3.23 3.18 3.11 3.08 3.05 3.10 26 1.86 1.83 1.80 1.78 1.76 1.79 2.98 2.93 2.87 2.84 2.81 2.86 28 1.73 1.70 1.67 1.65 1.63 1.66 2.77 2.72 2.67 2.64 2.61 2.65 30 1.62 1.59 1.56 1.54 1.52 1.55 2.59 2.54 2.49 2.46 2.44 2.48

32 1.52 1.49 1.46 1.44 1.43 1.45 2.42 2.38 2.33 2.31 2.29 2.32 4.4 OVERDRIVE PROTECTION CIRCUIT

The PA implements an overdrive protection circuit which intervenes when the average input power is exceeded by about 2-3dB. When the circuit intervenes the input attenuator is increased by 16dB and the LED indicator turns from Green to Red. This is a latched condition. In order to reset the attenuation, DC input power must be cycled OFF and ON.

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5.0 TYPICAL POWER AMPLIFIER PERFORMANCES This chapter gives typical power amplifier performances. The PA has repeatable performances from unit to unit.

5.1 GAIN

5.1.1 S2 BAND

Figure 2 – GAIN AT 10W COFDM S2-BAND

Figure 3– GAIN AT 20 W FM S2-BAND

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5.1.2 L2 BAND

Figure 4 - GAIN AT 10W COFDM L2-BAND

Figure 5 - GAIN AT 20 W FM L2-BAND

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5.1.3 SK BAND

Figure 6 –GAIN AT 10W COFDM SK-BAND

Figure 7 – GAIN AT 20W FM SK-BAND

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5.2 CURRENT

5.2.1 S2-BAND

Figure 8 – CURRENT AT 10W COFDM S2-BAND

Figure 9– CURRENT AT 20 W FM S2-BAND

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5.2.2 L2-BAND

Figure 10 – Current 10W COFDM L2-BAND

Figure 11 – Current 20W FM L2_BAND

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5.2.3 SK-BAND

Figure 12 – Current 10W COFDM SK-Band

Figure 13 – Current 20W FM SK-Band

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5.3 LINEARITY

The MER was measured with a Rhode & Schwartz EFA Test RCVR mod 2067 in Stationary mode QPSK. The MER in 16QAM is about 0.6dB less than the MER in QPSK mode. Other instruments such as the MXA Agilent Signal Analyzer N9020A gave about 2dB better results.

5.3.1 S2-BAND

Figure 14– MER AT 8W S2-BAND

Figure 15 –MER AT 10W S2-BAND

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5.3.2 L2-BAND

Figure 16 – MER AT 8W L2-BAND

Figure 17 – MER AT 10W L2-BAND

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5.3.3 SK-BAND

Figure 18 – MER AT 8W SK-BAND

Figure 19 – MER AT 10W SK-BAND

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5.4 POWER VARIATION OVER TEMPERATURE

Figure 20 - Power Variation Over Temperature

The figure above shows the variation over temperature of a typical power amplifier. Temperature is varied while the input signal is maintained constant.

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5.5 Large Signal S-PARAMETERS S11 and S21 were measured with -10dBm input causing the Pout to exceed 1-2W depending on frequency.

5.5.1 S2-BAND

-30

-20

-10

0

10

20

30

40

50

2.00 2.05 2.10 2.15 2.20 2.25 2.30 2.35 2.40 2.45 2.50

GHz

dB

S21

S11

S22

Figure 21 – S-PARAMETERS NARROW S2-BAND

-50

-40

-30

-20

-10

0

10

20

30

40

50

0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5

GHz

dB

S21

S11

S22

Figure 22 - S-PARAMETERS S2-BANDWIDE VIEW

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5.5.2 L2-BAND

Figure 23 –S-PARAMETERS L2-BAND NARROW VIEW

Figure 24- S-PARAMETERS L2-BAND WIDE VIEW

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5.5.3 SK-BAND

Figure 25 – S-PARAMETERS SK-BAND NARROW VIEW

Figure 26 - S-PARAMETERS SK-BAND WIDE VIEW

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APPENDIX 1 – ACRONYMS

AWG American Wire Gauge COFDM Coded Orthogonal Frequency Division Multiplexing CMT-R DES

Configurable Messenger Transmitter -Rack Mount Kit Data Entry Sheet

DVBT Digital Video Broadcasting Terrestrial DVM Digital Volt-Meter FM Frequency Modulation GMS Global Microwave Systems LO Local Oscillator M2T Messenger 2 Transmitter M2TE Messenger 2 Transmitter Enhanced MER Modulation Error Ratio PA Power Amplifier PAR Peak Average Ratio PWR Power QAM Quadrature Amplitude Modulation QPSK Quadrature Phase-Shift Keying R&S Rhode and Schwartz RCVR Receiver RF Radio frequency S/N Serial Number SDMT Standard Definition Messenger Transmitter TDR Test Data Record TX Transmitter VEPA Very Efficient Power Amplifier VMT Veta Miniature Transmitter VSWR Voltage Standing Wave Ratio

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