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Cobham Tactical Communications and Surveillance1916 Palomar Oaks Way, Suite 100, Carlsbad, CA 92008Tel: 760-496-0055FAX: 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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GMS Inc . doing business as Cobham Tactical Communications and Surveillance www.cobham.com/tcs

REVISION HISTORY

Version Date Author CommentsX1 April 23 2010 Silvano Padoan Initial release.X2 June 14 2010 Silvano Padoan Added paragraph 4.4X3 Oct. 20 2010 Silvano Padoan Adapted for rev X3 of the productX4 Nov. 20 2010 Silvano Padoan Added data for L2-band and SK-band1 Apr. 23 2011 Owen de Meyer Transferred from 100-M0135X4

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TABLE OF CONTENTS

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

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

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

3.0 SPECIFICATIONS ......................................................................................................................................................

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

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

4.2 EXTERNAL CONNECTIONS AND INDICATORS .............................................................................................4.2.1 RF-IN ................................................................................................................................................................

4.2.2

RF-OUT ............................................................................................................................................................4.2.3 Vcc ...................................................................................................................................................................4.2.4 GND LUG and NEG RTRN ............................................................................................................................4.2.5 PA Enable ........................................................................................................................................................4.2.6 0-15dB INPUT ATTENUATOR ......................................................................................................................4.2.7 REMOTE ATTEN. CONTROL .......................................................................................................................4.2.8 10W COFDM OR 20W FM OVERDRIVE IDENTIFIER ..............................................................................4.2.9 TEMPERATURE DETECTOR .......................................................................................................................4.2.10 ID LABEL ...................................................................................................................................................

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

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

5.1 GAIN ........................................................................................................................................................................5.1.1 S2 BAND .........................................................................................................................................................5.1.2 L2 BAND ........................................................................................................................................................5.1.3 SK BAND ........................................................................................................................................................5.2 CURRENT ................................................................................................................................................................5.2 CURRENT ................................................................................................................................................................5.2.1 S2-BAND ..............................................................................................................................................................5.2.2 L2-BAND ...............................................................................................................................................................5.2.3 SK-BAND .............................................................................................................................................................

5.3 LINEARITY .................................................................................................................................................................5.3.1 S2-BAND ..............................................................................................................................................................5.3.2 L2-BAND .............................................................................................................................................................

5.3.3 SK-BAND .............................................................................................................................................................5.4 POWER VARIATION OVER TEMPERATURE .........................................................................................................

5.5.1 S2-BAND ..............................................................................................................................................................5.5.2 L2-BAND ...............................................................................................................................................................

6.0 TEST PROCEDURE ..............................................................................................................................Error! Bookmark not define

6.1 Equipment needed ........................................................................................................................Error! Bookmark not define6.2 LARGE SIGNAL S-PARAMETERS TESTS ..........................................................................Error! Bookmark not define6.3 10W COFDM OR 20W FM TESTS Set up ......................................................................Error! Bookmark not define

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6.4 Preliminary checks ........................................................................................................................Error! Bookmark not define6.5 ROOM TEMPERATURE TESTS ................................................................................................Error! Bookmark not define6.6 TESTS OVER THE TEMPERATURE RANGE ....................................................................Error! Bookmark not define

6.6.1 TEST AT HOT ...........................................................................................................................Error! Bookmark not define6.6.2 EST AT COLD ...........................................................................................................................Error! Bookmark not define

LIST OF TABLESTable 1 - ABSOLUTE MAX RATINGS 1 ............................................................................................................Table 2 - SPECIFICATIONS ....................................................................................................................................Table 3 Power supply recommended power capability ........................................................................................ 1Table 4 - Current values to be used as indication of output power when a PWR meter is not

available .............................................................................................................................................................Table 5 Recommended Test Frequencies ............................................................... Error! Bookmark not defined

LIST OF FIGURESFigure 1- VEPA-10W PA EXTERNAL CONNECTIONS ......................................................................................Figure 2 GAIN AT 10W COFDM S2-BAND .......................................................................................................Figure 3 GAIN AT 20 W FM S2-BAND ................................................................................................................Figure 4 GAIN AT 10W COFDM L2-BAND ........................................................................................................Figure 5 - GAIN AT 20 W FM L2-BAND ..............................................................................................................Figure 6 GAIN AT 10W COFDM SK-BAND .......................................................................................................Figure 7 GAIN AT 20W FM SK-BAND ..............................................................................................................Figure 8 CURRENT AT 10W COFDM S2-BAND ..............................................................................................Figure 9 CURRENT AT 20 W FM S2-BAND ......................................................................................................Figure 10 Current 10W COFDM L2-BAND ........................................................................................................Figure 11 Current 20W FM L2_BAND ................................................................................................................Figure 12 Current 10W COFDM SK-Band ..........................................................................................................Figure 13 Current 20W FM SK-Band ...................................................................................................................Figure 14 MER AT 8W S2-BAND ........................................................................................................................Figure 15 MER AT 10W S2-BAND ......................................................................................................................Figure 16 MER AT 8W L2-BAND .......................................................................................................................

Figure 17 MER AT 10W L2-BAND .....................................................................................................................Figure 18 MER AT 8W SK-BAND .......................................................................................................................Figure 19 MER AT 10W SK-BAND .....................................................................................................................Figure 20 - Power Variation Over Temperature ...........................................................................................Figure 21 S-PARAMETERS NARROW S2-BAND ............................................................................................Figure 22 - S-PARAMETERS S2-BANDWIDE VIEW ..........................................................................................Figure 23 S-PARAMETERS L2-BAND NARROW VIEW .................................................................................Figure 24- S-PARAMETERS L2-BAND WIDE VIEW ..........................................................................................Figure 25 S-PARAMETERS SK-BAND NARROW VIEW ................................................................................Figure 26 - S-PARAMETERS SK-BAND WIDE VIEW ........................................................................................Figure 27-Test set up when a GMS transmitter is used as signal source Error! Bookmark not defineFigure 28- Test set up when a COFDM Signal Generator is used ............... Error! Bookmark not defined

APPENDICESAPPENDIX 1 PRELIMINARY MEASUREMENT REPORT ..................................Error! Bookmark not definedAPPENDIX 2 LARGE SIGNAL S-PARA DATA ENTRY SHEET ......................Error! Bookmark not definedAPPENDIX 3 DATA ENTRY SHEET (DES) 10W COFDM S2-BAND EXAMPLE Error! Bookmark not APPENDIX 4 DATA ENTRY SHEET (DES) 20W FM S2-BAND EXAMPLE Error! Bookmark not definAPPENDIX 5 TDR S2-BAND EXAMPLE ....................................................................Error! Bookmark not defined

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APPENDIX 6 ACRONYMS ................................................................................................................................

1.0 CAUTIONS AND WARNINGS

1.1 ELECTROMAGNETIC RADIATIONS

There is no consensus in the scientific community about the potential harmful effect of electromagneticradiations. This power amplifier will radiate an average 10W power with peak powers 14dB higher whenoperating with a COFDM DVBT transmitter. It is recommended that the operator minimizes exposure toelectromagnetic 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 voltagewithin this range and is capable of providing the current needed with some margin. At 12 Vdc the amplifierwill draw less than 4.5A when the input power is properly set to deliver 10W COFDM. For 20W FM tcurrent 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 at9VDc will be about 30% more.Make sure your power supply is capable of delivering the current needed. Current limiting should be avoidedas 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 againstexcessive VSWR by an isolator. However the reflected power will decrease the link range and will bdissipated 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 65 OC (149 F). Depending on customrequirements the PA might be shipped mounted on different size heat-sinks. One typical heat-sink has 15 fins2.2 (55mm) long on a 0.35 (8.9mm) plate. The temperature will raise about 40 OC (45 F) at 10W COFDwhen 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 temperaturdetector sticker is applied externally and internally to the PA. The sticker has five white dots which turn blackwhen the temperature reaches 60, 65, 71, 77, 82 OC. (140, 149, 160, 171, 180 F). A black 71 OC. (160 F) dwill 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 t14dB. To achieve the best efficiency the PA operates at the highest power that will allow the desired linearitywithout 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 inputattenuation when the overdrive exceeds 3dB. However the circuit has a discrete intervention time and verylarge 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 averagepower. However this requires the overdrive protection to be set higher. This will allow the operator to use itat COFDM levels which might be damaging.Therefore the PA is shipped in two possible configurations: 10W COFDM or 20W FM. The PA configured for10W COFDM operation has internal protection circuits which will intervene if the PA is overdriven 2-3dB ovethe nominal 10W. This PA is not capable of operating at 20W FM because this power will trigger theprotection circuit but operation at 10W FM is possible. This is indicated in a Caution label on the bottomcover:

The PA configured for 20W operation has internal protection circuits which will intervene if the PA isoverdriven 2-3dB over the nominal 20W. This PA can be operated normally in COFDM provided the COFDaverage power does not exceed 10W average. Operations at COFDM powers higher than 10W will not bedetected by the protection circuit and might cause permanent damage. This is indicated in a Caution labelon the bottom cover:

The operator should carefully set the input power accordingly. The PA is equipped with a variable attenuatorcontrolled 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 tadjust the power in 1dB steps until it reaches the desired level. During set up it is recommended that theoutput power be monitored with a power meter. If a power meter is not available a gross indication of powercan be assessed by monitoring the current. At 12 Vdc (measured at the terminals of the PA) the current willaverage typically 4.2A for 10W of COFDM output power and will be 400-500mA lower for 8W output powerAt 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 PROTECTIONSET FOR 10W OPERATION

CAUTION: CIRCUIT PROTECTION SETFOR 20W FM. OVERDRIVING OVER 10WCOFDM 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 norecommended 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 itspossible 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 approximateindication of power in absence of a reliable power meter (see table 4).

2.0 ABSOLUTE MAX RATINGS

Table 1 - ABSOLUTE MAX RATINGS1

MAX RF INPUT COFDM ( See note below) ATTENUATOR SET TO 0 < 4dBm Other attenuator settings < (4dBm + att setting)

MAX CONTINUOUS COFDM OUTPUT PWR 12W

MAX CONTINUOUS FM OUTPUT PWR 25WMAX SUPPLY VOLTAGE 35 Vdc MAX BASEPLATE TEMPERATURE 65oC

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 isrecommended not to exceed the normal operating power, because this will drive the PA to operate withdecrease of linearity and increase current /heat. Since the gain might vary from unit to unit and fromchannel to channel consult the TDR for your unit to determine what is the correct gain and then adjust theinput power accordingly.

For example in S2-band the gain is about 42 dB. To operate at 10W COFDM the input power is about -2dBmFor units set to operate at 20W FM the input power is 1 dBm. With the input attenuator set to 0 neverexceed 3dBm at the input. When the attenuator is set to values other than zero the max RF input powerincreases accordingly.

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3.0 SPECIFICATIONS

Table 2 - SPECIFICATIONS

Parameter SpecificationFrequency (GHz) 1.7 - 1.85 2.2-2.4 1.99-2.5 2.2-2.7Frequency Band L2 S1 S2 SKLinear Gain (dB center band with attenuator set to 0). (gainis adjustable through front panel switch or remote control) )(NOTE 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 VSWR 1.3:1 1.5:1 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)(NOTE 2) 8 W 31 31 30 3110W 28.5 29 28 28.5

Current (A@ 12 VDC) (NOTE 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

Weightlbs. 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-P06LCC0-0000Pin 1: 1dBPin 2: 2dBPin 3: 4dBPin 4: 8dBPin 5: NC

pin 6: GNDDC Power Connector Solder pinsRF Connectors SMA Female

Note 1: Average gain among units at the center of the band. See graphs for more detailsNote 2: Indicated MER is average value across the band. See graphs for more detailsNote 3: Indicated Current is average value across the band. See graphs for more details

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4.0 OPERATIONAL INSTRUCTIONS

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

4.1 USING A TRANSMITTER/PA COMBINATION

4.1.1 The old FM approachThe methodology of interfacing a digital transmitter with a linear PA is somewhat different that themethodology 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 bestefficiency. The non-linearity caused by this approach did not affect the quality of the link because theinformation 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 lowpass filter.In the FM world it made sense to mate a transmitter operating at its RF rated output power to an externalPower Amplifier in order to extend its range of operation. There was no need to modify the Power output ofthe transmitter if the PA had the correct gain. For example GMS sold a 200mW FM transmitter and anadditional 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 approachNewer Cobham/GMS transmitters are designed for operation with COFDMDVBT type signal. In this type omodulation the information is contained in the phase and amplitude of multiple carriers which aretransmitted simultaneously. These carriers, being spaced at regular frequency interval, combine in amplitudethus creating very large amplitude peaks. The result is that the Peak to Average Amplitude Ratio (PAR) is verlarge (typically limited to 14dB by the DAC in the modulator). Unlike the FM world neither the amplitude nothe 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 certainlevel of back OFF meaning that the average power transmitted is several dB lower than the P1dB of thevarious stages of the amplifier. But this has a price in term of power consumption and therefore transmittersare 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 finastage a device which has a P1dB around 29dBm. If we had chosen to use a device with greater P1dB the MERwould 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 2Wtransmitting system, but this is NOT the approach that provides the best results. Lets say that our amplifierhas an MER of 28 dB. If we connect a 25dB MER signal into it the 3rd order product and harmonics of thetransmitter will further re-grow in the PA. The resulting MER will be lower than 25dB and therefore the systemwill 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 200mW2) Use a PA with higher gain and an MER a little higher than 25dB3) When the transmitter is used in combination with the PA, the transmitter Power is Backed OFF (i.e. ainternal 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 athe 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 incombination with the PA.CAUTION: WHEN COMBINING A TRANSMITTER WITH A PA FOR THE FIRST TIME THE CUSTOMER SHOULD ALWAYTHAT THE POWER OUTPUT OF THE TRANMITTER IS COMPATIBLE WITH THE MAX ABSOLUTE RATING OFAMPLIFIER.

4.1.3 Matching a Transmitter to a PA

Cobham/GMS transmitters are calibrated at the factory to provide a constant output power over thefrequency 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 BACKEOFF 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 0by selecting the High Power mode.CAUTION: Failure to select Low Power Mode when the TX is used in combination with the PA will caularge overdrive, and will trigger the Overdrive Protection and/or damage the PAAn example will help clarify the issue.Cobham/GMS sells a transmitter call M2T which provides a 200mW (23dBm) COFDM output power. Thtransmitter is sold by itself or installed in a rack mount combination (called CMT-R) with a 10W PA. Since thPA has about 40 dB gain the output power of the transmitter is reduced by 7dB and the PA input attenuator isset to 15dB. There is an additional 1dB loss in cables and adapters.Therefore the output power would be:

Pout dBm = PTX - 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 TXwould 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 frequency2) 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 IQwill not be optimal. The customer should expect the transmitter to have powers ranging from 20-23 dBmtypically.At the time this manual was written Cobham/GMS is investigating the process of implementing a system sothat dual calibration factors could be stored in the transmitters. This will allow optimizing the TX-PAcombination and also the TX when operated in stand-alone mode.

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4.2 EXTERNAL CONNECTIONS AND INDICATORS

RF INOVERDRIVEWARNING

TEMPERATUREDETECTOR

GND LUG ANDNEG .RTRN

+Vcc

RF Out,Antenna Port

0-15dB INPUTATTENUATOR

REMOTE ATTEN.CONTROL

PA ENABLE

HEATSINKSIDE

LED STATUSINDICATOR

TEMPERATUREDETECTOR

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Figure 1- VEPA-10W PA EXTERNAL CONNECTIONS

4.2.1 RF-INSMA Input from signal source

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

4.2.3 VccPower supply input. Operating voltage ranges from 9Vdc to 32 Vdc. The input is reversepolarity protected .

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

4.2.5 PA Enable

Enable Pin Input Voltage High : Min 2.5Vdc Enable Pin Input Voltage Low : Max 0.8VdcEnable Pin Input Voltage Max : 5Vdc or < Vcc with a10k -100k resistor.Input current: 30uA to 40uAThe 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

16 positions rotary attenuator 0 to 15dB. This is factory set before shipment at 8dB. Thecustomer should apply input power consistent with the specified gain of the PA (see

10W COFDM OR 20W FMOVERDRIVE IDENTIFIER

ID LABEL

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specifications in Table 2) and then lower the attenuator setting until the desired output poweris achieved.

4.2.7 REMOTE ATTEN. CONTROL

The attenuation is set by grounding pins 1 to 4. This will allow attenuation values ranging from0 to 15dB. Pin 5 is not connected . Pin 6 is GND.

Pin Number Attenuation(dB)

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

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

4.2.9 TEMPERATURE DETECTORThe temperature detector sticker has five white dots which turn black when the temperaturereaches 60, 65, 71, 77, 82 OC. (140, 149, 160, 171, 180 F). A black 71 OC. (160 F) dot will vothe 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

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

PROD: VEPA 10W (VERYEFFICIENT PA) 1.99 2.5GHz

ITEM : 800-A1088X3M/N : VEPA10WS2S/N : XXXXXX-XX

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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 damagingthe amplifier.

1) Apply the load to the amplifier (make sure a good load is ALWAYS present when working with an

power amplifier).For operational set up, use an antenna with a good VSWR (< 1.5:1 recommended). The PA protected by an internal isolator against any mismatch; however the reflected power will decrease theefficiency 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 Outport.

2) Measure the signal level from your transmitter or signal generator before connecting it to the inputport. AN EXCESSIVE INPUT POWER MIGHT DAMAGE THE PA. The input level should bconservatively 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 pomode for best results. It is necessary to attenuate the power internally to the transmitter rather thanplacing an attenuator at the transmitter output because the linearity of the transmitter will be better.

Consult the transmitters manual for operation at low power.If needed add also external attenuator to the transmitter or signal generator until the desired power isobtainedStart 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 theinput attenuator set at 8. This will allow some margin for error if a mistake was made in thtransmitter settings.

4) Set your supply at the desired operation voltage within the 9-32Vdc range. Make sure the powersupply is capable of supplying the current required. The following table 1 gives current values afunction of voltage. A small margin for a possible current surge at start up is included.

Table 3 Power supply recommended power capability

Voltage(Vdc)

RecommendedSupply Currentcapability (A)

10W 20W FM9 8.0 12.0

10 7.0 11.012 6.0 9.014 5.0 8.0

16 5.0 7.018 4.0 6.020 4.0 5.522 4.0 5.524 3.0 4.526 3.0 4.528 3.0 4.030 3.0 4.032 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 inthe wire will reduce the voltage at the PA supply terminal and therefore will cause an increase incurrent. The current consumption indicated in the specification sheet and in Table 3 is valid when thevoltage 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 thecurrent 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 powerexceeds 10W(for COFDM) or 20W (for FM) an error was made in the setup of input powerDISCONNECT THE RF INPUT IMMEDIATELY and recheck the power at the output of the transmitt

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

Table 4 - Current values to be used as indication of output power when a PWR meter is notavailable

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

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 2.59 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 7.612 4.2 4.2 4.1 4.0 4.1 4.0 6.6 6.6 6.5 6.3 6.5 6.314 3.6 3.6 3.5 3.4 3.5 3.4 5.7 5.7 5.6 5.4 5.6 5.416 3.2 3.2 3.1 3.0 3.1 3.0 5.0 5.0 4.9 4.7 4.9 4.718 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 3.822 2.3 2.3 2.2 2.2 2.2 2.2 3.6 3.6 3.5 3.4 3.5 3.424 2.1 2.1 2.1 2.0 2.1 2.0 3.3 3.3 3.2 3.2 3.2 3.226 1.9 1.9 1.9 1.8 1.9 1.8 3.1 3.1 3.0 2.9 3.0 2.928 1.8 1.8 1.8 1.7 1.8 1.7 2.8 2.8 2.8 2.7 2.8 2.730 1.7 1.7 1.6 1.6 1.6 1.6 2.7 2.7 2.6 2.5 2.6 2.532 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 ind ication(A) to be used to estimate PWR when a PWR meter is not available L2-band

Voltage(Vdc)


Frequency (GHz) Frequency (GHz)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 ind ication(A) to be used to estimate PWR when a PWR meter is not available L2-band

Voltage(Vdc)


Frequency (GHz) Frequency (GHz)

1.7 1.75 1.8 1.85 1.7 1.75 1.8 1.8520 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 ind icatio n (A) to be used to estimate PWR when a PWR meter is not available SK-band

Voltage(Vdc)


Frequency (GHz) Frequency (GHz)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 8.210 4.848 4.764 4.668 4.62 4.572 4.644 7.76 7.62 7.47 7.39 7.32 7.412 4.04 3.97 3.89 3.85 3.81 3.87 6.46 6.35 6.22 6.16 6.10 6.114 3.46 3.40 3.33 3.30 3.27 3.32 5.54 5.44 5.33 5.28 5.23 5.316 3.03 2.98 2.92 2.89 2.86 2.90 4.85 4.76 4.67 4.62 4.57 4.618 2.69 2.65 2.59 2.57 2.54 2.58 4.31 4.23 4.15 4.11 4.06 4.120 2.42 2.38 2.33 2.31 2.29 2.32 3.88 3.81 3.73 3.70 3.66 3.722 2.20 2.17 2.12 2.10 2.08 2.11 3.53 3.46 3.39 3.36 3.33 3.324 2.02 1.99 1.95 1.93 1.91 1.94 3.23 3.18 3.11 3.08 3.05 3.126 1.86 1.83 1.80 1.78 1.76 1.79 2.98 2.93 2.87 2.84 2.81 2.828 1.73 1.70 1.67 1.65 1.63 1.66 2.77 2.72 2.67 2.64 2.61 2.630 1.62 1.59 1.56 1.54 1.52 1.55 2.59 2.54 2.49 2.46 2.44 2.432 1.52 1.49 1.46 1.44 1.43 1.45 2.42 2.38 2.33 2.31 2.29 2.3

4.4 OVERDRIVE PROTECTION CIRCUIT

The PA implements an overdrive protection circuit which intervenes when the average inputpower is exceeded by about 2-3dB. When the circuit intervenes the input attenuator isincreased 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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GMS Inc . doing business as Cobham Tactical Communications and Surveillance www.c

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

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5.1.2 L2 BAND

Figure 4 GAIN AT 10W COFDM L2-BAND Figure 5 - GAIN

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GMS Inc . doing business as Cobham Tactical Communications and Surveillance www.cob

5.1.3 SK BAND

Figure 6 GAIN AT 10W COFDM SK-BAND Figure 7 GAIN

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5.2 CURRENT

5.2.1 S2-BAND

Figure 8 CURRENT AT 10W COFDM S2-BAND Figure 9 CURRE

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5.2.2 L2-BAND

Figure 10 Current 10W COFDM L2-BAND Figure 11 Cur

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5.2.3 SK-BAND

Figure 12 Current 10W COFDM SK-Band Figure 13 Cur

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5.3 LINEARITY

The MER was measured with a Rhode & Schwartz EFA Test RCVR mod 2067 in Stationary mode QPSK. 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 ME

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5.3.2 L2-BAND

Figure 16 MER AT 8W L2-BAND Figure 17 M

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5.3.3 SK-BAND

Figure 18 MER AT 8W SK-BAND Figure 19 M

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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 whiconstant.

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

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

d

B

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

d

B

Figure 22 - S-PARAM

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5.5.2 L2-BAND

Figure 23 S-PARAMETERS L2-BAND NARROW VIEW Figure 24- S-PARAM

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5.5.3 SK-BAND

Figure 25 S-PARAMETERS SK-BAND NARROW VIEW Figure 26 - S-PARAM

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APPENDIX 1 ACRONYMS

AWG American Wire GaugeCOFDM Coded Orthogonal Frequency Division MultiplexingCMT-RDES

Configurable Messenger Transmitter -Rack Mount KitData Entry Sheet

DVBT Digital Video Broadcasting TerrestrialDVM Digital Volt-Meter

FM Frequency ModulationGMS Global Microwave SystemsLO Local OscillatorM2T Messenger 2 TransmitterM2TE Messenger 2 Transmitter EnhancedMER Modulation Error RatioPA Power AmplifierPAR Peak Average RatioPWR PowerQAM Quadrature Amplitude ModulationQPSK Quadrature Phase-Shift KeyingR&S Rhode and SchwartzRCVR ReceiverRF Radio frequencyS/N Serial NumberSDMT Standard Definition Messenger TransmitterTDR Test Data RecordTX TransmitterVEPA Very Efficient Power AmplifierVMT Veta Miniature TransmitterVSWR Voltage Standing Wave Ratio

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