Specifications

Section-4 Theory
October 17, 2013
4‐6
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WARNING:Disconnectprimarypower priortoservicing. 888‐2693‐004
Figure 4-4 RF Power Control Block Diagram
AnRFsamplefr
omaforwarddirectionalcoupleratthetransmittersystemoutputisdeliveredtoafrequency‐
compensateddetectorontheampcontrolboardintheLPU.Thedetectorfunctionsinbothrmsmode,forusewith
digitalmodulationformats,andpeakmode,forusewithanalogtelevisionformats.Thepe
akandaveragedetected
voltagesaredeliveredtoananalog‐to‐digitalconverterontheLPUfrontpanelboard.Adigitizedrepre sentationof
theforwardpowerlevelisdeliveredtothecontrolCPUonthesignalprocessingboard,wherethecoreautomatic
gaincontrolfunctionsareperformedinsoftware(dashedlines):thecu
rrentpowerleveliscomparedtoastored
forwardpowerreference(i.e.desiredpowerlevel)andthepowercommandsignaltotheRFattenuatorontheup‐
downconverter(UDC)boardisraisedorloweredaccordinglytomaintainaconstantoutputpowerlevel.The
forwardpowerreferencemaybeseteitherthr
oughthewebremoteinterfaceorthefrontpanelraise/lower
buttons.
4.2.6 TransmitterRFPowerwithM o dulesRemoved
Asmodulesareremovedfromservice,theoutputpowerproducedbytheamplifyingstagedropsaccordingtothe
formula:
Power(d
B)=20*log(modulesstillinservice/totalnumberofmodules)
Thisfo
rmulaisuniversaland maybeappliedtoanytypeofisolatedcombiner,not justthosefoundintheUAX.
Forth
eUAXfamilyoftransmitters,thistranslatestothefollowingoutputpowerlevelswithanysinglemodule
removedfromthetransmitter.
Table4‐1PowerOutputwithSingleModuleRemoved
FailedModule
Model PA PS
UAXPA(LP
U) OFF OFF
UAX2PA ‐6.0dB ‐6.0dB
UAX4PA ‐2.5dB ‐2.5dB
UAX8PA ‐1.2dB ‐1.2dB
DAC
ATTENUATOR
MODULATOR
UDC
LOW POWER UNIT (LPU)
DETECTOR
PAD
FILTER
ANTENNA
PAB
FORWARD
SAMPLE
REVERSE
SAMPLE
WEB
REMOTE
INTERFACE
FORWARD
REFERENCE
POWER
CURRENT
POWER
LEVEL
ETHERNET
SIGNAL PROCESSING
FRONT
PANEL
FPGA
ADC
RAISE
BUTTON
LOWER
BUTTON
LCD
POWER
SET
FRONT PANEL
CONTROL
uC
AMP CONTROL