HPOD C-, X-, Ku-Band High-Power Outdoor Amplifier Revision 6
Introduction MN/HPOD.IOM
1–5
1.3.1 SSPA Module
The amplifier module performs the core function of the unit. An isolator is at the RF input to
ensure good VSWR. The RF signal then passes through an input sample port and on to an
electronically controlled attenuator that adjusts the overall attenuation according to the user
input. After some amplification, a seco
nd attenuator is automatically controlled via a look‐up
tabletomaintaintheamplifiergainataconstantlevelovertemperaturevariations.
The RF signal is then amplified by a multi‐stage design that utilizes proprietary combi ning
techniques to meet the rated power requirements. The output circuitry contains a coupl
er to
provideasampledsignalformonitoringpurposes.Apowerdetectorcircuitalsoisincludedand
thereadingisaccessibleviaremotecommunication.Ahighpowercir culatorandloadislocated
attheoutputtoprovidegoodVSWRandprotectionfromexternalmismatch.
1.3.2 Power Supply
TheSSPAfeaturesaremovablepowersupply thatisalsopowerfactorcorrected.Itconnectsto
the main chassis via a specialized connector capable of the required high current. It supplies
several voltages necessary for the unit to operate. The 10V output is capable of 2000W and
supplies current to the power transistors in the RF amplifier m
odule via two paths, or cables
(10V A and 10V B). Circuitry within the RF module controls the output status of this power
supply.IftheRFmoduledoesnothavethe–5Vsupplyforanyreas on,itdoesnotallowthe10V
powersupplytotur
non.Thisprotects thepowertransistorswithintheRFmodulefromfailur e
duetoimproperpowersupplysequencing.The+24Voutputpowersthecoolingfansandisthe
sourceofpower forwaveguideswitchingwhentheSSPAis usedinredundancyconfiguratio ns.
The+5Vand+15VvoltagesareusedtooperatetheM&Cboardan
dotheroverheadfunctions.
1.3.3 Cooling System
The SSPA unit contains a robust heat sink and thermal design to maintain a low operating
temperature.Two temperature‐controlled fans,which aremonitored bythe M&C board,draw
cooloutsideairinacrossthepowersupplyandspecializedheatsinkandexhaustthewarmerair
out the bottom of the unit. The amplifier modu
le temperature is monitored, and if for any
reason the amplifier temperature exceeds a safe preset limit, the amplifier module supply is
shutdowntoprotecttheunitfromthermalfailure.
1.3.4 Monitor and Control (M&C)
The unit includes a microprocessor‐based system that provides monitoring and control of the
essentialparametersoftheunit.TheuserinterfaceswiththeunitthroughtheM&Csystemvia
the J6 | COM1 remote control/discrete communications port. The unit is capable of EIA‐232,
EIA‐485orEthernetremotecommunication.A discre
temutecontrol andrelaystatus outputis
alsoavailable.
The M&C system monitors the fan speed, unit temperature, all power suppl y voltages, power
transistor currents, output power, etc. Should a critical monitored parameter fail, the unit will
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