Comtech-ef-data PCB-4000 Instrukcja Użytkownika Pobierz pdf (Strona 19)

PCB-4000 1+1 Phase Combiner Revision 2

Introduction MN/PCB4000.IOM

1–5

Theamplifier gaindifferenceisautomaticallycomp ensatedforbythePCCBMonitorandControl

System.Uponpowerup,theM&Creadsthegainofeachindividu alamplifierascalibratedatthe

factory,andautomaticallyattenuatestheamplifierwiththemostgainsoastobeequalwiththe

lowergainunit.



For example, if SSPA #1 had a factory‐calibrate

d gain setting of 76 dB, and SSPA #2 had a

factory‐calibrated gain setting of 73 dB, the M&C system would automatically set the

attenuation setting of SSPA#1 to 3 dB to equalize the system gain. Although not generally

neededorrecommended,auserinputgainoffsetse

ttingisalsoprovidedforsystemfine‐tuning.

For operation and alignment information, see Chapter 3. INSTALLATION, STARTUP,

AND

TROUBLESHOOTINGPROCEDURES.



Notethat,due tothepowerdividerandcablelosses,theoverallgainofthesystemwillbeless

thantheindividualgain of eachamplifier. Pleasereferto thesystemtest datasheet for actual

systemgain.

1.3.2 System Attenuation

The PCB‐4000 makes it easy to adjust the overall system gain.  Upon input of the re quested

attenuation setting, the PCB‐4000 automatically adjusts the gain of each SSPA accordingly,

resulting in the desired attenuation value while maintaining optimum power combinin g

conditions.



TheSSPAsincludedinthesystemarecalibratedoverarange10dBbeyondspecifica

tion(30dB

vs. 20 dB). As explained above, a portion of the 30 dB range is required for gain equalization.

Therefore,themaximumallowableattenuationina1+1systemissoftwarelimitedto24dB,bu t

stillexceedssystemspecifications.

1.3.3 Soft Fail Protection

IntheeventofafailureofoneoftheSSPAs,thePCB‐4000controlsthewaveguideswitchessuch

that the good unit’s power is  routed around the “Magic‐Tee” combiner directly to the output

port.Thisres ultsinonly a3dBpowerloss,or“softfailure”.Withoutthewaveguideswitches,a

failureinoneuni

twouldresultina6dBpowerloss.



1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 87 88

Brak uwag

Comtech-ef-data PCB-4000 Instrukcja Użytkownika Strona 19