KLYSTRON FILAMENT CURRENT

• BACKGROUND
• SIGNAL SOURCE
• SIGNAL DESTINATION
• LIMITS AND FAULTS

 

 
 
 

BACKGROUND 

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The klystron cathode is indirectly heated and the required filament power is provided by the filament power supply.  The Namesplate Value filament current is transformer coupled to the tube filament (see figure 11-3 sheet) where it produces approximately a 6 volt  at 25 amperes drop across the klystron filament.  The filament current is a square wave, synchronized to the system PRF by the Mod-discaharge and Mid-PRT triggers.  By synchronizing the klystron filament current to the system PRF, variations in klystron filament voltage that would modulate the beam amplitude are avoided, and better transmitter stability is realized.  The exact filament current and filament voltage values are stamped on the tube nameplate.
 

SIGNAL SOURCE 

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 The source of the High limit are found on Filament Current Meter A1M1 (see figure 11-7 sheet 3), at terminal two.  There are two normally high signals originating from terminal two, FILSILOW at signal bubble 316-2 and FILIHI- at signal bubble 312-10. The source of the Low limit are also found on the Filament Current  Meter A1M1 at terminal one.  There are two normally high signals originating from terminal one, FILI2 at signal bubble 320-5 and FILILO- at bubble 313-10.
 
 

SIGNAL DESTINATION 

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 FILSILOW is used to control the Filament Power Supply Control (see figure 11-7 sheet 2).  The Filament Power Supply Control provide +28 VDC (FILRLYDRV) to PS1 filament power supply (see figure 11-3 sheet 3) K1 a three phase relay.  FILIHI- and FILIL0- changes their names to KYLFILCURH- and KLYFILCURL- respectively once on the transmitter RMS interface board A3A3 (see figure 11-7 sheet 10).  In a fault condition KLYFILCURH- and KLYFILCURL- is placed on the Fault Bus at PORT05EN- as Transmitter DATA (TDATA), it also exit at bubble 1004-11 remove Transmitter Available at 1004(see 11-7 sheet 11).  KLYFILCUR-- is renamed to KLYFILI- at bubble 1016-1 and then  KLYFILCUR- at signal bubble 1016 (see 11-7 sheet 1) and is used to turn ON the Klystron Filament Current lights on the A1A1 Fault Display Panel.  FILI2 which is renamed to FILAMENTCUR on the  Proportional Preheat board A1A3 (see 11-7 sheet 5),  goes low the Preheat board goes into proportional preheat or full preheat depending upon the duration of the fault.
 

LIMITS AND FAULTS 

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Upper and lower limits are determine by the klystron filament current NAMEPLATE VALUE +/- 2 amperes.  The upper and lower limits maybe displayed on the Filament Current Meter, by press and holding down Switch S11.  These limits are adjusted while holding S11 and adjusting the LO or HI pots located on the back of the meter.
 
 

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