4.3 FPS Theory of Operation Section 4: Theory of Operation
CV-6SLX User Manual 0101-8242-0, Rev. C
4.3.4 Filament Output Section
The filament output section of the FPS connects the filament power with the negative HV. The
filament power and the HV are connected to the filament by a two-conductor cable. The high
voltage (0–10 kV) from the HV Power Supply enters the FPS via J301. On standard FPS units
(PN 0620-6604-0), the high voltage is routed to the vacuum relay (K101). On such units, K101
either connects the negative HV to the secondary of the filament transformer or applies a
ground to the secondary of the filament transformer. The relay is driven from the Filament
Supply PCB via J103 pins 5 and 6.
FPS units with PN 0620-6604-0 omit the vacuum relay. On those units, the high voltage is
connected to the secondary of the filament transformer T1, which has a 10:1 ratio. The filament
transformer connects the high-voltage, low-current output of the FPS to the filament with low-
voltage, high-current filament current, superimposing the negative DC HV on the AC filament
current.