[Amps] no rf choke in 30S-1 filament/cathode circuit

[rfdude@comcast.net]

While overhauling the my 30S-1, I noticed the amp has no rf choke in the filament/cathode circuit. The cathode/filament is connected directly to the filament wires.
I find this unsuall since the filament transformer adds about 80-100pf more capacitance to the input circuit. Although Collins designed the matching circuits with about 220pf input, why not isolate the filament transformer? Most other amps in similar configurations do.
I am not second guessing the engineers at Collins just trying to understand their reasons.
Anybody have any comments?
73s
kb3bf, chris