I am guessing only.
It looks like additional filtering (by-pass) to supply by voltage divider( R17-R14) to tubes 6k7-6k8
AVC? That voltage could range from 78v to 180vdc.
After reviewing several like RCA Schematics.
However I don't claim to know.
A clearer Schematic is in Bietmans Vol. # 1 (1926-1938 page 178). But all voltages are also missing.
Look up the nominal operating voltages in a tube manual for 6k7 and 6k8, that should get you in the ball park.
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