[Jhunt]

My radio (Philco 70) does not have this capacitor, it was not used on all models. What does it do? Should I add it? I wonder if it was originally used on all chassis, and then removed or not used and then added. Thanks.

[morzh]

This capacitor supposedly phase-shifts the ripple 90 deg through it that when met with the ripple remaining after the choke, which is phase shifted the opposite way also 90 deg, they, being 180 degrees nullify each other.

The experience showed this is not super effective, so the cap could be taken out and the 38 cap could be increase without ill effects and with better filtering result.

[Jhunt]

Thank you for the information.

[Arran]

It would seem that a lot of early AC sets had these caps across the filter choke, or one of the filter chokes, maybe with the smaller value paper filter caps they made more of a difference then they did when the 1931 sets rolled around with larger value electrolytics?
Regards
Arran