How do you know you have hum? Are you listening
on a local receiver? If so it could be a form of
"tuneable hum" caused by the AC in the house wiring
modulating the received signal. If you have a good
scope, try looking at the waveform directly; any
hum will show as modulation riding on carrier.

The amounts of ripple you're seeing are very minimal,
as others noted...

Pete