Oh, yes... that sounds like the the hum that is typical when direct conversion receivers
are run off of an AC supply. If so, it really doesn't have anything to do with the ripple
on the power supply - instead it is due to local oscillator radiation from the receiver.
This signal is picked up by the power supply wiring, modulated in the power supply
rectifier diodes, and re-radiated, where it is picked up by the antenna and fed into
the receiver. Since it is zero beat with the VFO, only the demodulated sidebands are
heard. They may be rather raspy due to harmonics of the AC line frequency generated
in the process.
KK7B has a description of this problem in Experimental Methods in RF Design
There is a further discussion in section 4 of this web page: http://www.qrp.pops.net/hf-ragbag.asp
Basically the solution is to shield your VFO so the signal can't be picked up in other
parts of the circuit, and especially by equipment outside the receiver itself. This
also reduces microphonics.
But here is a test: if the hum is getting into the audio stages through the DC line,
then you should still hear it if you disable the oscillator. Try it and see. If the hum
goes away, then the problem isn't the audio stages, because they shouldn't be
affected. Similarly, if the receiver is picking up a modulated VFO signal via the
antenna, then disconnecting the antenna should reduce the hum. (But if the
receiver isn't shielded, it might be picking it up directly into the circuitry.) Try
shorting out or disconnecting the antenna input to see if that affects the hum.
Note that this problem is unique to direct conversion receivers: superhet
receivers don't radiate on the signal frequency, so the same power supply used
with a different receiver might not show any hum at all.