[Richard Crowley]

"Frank Stearns" wrote ...
"Richard Crowley" writes:
wrote ...
Does using a single diode as a half power step introduces RF noise
as
well?

No, because it doesn't cause any significant "slicing" of the
mains sinewave form (like a SCR dimmer does).

But it might cause visible flicker as the filament(s) are getting
only every-other pulse of current.

IIRC (and correct me if I'm wrong), *some* power diodes will have a
nasty
transient at conduct/non-conduct. This might or might not be a problem
in
the RF range, but a snubber cap parallel with the diode should take
care
of the problem.

Around 0.6v (for silicon)
That is what I call "insignificant"
YMMV.