On Sun, 30 Dec 2007 12:40:31 -0800, Roger wrote:

If the impedance of the perfect source is zero, what limits the power
output from the source?

Hi Roger,

What does it matter?

If the limit is supplied by the load, then the
perfect source has evolved into a real source as soon as the circuit has
been defined.

That is a stretch of the imagination as real sources don't have any of
the characteristics of a fictitious "perfect" source.

73's
Richard Clark, KB7QHC