Owen Duffy wrote:
These are not necessarily the same value. In fact, the dynamic source
resistance is usually much higher than the required load resistance, and
the ratio is usually higher for a pentode or tetrode than for a triode
operating at the same voltage and current.

So, immediately, there is an apparent conflict with the proposition that
the dynamic source resistance and the load resistance are the same.

Does that take into account the step-down transformation?
The "source load" that results in the "source load line",
is not the physical load in the system. It is the physical
load in the system transformed by the transmission
line, the filters, the tank circuits, and the transformers.
In short, it is the transformed load seen directly
*by the source - at the source*.

For instance, a source may have a dynamic source
resistance of 1000 ohms. A 20:1 tank circuit
transformation takes it to 50 ohms. The load line
for that amp has a slope of 1000, not 50.
--
73, Cecil http://www.w5dxp.com