On Sun, 6 Jun 2010 14:21:16 -0700 (PDT), Keith Dysart
wrote:

The 100W forward and 50W reflected have no relation to actual powers

From HP Journal V.6n.1-2:

Power from the source flows down
the main arms of the two couplers
(Fig. 2) and impinges on the load.
The power split off by the 20 db
forward coupler is all passed to the
forward detector, since the directiv
ity characteristic of the multi-hole
directional couplers prevents any
but a negligible amount of the splitoff
power from turning back and
being absorbed in the coupler's in
ternal termination. The power split
off the incident wave by the 10 db
reverse coupler, however, is essen
tially all absorbed in that coupler's
internal termination because of the
reversed direction of connection of
that coupler (Fig. 2).
If the magnitude of the reflection
coefficient ~.T. of the load is, say, 0.1,
Çf of the incident voltage will be
reflected back toward the source. As
this reflection passes back through
the main arm of the reverse coupler,
a 10 db split occurs and is applied
to the reverse detector. The remain
der of the reflection will proceed
back toward the generator where it
will be absorbed in the generator
impedance and in the termination
in the forward coupler.

********

Of course, in regard to this last sentence, HP engineers didn't know
jack-**** about power reflections, especially what could be absorbed
by the source.

73's
Richard Clark, KB7QHC