Jeff wrote:
To get the power delivered to the load, you must subtract
reflected power from forward power. In your case that seems
to be:
Pfwd - Pref = Pload = ~Psource
200w - 100w = 100w = ~100w

How can that be? If the meter is basically a directional coupler then the
forward power is just that. Subtracting any reflected power will just give a
stupid answer.

Subtracting any reflected power will give the power
being delivered to the load. Power reflected from
the load is power that is NOT delivered to the load.

The only errors will be due to the directivity of the
coupler, which will give a band of uncertainty which varies with VSWR, and
the error due to the accuracy of the detectors.

Consider the following example assuming a lossless
tuner and transmission line.

100W source+tuner--x--50 ohm coax-----291.42 ohm load

Assuming the tuner is properly tuned, what forward power
will a Bird read on the 50 ohm coax at point 'x'? What
reflected power? What is the net power being delivered
to the load?

My Bird does not subtract any reflected power to give a forward power
reading!! It can't I need to rotate the slug to read reverse power.

You're right. The operator must measure the forward power
and the reflected power and do the subtraction manually.
In the above example, the Bird will read 200w forward and
100w reflected. The operator must subtract those two values
to determine the net power delivered to the load.

This was my guess as to why the Bird was reading 200w in
the original posting. Note that a Bird between the source
and the tuner does NOT read the SWR on the transmission
line between the tuner and the load.
--
73, Cecil http://www.w5dxp.com