Dave wrote:
math please??? where do you get 4.17watts?? to me it looks like a 50 ohm
load on a 50 ohm meter so zero reflected power.

Let's compare the following two configurations.

100W--tuner--75 ohm coax--Bird--1/2WL 75 ohm coax--50 ohm load

100W--tuner--75 ohm coax--Bird--1/4WL 75 ohm coax--50 ohm load

The actual SWR on the coax is the same in both cases. The actual
forward power and reflected power are the same in both cases.
The SWR on the coax is 75/50 = 1.5:1. The actual forward power
is 104.1667w and the actual reflected power is 4.1667w.

In the first case the Bird will report an SWR of 1:1, a forward
power of 100w, and a reflected power of zero simply because the
ratio of net voltage to net current is 50 ohms at the Bird
measurement point.

In the second case the Bird will report an SWR of 2.25:1, a
forward power of 117.4w and a reflected power of 17.4w simply
because the ratio of net voltage to net current is 112.5 ohms
at the Bird measurement point.

The ratio of net voltage to net current alone is useless for
calculating SWR unless the Z0 environment (characteristic impedance)
exists and is known. Minus the humor, I believe this is Reg's main point.
--
73, Cecil http://www.qsl.net/w5dxp