Jeff Liebermann wrote:
Bird is very specific that their 50 ohm wattmeters are only useful in
a 50 ohm system.

What you seem to be missing is that it takes only a few
inches of 50 ohm coax on each side of the directional
wattmeter to force a "50 ohm system". 50 ohm coax *IS*
a 50 ohm system, i.e. the load doesn't matter.

All this is easily proven by wading through the math.
--
73, Cecil http://www.w5dxp.com
"According to the general theory of relativity,
space without ether is unthinkable." Albert Einstein