On Apr 9, 4:59 pm, Owen Duffy wrote:
Cecil Moore wrote . net:

Jim Kelley wrote:
And so that's your explanation for how 2 Joules per second can be
obtained from a source which is in fact producing only 1 Joule per
second.

Of course, I regularly obtain 200 watts of forward
power from my 100 watt IC-706. It's all due to
constructive interference.

If in fact the power delivered by the "100 watt IC706" radio was indeed
100W, and some directional wattmeter correctly indicated 200W forward, it
must indicate 200W-100W reflected which is indicative of a VSWR of 5.8,
which should have reduced power output from the IC706 markedly.

Taking another view, if the IC706 will tolerate VSWR of 2 before reducing
power (ie and still deliver exactly 100W), then the forward power would
be just 113W.

More likely, the IC706 levels its power output on the forward detector,
and runs 100W "forward" until the reflected power reaches about 12W
whereupon it reduces drive so maintain maximum reflected power =12W.

Did you make this example up on the fly, or is it the result of actual
observation on one or many occasions?

Owen

Let's see... 600 ohm line feeding a nominally 60 ohm dipole. (It's
not very high above the ground.) 600 ohm line is 1/2 wave long, and
essentially lossless. I feed 60 watts in, the 60 ohm dipole absorbs
60 watts. I suppose the forward power on the line is a bit more than
60 watts. My transmitter doesn't seem to have too much trouble with
the 60 ohm load, though a balun between the unbalanced transmitter
output and the balanced line is nice.

Cheers,
Tom