On Wed, 24 Dec 2003 06:11:10 GMT, Robert Casey
wrote:

Our rigs actually
present a very
low impedance to the antenna and transmission line. This is by design;
we want all
of the RF we manufactured to go to the antenna and none wasted as heat
in the
rig. Our rigs don't really look like the Thevinian equivalent (voltage
source with
internal resistor of 50 ohms) feeding a 50 ohm load.

Hi Robert,

Actually none of this is true. It is the glib explanation that is
bandied about commonly in this forum, but it contains its own internal
inconsistency of logic.

This illogic is present in the single statement:
Reflected power will
"bounce" off the rig and go back to the antenna.
The presumption is that the point of bouncing back, the transistion
point of the so-called low Z transmitter to the high Z line, performs
this action. It contains to howlers:
1. if it were true, no one would ever need a tuner whose sole purpose
is to do exactly that (the bouncing back);
2. if it were true, the original power coming from the transmitter
would see the same reflection and bounce right back in to turn to heat
(which is a fairly true representation of the problem of SWR).

As for the reality of the situation, answer me this:
1. How much power does your rig transmit?
2. How much power does your rig draw?
Correct me if the operation of dividing the first by the second does
not reveal an efficiency of roughly 40% and a power loss to heat of
roughly greater than that transmitted. Your rig has a massive heat
sink with a fan, n'est pas?

Too many of the pundits want to force a literal carbon composition
resistor into the mix so that they can point to its absence proving
Thevenin's Theorem does not apply. The same pundits ignore the fact
that Thevenin did not specify a resistor, he specified an impedance to
satisfy his theorem. It was Edison's pervsion of logic in trying to
persuade the investors that AC distribution was for the birds when it
came time to match loads. He inserted the false claim of resistance
forcing inefficiency. This perversion has been with us ever since and
qualifies such believers only as possible investors in the Edison DC
Power distribution company (which folded immediately due to
inefficiency in the market place).

73's
Richard Clark, KB7QHC