Richard Clark wrote:

On Thu, 25 Dec 2003 05:47:12 GMT, Robert Casey
wrote:



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?



n'est pas? ? Anyway, the power lost inside the transmitter I thought
was due to the
inneficiencies of a class A or B amp configuration.



Hi Robert,

Given you offer no evidence to the contrary, 40% efficiency seems to
be the confirmed rule. Giving it a name does nothing to reduce it or
enhance it, the calories expended rob us of RF output for the power
draw to generate that output. That power loss is confirmed through
everyone's experience as heat. Heat sinks and fans testify to our
acceptance of its loss.



Let's ignore, for the moment, the losses involved in the conversion of
DC power to
RF power. Now lets say we have 100 watts of RF. If the antenna is a
perfect
load (50 ohms resistive) and if the Thevenin impedance of the transmitter is
50 ohms, then yes, you got 50 watts of extra heat in the transmitter.
Now if the
transmiter has a very low Thevenin impedance, then more power is delivered
to the antenna and less waste in the transmitter. I'm not trying to do
the "transfer
the max power to the load and I don't care how much waste in the source"
Thevenin
thing we had in EE101. If I did that, and the amp is up to it, I could
transmit
even more power to the antenna, but I'd waste more in the source.

In any event Merry Xmas.