On Fri, 07 Mar 2008 15:15:08 GMT
Cecil Moore wrote:

Roger Sparks wrote:
So, rather than disproving Cecil's premise, you successfully
demonstrated that it was correct in the instantaneous case.

Roger, my premise has nothing to do with the instantaneous
case. I have made no assertions about instantaneous values.
My formula applies *only to average power*. Using that
formula on instantaneous values is an invalid thing to do,
a misuse of the tool.
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73, Cecil http://www.w5dxp.com

I find myself surprised at your insistance that the instantaneous case must be seperated from the average case in our example of waves on a transmission line. Our ability to measure within the confines of the sine wave is much greater than what is possible at optic frequencies so we are led to expect much more than averages.

It is informative to look at each problem from many angles. Keith's method is one way. Another way is to observe that when we begin considering what is happening with the source resistor, we are really bringing the source resistor into the circuit, i.e., bringing the source resistor outside of the 'black box'. Once we do that, we can see that the source prereflection load is not the same as the post reflection load. From this perspective, the equation "PRs = 50w + Pref" becomes a target to which we adjust the source voltage to acheive. We would accomplish that by using your equation but Keith's method.

It seems to me like Keith is using interference, both constructive and destructive, to calculate what the source load would be on the instantaneous basis. To me it seems like a validation of your premise.

Did I misunderstand your premise, and you were really trying to say that the inclusion of a 50 ohm source resistor would prevent the source from ever 'seeing' anything but a 100 ohm load? I don't think that was your intent.
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73, Roger, W7WKB