[AMPS] Conjugate Matching and Efficiency

[Ian White, G3SEK]

Jon Ogden wrote:
>on 5/27/01 7:25 AM, Ian White, G3SEK at G3SEK@ifwtech.com wrote:
>
>> That doesn't matter - you MUST still get the
>> same results as the other two viewpoints. If you don't, then at least
>> one of your analyses has to be incorrect.
>> 
>> Even a half-baked analysis can be made to look good on its own home
>> territory. That's the easy part. But one of the key scientific tests for
>> any idea is to make it work in hostile territory - in this case, the
>> viewpoints that you normally *don't* like to use.
>> 
>> Nobody has yet done this in a totally convincing way for the transmitter
>> conjugate matching problem - because if they had, the debate would be
>> finished.
>
>
>Ahh, but Ian, it has been shown that calculation of efficiency using a
>Thevenin source and calculation of efficiency using a Norton source does not
>give the same answer.
>

I should have said that all alternative viewpoints that are correctly
applied - *if* they can be correctly applied at all - must give
consistent results. 

>Therefore, since Norton and Thevenin sources are equivalent, the concept of
>calculating system efficiency based on them is flawed.
>
Exactly! Basic circuit theory says that Norton and Thevenin sources are
equivalent - that is, in any case where they *can* be applied correctly.
We can take that as a hard fact. The other hard fact is that they give
nonsense results when trying to calculate PA efficiency (with the unique
exception of 50%). Logically, Captain, that is all you need to prove
that those two theorems can *not* be applied to this problem.

>The reason WHY this is the case is something I've not been able to fully
>grasp nor have I seen good reason from anyone else.  The best I can come up
>with is that once you start to calculate efficiency you are starting to go
>inside the model of the source and using it for things it was not intended.
>You can't use the model to model itself.  It's weak, but so far I lack
>better answers.

That's not my idea of a "weak" conclusion - it's built on solid bedrock
of circuit theory and logic. 

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           http://www.ifwtech.com/g3sek

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