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[AMPS] Conjugate Matching In Class B and C Amplifiers

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Subject: [AMPS] Conjugate Matching In Class B and C Amplifiers
From: philk5pc@tyler.net (Phil Clements)
Date: Tue, 15 May 2001 19:23:48 -0500

> > >> W/o having read them, I'll confess that I am at a loss to know the back
> > >> ground.  What is the debate?

Mr. Maxwell's position is that you have a conjugate match, maximum power
transfer, AND with efficiencys greater than 50%.

> > >>
> > > As I understand it, Mr. Maxwell asserts that linear amplifiers are
> > > conjugately matched.  If this is true,  the efficiency  could not exceed
> > > 50%.

Axiom #1:
There is a conjugate match whenever all of the availale power from a
source or network is being delivered to the load.

Axiom #2:
There is a conjugate match if the delivery of power decreases whenever
the impedance of either the source or load is changed in either direction.

> >
> >OK.  You are correct Rich.  If conjugate match occurs, then an equal amount
> >of power is absorbed by both source and load - hence the 50% efficiency.

Maxwell says  because Rpd is generally less than RL, more power is delivered
to the load resistance than that dissipated in the dissipative plate resistance,
thus allowing efficiencies greater than 50%. The lower dissipative plate
resistance occurs because plate current is allowed to flow only when the plate
voltage is at the minimum of its sinusoidal swing.(Terman)

(((73)))
Phil, K5PC




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