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Re: [Amps] SWR and amplifiers

To: <amps@xxxxxxxxxxxxxx>
Subject: Re: [Amps] SWR and amplifiers
From: "Paul Christensen" <w9ac@xxxxxxxx>
Date: Wed, 24 May 2017 23:22:44 -0400
List-post: <mailto:amps@contesting.com>
>"...Then the power output is zero, the SWR is infinite, and all the
amplifier power is dissipated in the amplifier itself. Similarly, if we
short circuit the amplifier output connector, so that the amplifier sees
zero impedance, the SWR is also infinite and the same result holds."

Adding to Jim's comment:  In the infinite SWR case, all developed power is
dissipated in the amplifier, typically by plate dissipation in VT amps --
but not as a result of reflected power being absorbed by the
amplifier/generator.  The amplifier must only produce power dissipated in
the load, the line, and its internal resistance, but no more.  

A common SWR/wattmeter on an open or shorted lossless line behaves as if
there are forward and reflected energy flows.  In this case, the flows not
real but are representative of an equal power that would be dissipated in a
50-ohm resistor if forward and reflected waves were present.   

Paul, W9AC

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