R: [AMPS] Conjugate matching and amplifiers

[Jon Ogden]

Maurizio Panicara wrote:

>Although selective mismatching in RF amplifiers is not an heresy, but a
>practical, logical and controlled way of decreasing (fixing) stage gain,
>efficiency is something unavoidable at high power level in order not to
>waste energy and not to stress components without any reason.

Good points, Maurizio! 

Another case in a low signal level environment where you want to mismatch 
and amplifier is in a low noise amplifier configuration.  Minimum noise 
figure and a conjugate match don't go together.  Minimum noise figure is 
generally achieved at some mis-matched impedance.  However, in a receive 
path, we are concerned with noise performance and NOT with power transfer.

The problem is that most hams (US at least) have the idea in their mind 
that the amplifier must produce 1500 Watts output with 100 Watts of 
drive.  So they design around that.  This is a shortsighted and silly 
idea.  It certainly doesn't result in optimal efficiency and optimal 
performance.

73,

Jon
KE9NA
 

--------------------------------------------------------------------------
The Second Amendment is NOT about duck hunting!


Jon Ogden

jono@enteract.com
www.qsl.net/ke9na

"A life lived in fear is a life half lived."


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