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May 28th 04, 05:48 AM

On 27 May 2004 21:16:44 -0700, (alhearn) wrote:

If you read Chapter 13, "RF Power Amplifiers and Projects", in the
2004 ARRL Handbook, there are pages and pages of discussion of
matching plate or transistor output impedances to 50 ohms output

Hi Al,

Watch it, this is a heresy. ARRL is certainly not the end-all be-all
of design advice, but given these points are confirmed by professional
design guidelines and technical papers, one should be able to trust it
as a source written at a level suitable for amateur introduction.

and not once do they ever refer to output networks dissipating or
reflecting reflected power. Not once.

However, absence of discussion does not necessarily mean there is an
absence of concern.

It's always a matter of simply
matching one impedance to another to provide the highest power output
consistent with required linearity, while staying within the
amplifiying device's ratings.

Simple logic dictates as much.

Transmission lines have reflections; output matching networks and
tuners don't.

Simple logic does not allow this however. However, verifying this
property would be rather a challenge.

The reflections on transmission lines don't make it past
the end of the transmission line -- that's where the reflections take
place.

True, but only insofar as the tuner is adjusted to offer a conjugate.

Beyond the end of the transmission line, the reflections are
seen as mere impedances created by standing waves, which are created
by reflections, assuming mismatch.

Again, true after a fashion, but the distinction is only a matter of
point of view. Wave mechanics/lumped circuits give the same result.

73's
Richard Clark, KB7QHC

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