Frank wrote:
"Richard Harrison" wrote in message
...
Ian White, G3SEK wrote:
"The only technical issue is the "assumption" that the conjugate of the
load impedance is equal to the output impedance of the device."

It`s true if maximum power is being transferred.

King, Mimno, and Wing sat so on page 43 of "Transmission Lines,
Antennas, and Wave Guides":

"If a dissipationless network is inserted betweeen a constant-voltage
generator of internal impedance Zg, and a load of impedance ZR such that
maximum power is delivered to the load, at every pair of terminals the
impedances looking in opposite directions are conjugates of each other."

The authors, Arnie, Larry, and Alex were all teaching at Harvard in 1945
when their book was published.

Walter Maxwell, W2DU has been saying the same thing yet has mistaken
nay-sayerrs.

Best regards, Richard Harrison, KB5WZI

Maximum power transfer with conjugate matching is undisputed. The problem
with semi-conductor devices is that you cannot necessarily conjugate match
because the device operating parameters may be exceeded.

Exactly.

Richard's assertion relies on at least three things being true:

1. That maximum power is being transferred - for most states of
transmitter tuning, loading and drive levels, that is obviously *not*
true.

2. That the transmitter can be accurately represented as a
"constant-voltage generator of internal impedance Zg", i.e. as a
Thevenin source.

3. That as part of #2, Zg is a constant.

With all due respect to Richard - and above all, respect to Walt - it is
a tall order to prove that all three of those requirements for conjugate
matching are being met. I believe they can only be exactly met under a
few very special sets of operating conditions.

But it then follows that, for all *other* operating conditions, the
complete end-to-end conjugate matching referred to by King et al does
*not* exist.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek