On May 24, 7:49*pm, Cecil Moore wrote:
On May 24, 6:15*pm, Keith Dysart wrote:

This may be the root of my disagreement. Certainly the output can be
an arbitrarily perfect sine wave, but this simply depends on the
characteristics of the filter and not on whether the system is linear.

Since anything except a class-A amplifier is non-linear and since we
are talking about linear analysis, it seems we need to locate a point
in the system where V is a sine wave, I is a sine wave, and V/I is the
constant impedance at that point. IMO, that is the first point at
which we can use a linear math analysis and maybe that point is what
Walt is talking about. It's certainly not going to be the plate of a
class-C amplifier and it may not even be the load-line of the class-C
amplifier. There is probably some point in an otherwise non-linear
system where a linear analysis becomes possible. I think that point is
what Walt considers to be the linear source point, wherever that point
might be located.

Recalling that if a conjugate match is achieved at one ponit in a
system
it is achieved at all points....

It does not seem possible for a system to be non-linear at one end and
turn in to a linear system at some other point.

In fact, here is my personal take on the subject. Given an antenna
system that presents 50+j0 ohms looking into 50 ohm coax, the internal
impedance of the source doesn't matter. For any voltage source,
irrespective of the source impedance, if reflected energy doesn't
reach the source, the source impedance doesn't matter (except for
efficiency). Seems to me, the highest efficiency would be achieved by
a source with zero ohms of source impedance.

True, if the source impedance originates in dissipative components and
it is a voltage source. For a current source, infinite impedance
offers
the best efficiency.

....Keith

On May 25, 5:29*am, Keith Dysart wrote:
It does not seem possible for a system to be non-linear at one end and
turn in to a linear system at some other point.

Well, consider the following two systems. Z01 is 50 ohms and Z02 is
300 ohms. The two systems are identical except for the circuits hidden
inside the two identical source black boxes. Both sources are
supplying a 100v sine wave to the system.

Source1----Z01----+----1/4WL Z02----1800 ohm

Source2----Z01----+----1/4WL Z02----1800 ohm

Every passive voltage, current, power, and impedance measurement is
identical in both systems. As far as we can passively measure, both
systems are identical and linear. The only thing we don't know is what
is inside the two source boxes..

Inside the Source1 box is a linear ideal 50 ohm Thevenin equivalent
source delivering an ideal 100v sine wave. Inside the Source2 box is a
non-linear class-C amplifier filtered to provide an ideal 100v sine
wave.

Without changing the system conditions, can one make a passive
measurement to determine which system is conjugately matched and which
one is not conjugately matched? If one cannot tell the difference, are
they both conjugately matched, or both not conjugately matched, or
what?

Here's my take. A 50 ohm Z0-match exists in both systems and all
conditions are identical on the load side of that Z0-match. In
particular, at any point in the system on the load side of the Z0-
match, the impedance looking in one direction is the conjugate of the
impedance looking in the other direction. That is a characteristic of
a conjugate match. So are both systems conjugately matched between the
Z0-match and the load? If it walks and quacks like a duck ...
--
73, Cecil, w5dxp.com

On May 25, 8:45*am, Cecil Moore wrote:
On May 25, 5:29*am, Keith Dysart wrote:

It does not seem possible for a system to be non-linear at one end and
turn in to a linear system at some other point.

Well, consider the following two systems. Z01 is 50 ohms and Z02 is
300 ohms. The two systems are identical except for the circuits hidden
inside the two identical source black boxes. Both sources are
supplying a 100v sine wave to the system.

Source1----Z01----+----1/4WL Z02----1800 ohm

Source2----Z01----+----1/4WL Z02----1800 ohm

Every passive voltage, current, power, and impedance measurement is
identical in both systems. As far as we can passively measure, both
systems are identical and linear. The only thing we don't know is what
is inside the two source boxes..

Inside the Source1 box is a linear ideal 50 ohm Thevenin equivalent
source delivering an ideal 100v sine wave. Inside the Source2 box is a
non-linear class-C amplifier filtered to provide an ideal 100v sine
wave.

Without changing the system conditions, can one make a passive
measurement to determine which system is conjugately matched and which
one is not conjugately matched? If one cannot tell the difference, are
they both conjugately matched, or both not conjugately matched, or
what?

Here's my take. A 50 ohm Z0-match exists in both systems and all
conditions are identical on the load side of that Z0-match. In
particular, at any point in the system on the load side of the Z0-
match, the impedance looking in one direction is the conjugate of the
impedance looking in the other direction. That is a characteristic of
a conjugate match. So are both systems conjugately matched between the
Z0-match and the load? If it walks and quacks like a duck ...

Methinks you have so constrained the experiment as to make it
unsolvable.
But let us test that.

Consider a Source3, much like Source1: linear, ideal, but 100 ohms
output impedance. It is connected to the same load you specify for
Source1 and Source2 and adjusted to drive 100 volts in to the 50
ohm Z01 line.

You are presented with the circuits using Source1 and Source3.

We know that Source1 and Source3 can not both be conjugately
matched.

"Without changing the system conditions, can one make a passive
measurement to determine which system is conjugately matched and which
one is not conjugately matched? If one cannot tell the difference, are
they both conjugately matched, or both not conjugately matched, or
what?"

....Keith

On May 25, 8:45*pm, Keith Dysart wrote:
We know that Source1 and Source3 can not both be conjugately
matched.

But what difference does it make if all external conditions are
identical? If reflected energy is not allowed to reach the source, why
does the source impedance matter at all?
--
73, Cecil, w5dxp.com

On May 26, 9:17*am, Cecil Moore wrote:
If reflected energy is not allowed to reach the source, why
does the source impedance matter at all?

Continuing this thought thread - Assuming 50 ohm coax from the source
containing a forward traveling wave and no reflected wave, i.e. an SWR
of 1:1 on 50 ohm coax, what it to prohibit us from drawing our system
box through that piece of coax and considering the signal emerging
from that piece of coax to be the linear source signal which is
obviously associated with a V/I = 50 ohm impedance?
--
73, Cecil, w5dxp.com

On May 26, 1:19*pm, Cecil Moore wrote:
On May 26, 9:17*am, Cecil Moore wrote:

*If reflected energy is not allowed to reach the source, why
does the source impedance matter at all?

Continuing this thought thread - Assuming 50 ohm coax from the source
containing a forward traveling wave and no reflected wave, i.e. an SWR
of 1:1 on 50 ohm coax, what it to prohibit us from drawing our system
box through that piece of coax and considering the signal emerging
from that piece of coax to be the linear source signal which is
obviously associated with a V/I = 50 ohm impedance?
--
73, Cecil, w5dxp.com

If you are uninterested in source impedance (and many people seem
to be much more concerned with it than they need to be), then
by all means do not consider it, do not specify it, do not attempt
to compute it or measure it and do not make statements about what
the source impedance is.

But if source impedance is of concern for a particular application,
then please do compute and measure it properly.

....Keith

On May 27, 4:23*am, Keith Dysart wrote:
If you are uninterested in source impedance (and many people seem
to be much more concerned with it than they need to be), then
by all means do not consider it, do not specify it, do not attempt
to compute it or measure it and do not make statements about what
the source impedance is.

The question then becomes: If the system box does not include the
source and the system exhibits characteristics consistent with a
conjugate match, can we say the system is conjugately matched? For
instance:

100V---50 ohm coax---+---1/4WL 300 ohm feedline---1800 ohm load

This system exhibits all the characteristics of a conjugately matched
system. Can we say it is conjugately matched?
--
73, Cecil, w5dxp.com