On Mon, 6 Sep 2004 23:15:24 -0500, (Richard
Harrison) wrote:

The newly minted RF and the twice reflected RF are similar, both having
their volts and amps in-phase.

Hi Richard,

In a reality of 359 other possible phase angles, how does a
transmitter happen to always be "in-phase" to any reflection?

73's
Richard Clark, KB7QHC

Bob Nielsen wrote:
On Mon, 06 Sep 2004 22:26:16 GMT, Walter Maxwell wrote:

However, what happened to the Rolls-Royce? Did the Queen boot it out? As I
recall it from my pre-teen days, it was definitely a Brit. And how
did it manage
to land in Deutchland? Or did Neville Chamberlin manipulate this one too?


Still made in Britain, but owned by BMW, who also make the recent
incarnation of Minis.

The original MGs were built right here in Abingdon-on-Thames, and the
big factory where the Minis are made is just up the road in Oxford. Lots
of local people either are or have worked in the car industry... and
some of them are also hams.

Even when R-R Motors was an independent company, it used part of the big
Oxford factory. That much larger company eventually bought R-R, but in
turn has done deals in which first Honda and then BMW provided
transfusions of new technology in return for a large share of the
company itself. However, the company still makes its own cars under the
name Austin Rover.

R-R Motors has always been a separate operation, with very different
ways of doing things. For example, all the stories you've heard about
countless coats of paint, each one hand-applied and hand-rubbed, are
true. The comforting thing is that down at the other end of the factory,
cars for the rest of us are being stamped out with modern high-tech,
high-bake paint jobs that will wear far better.


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

Richard Harrison wrote:

Who makes the Rolls-Royce jet engines now?

Rolls-Royce do. The aero engine operation separated from the original
car building operation in the 1970s.

When the two companies split, they were smart enough to let both keep
the hugely valuable brand name - unlike Hewlett-Packard.


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

"Ian White, G3SEK" wrote in message
...
Richard Harrison wrote:

Who makes the Rolls-Royce jet engines now?

Rolls-Royce do. The aero engine operation separated from the original car
building operation in the 1970s.

When the two companies split, they were smart enough to let both keep the
hugely valuable brand name - unlike Hewlett-Packard.


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

Ummm, what part of hijack & pillage are you uncomfortable about?

Ed
wb6wsn

Ed Price wrote:

Who makes the Rolls-Royce jet engines now?

Rolls-Royce do. The aero engine operation separated from the original
car building operation in the 1970s.

When the two companies split, they were smart enough to let both keep
the hugely valuable brand name - unlike Hewlett-Packard.


Ummm, what part of hijack & pillage are you uncomfortable about?


No problem with the old "High-Priced" brand name at all - it's the other
one...


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

Richard Harrison wrote:
The newly minted RF and the twice reflected RF are similar, both having
their volts and amps in-phase. So, the similar RF constituents merge to
have a go at the reflection point.

Wonder why we have protection circuitry in transmitters?
The superposed forward voltage and reflected voltage can damage an
unprotected transmitter. The superposed forward current and reflected
current can cause over heating in an unprotected transmitter.

The transmitter sees whatever impedance it sees and that impedance
can be highly reactive. The superposed voltage can be high or low.
The superposed current can be high or low. The phase between the
superposed voltage and superposed current can have lots of values.

Just a for instance - assume the transmitter is putting out 70.7v
in phase with 1.4a at zero deg. The arriving reflected wave is 50v
at 90 deg and 1.0a at -90 deg. The load seen by the transmitter is
86.6v at 35 deg and 1.72a at -35 deg. Over voltage and over current
exist at the transmitter output. The forward power is 100w and the
reflected power is 50w. The net power being delivered to the reactive
"load" seen by the transmitter is 86.6*1.72*cos(70.4) = 50w.

The math model is trying to dictate reality. It is supposed to be
exactly the opposite. There is no magic barrier that automatically
rejects reflected energy from a transmitter. Reflected energy
arriving at the transmitter can drastically alter the impedance
away from the designed-for load impedance. The transmitter sees
one of the transformed impedances that exists on the SWR circle.

Note that the problem disappears in a matched system where reflected
energy is not allowed to reach the transmitter.
--
73, Cecil http://www.qsl.net/w5dxp


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Richard Clark wrote:
"In a reality of 359 other possible phase angles, how does a transmitter
happen to always be in-phase to any reflection?"

Connect any generator to any resistor, and current in the resistor is
in-phase with the applied voltage. The Zo of the common transmission
line is a reasonably good resistance. At radio frequencies, Zo is
independent of frequency.

The current in the incident wave is always in-phase with the voltage
applied to a transmission line. The current in the reflected wave is
always 180-degrees out-of-phase with the reflected voltage. It makes no
difference which was inverted by reflection, the volts or tha amps, one,
and only one, of them was flipped upside down. The transmission line can
and does handle the reflected wave.

Standing waves display interference between incident and reflected waves
whiich ideally have in-phase and out-of-phase constituents.

The fact that the Bird wattmeter works is evidence that the theory is
correct at least until a better theory replaces existing theory.

Best regards, Richard Harrison, KB5WZI

On Tue, 7 Sep 2004 09:40:36 -0500, (Richard
Harrison) wrote:

Richard Clark wrote:
"In a reality of 359 other possible phase angles, how does a transmitter
happen to always be in-phase to any reflection?"

Connect any generator to any resistor, and current in the resistor is
in-phase with the applied voltage.

Hi Richard,

In a world of mismatches, how does it happen that the transmitter
always sees an in-phase, resistive load? If this were the best of all
worlds, tuner manufacturers would be out of business, salesmen would
starve and Reggie would have nothing to write about.

73's
Richard Clark, KB7QHC

Cecil, W5DXP wrote:
"The superposed forward voltage and reflected voltage can damage an
unprotected transmitter."

To do so, they would be in-phase and not out-of-phase. Entirely possible
if the transmission line is the right length.

If the reflected volts are in the same phase as the newly munted volts,
which are larger? With a reflection coefficient of 1, and a lossless
line, the open-circuit value of transmitter volts would face some lower
value of line volts on opposite ends of the internal impedance of the
transmitter. Which way does the current flow?

Theory is that it flows from the higher to the lower. That is, from the
transmitter to the line.

Best regards, Richard Harrison, KB5WZI

Richard Clark wrote:
In a world of mismatches, how does it happen that the transmitter always
sees an in-phase, resistive load?"

It doesn`t. You can put a capacitor directly across its output
terminals, and the transmitter will energize the capacitor. But, a
transmission line is not a capacitor unless it is a short open circuit,
or the equivalent. A transmission line is a distributed network of
inductance and capacitance. This network transfers emergy in bucket
brigade fashion. The "brigade" presents a resistive impedance to both
the incident wave and to the reflected wave. Zo is an enforcer.

Best regards, Richard Harrison, KB5WZI