> At 11:25 AM 3/28/2002 -0500, you wrote:
> > > No. Watt meters that hams and most engineers use at RF measure
either
> > > voltage or Current. They do not measure *power*. Given the
voltage or
> > > current, analog meters use a graphical conversion (called a
meter scale) to
> > > equivalent power given under the assumption of a matched
> > > termination. Digital meters also perform a conversion in
firmware. None
> > > of these devices measure *power*.
> >
> >My example is relevant without the need of the Bird wattmeter. I
fully
> >accept the fact that the directional coupler samples RF
> >voltage. I'll respond to you as I did with Steve. Namely, in the
absence
> >of a load on a loss-less line, any and all reflected
> >power is being absorbed by the fixed-impedance source (i.e.,
broadband PA).
> >
> >If reflected power is not absorbed by the source, where is
absorbed?
> >
> >-Paul, W9AC
>
>
> I believe that the logical flaw in the argument lies in discussing
> reflected *power*. *Power* cannot reflected; only voltage and
current are
> reflected. We speak of reflected power merely as a convenience
because the
> meter we're looking at unfortunately has "power" written on it. In
truth,
> it should say "voltage," so that we could more easily talk about
what's
> really happening. Voltage and current presented to a resistive
load,
> together and in phase, result in "power." We speak of "power" being
> transferred down a transmission line, but this power is merely a
construct:
> the only things that we can measure on the transmission line are
voltage
> and current.
>
> Kim Elmore, N5OP
>
Hi Kim.
I don't agree.
Power is reflected.
The line holds power.
If you see my last post about a step voltage applied to an endless
line , you will agree that power enters the line and is reflected back
if the line is cut and terminated in an open or a short.
---
Ron
>
>
> >_______________________________________________
> >Amps mailing list
> >Amps@contesting.com
> >http://lists.contesting.com/mailman/listinfo/amps
>
> Kim Elmore, Ph.D.
> "All of weather is divided into three parts: Yes, No, and Maybe. The
> greatest of these is Maybe" The original Latin appears to be
garbled.
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
|