On Wed, 06 Sep 2006 23:24:45 GMT, Jim - NN7K wrote:

Thanks, Owen, and all and sorry to cause so much
grief. I fall on my sword! Have believed 99.44%

No need for that Jim, the discussion has challenged your thinking (and
mine), and that is part of the learning process.

of what was in the old VHF'er Magazine, as was

IMHO, it is not a very good article.

Forward Voltage, Forward Current, Reflected Voltage, Reflected
Current, Current, Voltage, Zo, VSWR, impedance and propagation
constant are all relevant, related but different and the article
doesn't adequately draw the distinction.

Indicators might sample one or more of voltage, or current, or
directional power. They are all different, a voltage sensor or a
current sensor alone at a single point will not allow you to determine
VSWR, a pair of directional power sensors will. Your Lecher lines
example needs a voltage or current sensor, not a directional power
sensor (which won't work), whereas a VSWR meter needs a pair of
directional power sensors, not a voltage or current sensor (which
won't work).

My view is that the article is imprecise, confused and contains bad
advice. It does play to one of the archetypal myths of ham radio!

I am considering whether I should create some more graphs of current,
voltage, and impedance etc that illustrate how those behave, and
incorporate it in a more complete permanent article on my web site.
(IIRC there were some graphs of voltage, current, phase in Fred
Terman's book, but I am thinking of going a little beyond that.)

Thanks for the response Jim.

73
Owen
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