Hi Cecil
I have a HP8405A Vector Voltmeter I'll give you and even pay the shipping
if that is of any help with the measurements.
Jerry
"Cecil Moore" wrote in message
om...
Roy Lewallen wrote:
It applies to a "loosely wound helix."
Please define the point at which a "loosely wound helix" with
a varying current turns into this lumped-circuit device that
forces equal currents through the coil. Is a 75m bugcatcher
coil a "loosely wound helix" or a "lumped-circuit"?
(My 75m bugcatcher coil is about 1/6 wavelength of wire.)
Only if we have perfect coupling between turns (as a toroid very nearly
represents) will we truly have equal currents at input and output, for
the reasons Tom recently explained. This is the idealized inductance
which some of the contributers to this discussion are having trouble
understanding.
Unfortunately, an idealized inductance is like a lossless transmission
line - it exists only in the human mind. What I would like to know is
what is the real-world phase shift through your toroidal inductor when
there is only a traveling wave (no standing wave). We can then use
the laws of reflection physics to determine what effect that phase
shift has on the amplitude of the standing wave current which is the
phasor sum of the forward current and reflected current. I'm actually
going to make those measurements as soon as I get off my old lazy ass.
Seems to me that although a toroidal current pickup may not have the
same magnitude characteristics because of variations in the permeability,
the phase would suffer no such effects. Am I correct on that point?
I'm somewhat handicapped in having no current probes for my 100 MHz
Leader and acquiring them would put a big dent in my Social Security
check. :-)
What I am toying with is a 6m rhombic. I could run it as a terminated
traveling-wave antenna or unterminate it and have a standing-wave
antenna. I could move all kinds of coil(s) up and down the the elements
to place them at nodes or loops or in-between and take measurements.
What do you think?
--
73, Cecil http://www.qsl.net/w5dxp